Science.gov

Sample records for ground-truth infrasound source

  1. Analysis of Signals from an Unique Ground-Truth Infrasound Source Observed at IMS Station IS26 in Southern Germany

    NASA Astrophysics Data System (ADS)

    Koch, Karl

    2010-05-01

    Quantitative modeling of infrasound signals and development and verification of the corresponding atmospheric propagation models requires the use of well-calibrated sources. Numerous sources have been detected by the currently installed network of about 40 of the final 60 IMS infrasound stations. Besides non-nuclear explosions such as mining and quarry blasts and atmospheric phenomena like auroras, these sources include meteorites, volcanic eruptions and supersonic aircraft including re-entering spacecraft and rocket launches. All these sources of infrasound have one feature in common, in that their source parameters are not precisely known and the quantitative interpretation of the corresponding signals is therefore somewhat ambiguous. A source considered well-calibrated has been identified producing repeated infrasound signals at the IMS infrasound station IS26 in the Bavarian forest. The source results from propulsion tests of the ARIANE-5 rocket's main engine at a testing facility near Heilbronn, southern Germany. The test facility is at a range of 320 km and a backazimuth of ~280° from IS26. Ground-truth information was obtained for nearly 100 tests conducted in a 5-year period. Review of the available data for IS26 revealed that at least 28 of these tests show signals above the background noise level. These signals are verified based on the consistency of various signal parameters, e.g., arrival times, durations, and estimates of propagation characteristics (backazimuth, apparent velocity). Signal levels observed are a factor of 2-8 above the noise and reach values of up to 250 mPa for peak amplitudes, and a factor of 2-3 less for RMS measurements. Furthermore, only tests conducted during the months from October to April produce observable signals, indicating a significant change in infrasound propagation conditions between summer and winter months.

  2. Generating regional infrasound celerity-range models using ground-truth information and the implications for event location

    NASA Astrophysics Data System (ADS)

    Nippress, Alexandra; Green, David N.; Marcillo, Omar E.; Arrowsmith, Stephen J.

    2014-05-01

    Celerity-range models, where celerity is defined as the epicentral distance divided by the total traveltime (similar to the definition of group velocity for dispersed seismic surface waves), can be used for the association of infrasound automatic detections, for event location and for the validation of acoustic propagation simulations. Signals recorded from ground truth events are used to establish celerity-range models, but data coverage is uneven in both space and time. To achieve a high density of regional recordings we use data from USArray seismic stations recording air-to-ground coupled waves from explosions during the summers of 2004-2008 at the Utah Training and Test Range, in the western United States, together with data from five microbarograph arrays at regional distances (<1000 km). We have developed a consistent methodology for analysing the infrasound and seismic data, including choosing filter characteristics from a limited group of two-octave wide filter bands and picking the maximum peak-to-peak arrival. We clearly observe tropospheric, thermospheric and stratospheric arrivals, in agreement with regional ray tracing models. Due to data availability and the dependence of infrasound propagation on the season, we develop three regional celerity-range models for the U.S. summer, with a total of 2211 data picks. The new models suggest event locations using the Geiger method could be improved in terms of both accuracy (up to 80 per cent closer to ground truth) and precision (error ellipse area reduced by >90 per cent) when compared to those estimated using the global International Data Center model, particularly for events where stations detect arrivals at ranges <350 km. Whilst adding data-based prior information into the Bayesian Infrasound Source Localization (BISL) method is also shown to increase precision, to increase accuracy, the parameter space must be expanded to include station-specific celerity distributions.

  3. Southwest U.S. Seismo-Acoustic Network: An Autonomous Data Aggregation, Detection, Localization and Ground-Truth Bulletin for the Infrasound Community

    NASA Astrophysics Data System (ADS)

    Jones, K. R.; Arrowsmith, S.

    2013-12-01

    The Southwest U.S. Seismo-Acoustic Network (SUSSAN) is a collaborative project designed to produce infrasound event detection bulletins for the infrasound community for research purposes. We are aggregating a large, unique, near real-time data set with available ground truth information from seismo-acoustic arrays across New Mexico, Utah, Nevada, California, Texas and Hawaii. The data are processed in near real-time (~ every 20 minutes) with detections being made on individual arrays and locations determined for networks of arrays. The detection and location data are then combined with any available ground truth information and compiled into a bulletin that will be released to the general public directly and eventually through the IRIS infrasound event bulletin. We use the open source Earthworm seismic data aggregation software to acquire waveform data either directly from the station operator or via the Incorporated Research Institutions for Seismology Data Management Center (IRIS DMC), if available. The data are processed using InfraMonitor, a powerful infrasound event detection and localization software program developed by Stephen Arrowsmith at Los Alamos National Laboratory (LANL). Our goal with this program is to provide the infrasound community with an event database that can be used collaboratively to study various natural and man-made sources. We encourage participation in this program directly or by making infrasound array data available through the IRIS DMC or other means. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. R&A 5317326

  4. Infrasound Generation from the Source Physics Experiments

    NASA Astrophysics Data System (ADS)

    Preston, L. A.; Schramm, K. A.; Jones, K. R.

    2015-12-01

    Understanding the acoustic and infrasound source generation mechanisms from underground explosions is of great importance for usage of this unique data type in non-proliferation activities. One of the purposes of the Source Physics Experiments (SPE), a series of underground explosive shots at the Nevada National Security Site (NNSS), is to gain an improved understanding of the generation and propagation of physical signals, such as seismic and infrasound, from the near to far field. Two of the SPE shots (SPE-1 and SPE-4') were designed to be small "Green's Function" sources with minimal spall or permanent surface deformation. We analyze infrasound data collected from these two shots at distances from ~300 m to ~1 km and frequencies up to 20 Hz. Using weather models based upon actual observations at the times of these sources, including 3-D variations in topography, temperatures, pressures, and winds, we synthesized full waveforms using Sandia's moving media acoustic propagation simulation suite. Several source mechanisms were simulated and compared and contrasted with observed waveforms using full waveform source inversion. We will discuss results of these source inversions including the relative roll of spall from these small explosions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  5. Snowpack ground-truth manual

    NASA Technical Reports Server (NTRS)

    Jones, E. B.

    1983-01-01

    As remote sensing increasingly becomes more of an operational tool in the field of snow management and snow hydrology, there is need for some degree of standardization of ""snowpack ground truth'' techniques. This manual provides a first step in standardizing these procedures and was prepared to meet the needs of remote sensing researchers in planning missions requiring ground truth as well as those providing the ground truth. Focus is on ground truth for remote sensors primarily operating in the microwave portion of the electromagnetic spectrum; nevertheless, the manual should be of value to other types of sensor programs. This first edition of ground truth procedures must be updated as new or modified techniques are developed.

  6. Ground-truth measurement systems

    NASA Technical Reports Server (NTRS)

    Serafin, R.; Seliga, T. A.; Lhermitte, R. M.; Nystuen, J. A.; Cherry, S.; Bringi, V. N.; Blackmer, R.; Heymsfield, G. M.

    1981-01-01

    Ground-truth measurements of precipitation and related weather events are an essential component of any satellite system designed for monitoring rainfall from space. Such measurements are required for testing, evaluation, and operations; they provide detailed information on the actual weather events, which can then be compared with satellite observations intended to provide both quantitative and qualitative information about them. Also, very comprehensive ground-truth observations should lead to a better understanding of precipitation fields and their relationships to satellite data. This process serves two very important functions: (a) aiding in the development and interpretation of schemes of analyzing satellite data, and (b) providing a continuing method for verifying satellite measurements.

  7. Infrasound Monitoring of the Volcanic Activities of Japanese Volcanoes in Korea

    NASA Astrophysics Data System (ADS)

    Lee, H. I.; Che, I. Y.; Shin, J. S.

    2015-12-01

    Since 1999 when our first infrasound array station(CHNAR) has been installed at Cheolwon, Korea Institute of Geoscience and Mineral Resources(KIGAM) is continuously observing infrasound signals with an infrasound array network, named KIN(Korean Infrasound Network). This network is comprised of eight seismo-acoustic array stations(BRDAR, YPDAR, KMPAR, CHNAR, YAGAR, KSGAR, ULDAR, TJIAR). The aperture size of the smallest array is 300m and the largest is about 1.4km. The number of infrasound sensors are between 4(TJIAR) and 18(YAGAR), and 1~5 seismometers are collocated with infrasound sensors. Many interesting infrasound signals associated with different type of sources, such as blasting, large earthquake, bolide, volcanic explosion are detected by KIN in the past 15 years. We have analyzed the infrasound signals possibly associated with the japanese volcanic explosions with reference to volcanic activity report published by Japanese Meteorological Agency. Analysis results of many events, for example, Asama volcano explosion in 2004 and Shinmoe volcano in 2011, are well matched with the official report. In some cases, however, corresponding infrasound signals are not identified. By comparison of the infrasound signals from different volcanoes, we also found that the characteristics of signals are distinguishing. It may imply that the specific volcano has its own unique fingerprint in terms of infrasound signal. It might be investigated by long-term infrasound monitoring for a specific volcano as a ground truth generating repetitive infrasound signal.

  8. Development of mine explosion ground truth smart sensors

    SciTech Connect

    Taylor, Steven R.; Harben, Phillip E.; Jarpe, Steve; Harris, David B.

    2015-09-14

    Accurate seismo-acoustic source location is one of the fundamental aspects of nuclear explosion monitoring. Critical to improved location is the compilation of ground truth data sets for which origin time and location are accurately known. Substantial effort by the National Laboratories and other seismic monitoring groups have been undertaken to acquire and develop ground truth catalogs that form the basis of location efforts (e.g. Sweeney, 1998; Bergmann et al., 2009; Waldhauser and Richards, 2004). In particular, more GT1 (Ground Truth 1 km) events are required to improve three-dimensional velocity models that are currently under development. Mine seismicity can form the basis of accurate ground truth datasets. Although the location of mining explosions can often be accurately determined using array methods (e.g. Harris, 1991) and from overhead observations (e.g. MacCarthy et al., 2008), accurate origin time estimation can be difficult. Occasionally, mine operators will share shot time, location, explosion size and even shot configuration, but this is rarely done, especially in foreign countries. Additionally, shot times provided by mine operators are often inaccurate. An inexpensive, ground truth event detector that could be mailed to a contact, placed in close proximity (< 5 km) to mining regions or earthquake aftershock regions that automatically transmits back ground-truth parameters, would greatly aid in development of ground truth datasets that could be used to improve nuclear explosion monitoring capabilities. We are developing an inexpensive, compact, lightweight smart sensor unit (or units) that could be used in the development of ground truth datasets for the purpose of improving nuclear explosion monitoring capabilities. The units must be easy to deploy, be able to operate autonomously for a significant period of time (> 6 months) and inexpensive enough to be discarded after useful operations have expired (although this may not be part of our business

  9. GT0 Explosion Sources for IMS Infrasound Calibration: Charge Design and Yield Estimation from Near-source Observations

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Hofstetter, R.

    2014-03-01

    Three large-scale on-surface explosions were conducted by the Geophysical Institute of Israel (GII) at the Sayarim Military Range, Negev desert, Israel: about 82 tons of strong high explosives in August 2009, and two explosions of about 10 and 100 tons of ANFO explosives in January 2011. It was a collaborative effort between Israel, CTBTO, USA and several European countries, with the main goal to provide fully controlled ground truth (GT0) infrasound sources, monitored by extensive observations, for calibration of International Monitoring System (IMS) infrasound stations in Europe, Middle East and Asia. In all shots, the explosives were assembled like a pyramid/hemisphere on dry desert alluvium, with a complicated explosion design, different from the ideal homogenous hemisphere used in similar experiments in the past. Strong boosters and an upward charge detonation scheme were applied to provide more energy radiated to the atmosphere. Under these conditions the evaluation of the actual explosion yield, an important source parameter, is crucial for the GT0 calibration experiment. Audio-visual, air-shock and acoustic records were utilized for interpretation of observed unique blast effects, and for determination of blast wave parameters suited for yield estimation and the associated relationships. High-pressure gauges were deployed at 100-600 m to record air-blast properties, evaluate the efficiency of the charge design and energy generation, and provide a reliable estimation of the charge yield. The yield estimators, based on empirical scaled relations for well-known basic air-blast parameters—the peak pressure, impulse and positive phase duration, as well as on the crater dimensions and seismic magnitudes, were analyzed. A novel empirical scaled relationship for the little-known secondary shock delay was developed, consistent for broad ranges of ANFO charges and distances, which facilitates using this stable and reliable air-blast parameter as a new potential

  10. West Texas array experiment: Noise and source characterization of short-range infrasound and acoustic signals, along with lab and field evaluation of Intermountain Laboratories infrasound microphones

    NASA Astrophysics Data System (ADS)

    Fisher, Aileen

    spatial wind noise filtering hoses or pipes. The grid was within the distance limits of a single gauge's normal hose array, and data were used to perform a spatial noise correlation study. The highest correlation values were not found in the lower frequencies as anticipated, owing to a lack of sources in the lower range and the uncorrelated nature of wind noise. The highest values, with cross-correlation averages between 0.4 and 0.7 from 3 to 17 m between gauges, were found at night from 10 and 20 Hz due to a continuous local noise source and low wind. Data from the larger array were used to identify continuous and impulsive signals in the area that comprise the ambient noise field. Ground truth infrasound and acoustic, time and location data were taken for a highway site, a wind farm, and a natural gas compressor. Close-range sound data were taken with a single IML "traveler" gauge. Spectrograms and spectrum peaks were used to identify their source signatures. Two regional location techniques were also tested with data from the large array by using a propane cannon as a controlled, impulsive source. A comparison is presented of the Multiple Signal Classification Algorithm (MUSIC) to a simple, quadratic, circular wavefront algorithm. MUSIC was unable to effectively separate noise and source eignenvalues and eigenvectors due to spatial aliasing of the propane cannon signal and a lack of incoherent noise. Only 33 out of 80 usable shots were located by MUSIC within 100 m. Future work with the algorithm should focus on location of impulsive and continuous signals with development of methods for accurate separation of signal and noise eigenvectors in the presence of coherent noise and possible spatial aliasing. The circular wavefront algorithm performed better with our specific dataset and successfully located 70 out of 80 propane cannon shots within 100 m of the original location, 66 of which were within 20 m. This method has low computation requirements, making it well

  11. Improved Bayesian Infrasonic Source Localization for regional infrasound

    DOE PAGES

    Blom, Philip S.; Marcillo, Omar; Arrowsmith, Stephen J.

    2015-10-20

    The Bayesian Infrasonic Source Localization (BISL) methodology is examined and simplified providing a generalized method of estimating the source location and time for an infrasonic event and the mathematical framework is used therein. The likelihood function describing an infrasonic detection used in BISL has been redefined to include the von Mises distribution developed in directional statistics and propagation-based, physically derived celerity-range and azimuth deviation models. Frameworks for constructing propagation-based celerity-range and azimuth deviation statistics are presented to demonstrate how stochastic propagation modelling methods can be used to improve the precision and accuracy of the posterior probability density function describing themore » source localization. Infrasonic signals recorded at a number of arrays in the western United States produced by rocket motor detonations at the Utah Test and Training Range are used to demonstrate the application of the new mathematical framework and to quantify the improvement obtained by using the stochastic propagation modelling methods. Moreover, using propagation-based priors, the spatial and temporal confidence bounds of the source decreased by more than 40 per cent in all cases and by as much as 80 per cent in one case. Further, the accuracy of the estimates remained high, keeping the ground truth within the 99 per cent confidence bounds for all cases.« less

  12. Improved Bayesian Infrasonic Source Localization for regional infrasound

    SciTech Connect

    Blom, Philip S.; Marcillo, Omar; Arrowsmith, Stephen J.

    2015-10-20

    The Bayesian Infrasonic Source Localization (BISL) methodology is examined and simplified providing a generalized method of estimating the source location and time for an infrasonic event and the mathematical framework is used therein. The likelihood function describing an infrasonic detection used in BISL has been redefined to include the von Mises distribution developed in directional statistics and propagation-based, physically derived celerity-range and azimuth deviation models. Frameworks for constructing propagation-based celerity-range and azimuth deviation statistics are presented to demonstrate how stochastic propagation modelling methods can be used to improve the precision and accuracy of the posterior probability density function describing the source localization. Infrasonic signals recorded at a number of arrays in the western United States produced by rocket motor detonations at the Utah Test and Training Range are used to demonstrate the application of the new mathematical framework and to quantify the improvement obtained by using the stochastic propagation modelling methods. Moreover, using propagation-based priors, the spatial and temporal confidence bounds of the source decreased by more than 40 per cent in all cases and by as much as 80 per cent in one case. Further, the accuracy of the estimates remained high, keeping the ground truth within the 99 per cent confidence bounds for all cases.

  13. Volcano Infrasound

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Fee, D.; Matoza, R. S.

    2013-12-01

    Open-vent volcanoes generate prodigious low frequency sound waves that tend to peak in the infrasound (<20 Hz) band. These long wavelength (> ~20 m) atmospheric pressure waves often propagate long distances with low intrinsic attenuation and can be well recorded with a variety of low frequency sensitive microphones. Infrasound records may be used to remotely monitor eruptions, identify active vents or track gravity-driven flows, and/or characterize source processes. Such studies provide information vital for both scientific study and volcano monitoring efforts. This presentation proposes to summarize and standardize some of the terminology used in the still young, yet rapidly growing field of volcano infrasound. Herein we suggest classification of typical infrasound waveform types, which include bimodal pulses, blast (or N-) waves, and a variety of infrasonic tremors (including broadband, harmonic, and monotonic signals). We summarize various metrics, including reduced pressure, intensity, power, and energy, in which infrasound excess pressures are often quantified. We also describe the spectrum of source types and radiation patterns, which are typically responsible for recorded infrasound. Finally we summarize the variety of propagation paths that are common for volcano infrasound radiating to local (<10 km), regional (out to several hundred kilometers), and global distances. The effort to establish common terminology requires community feedback, but is now timely as volcano infrasound studies proliferate and infrasound becomes a standard component of volcano monitoring.

  14. Relating ground truth collection to model sensitivity

    NASA Technical Reports Server (NTRS)

    Amar, Faouzi; Fung, Adrian K.; Karam, Mostafa A.; Mougin, Eric

    1993-01-01

    The importance of collecting high quality ground truth before a SAR mission over a forested area is two fold. First, the ground truth is used in the analysis and interpretation of the measured backscattering properties; second, it helps to justify the use of a scattering model to fit the measurements. Unfortunately, ground truth is often collected based on visual assessment of what is perceived to be important without regard to the mission itself. Sites are selected based on brief surveys of large areas, and the ground truth is collected by a process of selecting and grouping different scatterers. After the fact, it may turn out that some of the relevant parameters are missing. A three-layer canopy model based on the radiative transfer equations is used to determine, before hand, the relevant parameters to be collected. Detailed analysis of the contribution to scattering and attenuation of various forest components is carried out. The goal is to identify the forest parameters which most influence the backscattering as a function of frequency (P-, L-, and C-bands) and incident angle. The influence on backscattering and attenuation of branch diameters, lengths, angular distribution, and permittivity; trunk diameters, lengths, and permittivity; and needle sizes, their angular distribution, and permittivity are studied in order to maximize the efficiency of the ground truth collection efforts. Preliminary results indicate that while a scatterer may not contribute to the total backscattering, its contribution to attenuation may be significant depending on the frequency.

  15. The true false ground truths: What interest?

    NASA Astrophysics Data System (ADS)

    Chehdi, K.; Cariou, C.

    2016-10-01

    The existence of a few unreliable ground truth (GT) data sets which are often used as reference by the remote sensing community for the assessment and comparison of classification results is really problematic and poses a number of questions. Two of these ground truth data sets can be cited: "Pavia University" and "Indian Pine". A rigorous analysis of spectral signatures of pixels in these images shows that some classes which are considered as homogeneous from the ground truth are clearly not, since the pixels which belong to the same classes have different spectral signatures, and probably do not belong to the same category. The persistence in using data sets from a biased ground truth does not allow objective comparisons between classification methods and does not contribute to providing explanation of physical phenomena that images are supposed to reflect. In this communication, we present a fine and complete analysis of the spectral signatures of pixels within each class for the two ground truth data sets mentioned above. The metrics used show some incoherence and inaccuracy of these data which wrongly serve as references in several classification comparative studies.

  16. A repeating source of infrasound from the Wells, Nevada earthquake sequence

    SciTech Connect

    Arrowsmith, Stephen J.; Whitaker, Rod; Randall, George; Burlacu, Relu

    2009-01-01

    The Wells, Nevada earthquake of February 21, 2008, generated a complex seismoacoustic wakefield. In addition to epicentral infrasound, the earthquake triggered a secondary source of infrasound, which was also initiated by subsequent aftershocks. By applying simple constraints on the propagation of seismic and infrasound waves, we show that the secondary source is an isolated peak that appears to efficiently generate infrasound through the interaction with seismic surface waves. By measuring peak-to-peak amplitudes of epicentral and secondary arrivals and correcting them for the effects of distance and winds, we find that epicentral arrivals lit with empirical relationships of Mutschlecner and Whitaker (2005) and Le Pichon et al. (2006), which form the basis for a proposed infrasound discriminant (Anderson et al., Pers. Comm.). In contrast, the secondary arrivals are much higher in amplitude, highlighting the importance of being able to separate epicentral and secondary arrivals for infrasonic event discrimination.

  17. Seasonal variations of infrasonic arrivals from long term ground truth observations in Nevada and implication for event location

    NASA Astrophysics Data System (ADS)

    Negraru, Petru; Golden, Paul

    2017-01-01

    SUMMARYLong term <span class="hlt">ground</span> <span class="hlt">truth</span> observations were collected at two <span class="hlt">infrasound</span> arrays in Nevada to investigate how seasonal atmospheric variations affect the detection, travel time and signal characteristics (azimuth, trace velocity, frequency content and amplitudes) of infrasonic arrivals at regional distances. The arrays were located in different azimuthal directions from a munition disposal facility in Nevada. FNIAR, located 154 km north of the <span class="hlt">source</span> has a high detection rate throughout the year. Over 90% of the detonations have travel times indicative of stratospheric arrivals, while tropospheric waveguides are observed from only 27% of the detonations. The second array, DNIAR, located 293 km southeast of the <span class="hlt">source</span> exhibits strong seasonal variations with high stratospheric detection rates in winter and the virtual absence of stratospheric arrivals in summer. Tropospheric waveguides and thermospheric arrivals are also observed for DNIAR. Modelling through the Naval Research Laboratory Ground to Space (G2S) atmospheric sound speeds leads to mixed results: FNIAR arrivals are usually not predicted to be present at all (either stratospheric or tropospheric), while DNIAR arrivals are usually correctly predicted, but summer arrivals show a consistent travel time bias. In the end we show the possible improvement in location using empirically calibrated travel time and azimuth observations. Using the Bayesian <span class="hlt">Infrasound</span> <span class="hlt">Source</span> Localization we show that we can decrease the area enclosed by the 90% credibility contours by a factor of 2.5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA032401','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA032401"><span id="translatedtitle"><span class="hlt">Infrasound</span>, Its <span class="hlt">Sources</span> and Its Effects on Man</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1976-05-01</p> <p>that are harmful or even audible to man. Thus <span class="hlt">infrasound</span> exposure is not one of mankinds more press- ling environmental problems. g SECURITY...unwarranted conclusions <span class="hlt">infrasound</span> is not one of mankiuds more pressing about the effects of <span class="hlt">infrasound</span> on man. The environmental problems. upper frequency... health and welfare is via all those many factors above 20 Hz could be eliminated, 1 baiieve there that make up the annoyance response. Now it is would be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=earth+AND+warming&pg=6&id=ED396917','ERIC'); return false;" href="http://eric.ed.gov/?q=earth+AND+warming&pg=6&id=ED396917"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Studies. Teacher Handbook. Second Edition.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Boyce, Jesse; And Others</p> <p></p> <p><span class="hlt">Ground</span> <span class="hlt">Truth</span> Studies is an interdisciplinary activity-based program that draws on the broad range of sciences that make up the study of global change and the complementary technology of remote sensing. It integrates local environmental issues with global change topics, such as the greenhouse effect, loss of biological diversity, and ozone…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V23C4814K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4814K"><span id="translatedtitle"><span class="hlt">Source</span> Inversions of Volcano <span class="hlt">Infrasound</span>: Mass Outflux and Force System for Transient Explosive Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, K.; Fee, D.; Lees, J. M.; Yokoo, A.; Ruiz, M. C.</p> <p>2014-12-01</p> <p><span class="hlt">Sources</span> of volcano <span class="hlt">infrasound</span> associated with explosive eruptions are typically modeled assuming an acoustic monopole and/or dipole. While the monopole represents the mass outflux of erupted materials, the dipole represents a force system acting in the <span class="hlt">source</span> region during eruptions. Therefore, appropriate acoustic <span class="hlt">source</span> inversions of volcano <span class="hlt">infrasound</span> data can provide estimates of eruption parameters which are critical to understanding eruption dynamics. Reliability of the <span class="hlt">source</span> parameters is dominantly controlled by the accuracy of the acoustic Green's functions between the <span class="hlt">source</span> and receiver positions. Conventional <span class="hlt">source</span> inversions of volcano <span class="hlt">infrasound</span>, however, were typically performed using a simplified Green's function obtained in a free space or half space. This may result in intolerable errors in the <span class="hlt">source</span> parameters, especially when the <span class="hlt">infrasound</span> waveforms are significantly distorted by volcano topography and/or local atmospheric variability (i.e., layered velocity structure or wind). In this study we present a full waveform inversion technique for volcano <span class="hlt">infrasound</span> using numerical Green's functions. A full 3-D Finite-Difference Time-Domain (FDTD) method accelerated with GPU is used to compute accurate Green's functions taking into account volcano topography and local atmospheric conditions. The presented method is applied to data recorded at Sakurajima volcano (Japan) and Tungurahua volcano (Ecuador), which provide a large volume of high-quality data recorded by azimuthally well-distributed stations within 2 -- 6 km distance of the volcanoes. We analyze <span class="hlt">infrasound</span> signals associated with explosive eruptions exhibiting 1) distinct explosion waveforms followed by gas discharges and 2) strong anisotropic radiation patterns, which can be caused by either <span class="hlt">source</span> directivity or topographic barriers/reflections. Here the role of topography in controlling the <span class="hlt">infrasound</span> radiation is investigated through numerical modeling, and then the observed</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active"><span>1</span></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_1 --> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050192154','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050192154"><span id="translatedtitle">NASA <span class="hlt">Ground-Truthing</span> Capabilities Demonstrated</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lopez, Isaac; Seibert, Marc A.</p> <p>2004-01-01</p> <p>NASA Research and Education Network (NREN) <span class="hlt">ground</span> <span class="hlt">truthing</span> is a method of verifying the scientific validity of satellite images and clarifying irregularities in the imagery. <span class="hlt">Ground-truthed</span> imagery can be used to locate geological compositions of interest for a given area. On Mars, astronaut scientists could <span class="hlt">ground</span> <span class="hlt">truth</span> satellite imagery from the planet surface and then pinpoint optimum areas to explore. These astronauts would be able to <span class="hlt">ground</span> <span class="hlt">truth</span> imagery, get results back, and use the results during extravehicular activity without returning to Earth to process the data from the mission. NASA's first <span class="hlt">ground-truthing</span> experiment, performed on June 25 in the Utah desert, demonstrated the ability to extend powerful computing resources to remote locations. Designed by Dr. Richard Beck of the Department of Geography at the University of Cincinnati, who is serving as the lead field scientist, and assisted by Dr. Robert Vincent of Bowling Green State University, the demonstration also involved researchers from the NASA Glenn Research Center and the NASA Ames Research Center, who worked with the university field scientists to design, perform, and analyze results of the experiment. As shown real-time Hyperion satellite imagery (data) is sent to a mass storage facility, while scientists at a remote (Utah) site upload ground spectra (data) to a second mass storage facility. The grid pulls data from both mass storage facilities and performs up to 64 simultaneous band ratio conversions on the data. Moments later, the results from the grid are accessed by local scientists and sent directly to the remote science team. The results are used by the remote science team to locate and explore new critical compositions of interest. The process can be repeated as required to continue to validate the data set or to converge on alternate geophysical areas of interest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760016577','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760016577"><span id="translatedtitle">GEOS-3 phase B <span class="hlt">ground</span> <span class="hlt">truth</span> summary</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parsons, C. L.; Goodman, L. R.</p> <p>1975-01-01</p> <p><span class="hlt">Ground</span> <span class="hlt">truth</span> data collected during the experiment systems calibration and evaluation phase of the Geodynamics experimental Ocean Satellite (GEOS-3) experiment are summarized. Both National Weather Service analyses and aircraft sensor data are included. The data are structured to facilitate the use of the various data products in calibrating the GEOS-3 radar altimeter and in assessing the altimeter's sensitivity to geophysical phenomena. Brief statements are made concerning the quality and completeness of the included data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10170417','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10170417"><span id="translatedtitle">Fiber-optic <span class="hlt">ground-truth</span> thermometer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ekdahl, C.A. Jr.; Forman, P.; Veeser, L.</p> <p>1993-07-01</p> <p>By making a high accuracy measurement of the optical length of a long fiber optic cable, the authors can determine the absolute temperature averaged over its length and the temperature of a material in contact with it. They describe how to set up such a measurement and use it to determine the average temperature of the surface of the earth over a large enough area to be useful as a <span class="hlt">ground</span> <span class="hlt">truth</span> calibration for a satellite imaging system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1113634V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1113634V"><span id="translatedtitle">An operational approach for <span class="hlt">infrasound</span> multi-array processing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vergoz, J.; Le Pichon, A.; Herry, P.; Blanc, E.</p> <p>2009-04-01</p> <p>The <span class="hlt">infrasound</span> network of the International Monitoring Network (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) is currently not fully established. However, it has demonstrated its capability for detecting and locating infrasonic <span class="hlt">sources</span> like meteorites as well as volcanic eruptions on a global scale. Unfortunately, such <span class="hlt">ground</span> <span class="hlt">truth</span> events are rare. Therefore, regions with dense <span class="hlt">infrasound</span> networks have to be considered in order to test and calibrate detection and location procedures (Le Pichon. et al. 2008, J. Geophys. Res., 113, D12115, doi:10.1029/2007JD009509). In Central Europe, several years of continuous <span class="hlt">infrasound</span> recordings are available for many <span class="hlt">infrasound</span> arrays, where not all of them are part of the IMS. <span class="hlt">Infrasound</span> waveforms are routinely processed in the 0.1 to 4 Hz frequency band using PMCC as a real-time detector. After applying a categorization procedure to remove detections associated with environmental noise, a blind fusion provides a list of events to be reviewed by the analyst. In order to check the geophysical consistency of the located events, an interactive tool has been developed. All results of the automatic processing are presented along with a realistic estimate of the network detection capability which incorporates near-real time atmospheric updates. Among the dominant acoustic <span class="hlt">sources</span> of human origin, peaks in the geographical distribution of <span class="hlt">infrasound</span> events correspond well with seismically active regions where operational mines have been identified. With the increasing number of IMS and regional cluster <span class="hlt">infrasound</span> arrays deployed around the globe, conducting consistent analyses on a routine-basis provides an extensive database for discriminating between natural and artificial acoustic <span class="hlt">sources</span>. Continuing such studies may also help quantifying relationships between infrasonic observables and atmospheric specification problems, thus opening new fields for investigations into inverse problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830017890','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830017890"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Sampling and LANDSAT Accuracy Assessment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robinson, J. W.; Gunther, F. J.; Campbell, W. J.</p> <p>1982-01-01</p> <p>It is noted that the key factor in any accuracy assessment of remote sensing data is the method used for determining the <span class="hlt">ground</span> <span class="hlt">truth</span>, independent of the remote sensing data itself. The sampling and accuracy procedures developed for nuclear power plant siting study are described. The purpose of the sampling procedure was to provide data for developing supervised classifications for two study sites and for assessing the accuracy of that and the other procedures used. The purpose of the accuracy assessment was to allow the comparison of the cost and accuracy of various classification procedures as applied to various data types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210773B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210773B"><span id="translatedtitle">Monitoring the Earth's Atmosphere with the Global IMS <span class="hlt">Infrasound</span> Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brachet, Nicolas; Brown, David; Mialle, Pierrick; Le Bras, Ronan; Coyne, John; Given, Jeffrey</p> <p>2010-05-01</p> <p>, they represent valuable data for other civil applications like monitoring of natural hazards (volcanic activity, storm tracking) and climate change. Non-noise detections are used in network processing at the IDC along with seismic and hydroacoustic technologies. The arrival phases detected on the three waveform technologies may be combined and used for locating events in an automatically generated bulletin of events. This automatic event bulletin is routinely reviewed by analysts during the interactive review process. However, the fusion of <span class="hlt">infrasound</span> data with the other waveform technologies has only recently (in early 2010) become part of the IDC operational system, after a software development and testing period that began in 2004. The build-up of the IMS <span class="hlt">infrasound</span> network, the recent developments of the IDC <span class="hlt">infrasound</span> software, and the progress accomplished during the last decade in the domain of real-time atmospheric modelling have allowed better understanding of <span class="hlt">infrasound</span> signals and identification of a growing data set of <span class="hlt">ground-truth</span> <span class="hlt">sources</span>. These infragenic <span class="hlt">sources</span> originate from natural or man-made <span class="hlt">sources</span>. Some of the detected signals are emitted by local or regional phenomena recorded by a single IMS <span class="hlt">infrasound</span> station: man-made cultural activity, wind farms, aircraft, artillery exercises, ocean surf, thunderstorms, rumbling volcanoes, iceberg calving, aurora, avalanches. Other signals may be recorded by several IMS <span class="hlt">infrasound</span> stations at larger distances: ocean swell, sonic booms, and mountain associated waves. Only a small fraction of events meet the event definition criteria considering the Treaty verification mission of the Organization. Candidate event types for the IDC Reviewed Event Bulletin include atmospheric or surface explosions, meteor explosions, rocket launches, signals from large earthquakes and explosive volcanic eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRB..11512329W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRB..11512329W"><span id="translatedtitle"><span class="hlt">Source</span> location of the 19 February 2008 Oregon bolide using seismic networks and <span class="hlt">infrasound</span> arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, Kristoffer T.; Hedlin, Michael A. H.; de Groot-Hedlin, Catherine; Vergoz, Julien; Le Pichon, Alexis; Drob, Douglas P.</p> <p>2010-12-01</p> <p>On 19 February 2008 a bolide traveled across the sky along a southern trajectory ending in a terminal burst above Oregon. The event was well recorded by the USArray, other seismic networks, four <span class="hlt">infrasound</span> arrays, and several video cameras. We compare the results of locating the burst using these different sensor networks. Specifically, we reverse time migrate acoustic-to-seismic coupled signals recorded by the USArray out to 800 km range to image the <span class="hlt">source</span> in 2-D space and time. We also apply a grid search over <span class="hlt">source</span> altitude and time, minimizing the misfit between observed and predicted arrival times using 3-D ray tracing with a high-resolution atmospheric velocity model. Our seismic and video results suggest a point <span class="hlt">source</span> rather than a line <span class="hlt">source</span> associated with a hypersonic trajectory. We compare the seismic <span class="hlt">source</span> locations to those obtained by using different combinations of observed <span class="hlt">infrasound</span> array signal back azimuths and arrival times. We find that all locations are consistent. However, the seismic location is more accurate than the <span class="hlt">infrasound</span> locations due to the larger number of seismic sensors, a more favorable seismic <span class="hlt">source</span>-receiver geometry, and shorter ranges to the seismometers. For the <span class="hlt">infrasound</span> array locations, correcting for the wind improved the accuracy, but implementing arrival times while increasing the precision reduced the accuracy presumably due to limitations of the <span class="hlt">source</span> location method and/or atmospheric velocity model. We show that despite known complexities associated with acoustic-to-seismic coupling, aboveground <span class="hlt">infrasound</span> <span class="hlt">sources</span> can be located with dense seismic networks with remarkably high accuracy and precision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900043101&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900043101&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> observations for TRMM. [Tropical Rainfall Measuring Mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thiele, Otto W.</p> <p>1989-01-01</p> <p>Plans to obtain <span class="hlt">ground</span> <span class="hlt">truth</span> data for the validation of the Tropical Rainfall Measuring Mission (TRMM) are examined. The experimental rainfall measuring techniques considered for the program are discussed, including optical and Doppler rain gages, satellite beacon attenuation, underwater hydrophones, profilers, microwave attenuation, multiple frequency/polarization radar, and scanning and airborne Doppler radar. The TRMM validation program is considered, noting observations to compare averaged TRMM rainfall data with similar <span class="hlt">ground</span> <span class="hlt">truth</span> data and to compare the rainfall and height distribution data from TRMM with instantaneous <span class="hlt">ground</span> <span class="hlt">truth</span> data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/908043','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/908043"><span id="translatedtitle">Magnetic <span class="hlt">infrasound</span> sensor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Mueller, Fred M.; Bronisz, Lawrence; Grube, Holger; Nelson, David C.; Mace, Jonathan L.</p> <p>2006-11-14</p> <p>A magnetic <span class="hlt">infrasound</span> sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic <span class="hlt">infrasound</span> sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. <span class="hlt">Infrasound</span> <span class="hlt">sources</span> can be located and characterized by combining the measurements from one or more <span class="hlt">infrasound</span> sensors. The magnetic <span class="hlt">infrasound</span> sensor can be tuned to match <span class="hlt">infrasound</span> <span class="hlt">source</span> types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070017979&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070017979&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtruth"><span id="translatedtitle">Remote and <span class="hlt">Ground</span> <span class="hlt">Truth</span> Spectral Measurement Comparisons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abercromby, Kira Jorgensen; Hamada, Kris; Guyote, Michael; Okada, Jennifer; Barker, Edwin</p> <p>2007-01-01</p> <p>FORMOSAT III are a set of six research satellites from Taiwan that were launched in April 2006. The satellites are in 800 km, 71 degree inclination orbits and separated by 24 degrees in ascending node. <span class="hlt">Ground</span> <span class="hlt">truth</span> spectral measurements were taken of outer surface materials on FORMOSAT III. From those measurements, a computer model was built to predict the spectral reflectance, which included phase angle and orientation of the spacecraft relative to the observer. However, materials exposed to the space environment have exhibited spectral changes including a darkening and a reddening of the spectra. This reddening was seen as an increase in slope of the reflectance as the wavelength increases. Therefore, the model of pristine materials was augmented to include the space weathering effects. Remote data were collected on two of the six FORMOSAT satellites using the 1.6 meter telescope at AMOS (Air Force Maui Optical and Supercomputing) site with the Spica spectrometer. Due to the separation in ascending node, observations were made on whichever one of the six satellites was visible on that specific night. Three nights of data were collected using the red (6000 9500 angstroms) filter and two nights of data were collected using the blue (3200 -6600 angstroms) filter. A comparison of the data showed a good match to the pristine model for the blue filter region. The absorption feature near 5500 angstroms due to the copper colored Kapton multi-layer insulation (MLI) was very apparent in the remote samples and a good fit to the data was seen in both satellites observed. The features in the red filter regime agreed with the pristine model up through 7000 angstroms where the reddening begins and the slope of the remote sample increases. A comparison of the two satellites showed similar features in the red and blue filter regions, i.e. the satellites were aging at the same rate. A comparison of the pristine model to the first month of remote measurements showed the amount by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S13E..06L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S13E..06L"><span id="translatedtitle">Assessing the detection capability of the global IMS <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Vergoz, J.; Brachet, N.; Ceranna, L.; Green, D.; Evers, L.</p> <p>2008-12-01</p> <p>A global scale analysis based on available detection lists for all operating IMS <span class="hlt">infrasound</span> stations confirms that the primary factor controlling signal detectability is the seasonal variability of the stratospheric wind circulation. At most arrays, near %80 of the detections in the 0.2 to 2 Hz bandpass are associated with propagation downwind of the dominant wind direction. The seasonal transition in the bearings and number of detections between easterly and westerly directions is presented. The observed detection capability of the IMS network is compared to the predicted one using near-real time atmospheric updates and station- dependent wind noise models. The influence of individual model parameters on the network performance is systematically assessed. At frequencies of interest for detecting atmospheric explosions (0.2 to 2 Hz), the simulations predict that explosions equivalent to ~500 t of TNT would be detected by at least two stations of the full IMS network at any time of the year. Comprehensive <span class="hlt">ground-truth</span> databases provide a statistical approach for evaluating the potential of <span class="hlt">infrasound</span> monitoring. Accidental explosions are analysed and used here as benchmark for validating the calculated threshold maps. Such studies would help to optimize the siting of <span class="hlt">infrasound</span> arrays with respect to both the number and configuration in order to monitor infrasonic <span class="hlt">sources</span> of interest. They are an important step to enable a successful monitoring regime for atmospheric or surface events to act as an effective verification tool in any future enforcement of the CTBT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770018661','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770018661"><span id="translatedtitle">Snowpack <span class="hlt">ground</span> <span class="hlt">truth</span> Donner Pass site, Soda Springs, California</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.</p> <p>1977-01-01</p> <p><span class="hlt">Ground</span> <span class="hlt">truth</span> data taken near Soda Springs, California, on January 18, 1977, in support of the NASA Airborne Instrumentation Research Program are presented. <span class="hlt">Ground</span> <span class="hlt">truth</span> data taken in support of this mission were as follows: (1) snow depths were taken every 400 feet; (2) snow densities were taken every 1,200 feet; (3) two snowpits were dug, and limited density, vertical layer classifications, and soil observations were taken; and (4) temperatures of the upper 6 inches of the snowpack were taken at one location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA570079','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA570079"><span id="translatedtitle"><span class="hlt">Infrasound</span> Observations from the <span class="hlt">Source</span> Physics Experiment (Tests 1 and 2) at the Nevada National Security Site</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-09-01</p> <p><span class="hlt">INFRASOUND</span> OBSERVATIONS FROM THE <span class="hlt">SOURCE</span> PHYSICS EXPERIMENT ( TESTS 1 AND 2) AT THE NEVADA NATIONAL SECURITY SITE Kyle R. Jones1, Rod W. Whitaker2...series of explosions, we have the unique and rare opportunity to study <span class="hlt">infrasound</span> generated by a well-characterized <span class="hlt">source</span> from the same borehole ...two explosive tests (SPE-N-1 and SPE-N-2) were successfully conducted on May 3 and October 25, 2011, respectively. SPE-N-1 had a yield of 0.1 tons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S41B4486M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S41B4486M"><span id="translatedtitle">IDC <span class="hlt">Infrasound</span> technology development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mialle, P.; Brown, D. J.; Le Bras, R.; Charbit, M. J. C.; Given, J. W.</p> <p>2014-12-01</p> <p>The first atmospheric event built only from <span class="hlt">infrasound</span> arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 48 <span class="hlt">infrasound</span> stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The <span class="hlt">infrasound</span> component of the IMS daily registers infragenic signals originating from various <span class="hlt">sources</span> such as volcanic eruptions, earthquakes, microbaroms, meteorites entering the atmosphere and accidental explosions. The IDC routinely and automatically processes <span class="hlt">infrasound</span> data reviewed by interactive analysis; the detected and located events are then included in the IDC products. The IDC advances its methods and continuously improves its automatic system for the <span class="hlt">infrasound</span> technology. The IDC focuses on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria. An objective of this study is to reduce the number of associated <span class="hlt">infrasound</span> arrivals that are rejected from the automatic bulletins when generating the reviewed event bulletins. A number of ongoing projects at the IDC will be presented, such as: - improving the detection accuracy at the station processing stage by enhancing the <span class="hlt">infrasound</span> signal detector DFX-PMCC (Detection and Feature eXtraction - Progressive Multi-Channel Correlation) and by evaluating the performances of detection software. - separating <span class="hlt">infrasound</span> data from other waveform technologies at the automatic network processing stage for technology development and for preparing the implementation of next generation of waveform association algorithm. <span class="hlt">Infrasound</span> rules in Global Association (GA) are revisited to pursue a lower ratio of false alarms. - determining station noise for IMS <span class="hlt">infrasound</span>, seismic and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoJI.196..375M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoJI.196..375M"><span id="translatedtitle">Using physics-based priors in a Bayesian algorithm to enhance <span class="hlt">infrasound</span> <span class="hlt">source</span> location</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcillo, Omar; Arrowsmith, Stephen; Whitaker, Rod; Anderson, Dale; Nippress, Alexandra; Green, David N.; Drob, Douglas</p> <p>2014-01-01</p> <p>We show improvements in the precision of the Bayesian <span class="hlt">infrasound</span> <span class="hlt">source</span> localization (BISL) method by incorporating semi-empirical model-based prior information. Given a set of backazimuths and delay times at ≥2 arrays, BISL scans a parameter space (that comprises the horizontal coordinates, celerity and origin time) for the most likely solution. A key element of BISL is its flexibility; the method allows the incorporation of prior information to constrain the parameters. Our research focuses on generating model-based propagation catalogues using a comprehensive set of atmospheric scenarios, extracting celerity distributions based on range and azimuth from the catalogues and using these distributions as prior probability density functions to enhance the location solution from BISL. To illustrate the improvements in <span class="hlt">source</span> location precision, we compare the BISL results computed using uniform celerity distribution priors with those using enhanced priors; as applied to: (1) a set of events recorded across a regional network and (2) a large accidental chemical explosion recorded by six <span class="hlt">infrasound</span> arrays in Eurasia. Finally, we discuss efforts to improve the numerical implementation of BISL by expanding the parameter space to cover a richer set of parameters that can include station-specific celerity distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S31B1722G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S31B1722G"><span id="translatedtitle"><span class="hlt">Infrasound</span> Calibration Experiment at Sayarim, Israel: preliminary tests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gitterman, Y.; Hofstetter, A.; Garces, M.; Bowman, J. R.; Fee, D.; Israelsson, H.</p> <p>2009-12-01</p> <p>We are establishing a <span class="hlt">Ground</span> <span class="hlt">Truth</span> (GT0) <span class="hlt">infrasound</span> dataset for Middle East/Mediterranean region, through conducting a series of surface explosions at Sayarim Military Range (SMR), Negev desert, which culminated with an 82-ton explosion in August 2009. The dataset will be used to characterize the infrasonic propagation in the region, depending on <span class="hlt">source</span> features and atmosphere conditions, and thus to improve monitoring capabilities of International Monitoring System (IMS). Test explosions of broad yield range and various designs were conducted on the first stage, in different days and seasons, thus providing a wide range of atmospheric conditions. The goals were to: 1) test charge design and assembling, and train procedures of logistics and coordination, for preparation and conducting of the main explosion; 2) analyze atmospheric effects on <span class="hlt">infrasound</span> propagation in different azimuths based on collected meteo-data. In June-July 2008, we conducted a series of 13 detonations of outdated ammunition (in the range 0.2-10 ton) and two experimental shots of 1 ton of different explosives (TNT and Composition B). The two shots were placed close to an ammunition explosion and 10 min afterwards to help estimate ammunition actual yield (TNT). Some of these explosions were observed at IMS station I48TN (Tunisia) at ~2500 km, using array processing and analysis. Two test explosions of 1 ton and 5 tons of different recuperated HE explosives were conducted at SMR in December 2008. High-pressures in air-shock waves at close distances (150-250 m) were measured and speed video recording was done. The data obtained from the test series provided estimation of the explosion yield, that showed approximate TNT equivalency. We analyzed signals from the tests, recorded on seismic and acoustic channels at near-<span class="hlt">source</span> and local distances. We compared energy generation for different explosives, including cratering conditions, and investigated the influence of wind direction on <span class="hlt">infrasound</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8658G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8658G"><span id="translatedtitle">Sayarim <span class="hlt">Infrasound</span> Calibration Explosion provides first GT0 dataset for CTBTO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gitterman, Yefim</p> <p>2010-05-01</p> <p>The large-scale calibration explosion of about 82 tons of HE explosives, assembled as a pyramid on the soft sediment surface, was successfully conducted by the Geophysical Institute of Israel at Sayarim Military Range on 26 August 2009. High-pressure values, measured in the range 200-600 m, were higher than predicted, whereas the created crater and seismic magnitude were smaller than expected for this on-surface charge. These results confirm that the used explosives, charge design and upward detonation provided the necessary explosion energy generation and partition: maximum of energy to the atmosphere and minimum to the ground. The high-pressure observations were utilized for estimation of the important <span class="hlt">Ground</span> <span class="hlt">Truth</span> parameter - TNT equivalent yield of about 0.1 kT (based on positive impulse in air-shock wave). Thus the Sayarim Explosion provided the first full GT0 <span class="hlt">source</span> dataset for on-surface large-scale explosions, recorded by <span class="hlt">infrasound</span> stations of International Monitoring System (IMS). <span class="hlt">Infrasound</span> signals were well observed at distances up to 3,500 km, at numerous portable and permanent stations in Israel, Mediterranean countries and north-central Europe, including two IMS stations I26DE and I48TN and two portable arrays in Austria and Northern Italy deployed by the CTBTO team. Obtained records were used for analysis of <span class="hlt">infrasound</span> signal propagation, <span class="hlt">source</span> location and yield estimation, and comparison with GT0 <span class="hlt">source</span> parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S43B2244N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S43B2244N"><span id="translatedtitle">Empirical Relationships from Regional <span class="hlt">Infrasound</span> Signals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Negraru, P. T.; Golden, P.</p> <p>2011-12-01</p> <p>Two yearlong <span class="hlt">infrasound</span> observations were collected at two arrays located within the so called "Zone of Silence" or "Shadow Zone" from well controlled explosive <span class="hlt">sources</span> to investigate the long term atmospheric effects on signal propagation. The first array (FNIAR) is located north of Fallon NV, at 154 km from the munitions disposal facility outside of Hawthorne NV, while the second array (DNIAR) is located near Mercury NV, approximately 293 km south east of the detonation site. Based on celerity values, approximately 80% of the observed arrivals at FNIAR are considered stratospheric (celerities below 300 m/s), while 20% of them propagated as tropospheric waveguides with celerities of 330-345 m/s. Although there is considerable scatter in the celerity values, two seasonal effects were observed for both years; 1) a gradual decrease in celerity from summer to winter (July/January period) and 2) an increase in celerity values that starts in April. In the winter months celerity values can be extremely variable, and we have observed signals with celerities as low as 240 m/s. In contrast, at DNIAR we observe much stronger seasonal variations. In winter months we have observed tropospheric, stratospheric and thermospheric arrivals while in the summer mostly tropospheric and slower thermospheric arrivals dominate. This interpretation is consistent with the current seasonal variation of the stratospheric winds and was confirmed by ray tracing with G2S models. In addition we also discuss how the observed <span class="hlt">infrasound</span> arrivals can be used to improve <span class="hlt">ground</span> <span class="hlt">truth</span> estimation methods (location, origin times and yield). For instance an empirical wind parameter derived from G2S models suggests that the differences in celerity values observed for both arrays can be explained by changes in the wind conditions. Currently we have started working on improving location algorithms that take into account empirical celerity models derived from celerity/wind plots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730007768','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730007768"><span id="translatedtitle">The importance of <span class="hlt">ground</span> <span class="hlt">truth</span> data in remote sensing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoffer, R. M.</p> <p>1972-01-01</p> <p>Surface observation data is discussed as an essential part of remote sensing research. One of the most important aspects of <span class="hlt">ground</span> <span class="hlt">truth</span> is the collection of measurements and observations about the type, size, condition and other physical or chemical properties of importance concerning the materials on the earth's surface that are being sensed remotely. The use of a variety of sensor systems in combination at different altitudes is emphasized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037035','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037035"><span id="translatedtitle">Aeolian dunes as <span class="hlt">ground</span> <span class="hlt">truth</span> for atmospheric modeling on Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hayward, R.K.; Titus, T.N.; Michaels, T.I.; Fenton, L.K.; Colaprete, A.; Christensen, P.R.</p> <p>2009-01-01</p> <p>Martian aeolian dunes preserve a record of atmosphere/surface interaction on a variety of scales, serving as <span class="hlt">ground</span> <span class="hlt">truth</span> for both Global Climate Models (GCMs) and mesoscale climate models, such as the Mars Regional Atmospheric Modeling System (MRAMS). We hypothesize that the location of dune fields, expressed globally by geographic distribution and locally by dune centroid azimuth (DCA), may record the long-term integration of atmospheric activity across a broad area, preserving GCM-scale atmospheric trends. In contrast, individual dune morphology, as expressed in slipface orientation (SF), may be more sensitive to localized variations in circulation, preserving topographically controlled mesoscale trends. We test this hypothesis by comparing the geographic distribution, DCA, and SF of dunes with output from the Ames Mars GCM and, at a local study site, with output from MRAMS. When compared to the GCM: 1) dunes generally lie adjacent to areas with strongest winds, 2) DCA agrees fairly well with GCM modeled wind directions in smooth-floored craters, and 3) SF does not agree well with GCM modeled wind directions. When compared to MRAMS modeled winds at our study site: 1) DCA generally coincides with the part of the crater where modeled mean winds are weak, and 2) SFs are consistent with some weak, topographically influenced modeled winds. We conclude that: 1) geographic distribution may be valuable as <span class="hlt">ground</span> <span class="hlt">truth</span> for GCMs, 2) DCA may be useful as <span class="hlt">ground</span> <span class="hlt">truth</span> for both GCM and mesoscale models, and 3) SF may be useful as <span class="hlt">ground</span> <span class="hlt">truth</span> for mesoscale models. Copyright 2009 by the American Geophysical Union.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_2 --> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMAE31A0273A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMAE31A0273A"><span id="translatedtitle"><span class="hlt">Infrasound</span> Observations from Lightning</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Thomas, R. J.; Jones, K. R.</p> <p>2008-12-01</p> <p>To provide additional insight into the nature of lightning, we have investigated its <span class="hlt">infrasound</span> manifestations. An array of three stations in a triangular configuration, with three sensors each, was deployed during the Summer of 2008 (July 24 to July 28) in the Magdalena mountains of New Mexico, to monitor <span class="hlt">infrasound</span> (below 20 Hz) <span class="hlt">sources</span> due to lightning. Hyperbolic formulations of time of arrival (TOA) measurements and interferometric techniques were used to locate lightning <span class="hlt">sources</span> occurring over and outside the network. A comparative analysis of simultaneous Lightning Mapping Array (LMA) data and <span class="hlt">infrasound</span> measurements operating in the same area was made. The LMA locates the <span class="hlt">sources</span> of impulsive RF radiation produced by lightning flashes in three spatial dimensions and time, operating in the 60 - 66 MHz television band. The comparison showed strong evidence that lightning does produce <span class="hlt">infrasound</span>. This work is a continuation of the study of the frequency spectrum of thunder conducted by Holmes et al., who reported measurements of <span class="hlt">infrasound</span> frequencies. The integration of <span class="hlt">infrasound</span> measurements with RF <span class="hlt">source</span> localization by the LMA shows great potential for improved understanding of lightning processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/919172','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/919172"><span id="translatedtitle">Automated <span class="hlt">infrasound</span> signal detection algorithms implemented in MatSeis - Infra Tool.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hart, Darren</p> <p>2004-07-01</p> <p>MatSeis's <span class="hlt">infrasound</span> analysis tool, Infra Tool, uses frequency slowness processing to deconstruct the array data into three outputs per processing step: correlation, azimuth and slowness. Until now, an experienced analyst trained to recognize a pattern observed in outputs from signal processing manually accomplished <span class="hlt">infrasound</span> signal detection. Our goal was to automate the process of <span class="hlt">infrasound</span> signal detection. The critical aspect of <span class="hlt">infrasound</span> signal detection is to identify consecutive processing steps where the azimuth is constant (flat) while the time-lag correlation of the windowed waveform is above background value. These two statements describe the arrival of a correlated set of wavefronts at an array. The Hough Transform and Inverse Slope methods are used to determine the representative slope for a specified number of azimuth data points. The representative slope is then used in conjunction with associated correlation value and azimuth data variance to determine if and when an <span class="hlt">infrasound</span> signal was detected. A format for an <span class="hlt">infrasound</span> signal detection output file is also proposed. The detection output file will list the processed array element names, followed by detection characteristics for each method. Each detection is supplied with a listing of frequency slowness processing characteristics: human time (YYYY/MM/DD HH:MM:SS.SSS), epochal time, correlation, fstat, azimuth (deg) and trace velocity (km/s). As an example, a <span class="hlt">ground</span> <span class="hlt">truth</span> event was processed using the four-element DLIAR <span class="hlt">infrasound</span> array located in New Mexico. The event is known as the Watusi chemical explosion, which occurred on 2002/09/28 at 21:25:17 with an explosive yield of 38,000 lb TNT equivalent. Knowing the <span class="hlt">source</span> and array location, the array-to-event distance was computed to be approximately 890 km. This test determined the station-to-event azimuth (281.8 and 282.1 degrees) to within 1.6 and 1.4 degrees for the Inverse Slope and Hough Transform detection algorithms, respectively, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH32C..03A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH32C..03A"><span id="translatedtitle"><span class="hlt">Infrasound</span> Monitoring of Natural Hazards</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arrowsmith, S.</p> <p>2015-12-01</p> <p><span class="hlt">Infrasound</span> is generated by a wide variety of energetic natural and anthropogenic phenomena that originate in the solid earth, ocean, and atmosphere. Because the absorption of <span class="hlt">infrasound</span> is low, it can propagate long distances through atmospheric waveguides, making it a valuable tool for remote monitoring of hazards. Advances in using <span class="hlt">infrasound</span> for monitoring energetic events in the solid earth, oceans, and atmosphere are being driven by the wealth of new datasets in addition to advances in modeling <span class="hlt">source</span> and propagation physics. This presentation provides an overview of recent advances in <span class="hlt">infrasound</span> monitoring of natural hazards, focusing on selected hazards in the earth (earthquakes and volcanoes), ocean (tsunamis), and atmosphere (meteoroids).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002785','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002785"><span id="translatedtitle">Compositional <span class="hlt">Ground</span> <span class="hlt">Truth</span> of Diviner Lunar Radiometer Observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenhagen, B. T.; Thomas, I. R.; Bowles, N. E.; Allen, C. C.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.</p> <p>2012-01-01</p> <p>The Moon affords us a unique opportunity to "<span class="hlt">ground</span> <span class="hlt">truth</span>" thermal infrared (i.e. 3 to 25 micron) observations of an airless body. The Moon is the most accessable member of the most abundant class of solar system bodies, which includes Mercury, astroids, and icy satellites. The Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. And the Diviner Lunar Radiometer (Diviner) is the first instrument to globally map the spectral thermal emission of an airless body. Here we compare Diviner observations of Apollo sites to compositional and spectral measurements of Apollo lunar soil samples in simulated lunar environment (SLE).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SPIE.7538E..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7538E..08M"><span id="translatedtitle">Automatic trajectory clustering for generating <span class="hlt">ground</span> <span class="hlt">truth</span> data sets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moehrmann, Julia; Heidemann, Gunther</p> <p>2010-01-01</p> <p>We present a novel approach towards the creation of vision based recognition tasks. A lot of domain specific recognition systems have been presented in the past which make use of the large amounts of available video data. The creation of <span class="hlt">ground</span> <span class="hlt">truth</span> data sets for the training of theses systems remains difficult and tiresome. We present a system which automatically creates clusters of 2D trajectories. The results of this clustering can then be used to perform the actual labeling of the data, or rather the selection of events or features of interest by the user. The selected clusters can be used as positive training data for a user defined recognition task - without the need to adapt the system. The proposed technique reduces the necessary user interaction and allows the creation of application independent <span class="hlt">ground</span> <span class="hlt">truth</span> data sets with minimal effort. In order to achieve the automatic clustering we have developed a distance metric based on the Hidden Markov Model representations of three sequences - movement, speed and orientation - derived from the initial trajectory. The proposed system yields promising results and could prove to be an important steps towards mining very large data sets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22347383','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22347383"><span id="translatedtitle">Fish farms at sea: the <span class="hlt">ground</span> <span class="hlt">truth</span> from Google Earth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trujillo, Pablo; Piroddi, Chiara; Jacquet, Jennifer</p> <p>2012-01-01</p> <p>In the face of global overfishing of wild-caught seafood, ocean fish farming has augmented the supply of fresh fish to western markets and become one of the fastest growing global industries. Accurate reporting of quantities of wild-caught fish has been problematic and we questioned whether similar discrepancies in data exist in statistics for farmed fish production. In the Mediterranean Sea, ocean fish farming is prevalent and stationary cages can be seen off the coasts of 16 countries using satellite imagery available through Google Earth. Using this tool, we demonstrate here that a few trained scientists now have the capacity to <span class="hlt">ground</span> <span class="hlt">truth</span> farmed fish production data reported by the Mediterranean countries. With Google Earth, we could examine 91% of the Mediterranean coast and count 248 tuna cages (circular cages >40 m diameter) and 20,976 other fish cages within 10 km offshore, the majority of which were off Greece (49%) and Turkey (31%). Combining satellite imagery with assumptions about cage volume, fish density, harvest rates, and seasonal capacity, we make a conservative approximation of ocean-farmed finfish production for 16 Mediterranean countries. Our overall estimate of 225,736 t of farmed finfish (not including tuna) in the Mediterranean Sea in 2006 is only slightly more than the United Nations Food and Agriculture Organization reports. The results demonstrate the reliability of recent FAO farmed fish production statistics for the Mediterranean as well as the promise of Google Earth to collect and <span class="hlt">ground</span> <span class="hlt">truth</span> data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25729465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25729465"><span id="translatedtitle">Combining <span class="hlt">Ground-Truthing</span> and Technology to Improve Accuracy in Establishing Children's Food Purchasing Behaviors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coakley, Hannah Lee; Steeves, Elizabeth Anderson; Jones-Smith, Jessica C; Hopkins, Laura; Braunstein, Nadine; Mui, Yeeli; Gittelsohn, Joel</p> <p></p> <p>Developing nutrition-focused environmental interventions for youth requires accurate assessment of where they purchase food. We have developed an innovative, technology-based method to improve the accuracy of food <span class="hlt">source</span> recall among children using a tablet PC and <span class="hlt">ground-truthing</span> methodologies. As part of the B'more Healthy Communties for Kids study, we mapped and digitally photographed every food <span class="hlt">source</span> within a half-mile radius of 14 Baltimore City recreation centers. This food <span class="hlt">source</span> database was then used with children from the surrounding neighborhoods to search for and identify the food <span class="hlt">sources</span> they frequent. This novel integration of traditional data collection and technology enables researchers to gather highly accurate information on food <span class="hlt">source</span> usage among children in Baltimore City. Funding is provided by the NICHD U-54 Grant #1U54HD070725-02.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4344129','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4344129"><span id="translatedtitle">Combining <span class="hlt">Ground-Truthing</span> and Technology to Improve Accuracy in Establishing Children's Food Purchasing Behaviors</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Coakley, Hannah Lee; Steeves, Elizabeth Anderson; Jones-Smith, Jessica C; Hopkins, Laura; Braunstein, Nadine; Mui, Yeeli; Gittelsohn, Joel</p> <p>2015-01-01</p> <p>Developing nutrition-focused environmental interventions for youth requires accurate assessment of where they purchase food. We have developed an innovative, technology-based method to improve the accuracy of food <span class="hlt">source</span> recall among children using a tablet PC and <span class="hlt">ground-truthing</span> methodologies. As part of the B'more Healthy Communties for Kids study, we mapped and digitally photographed every food <span class="hlt">source</span> within a half-mile radius of 14 Baltimore City recreation centers. This food <span class="hlt">source</span> database was then used with children from the surrounding neighborhoods to search for and identify the food <span class="hlt">sources</span> they frequent. This novel integration of traditional data collection and technology enables researchers to gather highly accurate information on food <span class="hlt">source</span> usage among children in Baltimore City. Funding is provided by the NICHD U-54 Grant #1U54HD070725-02. PMID:25729465</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/881638','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/881638"><span id="translatedtitle">New <span class="hlt">Ground</span> <span class="hlt">Truth</span> Capability from InSAR Time Series Analysis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buckley, S; Vincent, P; Yang, D</p> <p>2005-07-13</p> <p>We demonstrate that next-generation interferometric synthetic aperture radar (InSAR) processing techniques applied to existing data provide rich InSAR <span class="hlt">ground</span> <span class="hlt">truth</span> content for exploitation in seismic <span class="hlt">source</span> identification. InSAR time series analyses utilize tens of interferograms and can be implemented in different ways. In one such approach, conventional InSAR displacement maps are inverted in a final post-processing step. Alternatively, computationally intensive data reduction can be performed with specialized InSAR processing algorithms. The typical final result of these approaches is a synthesized set of cumulative displacement maps. Examples from our recent work demonstrate that these InSAR processing techniques can provide appealing new <span class="hlt">ground</span> <span class="hlt">truth</span> capabilities. We construct movies showing the areal and temporal evolution of deformation associated with previous nuclear tests. In other analyses, we extract time histories of centimeter-scale surface displacement associated with tunneling. The potential exists to identify millimeter per year surface movements when sufficient data exists for InSAR techniques to isolate and remove phase signatures associated with digital elevation model errors and the atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080009512','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080009512"><span id="translatedtitle">Generating high precision ionospheric <span class="hlt">ground-truth</span> measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Komjathy, Attila (Inventor); Sparks, Lawrence (Inventor); Mannucci, Anthony J. (Inventor)</p> <p>2007-01-01</p> <p>A method, apparatus and article of manufacture provide ionospheric <span class="hlt">ground-truth</span> measurements for use in a wide-area augmentation system (WAAS). Ionospheric pseudorange/code and carrier phase data as primary observables is received by a WAAS receiver. A polynomial fit is performed on the phase data that is examined to identify any cycle slips in the phase data. The phase data is then leveled. Satellite and receiver biases are obtained and applied to the leveled phase data to obtain unbiased phase-leveled ionospheric measurements that are used in a WAAS system. In addition, one of several measurements may be selected and data is output that provides information on the quality of the measurements that are used to determine corrective messages as part of the WAAS system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1134255','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1134255"><span id="translatedtitle">AMS <span class="hlt">Ground</span> <span class="hlt">Truth</span> Measurements: Calibration and Test Lines</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wasiolek, P.</p> <p>2013-11-01</p> <p>Airborne gamma spectrometry is one of the primary techniques used to define the extent of ground contamination after a radiological incident. Its usefulness was demonstrated extensively during the response to the Fukushima nuclear power plant (NPP) accident in March-May 2011. To map ground contamination a set of scintillation detectors is mounted on an airborne platform (airplane or helicopter) and flown over contaminated areas. The acquisition system collects spectral information together with the aircraft position and altitude every second. To provide useful information to decision makers, the count rate data expressed in counts per second (cps) needs to be converted to the terrestrial component of the exposure rate 1 m above ground, or surface activity of isotopes of concern. This is done using conversion coefficients derived from calibration flights. During a large scale radiological event, multiple flights may be necessary and may require use of assets from different agencies. However, as the production of a single, consistent map product depicting the ground contamination is the primary goal, it is critical to establish very early into the event a common calibration line. Such a line should be flown periodically in order to normalize data collected from different aerial acquisition systems and potentially flown at different flight altitudes and speeds. In order to verify and validate individual aerial systems, the calibration line needs to be characterized in terms of <span class="hlt">ground</span> <span class="hlt">truth</span> measurements. This is especially important if the contamination is due to short-lived radionuclides. The process of establishing such a line, as well as necessary <span class="hlt">ground</span> <span class="hlt">truth</span> measurements, is described in this document.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/878633','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/878633"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Collection for Mining Explosions in Northern Fennoscandia and Northwestern Russia</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harris, D B; Ringdal, R; Kremenetskaya, E; Mykkeltveit, S; Rock, D W; Maercklin, N; Schweitzer, J; Hauk, T F; Lewis, J P</p> <p>2005-07-13</p> <p>We concluded comprehensive <span class="hlt">ground</span> <span class="hlt">truth</span> collection at the Khibiny, Olenegorsk, Kovdor, and Zapolyarnyi mines, and have basic information on 2,052 explosions. In the past two years we used this <span class="hlt">ground</span> <span class="hlt">truth</span> information to extract waveform data from the ARCES array and a number of regional stations (KEV, LVZ, APA) as well as from six stations that we deployed along two lines stretching between the Khibiny Massif mines and the region around the ARCES array. We calculated P/S ratios using the ARCES array data for many of these events comprising several <span class="hlt">source</span> types (compact underground explosions, underground ripple-fired explosions, surface ripple-fired explosions). We found that the P/S ratios of small compact underground explosions in mines of the Khibiny Massif are systematically lower than the P/S ratios of large ripple-fired surface explosions. We had anticipated that smaller underground shots would appear more like single well-coupled explosions, thus having higher P/S ratios than large ripple-fired explosions. A possible explanation for this phenomenon is that the compact underground explosions in these mines are designed to fracture and drop a large quantity of ore from the ceiling of a horizontal shaft. The potential energy released by the falling ore may express as shear wave energy, which may be considerably greater than the (P wave) energy released directly by the explosive. We concluded the deployment of the six stations along the Khibiny-ARCES lines this past summer; this year we are examining the data from these stations to see how P/S ratios vary with range from the <span class="hlt">source</span>. We have an update on the P/S ratio analysis contrasting different <span class="hlt">source</span> types, with the addition of an analysis of range dependence using data from the temporary stations. The portable stations were redeployed in the fall of 2004 to the Kiruna and Malmberget underground mines in northern Sweden. The stations deployed in Malmberget also record events from the surface mining</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780004567','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780004567"><span id="translatedtitle">Improved <span class="hlt">ground</span> <span class="hlt">truth</span> geoid for the GEOS-3 calibration area</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mourad, A. G.; Gopalapillai, S.; Kuhner, M.; Fubara, D. M.</p> <p>1977-01-01</p> <p>The purpose of this investigation is to develop methods and procedures are reported for computing a detailed geoid to be used as geodetic <span class="hlt">ground</span> <span class="hlt">truth</span> for the calibration and verification of GEOS-3 altimeter data. The technique developed is based on rectifying the best available detailed geoid so that the rectified geoid will have correct scale, orientation, shape and position with respect to the geocenter. The approach involved the development of a mathematical model based on a second degree polynomial, in rectangular Cartesian coordinates, describing the geoid undulations at the control stations. A generalized least squares solution was obtained for the polynomial which describes the variation of the undulation differences between the control stations geoid and the gravimetric geoid. Three rectified geoid were determined. These geoids correspond to three sets of tracking station data: (1) WFC/C-band data; (2) GSFC/C-band data; and (3) OSU-275 data. The absolute accuracy of these rectified geoids is linearly correlated with the uncertainties of the tracking station coordinates and, to a certain extent, with those of the detailed geoid being rectified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25267257','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25267257"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> data generation for skull-face overlay.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ibáñez, O; Cavalli, F; Campomanes-Álvarez, B R; Campomanes-Álvarez, C; Valsecchi, A; Huete, M I</p> <p>2015-05-01</p> <p>Objective and unbiased validation studies over a significant number of cases are required to get a more solid picture on craniofacial superimposition reliability. It will not be possible to compare the performance of existing and upcoming methods for craniofacial superimposition without a common forensic database available for the research community. Skull-face overlay is a key task within craniofacial superimposition that has a direct influence on the subsequent task devoted to evaluate the skull-face relationships. In this work, we present the procedure to create for the first time such a dataset. We have also created a database with 19 skull-face overlay cases for which we are trying to overcome legal issues that allow us to make it public. The quantitative analysis made in the segmentation and registration stages, together with the visual assessment of the 19 face-to-face overlays, allows us to conclude that the results can be considered as a gold standard. With such a <span class="hlt">ground</span> <span class="hlt">truth</span> dataset, a new horizon is opened for the development of new automatic methods whose performance could be now objectively measured and compared against previous and future proposals. Additionally, other uses are expected to be explored to better understand the visual evaluation process of craniofacial relationships in craniofacial identification. It could be very useful also as a starting point for further studies on the prediction of the resulting facial morphology after corrective or reconstructive interventionism in maxillofacial surgery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4917178','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4917178"><span id="translatedtitle">Object Segmentation and <span class="hlt">Ground</span> <span class="hlt">Truth</span> in 3D Embryonic Imaging</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rajasekaran, Bhavna; Uriu, Koichiro; Valentin, Guillaume; Tinevez, Jean-Yves; Oates, Andrew C.</p> <p>2016-01-01</p> <p>Many questions in developmental biology depend on measuring the position and movement of individual cells within developing embryos. Yet, tools that provide this data are often challenged by high cell density and their accuracy is difficult to measure. Here, we present a three-step procedure to address this problem. Step one is a novel segmentation algorithm based on image derivatives that, in combination with selective post-processing, reliably and automatically segments cell nuclei from images of densely packed tissue. Step two is a quantitative validation using synthetic images to ascertain the efficiency of the algorithm with respect to signal-to-noise ratio and object density. Finally, we propose an original method to generate reliable and experimentally faithful <span class="hlt">ground</span> <span class="hlt">truth</span> datasets: Sparse-dense dual-labeled embryo chimeras are used to unambiguously measure segmentation errors within experimental data. Together, the three steps outlined here establish a robust, iterative procedure to fine-tune image analysis algorithms and microscopy settings associated with embryonic 3D image data sets. PMID:27332860</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27332860','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27332860"><span id="translatedtitle">Object Segmentation and <span class="hlt">Ground</span> <span class="hlt">Truth</span> in 3D Embryonic Imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rajasekaran, Bhavna; Uriu, Koichiro; Valentin, Guillaume; Tinevez, Jean-Yves; Oates, Andrew C</p> <p>2016-01-01</p> <p>Many questions in developmental biology depend on measuring the position and movement of individual cells within developing embryos. Yet, tools that provide this data are often challenged by high cell density and their accuracy is difficult to measure. Here, we present a three-step procedure to address this problem. Step one is a novel segmentation algorithm based on image derivatives that, in combination with selective post-processing, reliably and automatically segments cell nuclei from images of densely packed tissue. Step two is a quantitative validation using synthetic images to ascertain the efficiency of the algorithm with respect to signal-to-noise ratio and object density. Finally, we propose an original method to generate reliable and experimentally faithful <span class="hlt">ground</span> <span class="hlt">truth</span> datasets: Sparse-dense dual-labeled embryo chimeras are used to unambiguously measure segmentation errors within experimental data. Together, the three steps outlined here establish a robust, iterative procedure to fine-tune image analysis algorithms and microscopy settings associated with embryonic 3D image data sets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoJI.200..779J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoJI.200..779J"><span id="translatedtitle">Modelling <span class="hlt">infrasound</span> signal generation from two underground explosions at the <span class="hlt">Source</span> Physics Experiment using the Rayleigh integral</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, Kyle R.; Whitaker, Rodney W.; Arrowsmith, Stephen J.</p> <p>2015-02-01</p> <p>We use the Rayleigh integral (RI) as an approximation to the Helmholtz-Kirchoff integral to model <span class="hlt">infrasound</span> generation and propagation from underground chemical explosions at distances of 250 m out to 5 km as part of the <span class="hlt">Source</span> Physics Experiment (SPE). Using a sparse network of surface accelerometers installed above ground zero, we are able to accurately create synthetic acoustic waveforms and compare them to the observed data. Although the underground explosive <span class="hlt">sources</span> were designed to be symmetric, the resulting seismic wave at the surface shows an asymmetric propagation pattern that is stronger to the northeast of the borehole. This asymmetric bias may be attributed to the subsurface geology and faulting of the area and is observed in the acoustic waveforms. We compare observed and modelled results from two of the underground SPE tests with a sensitivity study to evaluate the asymmetry observed in the data. This work shows that it is possible to model <span class="hlt">infrasound</span> signals from underground explosive <span class="hlt">sources</span> using the RI and that asymmetries observed in the data can be modelled with this technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820017719','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820017719"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> crop proportion summaries for US segments, 1976-1979</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Horvath, R. (Principal Investigator); Rice, D.; Wessling, T.</p> <p>1981-01-01</p> <p>The original <span class="hlt">ground</span> <span class="hlt">truth</span> data was collected, digitized, and registered to LANDSAT data for use in the LACIE and AgRISTARS projects. The numerous <span class="hlt">ground</span> <span class="hlt">truth</span> categories were consolidated into fewer classes of crops or crop conditions and counted occurrences of these classes for each segment. Tables are presented in which the individual entries are the percentage of total segment area assigned to a given class. The <span class="hlt">ground</span> <span class="hlt">truth</span> summaries were prepared from a 20% sample of the scene. An analysis indicates that this size of sample provides sufficient accuracy for use of the data in initial segment screening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA435517','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA435517"><span id="translatedtitle">Tactical <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2005-05-01</p> <p>ambient pressure field, including sensor- induced turbulence, "* Detector artifacts, such as thermal and seismic feedthrough, "* Sound noise, including wind...suggestions that might provide a near-term enhancement of the effectiveness of a tactical <span class="hlt">infrasound</span> system into Recommendation #1. The other sug- gestions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMNH33C..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMNH33C..02M"><span id="translatedtitle">Local and remote <span class="hlt">infrasound</span> from explosive volcanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matoza, R. S.; Fee, D.; LE Pichon, A.</p> <p>2014-12-01</p> <p>Explosive volcanic eruptions can inject large volumes of ash into heavily travelled air corridors and thus pose a significant societal and economic hazard. In remote volcanic regions, satellite data are sometimes the only technology available to observe volcanic eruptions and constrain ash-release parameters for aviation safety. <span class="hlt">Infrasound</span> (acoustic waves ~0.01-20 Hz) data fill this critical observational gap, providing ground-based data for remote volcanic eruptions. Explosive volcanic eruptions are among the most powerful <span class="hlt">sources</span> of <span class="hlt">infrasound</span> observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. Advances in <span class="hlt">infrasound</span> technology and the efficient propagation of <span class="hlt">infrasound</span> in the atmosphere therefore greatly enhance our ability to monitor volcanoes in remote regions such as the North Pacific Ocean. <span class="hlt">Infrasound</span> data can be exploited to detect, locate, and provide detailed chronologies of the timing of explosive volcanic eruptions for use in ash transport and dispersal models. We highlight results from case studies of multiple eruptions recorded by the International Monitoring System and dedicated regional <span class="hlt">infrasound</span> networks (2008 Kasatochi, Alaska, USA; 2008 Okmok, Alaska, USA; 2009 Sarychev Peak, Kuriles, Russian Federation; 2010 Eyjafjallajökull, Icleand) and show how <span class="hlt">infrasound</span> is currently used in volcano monitoring. We also present progress towards characterizing and modeling the variability in <span class="hlt">source</span> mechanisms of <span class="hlt">infrasound</span> from explosive eruptions using dedicated local <span class="hlt">infrasound</span> field deployments at volcanoes Karymsky, Russian Federation and Sakurajima, Japan.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMNS22A..08K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMNS22A..08K"><span id="translatedtitle">Field Experiment Provides <span class="hlt">Ground</span> <span class="hlt">Truth</span> for Surface NMR Measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knight, R. J.; Abraham, J. D.; Cannia, J. C.; Dlubac, K. I.; Grau, B.; Grunewald, E. D.; Irons, T.; Song, Y.; Walsh, D.</p> <p>2010-12-01</p> <p> months later, borehole NMR T2 measurements were repeated with a second instrument; and logging measurements were made of the ambient magnetic field. Comparison of the three measurements of NMR relaxation show that T2* at this site is affected by inhomogeneity in the background magnetic field; this effect is most pronounced in sand and gravel units where dephasing, rather than surface relaxation, dominates the NMR response. When the borehole T2 measurements are transformed to T2*, by incorporating a term to account for this effect, we find good agreement between the two forms of measurement over the investigated depth range. The ability to <span class="hlt">ground</span> <span class="hlt">truth</span> the SNMR measurement has advanced our understanding of the time constant measured by SNMR, T2*, and its relationship to pore-scale properties. This is a critical step in developing SNMR as a reliable geophysical method for evaluation of groundwater resources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15014481','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15014481"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Collection for Mining Explosions in Northern Fennoscandia and Russia</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harris, D; Ringdal, F; Kremenetskaya, E; Mykkeltveit, S; Rock, D E; Schweitzer, J; Hauk, T; Lewis, J</p> <p>2004-07-15</p> <p>Analysis of data from our deployments and <span class="hlt">ground</span> <span class="hlt">truth</span> collection in northern Fennoscandia and northwestern Russia shows systematic variations in the P/S ratios of different types of explosions. The fact that this fundamental discriminant varies with firing practice is not in itself surprising - such variations probably contribute to the spread in P/S ratios normally observed for ripple-fired explosions. However, the nature of the variations is sometimes counterintuitive. Last year [Harris, 2003] we found that the P/S ratios of small compact underground explosions in mines of the Khibiny Massif are systematically lower than the P/S ratios of large ripple-fired surface explosions. We had anticipated that smaller underground shots would be more like single well-coupled explosions, thus having higher P/S ratios than large ripple-fired explosions. We now are performing a more extensive analysis of the data including compact and large ripple-fired explosions at additional mines and different types of explosions: small surface shots and large ripple-fired underground explosions. Our data are more complete as a result of an additional year of collection and allow a more complete sampling of the signals in range from the <span class="hlt">source</span>. As of this writing we have measured Pn/Lg ratios on a larger number of explosions of three types: compact underground explosions, surface ripple-fired explosions and now underground ripple-fired explosions. We find that both types of underground explosions have systematically lower P/S ratios than surface ripple-fired shots; this effect is most pronounced in the 4-8 Hz frequency band. This result appears to be due to relatively diminished shear wave excitation by the surface explosions. We speculate that the relatively large shear phases in underground explosions may be caused by large amounts of rockfall in these events, which are designed to collapse the ceilings of tunnels. We have continued comprehensive <span class="hlt">ground</span> <span class="hlt">truth</span> collection at the Khibiny</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120.8223J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120.8223J"><span id="translatedtitle"><span class="hlt">Infrasound</span> from volcanic rockfalls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Jeffrey B.; Ronan, Timothy J.</p> <p>2015-12-01</p> <p>Proximal <span class="hlt">infrasound</span> arrays can robustly track rapidly moving gravity-driven mass wasting, which occurs commonly at erupting volcanoes. This study reports on detection, localization, and quantification of frequent small rockfalls and infrequent pyroclastic density currents descending the southeast flanks of Santiaguito's active Caliente Dome in January of 2014. Such activities are identified as moving <span class="hlt">sources</span>, which descend several hundred meters at bulk flow speeds of up to ~10 m/s, which is considerably slower than the descent velocity of individual blocks. <span class="hlt">Infrasound</span> rockfall signal character is readily distinguishable from explosion <span class="hlt">infrasound</span>, which is manifested by a relatively fixed location <span class="hlt">source</span> with lower frequency content. In contrast, the rockfalls of Santiaguito possess higher frequencies dominated by 7.5 to 20 Hz energy. During our observation periods typical rockfall signals occurred ~10 times per hour and lasted tens of seconds or more. Array beamforming permitted detection of rockfall transients with amplitudes of only a few tens of millipascals that would be impossible to distinguish from noise using a single sensor. Conjoint time-synchronized video is used to corroborate location and to characterize various gravity-driven events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26736941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26736941"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> delineation for medical image segmentation based on Local Consistency and Distribution Map analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Irene; Sun, Xinyao; Alsufyani, Noura; Xiong, Zhihui; Major, Paul; Basu, Anup</p> <p>2015-01-01</p> <p>Computer-aided detection (CAD) systems are being increasingly deployed for medical applications in recent years with the goal to speed up tedious tasks and improve precision. Among others, segmentation is an important component in CAD systems as a preprocessing step to help recognize patterns in medical images. In order to assess the accuracy of a CAD segmentation algorithm, comparison with <span class="hlt">ground</span> <span class="hlt">truth</span> data is necessary. To-date, <span class="hlt">ground</span> <span class="hlt">truth</span> delineation relies mainly on contours that are either manually defined by clinical experts or automatically generated by software. In this paper, we propose a systematic <span class="hlt">ground</span> <span class="hlt">truth</span> delineation method based on a Local Consistency Set Analysis approach, which can be used to establish an accurate <span class="hlt">ground</span> <span class="hlt">truth</span> representation, or if <span class="hlt">ground</span> <span class="hlt">truth</span> is available, to assess the accuracy of a CAD generated segmentation algorithm. We validate our computational model using medical data. Experimental results demonstrate the robustness of our approach. In contrast to current methods, our model also provides consistency information at distributed boundary pixel level, and thus is invariant to global compensation error.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770044981&hterms=asp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dasp','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770044981&hterms=asp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dasp"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> management system to support multispectral scanner /MSS/ digital analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coiner, J. C.; Ungar, S. G.</p> <p>1977-01-01</p> <p>A computerized geographic information system for management of <span class="hlt">ground</span> <span class="hlt">truth</span> has been designed and implemented to relate MSS classification results to in situ observations. The <span class="hlt">ground</span> <span class="hlt">truth</span> system transforms, generalizes and rectifies ground observations to conform to the pixel size and shape of high resolution MSS aircraft data. These observations can then be aggregated for comparison to lower resolution sensor data. Construction of a digital <span class="hlt">ground</span> <span class="hlt">truth</span> array allows direct pixel by pixel comparison between classification results of MSS data and <span class="hlt">ground</span> <span class="hlt">truth</span>. By making comparisons, analysts can identify spatial distribution of error within the MSS data as well as usual figures of merit for the classifications. Use of the <span class="hlt">ground</span> <span class="hlt">truth</span> system permits investigators to compare a variety of environmental or anthropogenic data, such as soil color or tillage patterns, with classification results and allows direct inclusion of such data into classification operations. To illustrate the system, examples from classification of simulated Thematic Mapper data for agricultural test sites in North Dakota and Kansas are provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S14A..07W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S14A..07W"><span id="translatedtitle">Infrasonic <span class="hlt">source</span> location imaging with the USArray: Application to one year of seismic data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, K. T.; Shelby, R.; Hedlin, M. A.; Degroot-Hedlin, C. D.</p> <p>2010-12-01</p> <p>The USArray directly measures ground motion, which can mostly be attributed to ocean waves, earthquakes, volcanoes, and weather systems that load the Earth’s surface. Another <span class="hlt">source</span> of ground motion is the transfer of atmospheric acoustic energy into seismic energy at the Earth’s surface. <span class="hlt">Infrasound</span> (low frequency sound below ~20 Hz) can travel great distances unattenuated in atmospheric ducts. The infrasonic wave field is rich due to a variety of anthropogenic and geophysical phenomena including earthquakes, volcanoes, landslides, meteors, lightning and sprites, auroras, and oceanic and atmospheric processes. Globally spaced microbarometer arrays with apertures of 100 m to 2 km are typically used to study these <span class="hlt">sources</span>. However, these arrays are separated by thousands of kilometers, which places considerable limits on what they can teach us about <span class="hlt">infrasound</span> <span class="hlt">source</span> physics. The USArray is in a position to study <span class="hlt">infrasound</span> <span class="hlt">sources</span> in unprecedented detail. Here we apply reverse-time migration to acoustic-to-seismic coupled signals recorded by the USArray to detect and locate in two-dimensional space and time several hundred <span class="hlt">infrasound</span> <span class="hlt">sources</span> in the western U.S. that occurred during 2008. Each event is visually inspected and assigned a quality rating. Confidence regions are determined using a bootstrap technique. The highest quality signals can be observed out to at least 1500 km range. We report the <span class="hlt">source</span> location parameters for these events and investigate detection and location patterns. These results suggest that seismic networks near nuclear test monitoring <span class="hlt">infrasound</span> arrays could be used to reduce the false alarm rate by identifying nearby, repeating <span class="hlt">sources</span> of <span class="hlt">infrasound</span> that create signals that are detected by the <span class="hlt">infrasound</span> arrays. More fundamentally, these detected events comprise a <span class="hlt">ground</span> <span class="hlt">truth</span> database that can be used to validate or improve atmospheric velocity models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770032220&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770032220&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dtruth"><span id="translatedtitle">Estimation of the probability of error without <span class="hlt">ground</span> <span class="hlt">truth</span> and known a priori probabilities. [remote sensor performance</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Havens, K. A.; Minster, T. C.; Thadani, S. G.</p> <p>1976-01-01</p> <p>The probability of error or, alternatively, the probability of correct classification (PCC) is an important criterion in analyzing the performance of a classifier. Labeled samples (those with <span class="hlt">ground</span> <span class="hlt">truth</span>) are usually employed to evaluate the performance of a classifier. Occasionally, the numbers of labeled samples are inadequate, or no labeled samples are available to evaluate a classifier's performance; for example, when crop signatures from one area from which <span class="hlt">ground</span> <span class="hlt">truth</span> is available are used to classify another area from which no <span class="hlt">ground</span> <span class="hlt">truth</span> is available. This paper reports the results of an experiment to estimate the probability of error using unlabeled test samples (i.e., without the aid of <span class="hlt">ground</span> <span class="hlt">truth</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28113848','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28113848"><span id="translatedtitle">An Empirical Study into Annotator Agreement, <span class="hlt">Ground</span> <span class="hlt">Truth</span> Estimation, and Algorithm Evaluation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lampert, Thomas A; Stumpf, Andre; Gancarski, Pierre</p> <p>2016-03-21</p> <p>Although agreement between annotators who mark feature locations within images has been studied in the past from a statistical viewpoint, little work has attempted to quantify the extent to which this phenomenon affects the evaluation of foreground-background segmentation algorithms. Many researchers utilise <span class="hlt">ground</span> <span class="hlt">truth</span> in experimentation and more often than not this <span class="hlt">ground</span> <span class="hlt">truth</span> is derived from one annotator's opinion. How does the difference in opinion affect an algorithm's evaluation? A methodology is applied to four image processing problems to quantify the inter-annotator variance and to offer insight into the mechanisms behind agreement and the use of <span class="hlt">ground</span> <span class="hlt">truth</span>. It is found that when detecting linear structures annotator agreement is very low. The agreement in a structure's position can be partially explained through basic image properties. Automatic segmentation algorithms are compared to annotator agreement and it is found that there is a clear relation between the two. Several <span class="hlt">ground</span> <span class="hlt">truth</span> estimation methods are used to infer a number of algorithm performances. It is found that: the rank of a detector is highly dependent upon the method used to form the <span class="hlt">ground</span> <span class="hlt">truth</span>; and that although STAPLE and LSML appear to represent the mean of the performance measured using individual annotations, when there are few annotations, or there is a large variance in them, these estimates tend to degrade. Furthermore, one of the most commonly adopted combination methods-consensus voting- accentuates more obvious features, resulting in an overestimation of performance. It is concluded that in some datasets it is not possible to confidently infer an algorithm ranking when evaluating upon one <span class="hlt">ground</span> <span class="hlt">truth</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/973116','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/973116"><span id="translatedtitle">Retina Lesion and Microaneurysm Segmentation using Morphological Reconstruction Methods with <span class="hlt">Ground-Truth</span> Data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Karnowski, Thomas Paul; Tobin Jr, Kenneth William; Chaum, Edward; Muthusamy Govindasamy, Vijaya Priya</p> <p>2009-09-01</p> <p>In this work we report on a method for lesion segmentation based on the morphological reconstruction methods of Sbeh et. al. We adapt the method to include segmentation of dark lesions with a given vasculature segmentation. The segmentation is performed at a variety of scales determined using <span class="hlt">ground-truth</span> data. Since the method tends to over-segment imagery, <span class="hlt">ground-truth</span> data was used to create post-processing filters to separate nuisance blobs from true lesions. A sensitivity and specificity of 90% of classification of blobs into nuisance and actual lesion was achieved on two data sets of 86 images and 1296 images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060038023&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060038023&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtruth"><span id="translatedtitle">Automated Analysis of Radar Imagery of Venus: Handling Lack of <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burl, M.; Fayyad, U.; Perona, P.; Smyth, P.</p> <p>1994-01-01</p> <p>Lack of verifiable <span class="hlt">ground</span> <span class="hlt">truth</span> is a common problem in remote sensing image analysis. For example, consider the synthetic aperture radar (SAR) image data of Venus obtained by the Magellan spacecraft. Planetary scientists are interested in automatically cataloging the locations of all the small volcanoes in this data set; however, the problem is very difficult and cannot be performed with perfect reliability even by human experts. Thus, training and evaluating the performance of an automatic algorithm on this data set must be handled carefully. We discuss the use of weighted free-response receiver-operating characteristics (wFROC) for evaluating detection performance when the <span class="hlt">ground</span> <span class="hlt">truth</span> is subjective.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19163946','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19163946"><span id="translatedtitle">Retina lesion and microaneurysm segmentation using morphological reconstruction methods with <span class="hlt">ground-truth</span> data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Karnowski, Thomas P; Govindasamy, V; Tobin, Kenneth W; Chaum, Edward; Abramoff, M D</p> <p>2008-01-01</p> <p>In this work we report on a method for lesion segmentation based on the morphological reconstruction methods of Sbeh et. al. We adapt the method to include segmentation of dark lesions with a given vasculature segmentation. The segmentation is performed at a variety of scales determined using <span class="hlt">ground-truth</span> data. Since the method tends to over-segment imagery, <span class="hlt">ground-truth</span> data was used to create post-processing filters to separate nuisance blobs from true lesions. A sensitivity and specificity of 90% of classification of blobs into nuisance and actual lesion was achieved on two data sets of 86 images and 1296 images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4580633','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4580633"><span id="translatedtitle">Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: <span class="hlt">Ground-Truth</span> Detection Probability and Inclusion of Activity Sensor Measures</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Blecha, Kevin A.; Alldredge, Mat W.</p> <p>2015-01-01</p> <p>Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor) we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a <span class="hlt">ground-truthing</span> component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for <span class="hlt">sources</span> of <span class="hlt">ground-truthing</span> false-absences can bias the number of predicted feeding events to be low. Thus we account for some <span class="hlt">ground-truthing</span> error <span class="hlt">sources</span> directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the <span class="hlt">ground-truthing</span> false-absence rate is relatively low (4%) using a search delay of 2–60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores. PMID:26398546</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26398546','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26398546"><span id="translatedtitle">Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: <span class="hlt">Ground-Truth</span> Detection Probability and Inclusion of Activity Sensor Measures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blecha, Kevin A; Alldredge, Mat W</p> <p>2015-01-01</p> <p>Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor) we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a <span class="hlt">ground-truthing</span> component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for <span class="hlt">sources</span> of <span class="hlt">ground-truthing</span> false-absences can bias the number of predicted feeding events to be low. Thus we account for some <span class="hlt">ground-truthing</span> error <span class="hlt">sources</span> directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the <span class="hlt">ground-truthing</span> false-absence rate is relatively low (4%) using a search delay of 2-60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813473M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813473M"><span id="translatedtitle"><span class="hlt">Infrasound</span> research of volcanic eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchetti, Emanuele; Ripepe, Maurizio</p> <p>2016-04-01</p> <p>Volcanic eruptions are efficient <span class="hlt">sources</span> of <span class="hlt">infrasound</span> produced by the rapid perturbation of the atmosphere by the explosive <span class="hlt">source</span>. Being able to propagate up to large distances from the <span class="hlt">source</span>, infrasonic waves from major (VEI 4 or larger) volcanic eruptions have been recorded for many decades with analogue micro-barometers at large regional distances. In late 1980s, near-field observations became progressively more common and started to have direct impact on the understanding and modeling of explosive <span class="hlt">source</span> dynamics, to eventually play a primary role in volcano research. Nowadays, <span class="hlt">infrasound</span> observation from a large variety of volcanic eruptions, spanning from VEI 0 to VEI 5 events, has shown a dramatic variability in terms of signature, excess pressure and frequency content of radiated <span class="hlt">infrasound</span> and has been used to infer complex eruptive <span class="hlt">source</span> mechanisms for the different kinds of events. Improved processing capability and sensors has allowed unprecedented precise locations of the explosive <span class="hlt">source</span> and is progressively increasing the possibility to monitor volcanoes from distant records. Very broadband <span class="hlt">infrasound</span> observations is also showing the relation between volcanic eruptions and the atmosphere, with the eruptive mass injection in the atmosphere triggering acoustic-gravity waves which eventually might control the ash dispersal and fallout.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790015305','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790015305"><span id="translatedtitle">Detailed analysis of CAMS procedures for phase 3 using <span class="hlt">ground</span> <span class="hlt">truth</span> inventories</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Carnes, J. G.</p> <p>1979-01-01</p> <p>The results of a study of Procedure 1 as used during LACIE Phase 3 are presented. The study was performed by comparing the Procedure 1 classification results with digitized <span class="hlt">ground-truth</span> inventories. The proportion estimation accuracy, dot labeling accuracy, and clustering effectiveness are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760018620','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760018620"><span id="translatedtitle">Soil moisture <span class="hlt">ground</span> <span class="hlt">truth</span>: Steamboat Springs, Colorado, site and Walden, Colorado, site</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.</p> <p>1976-01-01</p> <p><span class="hlt">Ground-truth</span> data taken at Steamboat Springs and Walden, Colorado in support of the NASA missions in these areas during the period March 8, 1976 through March 11, 1976 was presented. This includes the following information: snow course data for Steamboat Springs and Walden, snow pit and snow quality data for Steamboat Springs, and soil moisture report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005SPIE.5794.1030P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005SPIE.5794.1030P"><span id="translatedtitle">Semi-automated based <span class="hlt">ground-truthing</span> GUI for airborne imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phan, Chung; Lydic, Rich; Moore, Tim; Trang, Anh; Agarwal, Sanjeev; Tiwari, Spandan</p> <p>2005-06-01</p> <p>Over the past several years, an enormous amount of airborne imagery consisting of various formats has been collected and will continue into the future to support airborne mine/minefield detection processes, improve algorithm development, and aid in imaging sensor development. The <span class="hlt">ground-truthing</span> of imagery is a very essential part of the algorithm development process to help validate the detection performance of the sensor and improving algorithm techniques. The GUI (Graphical User Interface) called SemiTruth was developed using Matlab software incorporating signal processing, image processing, and statistics toolboxes to aid in <span class="hlt">ground-truthing</span> imagery. The semi-automated <span class="hlt">ground-truthing</span> GUI is made possible with the current data collection method, that is including UTM/GPS (Universal Transverse Mercator/Global Positioning System) coordinate measurements for the mine target and fiducial locations on the given minefield layout to support in identification of the targets on the raw imagery. This semi-automated <span class="hlt">ground-truthing</span> effort has developed by the US Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD), Countermine Division, Airborne Application Branch with some support by the University of Missouri-Rolla.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740011846','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740011846"><span id="translatedtitle">Application of remote sensing in agriculture and forestry and <span class="hlt">ground</span> <span class="hlt">truth</span> documentation in resource planning</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1974-01-01</p> <p>Varied small scale imagery was used for detecting and assessing damage by the southern pine beetle. The usefulness of ERTS scanner imagery for vegetation classification and pine beetle damage detection and assessment is evaluated. <span class="hlt">Ground</span> <span class="hlt">truth</span> acquisition for forest identification using multispectral aerial photographs is reviewed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRD..118.6122F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRD..118.6122F"><span id="translatedtitle">Overview of the 2009 and 2011 Sayarim <span class="hlt">Infrasound</span> Calibration Experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fee, David; Waxler, Roger; Assink, Jelle; Gitterman, Yefim; Given, Jeffrey; Coyne, John; Mialle, Pierrick; Garces, Milton; Drob, Douglas; Kleinert, Dan; Hofstetter, Rami; Grenard, Patrick</p> <p>2013-06-01</p> <p>Three large-scale <span class="hlt">infrasound</span> calibration experiments were conducted in 2009 and 2011 to test the International Monitoring System (IMS) <span class="hlt">infrasound</span> network and provide <span class="hlt">ground</span> <span class="hlt">truth</span> data for <span class="hlt">infrasound</span> propagation studies. Here we provide an overview of the deployment, detonation, atmospheric specifications, <span class="hlt">infrasound</span> array observations, and propagation modeling for the experiments. The experiments at the Sayarim Military Range, Israel, had equivalent TNT yields of 96.0, 7.4, and 76.8 t of explosives on 26 August 2009, 24 January 2011, and 26 January 2011, respectively. Successful international collaboration resulted in the deployment of numerous portable <span class="hlt">infrasound</span> arrays in the region to supplement the IMS network and increase station density. <span class="hlt">Infrasound</span> from the detonations is detected out to ~3500 km to the northwest in 2009 and ~6300 km to the northeast in 2011, reflecting the highly anisotropic nature of long-range <span class="hlt">infrasound</span> propagation. For 2009, the moderately strong stratospheric wind jet results in a well-predicted set of arrivals at numerous arrays to the west-northwest. A second set of arrivals is also apparent, with low celerities and high frequencies. These arrivals are not predicted by the propagation modeling and result from unresolved atmospheric features. Strong eastward tropospheric winds (up to ~70 m/s) in 2011 produce high-amplitude tropospheric arrivals recorded out to >1000 km to the east. Significant eastward stratospheric winds (up to ~80 m/s) in 2011 generate numerous stratospheric arrivals and permit the long-range detection (i.e., >1000 km). No detections are made in directions opposite the tropospheric and stratospheric wind jets for any of the explosions. Comparison of predicted transmission loss and observed <span class="hlt">infrasound</span> arrivals gives qualitative agreement. Propagation modeling for the 2011 experiments predicts lower transmission loss in the direction of the downwind propagation compared to the 2009 experiment, consistent with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SPIE.7625E..2KO','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7625E..2KO"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> and CT image model simulation for pathophysiological human airway system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortner, Margarete; Fetita, Catalin; Brillet, Pierre-Yves; Pr"teux, Françoise; Grenier, Philippe</p> <p>2010-02-01</p> <p>Recurrent problem in medical image segmentation and analysis, establishing a <span class="hlt">ground</span> <span class="hlt">truth</span> for assessment purposes is often difficult. Facing this problem, the scientific community orients its efforts towards the development of objective methods for evaluation, namely by building up or simulating the missing <span class="hlt">ground</span> <span class="hlt">truth</span> for analysis. This paper focuses on the case of human pulmonary airways and develops a method 1) to simulate the <span class="hlt">ground</span> <span class="hlt">truth</span> for different pathophysiological configurations of the bronchial tree as a mesh model, and 2) to generate synthetic 3D CT images of airways associated with the simulated <span class="hlt">ground</span> <span class="hlt">truth</span>. The airway model is here built up based on the information provided by a medial axis (describing bronchus shape, subdivision geometry and local radii), which is computed from real CT data to ensure realism and matching with a patient-specific morphology. The model parameters can be further on adjusted to simulate various pathophysiological conditions of the same patient (longitudinal studies). Based on the airway mesh model, a 3D image model is synthesized by simulating the CT acquisition process. The image realism is achieved by including textural features of the surrounding pulmonary tissue which are obtained by segmentation from the same original CT data providing the airway axis. By varying the scanning simulation parameters, several 3D image models can be generated for the same airway mesh <span class="hlt">ground</span> <span class="hlt">truth</span>. Simulation results for physiological and pathological configurations are presented and discussed, illustrating the interest of such a modeling process for designing computer-aided diagnosis systems or for assessing their sensitivity, mainly for follow-up studies in asthma and COPD.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA569455','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569455"><span id="translatedtitle">Multiple-Array Detection, Association and Location of <span class="hlt">Infrasound</span> and Seismo-Acoustic Events - Utilization of <span class="hlt">Ground</span> <span class="hlt">Truth</span> Information</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-09-01</p> <p>radius) of the array, the ray was identified as an eigenray for the infrasonic phase. Of the eigenrays computed on a given day, the ray with highest...turning height was selected as a representative 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies 674 eigenray for...study along with the ray-tracing results. The refraction altitudes of each daily eigenray from the mine to the individual arrays are superimposed on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27199639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27199639"><span id="translatedtitle">Evaluation of Event-Based Algorithms for Optical Flow with <span class="hlt">Ground-Truth</span> from Inertial Measurement Sensor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rueckauer, Bodo; Delbruck, Tobi</p> <p>2016-01-01</p> <p>In this study we compare nine optical flow algorithms that locally measure the flow normal to edges according to accuracy and computation cost. In contrast to conventional, frame-based motion flow algorithms, our open-<span class="hlt">source</span> implementations compute optical flow based on address-events from a neuromorphic Dynamic Vision Sensor (DVS). For this benchmarking we created a dataset of two synthesized and three real samples recorded from a 240 × 180 pixel Dynamic and Active-pixel Vision Sensor (DAVIS). This dataset contains events from the DVS as well as conventional frames to support testing state-of-the-art frame-based methods. We introduce a new <span class="hlt">source</span> for the <span class="hlt">ground</span> <span class="hlt">truth</span>: In the special case that the perceived motion stems solely from a rotation of the vision sensor around its three camera axes, the true optical flow can be estimated using gyro data from the inertial measurement unit integrated with the DAVIS camera. This provides a <span class="hlt">ground-truth</span> to which we can compare algorithms that measure optical flow by means of motion cues. An analysis of error <span class="hlt">sources</span> led to the use of a refractory period, more accurate numerical derivatives and a Savitzky-Golay filter to achieve significant improvements in accuracy. Our pure Java implementations of two recently published algorithms reduce computational cost by up to 29% compared to the original implementations. Two of the algorithms introduced in this paper further speed up processing by a factor of 10 compared with the original implementations, at equal or better accuracy. On a desktop PC, they run in real-time on dense natural input recorded by a DAVIS camera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4842780','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4842780"><span id="translatedtitle">Evaluation of Event-Based Algorithms for Optical Flow with <span class="hlt">Ground-Truth</span> from Inertial Measurement Sensor</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rueckauer, Bodo; Delbruck, Tobi</p> <p>2016-01-01</p> <p>In this study we compare nine optical flow algorithms that locally measure the flow normal to edges according to accuracy and computation cost. In contrast to conventional, frame-based motion flow algorithms, our open-<span class="hlt">source</span> implementations compute optical flow based on address-events from a neuromorphic Dynamic Vision Sensor (DVS). For this benchmarking we created a dataset of two synthesized and three real samples recorded from a 240 × 180 pixel Dynamic and Active-pixel Vision Sensor (DAVIS). This dataset contains events from the DVS as well as conventional frames to support testing state-of-the-art frame-based methods. We introduce a new <span class="hlt">source</span> for the <span class="hlt">ground</span> <span class="hlt">truth</span>: In the special case that the perceived motion stems solely from a rotation of the vision sensor around its three camera axes, the true optical flow can be estimated using gyro data from the inertial measurement unit integrated with the DAVIS camera. This provides a <span class="hlt">ground-truth</span> to which we can compare algorithms that measure optical flow by means of motion cues. An analysis of error <span class="hlt">sources</span> led to the use of a refractory period, more accurate numerical derivatives and a Savitzky-Golay filter to achieve significant improvements in accuracy. Our pure Java implementations of two recently published algorithms reduce computational cost by up to 29% compared to the original implementations. Two of the algorithms introduced in this paper further speed up processing by a factor of 10 compared with the original implementations, at equal or better accuracy. On a desktop PC, they run in real-time on dense natural input recorded by a DAVIS camera. PMID:27199639</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A31A0033M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0033M"><span id="translatedtitle">Listening to Earthquakes with <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mucek, A. E.; Langston, C. A.</p> <p>2011-12-01</p> <p>A tripartite <span class="hlt">infrasound</span> array was installed to listen to earthquakes occurring along the Guy-Greenbrier fault in Arkansas. The active earthquake swarm is believed to be caused by deep waste water injections and will allow us to explain the mechanisms causing earthquake "booms" that have been heard during an earthquake. The array has an aperture of 50 meters and is installed next to the X301 seismograph station run by the Center for Earthquake Research and Information (CERI). This arrangement allows simultaneous recording of seismic and acoustic changes from the arrival of an earthquake. Other acoustic and seismic <span class="hlt">sources</span> that have been found include thunder from thunderstorms, gunshots, quarry explosions and hydraulic fracturing activity from the local gas wells. The duration of the experiment is from the last week of June to the last week of September 2011. During the first month and a half, seven local earthquakes were recorded, along with numerous occurrences of the other <span class="hlt">infrasound</span> <span class="hlt">sources</span>. Phase arrival times of the recorded waves allow us to estimate wave slowness and azimuth of <span class="hlt">infrasound</span> events. Using these two properties, we can determine whether earthquake "booms" occur at a site from the arrival of the P-wave or whether the earthquake "booms" occur elsewhere and travel through the atmosphere. Preliminary results show that the <span class="hlt">infrasound</span> correlates well to the ground motion during an earthquake for frequencies below 15 Hertz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JVGR..206...61J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JVGR..206...61J"><span id="translatedtitle">Volcano <span class="hlt">infrasound</span>: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Jeffrey Bruce; Ripepe, Maurizio</p> <p>2011-09-01</p> <p>Exploding volcanoes, which produce intense <span class="hlt">infrasound</span>, are reminiscent of the veritable explosion of volcano <span class="hlt">infrasound</span> papers published during the last decade. Volcano <span class="hlt">infrasound</span> is effective for tracking and quantifying eruptive phenomena because it corresponds to activity occurring near and around the volcanic vent, as opposed to seismic signals, which are generated by both surface and internal volcanic processes. As with seismology, <span class="hlt">infrasound</span> can be recorded remotely, during inclement weather, or in the dark to provide a continuous record of a volcano's unrest. Moreover, it can also be exploited at regional or global distances, where seismic monitoring has limited efficacy. This paper provides a literature overview of the current state of the field and summarizes applications of <span class="hlt">infrasound</span> as a tool for better understanding volcanic activity. Many <span class="hlt">infrasound</span> studies have focused on integration with other geophysical data, including seismic, thermal, electromagnetic radiation, and gas spectroscopy and they have generally improved our understanding of eruption dynamics. Other work has incorporated <span class="hlt">infrasound</span> into volcano surveillance to enhance capabilities for monitoring hazardous volcanoes and reducing risk. This paper aims to provide an overview of volcano airwave studies (from analog microbarometer to modern pressure transducer) and summarizes how <span class="hlt">infrasound</span> is currently used to infer eruption dynamics. It also outlines the relative merits of local and regional <span class="hlt">infrasound</span> surveillance, highlights differences between array and network sensor topologies, and concludes with mention of sensor technologies appropriate for volcano <span class="hlt">infrasound</span> study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S43D..02A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S43D..02A"><span id="translatedtitle">Recent Advances in <span class="hlt">Infrasound</span> Science for National Security Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arrowsmith, S.; Blom, P. S.; Marcillo, O. E.; Whitaker, R. W.</p> <p>2014-12-01</p> <p><span class="hlt">Infrasound</span> is sound below the frequency-threshold of human hearing, covering the frequency range from 0.01 - 20 Hz. <span class="hlt">Infrasound</span> science studies the generation, propagation, measurement, and analysis of <span class="hlt">infrasound</span>. <span class="hlt">Sources</span> of <span class="hlt">infrasound</span> include a wide variety of energetic natural and manmade phenomena that include chemical and nuclear explosions, rockets and missiles, and aircraft. The dominant factors influencing the propagation of <span class="hlt">infrasound</span> are the spatial and temporal variations in temperature, wind speed, and wind direction. In recent years, <span class="hlt">Infrasound</span> Science has experienced a renaissance due to the installation of an international monitoring system of 60 <span class="hlt">infrasound</span> arrays for monitoring the Comprehensive Nuclear Test Ban Treaty, and to the demonstrated value of regional <span class="hlt">infrasound</span> networks for both scientific and applied purposes. Furthermore, in the past decade, significant advances have been made on using measurements of <span class="hlt">infrasound</span> to invert for these properties of the atmosphere at altitudes where alternative measurement techniques are extremely costly. This presentation provides a review of recent advances in <span class="hlt">infrasound</span> science as relevant to National Security applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JVGR..256..105J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JVGR..256..105J"><span id="translatedtitle">Detecting geyser activity with <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, J. B.; Anderson, J. F.; Anthony, R. E.; Sciotto, M.</p> <p>2013-04-01</p> <p>We monitored geyser activity in the Lower Geyser Basin (LGB) of Yellowstone National Park with dual four-element microphone arrays separated by ~ 600 m. The arrays were independently used to identify incident coherent plane wave energy, then conjoint cross beam back-azimuths from the two arrays were used to precisely locate signal <span class="hlt">sources</span>. During a week in August 2011 we located repeating <span class="hlt">infrasound</span> events, peaked in energy between 1 and 10 Hz, originating from at least five independent geothermal features, including the episodically erupting Great Fountain, Fountain and Kaleidoscope Geysers, as well as periodic <span class="hlt">infrasound</span> from nearby Botryoidal and persistent sound from Firehole Spring. Although activity from nearby cone-type geysers was not detected in the <span class="hlt">infrasound</span> band up through 50 Hz, the major fountain-type geysers (i.e., with columns greater than 10 m) could be detected at several kilometers, and two minor geysers (i.e., a few meters in eruption height) could be tracked at distances up to a few hundred meters. Detection of geyser activity was especially comprehensive at night when ambient noise was low. We conclude that <span class="hlt">infrasound</span> monitoring of fountain-type geysers permits convenient tracking of geyser activity, episodicity, signal duration, energy content, and spectral content. These parameters enable objective statistical quantification of geyser behavior and changes over time that may be due to external forcing. Infrasonic study of geyser activity in an individual basin has great monitoring utility and can be reasonably accomplished with two or more distributed sensor arrays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AIPC..852...51P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..852...51P"><span id="translatedtitle">Success Stories: Data Collection And <span class="hlt">Ground</span> <span class="hlt">Truth</span> For The Portuguese Case Study (Caia Irrigation District)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perdigão, A.; Oliveira, P.; Chinita, A.; Chinita, S.; Maia, J.; Nunes, J.</p> <p>2006-08-01</p> <p>A Field Campaign has been carried on the Caia Irrigation District area pilot zone, in order to obtain <span class="hlt">ground</span> <span class="hlt">truth</span> for EO calibration and for an improved Irrigation Advisory System, owing to supply a more reliable and quick information to the water board district and to the farmer. These <span class="hlt">ground</span> <span class="hlt">truth</span> observations included weekly data on crop phenology and vegetation fraction for Maize, Sugar Beet and Tomato. The aim of the operation was to provide maps based on GIS technology of crop phenological parameters, based on methods (models and algorithms) in order to derive them from EO (for each pixel) and to obtain DEMETER products (which may involve spatial aggregation or separation). Irrigation Advisory Services using Earth Observation Technologies are important management tools, owing to improve monitoring and water management, supplying farmers with important information concerning water use in order to be in accordance with the eco-compatibility principles</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19980201635&hterms=CANOPY&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCANOPY','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19980201635&hterms=CANOPY&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DCANOPY"><span id="translatedtitle">A <span class="hlt">Ground</span> <span class="hlt">Truthing</span> Method for AVIRIS Overflights Using Canopy Absorption Spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gamon, John A.; Serrano, Lydia; Roberts, Dar A.; Ustin, Susan L.</p> <p>1996-01-01</p> <p>Remote sensing for ecological field studies requires <span class="hlt">ground</span> <span class="hlt">truthing</span> for accurate interpretation of remote imagery. However, traditional vegetation sampling methods are time consuming and hard to relate to the scale of an AVIRIS scene. The large errors associated with manual field sampling, the contrasting formats of remote and ground data, and problems with coregistration of field sites with AVIRIS pixels can lead to difficulties in interpreting AVIRIS data. As part of a larger study of fire risk in the Santa Monica Mountains of southern California, we explored a ground-based optical method of sampling vegetation using spectrometers mounted both above and below vegetation canopies. The goal was to use optical methods to provide a rapid, consistent, and objective means of "<span class="hlt">ground</span> <span class="hlt">truthing</span>" that could be related both to AVIRIS imagery and to conventional ground sampling (e.g., plot harvests and pigment assays).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28350382','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28350382"><span id="translatedtitle">A dataset of stereoscopic images and <span class="hlt">ground-truth</span> disparity mimicking human fixations in peripersonal space.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Canessa, Andrea; Gibaldi, Agostino; Chessa, Manuela; Fato, Marco; Solari, Fabio; Sabatini, Silvio P</p> <p>2017-03-28</p> <p>Binocular stereopsis is the ability of a visual system, belonging to a live being or a machine, to interpret the different visual information deriving from two eyes/cameras for depth perception. From this perspective, the <span class="hlt">ground-truth</span> information about three-dimensional visual space, which is hardly available, is an ideal tool both for evaluating human performance and for benchmarking machine vision algorithms. In the present work, we implemented a rendering methodology in which the camera pose mimics realistic eye pose for a fixating observer, thus including convergent eye geometry and cyclotorsion. The virtual environment we developed relies on highly accurate 3D virtual models, and its full controllability allows us to obtain the stereoscopic pairs together with the <span class="hlt">ground-truth</span> depth and camera pose information. We thus created a stereoscopic dataset: GENUA PESTO-GENoa hUman Active fixation database: PEripersonal space STereoscopic images and grOund truth disparity. The dataset aims to provide a unified framework useful for a number of problems relevant to human and computer vision, from scene exploration and eye movement studies to 3D scene reconstruction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5369322','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5369322"><span id="translatedtitle">A dataset of stereoscopic images and <span class="hlt">ground-truth</span> disparity mimicking human fixations in peripersonal space</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Canessa, Andrea; Gibaldi, Agostino; Chessa, Manuela; Fato, Marco; Solari, Fabio; Sabatini, Silvio P.</p> <p>2017-01-01</p> <p>Binocular stereopsis is the ability of a visual system, belonging to a live being or a machine, to interpret the different visual information deriving from two eyes/cameras for depth perception. From this perspective, the <span class="hlt">ground-truth</span> information about three-dimensional visual space, which is hardly available, is an ideal tool both for evaluating human performance and for benchmarking machine vision algorithms. In the present work, we implemented a rendering methodology in which the camera pose mimics realistic eye pose for a fixating observer, thus including convergent eye geometry and cyclotorsion. The virtual environment we developed relies on highly accurate 3D virtual models, and its full controllability allows us to obtain the stereoscopic pairs together with the <span class="hlt">ground-truth</span> depth and camera pose information. We thus created a stereoscopic dataset: GENUA PESTO—GENoa hUman Active fixation database: PEripersonal space STereoscopic images and grOund truth disparity. The dataset aims to provide a unified framework useful for a number of problems relevant to human and computer vision, from scene exploration and eye movement studies to 3D scene reconstruction. PMID:28350382</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..327..585J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..327..585J"><span id="translatedtitle"><span class="hlt">Infrasound</span> tremor from bubble burst eruptions in the viscous shallow crater lake of White Island, New Zealand, and its implications for interpreting volcanic <span class="hlt">source</span> processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jolly, Arthur; Kennedy, Ben; Edwards, Matt; Jousset, Philippe; Scheu, Bettina</p> <p>2016-11-01</p> <p>White Island volcano, New Zealand, produced two periods (January-February and July 2013) of episodic and persistent eruptions through a viscous shallow mud/sulphur pool. The eruptions included an initial hemispherical bubble burst, which was intermittently followed by an up-channel gas jet, and finally a late stage heaving of a mud/sulphur/water suspension. The late stage heave was systematically directed south-eastward as far as 30-40 m from the vent. The associated <span class="hlt">infrasound</span> time-series included harmonic tremor on permanent stations WIZ and WSRZ. Detailed inspection showed that the tremor was composed of numerous discrete double pulse events without a strong periodic event repetition. The first pulse had highly similar waveforms event-to-event and a notable distortion of the waveform period between the two <span class="hlt">infrasound</span> stations located on opposites sides from the directed eruption <span class="hlt">source</span>. The second pulse occurred about 1.5-2.5 s later and was weakly observed on station WSRZ. Where the video can be rigorously linked to the double pulse <span class="hlt">infrasound</span> signals we interpret aspects of the distinctive eruptive regimes. For this case, the regime dynamics are driven by the propagation of numerous discrete gas slugs though the shallow viscous muddy crater lake, each generating a distinct bubble burst with subsequent eruption heave and associated double pulse <span class="hlt">infrasound</span> events. The double pulse events are the <span class="hlt">source</span> of the persistent harmonic tremor having fundamental and overtone spectral frequencies but are not interpreted as related to cavity resonance or a repetitious comb function. Instead the activity is produced by a single event producing a specific two pulse <span class="hlt">source</span> time function. The observed distortion in the first pulse wave period at WIZ and WSRZ may be ascribed to a Doppler shift associated with the directivity observed in the initial jet/heave eruption process. We surmise that double pulse <span class="hlt">source</span> dynamics and directivity effects may be generically extended to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9644E..1NR','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9644E..1NR"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> and mapping capability of urban areas in large scale using GE images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramzi, Ahmed I.</p> <p>2015-10-01</p> <p>Monitoring and mapping complex urban features (e.g. roads and buildings) from remotely sensed data multispectral and hyperspectral has gained enormous research interest. Accurate <span class="hlt">ground</span> <span class="hlt">truth</span> allows for high quality assessment of classified images and to verify the produced map. <span class="hlt">Ground</span> <span class="hlt">truth</span> can be acquired from: field using the handheld Global Positioning System (GPS) device and from Images with high resolution extracted from Google Earth in additional to field. <span class="hlt">Ground</span> <span class="hlt">truth</span> or training samples could be achieved from VHR satellite images such as QuickBird, Ikonos, Geoeye-1 and Wordview images. Archived images are costly for researchers in developing countries. Images from GE with high spatial resolution are free for public and can be used directly producing large scale maps, in producing LULC mapping and training samples. Google Earth (GE) provides free access to high resolution satellite imagery, but is the quality good enough to map urban areas. Costal of the Red sea, Marsa Alam could be mapped using GE images. The main objective of this research is exploring the accuracy assessment of producing large scale maps from free Google Earth imagery and to collect <span class="hlt">ground</span> <span class="hlt">truth</span> or training samples in limited geographical extend. This research will be performed on Marsa Alam city or located on the western shore of the Red Sea, Red sea Governorate, Egypt. Marsa Alam is located 274 km south of Hurghada. The proposed methodology involves image collection taken into consideration the resolution of collected photographs which depend on the height of view. After that, image rectification using suitable rectification methods with different number and distributions of GCPs and CPs. Database and Geographic information systems (GIS) layers were created by on-screen vectorization based on the requirement of large scale maps. Attribute data have been collected from the field. The obtained results show that the planmetric accuracy of the produced map from Google Earth Images met map</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930020045&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930020045&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtruth"><span id="translatedtitle">Geographic information system for fusion and analysis of high-resolution remote sensing and <span class="hlt">ground</span> <span class="hlt">truth</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Freeman, Anthony; Dubois, Pascale; Leberl, Franz; Norikane, L.; Way, Jobea</p> <p>1991-01-01</p> <p>Viewgraphs on Geographic Information System for fusion and analysis of high-resolution remote sensing and <span class="hlt">ground</span> <span class="hlt">truth</span> data are presented. Topics covered include: scientific objectives; schedule; and Geographic Information System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRB..114.4305M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRB..114.4305M"><span id="translatedtitle">The <span class="hlt">source</span> of <span class="hlt">infrasound</span> associated with long-period events at Mount St. Helens</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matoza, Robin S.; GarcéS, Milton A.; Chouet, Bernard A.; D'Auria, Luca; Hedlin, Michael A. H.; de Groot-Hedlin, Catherine; Waite, Gregory P.</p> <p>2009-04-01</p> <p>During the early stages of the 2004-2008 Mount St. Helens eruption, the <span class="hlt">source</span> process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and <span class="hlt">source</span> configuration are considered. The simulations show that a shallow <span class="hlt">source</span> buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from the <span class="hlt">source</span> epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point <span class="hlt">source</span>. The observations therefore require a more complex <span class="hlt">source</span> process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the "valve" sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S33B2426W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S33B2426W"><span id="translatedtitle">Modeling the <span class="hlt">Infrasound</span> Acoustic Signal Generation of Underground Explosions at the <span class="hlt">Source</span> Physics Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whitaker, R. W.; Jones, K. R.; Arrowsmith, S.</p> <p>2013-12-01</p> <p>One of the primary goals of the <span class="hlt">Source</span> Physics Experiment is to improve upon and develop new physics based models for underground nuclear explosions using scaled, underground chemical explosions as proxies. Jones et. al, (AGU 2012) previously presented results describing the use of the Rayleigh integral (RI) to model the <span class="hlt">source</span> region of the SPE explosions. While these results showed that the <span class="hlt">source</span> region could be modeled using the RI, there were some complexities in the produced, synthetic waveforms that were unaccounted for when compared to the observed data. To gain insight into these complexities and to verify the results of the RI method, we used CAVEAT, a two-dimensional computational fluid dynamics, time-domain finite-difference code developed at Los Alamos National Labs (LANL). CAVEAT has been used in the solution of high speed and low speed fluid problems. While the RI uses the observed acceleration records from the 12 vertical surface accelerometers installed above ground zero, CAVEAT employs a synthetic <span class="hlt">source</span>-time function, based on the acceleration records, that varies with range and time. This model provides a velocity boundary condition at the bottom boundary of the CAVEAT computation mesh that drives the atmospheric pressure wave into the atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034982','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034982"><span id="translatedtitle">The <span class="hlt">source</span> of <span class="hlt">infrasound</span> associated with long-period events at mount St. Helens</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Matoza, R.S.; Garces, M.A.; Chouet, B.A.; D'Auria, L.; Hedlin, M.A.H.; De Groot-Hedlin, C.; Waite, G.P.</p> <p>2009-01-01</p> <p>During the early stages of the 2004-2008 Mount St. Helens eruption, the <span class="hlt">source</span> process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and <span class="hlt">source</span> configuration are considered. The simulations show that a shallow <span class="hlt">source</span> buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from , the <span class="hlt">source</span> epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point <span class="hlt">source</span>. The observations therefore require a more complex <span class="hlt">source</span> process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the "valve" sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813340P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813340P"><span id="translatedtitle">Station characteristics of the Singapore <span class="hlt">Infrasound</span> Array</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perttu, Anna; Taisne, Benoit; Caudron, Corentin; Garces, Milton; Avila Encillo, Jeffrey; Ildefonso, Sorvigenaleon</p> <p>2016-04-01</p> <p>Singapore, located in Southeast Asia, presents an ideal location for an additional regional <span class="hlt">infrasound</span> array, with diverse persistent natural and anthropogenic regional <span class="hlt">infrasound</span> <span class="hlt">sources</span>, including ~750 active or potentially active volcanoes within 4,000 kilometers. Previous studies have focused on theoretical and calculated regional signal detection capability improvement with the addition of a Singapore array. The Earth Observatory of Singapore installed a five element <span class="hlt">infrasound</span> array in northcentral Singapore in late 2014, and this station began consistent real-time data transmission mid-2015. The Singapore array uses MB2005s microbarometers and Nanometrics Taurus digitizers. Automated array processing is carried out with the INFrasonic EneRgy Nth Octave (INFERNO) energy estimation suite, and PMCC (Progressive MultiChannel Correlation). The addition of the Singapore <span class="hlt">infrasound</span> array to the existing International Monitoring System (IMS) <span class="hlt">infrasound</span> stations in the region has increased regional <span class="hlt">infrasound</span> detection capability, which is illustrated with the preliminary work on three observed meteor events of various sizes in late 2015. A meteor observed in Bangkok, Thailand in early September, 2015 was picked up by the CTBTO, however, another meteor observed in Bangkok in November was only recorded on the Singapore array. Additionally, another meteor observed over Sumatra was only recorded by one IMS station and the Singapore array. This study uses array processing and Power Spectral Density results for both the Singapore and publicly available regional IMS stations to examine station characteristics and detection capability of the Singapore array in the context of the regional IMS network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8465L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8465L"><span id="translatedtitle">Ten Years of <span class="hlt">Infrasound</span> Observation in Korea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Hee-Il; Che, Il-Young; Kim, Tae Sung</p> <p>2010-05-01</p> <p>Over the ten years after the installation of our first seismo-acoustic array station (CHNAR) in September 1999, Korea Institute of Geoscience and Mineral Resources (KIGAM) has been continuously observing <span class="hlt">infrasound</span> with an <span class="hlt">infrasound</span> array network, named KIN (Korean <span class="hlt">Infrasound</span> Network) in Korea. This network consists of seven seismo-acoustic arrays (BRDAR, KMPAR, CHNAR, YAGAR, KSGAR, ULDAR and TJIAR). The aperture size of the smallest array (KMPAR and TJIAR) is about 300m and the largest is about 1.4km. The number of acoustic gauges are between 4 (TJIAR) and 18 (YAGAR), and 1 or 5 seismometers are collocated at the center of the acoustic array. All seismic and infrasonic signals of the arrays are digitized at 40 samples/sec and transmitted to KIGAM in real time. Many interesting <span class="hlt">infrasound</span> signals associated with different kind of anthropogenic <span class="hlt">source</span> as well as natural one are detected by KIN. Ten years of seismo-acoustic data are analyzed by using PMCC program, and identified more than five thousand of infrasonic events and catalogued in our <span class="hlt">infrasound</span> database. This database is used to study characteristics of seasonally dependent propagation of the <span class="hlt">infrasound</span> wave in local scale, as well as to better understand how atmospheric condition affects the detection ratio at a specific station throughout the year. It also played a valuable role in discriminating the anthropogenic events such as the second nuclear test on 25 May 2009 in North Korea, from natural earthquakes, which is important in estimating the seismicity in Korea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4634638','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4634638"><span id="translatedtitle">A Method for Assessing <span class="hlt">Ground-Truth</span> Accuracy of the 5DCT Technique</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dou, T. H.; Thomas, D. H.; O'Connell, D.; Lamb, J.M.; Lee, P.; Low, D.A.</p> <p>2015-01-01</p> <p>Purpose To develop a technique that assesses the accuracy of the breathing phase-specific volume image generation process by patient-specific breathing motion model using the original free-breathing CT scans as <span class="hlt">ground</span> <span class="hlt">truths</span>. Methods 16 lung cancer patients underwent a previously published protocol in which 25 free-breathing fast helical CT scans were acquired with a simultaneous breathing surrogate. A patient-specific motion model was constructed based on the tissue displacements determined by a state-of-the-art deformable image registration. The first image was arbitrarily selected as the reference image. The motion model was used, along with the free-breathing phase information of the original 25 image datasets, to generate a set of deformation vector fields (DVF) that mapped the reference image to the 24 non-reference images. The high-pitch helically acquired original scans served as <span class="hlt">ground</span> <span class="hlt">truths</span> because they captured the instantaneous tissue positions during free breathing. Image similarity between the simulated and the original scans was assessed using deformable registration that evaluated the point-wise discordance throughout the lungs. Results Qualitative comparisons using image overlays showed excellent agreement between the simulated and the original images. Even large 2 cm diaphragm displacements were very well modeled, as was sliding motion across the lung-chest wall boundary. The mean error across the patient cohort was 1.15±0.37 mm, while the mean 95th percentile error was 2.47±0.78 mm. Conclusion The proposed <span class="hlt">ground</span> <span class="hlt">truth</span> based technique provided voxel-by-voxel accuracy analysis that could identify organ or tumor-specific motion modeling errors for treatment planning. Despite a large variety of breathing patterns and lung deformations during the free-breathing scanning session, the 5DCT technique was able to accurately reproduce the original helical CT scans, suggesting its applicability to a wide range of patients. PMID:26530763</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024440','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024440"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> seismic events and location capability at Degelen mountain, Kazakhstan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Trabant, C.; Thurber, C.; Leith, W.</p> <p>2002-01-01</p> <p>We utilized nuclear explosions from the Degelen Mountain sub-region of the Semipalatinsk Test Site (STS), Kazakhstan, to assess seismic location capability directly. Excellent <span class="hlt">ground</span> <span class="hlt">truth</span> information for these events was either known or was estimated from maps of the Degelen Mountain adit complex. Origin times were refined for events for which absolute origin time information was unknown using catalog arrival times, our <span class="hlt">ground</span> <span class="hlt">truth</span> location estimates, and a time baseline provided by fixing known origin times during a joint hypocenter determination (JHD). Precise arrival time picks were determined using a waveform cross-correlation process applied to the available digital data. These data were used in a JHD analysis. We found that very accurate locations were possible when high precision, waveform cross-correlation arrival times were combined with JHD. Relocation with our full digital data set resulted in a mean mislocation of 2 km and a mean 95% confidence ellipse (CE) area of 6.6 km2 (90% CE: 5.1 km2), however, only 5 of the 18 computed error ellipses actually covered the associated <span class="hlt">ground</span> <span class="hlt">truth</span> location estimate. To test a more realistic nuclear test monitoring scenario, we applied our JHD analysis to a set of seven events (one fixed) using data only from seismic stations within 40?? epicentral distance. Relocation with these data resulted in a mean mislocation of 7.4 km, with four of the 95% error ellipses covering less than 570 km2 (90% CE: 438 km2), and the other two covering 1730 and 8869 km2 (90% CE: 1331 and 6822 km2). Location uncertainties calculated using JHD often underestimated the true error, but a circular region with a radius equal to the mislocation covered less than 1000 km2 for all events having more than three observations. ?? 2002 Elsevier Science B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22098573','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22098573"><span id="translatedtitle">Reference-free <span class="hlt">ground</span> <span class="hlt">truth</span> metric for metal artifact evaluation in CT images</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kratz, Baerbel; Ens, Svitlana; Mueller, Jan; Buzug, Thorsten M.</p> <p>2011-07-15</p> <p>Purpose: In computed tomography (CT), metal objects in the region of interest introduce data inconsistencies during acquisition. Reconstructing these data results in an image with star shaped artifacts induced by the metal inconsistencies. To enhance image quality, the influence of the metal objects can be reduced by different metal artifact reduction (MAR) strategies. For an adequate evaluation of new MAR approaches a <span class="hlt">ground</span> <span class="hlt">truth</span> reference data set is needed. In technical evaluations, where phantoms can be measured with and without metal inserts, <span class="hlt">ground</span> <span class="hlt">truth</span> data can easily be obtained by a second reference data acquisition. Obviously, this is not possible for clinical data. Here, an alternative evaluation method is presented without the need of an additionally acquired reference data set. Methods: The proposed metric is based on an inherent <span class="hlt">ground</span> <span class="hlt">truth</span> for metal artifacts as well as MAR methods comparison, where no reference information in terms of a second acquisition is needed. The method is based on the forward projection of a reconstructed image, which is compared to the actually measured projection data. Results: The new evaluation technique is performed on phantom and on clinical CT data with and without MAR. The metric results are then compared with methods using a reference data set as well as an expert-based classification. It is shown that the new approach is an adequate quantification technique for artifact strength in reconstructed metal or MAR CT images. Conclusions: The presented method works solely on the original projection data itself, which yields some advantages compared to distance measures in image domain using two data sets. Beside this, no parameters have to be manually chosen. The new metric is a useful evaluation alternative when no reference data are available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AdWR...25..651Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AdWR...25..651Y"><span id="translatedtitle">Model vs. design sensitivity to the <span class="hlt">ground-truth</span> problem of rainfall observation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoo, Chulsang; Ha, Eunho; Shin, Sha-Chul</p> <p></p> <p>In this study three multi-dimensional rainfall models, the Waymire-Gupta-Rodriguez-Iturbe multi-dimensional rainfall model (WGR model) [Water Resour. Res. 20 (10) (1984) 1453], the noise forced diffusive rainfall model (NFD model) [J. Atmos. Ocean Technol. 6 (1989) 985] and the Yoo-Valdes-North model (YVN model) [Water Resour. Res. 32 (7) (1996) 2175], are compared with their applications to the <span class="hlt">ground-truth</span> problem to capture the sensor bias using multiple raingauges. All the model parameters used are those estimated tuned to the GATE by Valdes et al. [J. Geophys. Res. (Atmos.) 95 (D3) (1990) 2101], North and Nakamoto [J. Atmos. Ocean Technol. 6 (1989) 985] and Yoo et al. [Water Resour. Res. 32 (7) (1996) 2175], respectively, and the root mean square errors (RMSEs) for each model are estimated to compare. The difference among models can be seen easily from the comparison of their spectra, which, in turn, affects the RMSEs for the <span class="hlt">ground-truth</span> problem. Two conclusions could be deduced from the results of the study: (1) The rainfall model is the more crucial factor for the <span class="hlt">ground-truth</span> problem than the <span class="hlt">ground-truth</span> design. That is, the design factors, such as the number of raingauges, the size of the field of view (FOV), and the distance between the first and the last raingauges, were found to be much less sensitive to the RMSEs than the model itself. For example, the RMSEs estimated for a model could be more than twice of another model's, which could result in more than four times of satellite observations required to capture the sensor bias. However, twice the number of raingauges, twice the size of the FOV, or twice the length between the first and the last raingauges resulted in less than 20% difference of the RMSEs. (2) The model sensitivity is much higher than the parameter sensitivity to the RMSEs. For example, just about 25% difference of the RMSEs could be expected even when applying the NFD model parameters 100% bigger or smaller. Considering that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760009510','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760009510"><span id="translatedtitle">Soil moisture <span class="hlt">ground</span> <span class="hlt">truth</span>, Lafayette, Indiana, site; St. Charles Missouri, site; Centralia, Missouri, site</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.</p> <p>1975-01-01</p> <p>The soil moisture <span class="hlt">ground-truth</span> measurements and ground-cover descriptions taken at three soil moisture survey sites located near Lafayette, Indiana; St. Charles, Missouri; and Centralia, Missouri are given. The data were taken on November 10, 1975, in connection with airborne remote sensing missions being flown by the Environmental Research Institute of Michigan under the auspices of the National Aeronautics and Space Administration. Emphasis was placed on the soil moisture in bare fields. Soil moisture was sampled in the top 0 to 1 in. and 0 to 6 in. by means of a soil sampling push tube. These samples were then placed in plastic bags and awaited gravimetric analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890045478&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890045478&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle">TRMM <span class="hlt">ground</span> <span class="hlt">truth</span> in a monsoon environment - Darwin, Australia. [Tropical Rainfall Measuring Mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keenan, T. D.; Holland, G. J.; Manton, M. J.; Simpson, J.</p> <p>1988-01-01</p> <p>A <span class="hlt">ground</span> <span class="hlt">truth</span> station for the Tropical Rainfall Measuring Mission (TRMM) is described. The station is situated in Darwin, Australia in a monsoon environment typical for Southeast Asia. The climatological features of the site, and the Darwin observational program are examined. The instruments and operations at the station are discussed, including a Doppler radar making full upper tropospheric soundings every 12 hrs and wind soundings every 6 hrs, and a mesoscale raingauge and surface observing network operating continuously through the summer monsoon seasons. The spatial and temporal characteristics of rainfall in the area and an outline of the research objectives of the program are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21335879','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21335879"><span id="translatedtitle">Computed tomography as <span class="hlt">ground</span> <span class="hlt">truth</span> for stereo vision measurements of skin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vanberlo, Amy M; Campbell, Aaron R; Ellis, Randy E</p> <p>2011-01-01</p> <p>Although dysesthesia is a common surgical complication, there is no accepted method for quantitatively tracking its progression. To address this, two types of computer vision technologies were tested in a total of four configurations. Surface regions on plastic models of limbs were delineated with colored tape, imaged, and compared with computed tomography scans. The most accurate system used visually projected texture captured by a binocular stereo camera, capable of measuring areas to within 3.4% of the <span class="hlt">ground-truth</span> areas. This simple, inexpensive technology shows promise for postoperative monitoring of dysesthesia surrounding surgical scars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760021545','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760021545"><span id="translatedtitle">Snowpack <span class="hlt">ground</span> <span class="hlt">truth</span>: Radar test site, Steamboat Springs, Colorado, 8-16 April 1976</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Howell, S.; Jones, E. B.; Leaf, C. F.</p> <p>1976-01-01</p> <p><span class="hlt">Ground-truth</span> data taken at Steamboat Springs, Colorado is presented. Data taken during the period April 8, 1976 - April 16, 1976 included the following: (1) snow depths and densities at selected locations (using a Mount Rose snow tube); (2) snow pits for temperature, density, and liquid water determinations using the freezing calorimetry technique and vertical layer classification; (3) snow walls were also constructed of various cross sections and documented with respect to sizes and snow characteristics; (4) soil moisture at selected locations; and (5) appropriate air temperature and weather data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920073185&hterms=K-12+education&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DK-12%2Beducation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920073185&hterms=K-12+education&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DK-12%2Beducation"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Studies - A hands-on environmental science program for students, grades K-12</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Katzenberger, John; Chappell, Charles R.</p> <p>1992-01-01</p> <p>The paper discusses the background and the objectives of the <span class="hlt">Ground</span> <span class="hlt">Truth</span> Studies (GTSs), an activity-based teaching program which integrates local environmental studies with global change topics, utilizing remotely sensed earth imagery. Special attention is given to the five key concepts around which the GTS programs are organized, the pilot program, the initial pilot study evaluation, and the GTS Handbook. The GTS Handbook contains a primer on global change and remote sensing, aerial and satellite images, student activities, glossary, and an appendix of reference material. Also described is a K-12 teacher training model. International participation in the program is to be initiated during the 1992-1993 school year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJAEO..38..115M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJAEO..38..115M"><span id="translatedtitle">Methods for improving accuracy and extending results beyond periods covered by traditional <span class="hlt">ground-truth</span> in remote sensing classification of a complex landscape</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mueller-Warrant, George W.; Whittaker, Gerald W.; Banowetz, Gary M.; Griffith, Stephen M.; Barnhart, Bradley L.</p> <p>2015-06-01</p> <p>Successful development of approaches to quantify impacts of diverse landuse and associated agricultural management practices on ecosystem services is frequently limited by lack of historical and contemporary landuse data. We hypothesized that <span class="hlt">ground</span> <span class="hlt">truth</span> data from one year could be used to extrapolate previous or future landuse in a complex landscape where cropping systems do not generally change greatly from year to year because the majority of crops are established perennials or the same annual crops grown on the same fields over multiple years. Prior to testing this hypothesis, it was first necessary to classify 57 major landuses in the Willamette Valley of western Oregon from 2005 to 2011 using normal same year <span class="hlt">ground-truth</span>, elaborating on previously published work and traditional <span class="hlt">sources</span> such as Cropland Data Layers (CDL) to more fully include minor crops grown in the region. Available remote sensing data included Landsat, MODIS 16-day composites, and National Aerial Imagery Program (NAIP) imagery, all of which were resampled to a common 30 m resolution. The frequent presence of clouds and Landsat7 scan line gaps forced us to conduct of series of separate classifications in each year, which were then merged by choosing whichever classification used the highest number of cloud- and gap-free bands at any given pixel. Procedures adopted to improve accuracy beyond that achieved by maximum likelihood pixel classification included majority-rule reclassification of pixels within 91,442 Common Land Unit (CLU) polygons, smoothing and aggregation of areas outside the CLU polygons, and majority-rule reclassification over time of forest and urban development areas. Final classifications in all seven years separated annually disturbed agriculture, established perennial crops, forest, and urban development from each other at 90 to 95% overall 4-class validation accuracy. In the most successful use of subsequent year <span class="hlt">ground-truth</span> data to classify prior year landuse, an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S41B4490W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S41B4490W"><span id="translatedtitle">Recent <span class="hlt">Infrasound</span> Calibration Activity at Los Alamos</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whitaker, R. W.; Marcillo, O. E.</p> <p>2014-12-01</p> <p>Absolute <span class="hlt">infrasound</span> sensor calibration is necessary for estimating <span class="hlt">source</span> sizes from measured waveforms. This can be an important function in treaty monitoring. The Los Alamos <span class="hlt">infrasound</span> calibration chamber is capable of absolute calibration. Early in 2014 the Los Alamos <span class="hlt">infrasound</span> calibration chamber resumed operations in its new location after an unplanned move two years earlier. The chamber has two <span class="hlt">sources</span> of calibration signals. The first is the original mechanical piston, and the second is a CLD Dynamics Model 316 electro-mechanical unit that can be digitally controlled and provide a richer set of calibration options. During 2008-2010 a number of upgrades were incorporated for improved operation and recording. In this poster we give an overview of recent chamber work on sensor calibrations, calibration with the CLD unit, some measurements with different porous hoses and work with impulse <span class="hlt">sources</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.B51G0486D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.B51G0486D"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truthing</span> for methane hotspots at Railroad Valley, NV - application to Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Detweiler, A. M.; Kelley, C. A.; Bebout, B.; McKay, C. P.; DeMarines, J.; Yates, E. L.; Iraci, L. T.</p> <p>2011-12-01</p> <p>.7%. Temperature and relative humidity sensors were placed in the playa at 5, 20, and 30 cm below the surface. Since the relative humidity neared 100% (down to 20 cm below the surface), high enough to support microbial life, the observed absence of methane production in the playa itself is likely due to the low POC content, compared to other methane-producing environments. The spatial distribution of methane in combination with the spectral reflectance at the RRV dry lakebed makes it a good Mars analog. The <span class="hlt">ground</span> <span class="hlt">truthing</span> and satellite calibration work accomplished at RRV is a good exercise in preparation to identifying the origins of methane observed in the atmosphere of Mars during the upcoming 2012 Mars Science Laboratory and 2016 ExoMars Trace Gas Orbiter missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/805807','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/805807"><span id="translatedtitle">Assessment of MTI Water Temperature Thermal Discharge Retrievals with <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kurzeja, R.J.</p> <p>2002-12-06</p> <p>Surface water temperatures calculated from Multispectral Thermal Imager (MTI) brightness temperatures and the robust retrieval algorithm, developed by the Los Alamos National Laboratory (LANL), are compared with <span class="hlt">ground</span> <span class="hlt">truth</span> measurements at a mid-latitude cold-water site along the Atlantic coast near Plymouth, MA. In contrast to the relative uniformity of the sea-surface temperature in the open ocean the water temperature near Pilgrim exhibits strong spatial gradients and temporal variability. This made it critical that all images be accurately registered in order to extract temperature values at the six buoy locations. Sixteen images during a one-year period from August 2000 to July 2001 were selected for the study. The RMS error of Pilgrim water temperature is about 3.5 C for the 4 buoys located in open water. The RMS error of the combined temperatures from 3 of the open-water buoys is 2.8 C. The RMS error includes errors in the <span class="hlt">ground</span> <span class="hlt">truth</span>. The magnitude of this error is estimated to range between 0.8 and 2.3 C. The two main components of this error are warm-layer effect and spatial variability. The actual error in the MTI retrievals for Pilgrim daytime conditions is estimated to be between 2.7 and 3.4 C for individual buoys and between 1.7 and 2.7 C for the combined open-water buoys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ISPAn..I4..157M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ISPAn..I4..157M"><span id="translatedtitle">Field <span class="hlt">Ground</span> <span class="hlt">Truthing</span> Data Collector - a Mobile Toolkit for Image Analysis and Processing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meng, X.</p> <p>2012-07-01</p> <p>Field <span class="hlt">Ground</span> <span class="hlt">Truthing</span> Data Collector is one of the four key components of the NASA funded ICCaRS project, being developed in Southeast Michigan. The ICCaRS <span class="hlt">ground</span> <span class="hlt">truthing</span> toolkit entertains comprehensive functions: 1) Field functions, including determining locations through GPS, gathering and geo-referencing visual data, laying out ground control points for AEROKAT flights, measuring the flight distance and height, and entering observations of land cover (and use) and health conditions of ecosystems and environments in the vicinity of the flight field; 2) Server synchronization functions, such as, downloading study-area maps, aerial photos and satellite images, uploading and synchronizing field-collected data with the distributed databases, calling the geospatial web services on the server side to conduct spatial querying, image analysis and processing, and receiving the processed results in field for near-real-time validation; and 3) Social network communication functions for direct technical assistance and pedagogical support, e.g., having video-conference calls in field with the supporting educators, scientists, and technologists, participating in Webinars, or engaging discussions with other-learning portals. This customized software package is being built on Apple iPhone/iPad and Google Maps/Earth. The technical infrastructures, data models, coupling methods between distributed geospatial data processing and field data collector tools, remote communication interfaces, coding schema, and functional flow charts will be illustrated and explained at the presentation. A pilot case study will be also demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9786E..22S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9786E..22S"><span id="translatedtitle">Phantom-based <span class="hlt">ground-truth</span> generation for cerebral vessel segmentation and pulsatile deformation analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schetelig, Daniel; Säring, Dennis; Illies, Till; Sedlacik, Jan; Kording, Fabian; Werner, René</p> <p>2016-03-01</p> <p>Hemodynamic and mechanical factors of the vascular system are assumed to play a major role in understanding, e.g., initiation, growth and rupture of cerebral aneurysms. Among those factors, cardiac cycle-related pulsatile motion and deformation of cerebral vessels currently attract much interest. However, imaging of those effects requires high spatial and temporal resolution and remains challenging { and similarly does the analysis of the acquired images: Flow velocity changes and contrast media inflow cause vessel intensity variations in related temporally resolved computed tomography and magnetic resonance angiography data over the cardiac cycle and impede application of intensity threshold-based segmentation and subsequent motion analysis. In this work, a flow phantom for generation of <span class="hlt">ground-truth</span> images for evaluation of appropriate segmentation and motion analysis algorithms is developed. The acquired <span class="hlt">ground-truth</span> data is used to illustrate the interplay between intensity fluctuations and (erroneous) motion quantification by standard threshold-based segmentation, and an adaptive threshold-based segmentation approach is proposed that alleviates respective issues. The results of the phantom study are further demonstrated to be transferable to patient data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51C2692M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2692M"><span id="translatedtitle">Overview of IMS <span class="hlt">infrasound</span> station and engineering projects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marty, J.; Doury, B.; Kramer, A.; Martysevich, P.</p> <p>2015-12-01</p> <p>The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBTO) has a continuous interest in enhancing its capability in acoustic <span class="hlt">source</span> detection, localization and characterization. The <span class="hlt">infrasound</span> component of the International Monitoring System (IMS) constitutes the only worldwide ground-based <span class="hlt">infrasound</span> network. It consists of sixty stations, among which forty-eight are already certified and continuously transmit data to the International Data Centre (IDC) in Vienna, Austria. Each <span class="hlt">infrasound</span> station is composed of an array of <span class="hlt">infrasound</span> sensors capable of measuring micro-pressure changes produced at ground level by infrasonic waves. The characteristics of infrasonic waves are computed in near real-time by IDC automatic detection software and are used as an input to IDC <span class="hlt">source</span> categorization and localization algorithms. The PTS is continuously working towards the completion and sustainment of the IMS <span class="hlt">infrasound</span> network. The objective of this presentation is to review the main activities performed in the IMS <span class="hlt">infrasound</span> network over the last five years. This includes construction, installation, certification, major upgrade and revalidation activities. Major technology development projects to improve the reliability and robustness of IMS <span class="hlt">infrasound</span> stations as well as their compliance with IMS Operational Manual requirements will also be presented. This includes advances in array geometry, wind noise reduction, system calibration, meteorological data as well as power and communication infrastructures. Finally the impact of all these changes on the overall detection capability of the IMS <span class="hlt">infrasound</span> network will be highlighted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRE..118..369I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRE..118..369I"><span id="translatedtitle">Development, importance, and effect of a <span class="hlt">ground</span> <span class="hlt">truth</span> correction for the Moon Mineralogy Mapper reflectance data set</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isaacson, Peter J.; Petro, Noah E.; Pieters, Carle M.; Besse, Sebastien; Boardman, Joseph W.; Clark, Roger N.; Green, Robert O.; Lundeen, Sarah; Malaret, Erick; McLaughlin, Stephanie; Sunshine, Jessica M.; Taylor, Lawrence A.</p> <p>2013-03-01</p> <p>We evaluate the effect and importance of a <span class="hlt">ground</span> <span class="hlt">truth</span> correction for the Moon Mineralogy Mapper (M3) level 2 (reflectance) data set. This correction is derived from extensive laboratory characterizations of mature feldspathic lunar soils and is designed to improve the accuracy of 1 µm absorption features in M3 reflectance data. To evaluate the correction, the band strength across a subset of the feldspathic highlands terrane (FHT) is analyzed with M3 imaging spectroscopy data. Using M3 reflectance data and derived products, we find significant differences in band strength and shape between M3 observations collected over identical terrain but under different observational and operational conditions. The <span class="hlt">ground</span> <span class="hlt">truth</span> correction minimizes these differences in 1 µm band strengths and also brings the 1 µm band strengths measured with M3 data into closer agreement with laboratory measurements of lunar soil samples. Although the FHT region studied was found to have very low band strengths, the M3 <span class="hlt">ground</span> <span class="hlt">truth</span> correction results in overall stronger absorption features for all mature soils relative to uncorrected level 2 (reflectance) data for the same region. These differences between M3 data collected under different operational conditions and the effects of the <span class="hlt">ground</span> <span class="hlt">truth</span> correction, while minor in appearance, can have significant implications for interpretations of any regional soil analyses with M3 data that rely on absolute 1 µm absorption feature strength. The M3 <span class="hlt">ground</span> <span class="hlt">truth</span> correction corrects only wavelengths below ~1500 nm, and comparisons between corrected and uncorrected wavelengths must be done with caution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27830168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27830168"><span id="translatedtitle">A large dataset of synthetic SEM images of powder materials and their <span class="hlt">ground</span> <span class="hlt">truth</span> 3D structures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>DeCost, Brian L; Holm, Elizabeth A</p> <p>2016-12-01</p> <p>This data article presents a data set comprised of 2048 synthetic scanning electron microscope (SEM) images of powder materials and descriptions of the corresponding 3D structures that they represent. These images were created using open <span class="hlt">source</span> rendering software, and the generating scripts are included with the data set. Eight particle size distributions are represented with 256 independent images from each. The particle size distributions are relatively similar to each other, so that the dataset offers a useful benchmark to assess the fidelity of image analysis techniques. The characteristics of the PSDs and the resulting images are described and analyzed in more detail in the research article "Characterizing powder materials using keypoint-based computer vision methods" (B.L. DeCost, E.A. Holm, 2016) [1]. These data are freely available in a Mendeley Data archive "A large dataset of synthetic SEM images of powder materials and their <span class="hlt">ground</span> <span class="hlt">truth</span> 3D structures" (B.L. DeCost, E.A. Holm, 2016) located at http://dx.doi.org/10.17632/tj4syyj9mr.1[2] for any academic, educational, or research purposes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CSR...138...65B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CSR...138...65B"><span id="translatedtitle">A multivariate analytical method to characterize sediment attributes from high-frequency acoustic backscatter and <span class="hlt">ground-truthing</span> data (Jade Bay, German North Sea coast)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Biondo, Manuela; Bartholomä, Alexander</p> <p>2017-04-01</p> <p>One of the burning issues on the topic of acoustic seabed classification is the lack of solid, repeatable, statistical procedures that can support the verification of acoustic variability in relation to seabed properties. Acoustic sediment classification schemes often lead to biased and subjective interpretation, as they ultimately aim at an oversimplified categorization of the seabed based on conventionally defined sediment types. However, grain size variability alone cannot be accounted for acoustic diversity, which will be ultimately affected by multiple physical processes, scale of heterogeneity, instrument settings, data quality, image processing and segmentation performances. Understanding and assessing the weight of all of these factors on backscatter is a difficult task, due to the spatially limited and fragmentary knowledge of the seabed from of direct observations (e.g. grab samples, cores, videos). In particular, large-scale mapping requires an enormous availability of <span class="hlt">ground-truthing</span> data that is often obtained from heterogeneous and multidisciplinary <span class="hlt">sources</span>, resulting into a further chance of misclassification. Independently from all of these limitations, acoustic segments still contain signals for seabed changes that, if appropriate procedures are established, can be translated into meaningful knowledge. In this study we design a simple, repeatable method, based on multivariate procedures, with the scope to classify a 100 km2, high-frequency (450 kHz) sidescan sonar mosaic acquired in the year 2012 in the shallow upper-mesotidal inlet of the Jade Bay (German North Sea coast). The tool used for the automated classification of the backscatter mosaic is the QTC SWATHVIEWTMsoftware. The <span class="hlt">ground-truthing</span> database included grab sample data from multiple <span class="hlt">sources</span> (2009-2011). The method was designed to extrapolate quantitative descriptors for acoustic backscatter and model their spatial changes in relation to grain size distribution and morphology. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.U32B..03E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.U32B..03E"><span id="translatedtitle">Implications from Meteoric and Volcanic <span class="hlt">Infrasound</span> Measured in the Netherlands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evers, L.</p> <p>2003-12-01</p> <p><span class="hlt">Infrasound</span> observations started in the Netherlands in 1986. Since then, several array configurations and instruments have been developed, tested and made operational. Currently, three <span class="hlt">infrasound</span> arrays are continuously measuring <span class="hlt">infrasound</span> with in-house developed microbarometers. The array apertures vary from 30 to 1500 meters and the number of instruments from 6 to 16 microbarometers. The inter-array distance ranges from 50 up to 150 km. This dense network of <span class="hlt">infrasound</span> arrays is used to distinguish between earthquakes and <span class="hlt">sources</span> in the atmosphere. Sonic booms, for example, can be experienced in the same manner as small (gas induced) earthquakes. Furthermore, Comprehensive Nuclear-Test-Ban Treaty (CTBT) related research is done. Meteors are one of the few natural impulsive <span class="hlt">sources</span> generating energy in kT TNT equivalent range. Therefore, the study of meteors is essential to the CTBT where <span class="hlt">infrasound</span> is applied as monitoring technique. Studies of meteors in the Netherlands have shown the capability of <span class="hlt">infrasound</span> to trace a meteor through the stratosphere. The propagation of <span class="hlt">infrasound</span> is in first order dependent on the wind and temperature structure of the atmosphere. The meteor's path could be reconstructed by using ECMWF atmospheric models for wind and temperature. The results were compared to visual observations, confirming the location, direction and reported origin time. The accuracy of the localization mainly depends on the applied atmospheric model and array resolution. Successfully applying <span class="hlt">infrasound</span> depends on the array configuration that should be based on the -frequency depend- spatial coherence of the signals of interest. The array aperture and inter-element distance will play a decisive role in detecting low signal-to-noise ratios. This is shown by results from studies on volcanic <span class="hlt">infrasound</span> from Mt. Etna (Italy) detected in the Netherlands. Sub-array processing on the 16 element array revealed an increased detectability of <span class="hlt">infrasound</span> for small</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S11A1933M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S11A1933M"><span id="translatedtitle"><span class="hlt">Infrasound</span> Studies of Alaskan Volcanoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McNutt, S. R.; Arnoult, K.; Szuberla, C.; Olson, J. V.; Wilson, C. R.</p> <p>2010-12-01</p> <p><span class="hlt">Infrasound</span> has been used to study a number of Alaskan volcanic eruptions over the last 15 years. Arrays include the I53US array of 8 sensors in Fairbanks installed in 2002 under the CTBT umbrella; an array of 4 sensors installed at Okmok Volcano in summer 2010 by the Alaska Volcano Observatory (AVO); and a 6-sensor array installed in Dillingham in September 2010 by the UAF <span class="hlt">Infrasound</span> Group. Individual sensors have been installed by AVO at Pavlof (1996), Shishaldin (1997), Augustine (2006), Fourpeaked (2006), and Redoubt (2009) volcanoes. These have been especially valuable because they provide precise <span class="hlt">source</span> timing and signal strength that allow the correct identification of atmospheric paths. Small volcanic explosions have been recorded at local stations only for Pavlof, Shishaldin and Fourpeaked volcanoes. The more interesting large explosive eruptions have been recorded on both local stations and arrays from eruptions at Augustine in 2006 (13 events), Fourpeaked in 2006 (2 events), Cleveland in 2007 (1 event), Okmok in 2008 (1 sustained event), Kasatochi in 2008 (5 events), and Redoubt in 2009 (over 30 events). Pressures up to 6 Pa have been recorded for the largest Redoubt event at a distance of 547 km from the array, and 1.2 Pa for the largest Kasatochi event at a distance of 2104 km. We determined reduced pressures (equivalent pressure at 1 km assuming 1/r decay) and find that Kasatochi exceeds 2500 Pa and Redoubt 1600 Pa. The smaller explosive eruptions at Augustine yield reduced pressures of 40 to 300 Pa. There is reasonable correlation between measured pressures and signal durations and the ash cloud heights and tephra volumes, hence the <span class="hlt">infrasound</span> data are useful for hazard assessment. However, the long travel times (3 sec per km) suggest that <span class="hlt">infrasound</span> array data arrive too late for primary detection but are good for estimating other attributes such as size. <span class="hlt">Infrasound</span> data may also be combined with seismic data to determine the partitioning of energy</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880010481','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880010481"><span id="translatedtitle">Design of the primary pre-TRMM and TRMM <span class="hlt">ground</span> <span class="hlt">truth</span> site</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garstang, Michael</p> <p>1988-01-01</p> <p>The primary objective of the Tropical Rain Measuring Mission (TRMM) were to: integrate the rain gage measurements with radar measurements of rainfall using the KSFC/Patrick digitized radar and associated rainfall network; delineate the major rain bearing systems over Florida using the Weather Service reported radar/rainfall distributions; combine the integrated measurements with the delineated rain bearing systems; use the results of the combined measurements and delineated rain bearing systems to represent patterns of rainfall which actually exist and contribute significantly to the rainfall to test sampling strategies and based on the results of these analyses decide upon the <span class="hlt">ground</span> <span class="hlt">truth</span> network; and complete the design begun in Phase 1 of a multi-scale (space and time) surface observing precipitation network centered upon KSFC. Work accomplished and in progress is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900043102&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900043102&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle">The <span class="hlt">ground</span> <span class="hlt">truth</span> analysis of rain gauge data for the TRMM project. [Tropical Rainfall Measuring Mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kowalewsky, Karen J.; Thiele, Otto</p> <p>1989-01-01</p> <p>As a part of the Tropical Rainfall Measuring Missioin (TRMM) <span class="hlt">ground</span> <span class="hlt">truth</span> program to determine the diurnal variability of the area wide rain rates, the rain rate PDFs, and their effect on the area integral algorithm, rain rate data have been collected from a network of gages located in the area near the Cape Canaveral and Kennedy Space Center, in the period beginning in September 1987. In the preliminary statistical analysis, based on the rain rates derived from the eleven gages, the seasonal diurnal rainfall and network averaged rain rates are determined. The analysis was performed in two steps: determination of the hourly and daily rain accumulations and rain rates; and computation of the fraction of hourly and daily rain rates that exceed a particular threshold, and analysis of the hourly and daily rain rate PDFs for the network. The results indicate that there are diurnal and seasonal variations in the components which determine the network rain rate PDFs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160008877','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160008877"><span id="translatedtitle">Comparing Eyewitness-Derived Trajectories of Bright Meteors to <span class="hlt">Ground</span> <span class="hlt">Truth</span> Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moser, D. E.</p> <p>2016-01-01</p> <p>The NASA Meteoroid Environment Office is a US government agency tasked with analyzing meteors of public interest. When queried about a meteor observed over the United States, the MEO must respond with a characterization of the trajectory, orbit, and size within a few hours. If the event is outside meteor network coverage and there is no imagery recorded by the public, a timely assessment can be difficult if not impossible. In this situation, visual reports made by eyewitnesses may be the only resource available. This has led to the development of a tool to quickly calculate crude meteor trajectories from eyewitness reports made to the American Meteor Society. A description of the tool, example case studies, and a comparison to <span class="hlt">ground</span> <span class="hlt">truth</span> data observed by the NASA All Sky Fireball Network are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950002611&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950002611&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> measurement for the analysis of airborne SAR data recorded over Oberpfaffenhofen, FRG, 1989</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bayer, T.; Wieneke, F.; Winter, R.</p> <p>1990-01-01</p> <p>As a preliminary investigation to the joint multiparameter SIR-C/X-SAR shuttle experiment of NASA/JPL (USA), DLR (FRG), and PSN (Italy) which is scheduled for the year 1992 an airborne SAR campaign was conducted over Oberpfaffenhofen, FRG, in August 1989. Primarily this campaign was planned to test and verify equipment and algorithms developed at the DLR to calibrate multifrequency polarimetric SAR data. Oberpfaffenhofen is designated as one of the super test sites for the SIR-C/X-SAR experiment which will be imaged under all circumstances except severe mission errors. A super test site drives radar parameters and look directions and the recorded SAR data will be calibrated. In addition ancillary data will be available for the site. During the airborne STAR campaign conducted in the week of August 14th 1989 various sensor types were used to record remote sensing data over the calibration test site and its vicinity: the polarimetric DC-8 JPL-SAR (P-, L-, C-band), the DLR airborne SAR (C-, X-band), color infrared aerial photography (DLR), and the truck-mounted scatterometer (C- and X-band) of the Institute for Navigation, University of Stuttgart (INS). Because of this variety of different sensor types used and out of the fact that sufficiently large forested and agriculturally used areas were planned to be covered by these sensors, the interest of several German research groups involved in investigations concerning SAR land applications arose. The following groups carried out different <span class="hlt">ground-truth</span> measurements: University of Bonn, Institute for plant cultivation (plant morphology and moisture content); University of Braunschweig, Institute for Geography (soil moisture and surface roughness); University of Freiburg, Institute for Geography (dielectric soil properties, landuse); and University of Munich, Institute for Geography (landuse inventory, plant, surface, and soil parameters). This paper presents the joint <span class="hlt">ground</span> <span class="hlt">truth</span> activities of the Institute for Geography</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22075810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22075810"><span id="translatedtitle">Towards a repository for standardized medical image and signal case data annotated with <span class="hlt">ground</span> <span class="hlt">truth</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deserno, Thomas M; Welter, Petra; Horsch, Alexander</p> <p>2012-04-01</p> <p>Validation of medical signal and image processing systems requires quality-assured, representative and generally acknowledged databases accompanied by appropriate reference (<span class="hlt">ground</span> <span class="hlt">truth</span>) and clinical metadata, which are composed laboriously for each project and are not shared with the scientific community. In our vision, such data will be stored centrally in an open repository. We propose an architecture for a standardized case data and <span class="hlt">ground</span> <span class="hlt">truth</span> information repository supporting the evaluation and analysis of computer-aided diagnosis based on (a) the Reference Model for an Open Archival Information System (OAIS) provided by the NASA Consultative Committee for Space Data Systems (ISO 14721:2003), (b) the Dublin Core Metadata Initiative (DCMI) Element Set (ISO 15836:2009), (c) the Open Archive Initiative (OAI) Protocol for Metadata Harvesting, and (d) the Image Retrieval in Medical Applications (IRMA) framework. In our implementation, a portal bunches all of the functionalities that are needed for data submission and retrieval. The complete life cycle of the data (define, create, store, sustain, share, use, and improve) is managed. Sophisticated search tools make it easier to use the datasets, which may be merged from different providers. An integrated history record guarantees reproducibility. A standardized creation report is generated with a permanent digital object identifier. This creation report must be referenced by all of the data users. Peer-reviewed e-publishing of these reports will create a reputation for the data contributors and will form de-facto standards regarding image and signal datasets. Good practice guidelines for validation methodology complement the concept of the case repository. This procedure will increase the comparability of evaluation studies for medical signal and image processing methods and applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.4411L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4411L"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> and detection threshold from WWII naval clean-up in Denmark</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Larsen, Tine B.; Dahl-Jensen, Trine; Voss, Peter</p> <p>2013-04-01</p> <p>The sea bed below the Danish territorial waters is still littered with unexploded mines and other ammunition from World War II. The mines were air dropped by the RAF and the positions of the mines are unknown. As the mines still pose a potential threat to fishery and other marine activities, the Admiral Danish Fleet under the Danish Navy searches for the mines and destroy them by detonation, where they are found. The largest mines destroyed in this manner in 2012 are equivalent to 800 kg TNT each. The Seismological Service at the National Geological Survey of Denmark and Greenland is notified by the navy when ammunition in excess of 100 kg TNT is detonated. The notifications include information about position, detonation time and the estimated amount of explosives. The larger explosions are clearly registered not only on the Danish seismographs, but also on seismographs in the neighbouring countries. This includes the large seismograph arrays in Norway, Sweden, and Finland. Until recently the information from the Danish navy was only utilized to rid the Danish earthquake catalogue of explosions. But the high quality information provided by the navy enables us to use these <span class="hlt">ground</span> <span class="hlt">truth</span> events to assess the quality of our earthquake catalogue. The mines are scattered though out the Danish territorial waters, thus we can use the explosions to test the accuracy of the determined epicentres in all parts of the country. E.g. a detonation of 135 kg in Begstrup Vig in the central part of Denmark was located using Danish, Norwegian and Swedish stations with an accuracy of less than 2 km from <span class="hlt">ground</span> <span class="hlt">truth</span>. A systematic study of the explosions will sharpen our understanding of the seismicity in Denmark, and result in a more detailed understanding of the detection threshold. Furthermore the study will shed light on the sensitivity of the network to various seismograph outages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S43D..03J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S43D..03J"><span id="translatedtitle">Spall Effects on <span class="hlt">Infrasound</span> Generation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, K. R.; Rodgers, A. J.; Whitaker, R. W.; Ezzedine, S. M.; Vorobiev, O.</p> <p>2014-12-01</p> <p>Spall effects from buried explosions are seen in near-<span class="hlt">source</span> surface accelerations and depend on explosion yield, emplacement depth-of-burial and material strength. Investigations of <span class="hlt">infrasound</span> from buried explosions have shown how atmospheric overpressure can be derived from surface acceleration through application of the Rayleigh Integral (Bannister, 1980). Recently, underground chemical explosions as part of the <span class="hlt">Source</span> Physics Experiment (SPE) at the Nevada National Security Site (NNSS) have been shown to generate spall signatures in local-distance <span class="hlt">infrasound</span> (Jones et al. 2014). We are investigating the effects of spall on <span class="hlt">infrasound</span> generation using two approaches. The first approach uses the Rayleigh integral to compute overpressures for buried explosions from synthetic vertical acceleration data at surface ground zero. To obtain the synthetic surface accelerations we use reported models from nuclear explosion studies and systematically vary parameters such as the spall duration, depth of burial and magnitude. The effect on the resulting acoustic waveform shape will be investigated. The second method uses a hydrodynamic approach to more fully characterize the varied parameters to produce the acoustic waveforms. As the spall decreases we find that the acoustic waveform shape changes dramatically. This waveform signature may provide diagnostics on the explosive <span class="hlt">source</span> and may be a useful metric for underground explosion monitoring. This work was done under award number DE-AC52-06NA25946. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APS..MAR.H3002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..MAR.H3002B"><span id="translatedtitle">Global <span class="hlt">Infrasound</span> Monitoring of the Atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bass, Henry</p> <p>2003-03-01</p> <p>As a signatory to the Comprehensive Nuclear Test Ban Treaty (CTBT), the United States has responsiblity for establishing and operating eight <span class="hlt">infrasound</span> arrays from Alaska to the Antarctic through the Pacific Basin, and along the U. S. west coast. (In this context, <span class="hlt">infrasound</span> is defined as acoustic waves in the frequency range 0.02 Hz to 4Hz.) In addition, the U. S. has non-CTBTO <span class="hlt">infrasound</span> arrays in New Mexico, Utah, Nevada, Wyoming, Texas, and Maryland. The CTBT Office will install and operate an additional 52 states to provide worldwide coverage. This immense array of sensors provides a rare opportunity to study low frequency sound on a global scale. An international community of interested scieintists is beginning to emerge with different interests in the use of data from this global network. Much of the research interest lies in the ability to remotely monitor events of interest. These include volcanoes, severe storms, and bolides. The signals received at the individual stations are strongly dependent on the state of the intervening atmosphere therefore there is an opportunity to use tomography to gain more detailed knowledge of changes in the upper atmosphere. There are still great opportunities to improve the quality of the <span class="hlt">infrasound</span> stations. Wind noise continues to limit the signal to noise level. Modern signal processing techniques might be used to lower wind noise levels and allow the detection of even weaker signals. Current generation <span class="hlt">infrasound</span> stations are large and expensive. Reduction in complexity would allow a finer grid of stations and the study of higher frequency signals. There are numerous opportunities for collaborations in the use of this unique data <span class="hlt">source</span> at the national and international levels. The US <span class="hlt">Infrasound</span> Team and international collaborators are open to new ideas and colleagues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PApGe.167..437D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PApGe.167..437D"><span id="translatedtitle">The Temporal Morphology of <span class="hlt">Infrasound</span> Propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drob, Douglas P.; Garcés, Milton; Hedlin, Michael; Brachet, Nicolas</p> <p>2010-05-01</p> <p>Expert knowledge suggests that the performance of automated <span class="hlt">infrasound</span> event association and <span class="hlt">source</span> location algorithms could be greatly improved by the ability to continually update station travel-time curves to properly account for the hourly, daily, and seasonal changes of the atmospheric state. With the goal of reducing false alarm rates and improving network detection capability we endeavor to develop, validate, and integrate this capability into <span class="hlt">infrasound</span> processing operations at the International Data Centre of the Comprehensive Nuclear Test-Ban Treaty Organization. Numerous studies have demonstrated that incorporation of hybrid ground-to-space (G2S) enviromental specifications in numerical calculations of <span class="hlt">infrasound</span> signal travel time and azimuth deviation yields significantly improved results over that of climatological atmospheric specifications, specifically for tropospheric and stratospheric modes. A robust infrastructure currently exists to generate hybrid G2S vector spherical harmonic coefficients, based on existing operational and emperical models on a real-time basis (every 3- to 6-hours) (D rob et al., 2003). Thus the next requirement in this endeavor is to refine numerical procedures to calculate <span class="hlt">infrasound</span> propagation characteristics for robust automatic <span class="hlt">infrasound</span> arrival identification and network detection, location, and characterization algorithms. We present results from a new code that integrates the local (range-independent) τp ray equations to provide travel time, range, turning point, and azimuth deviation for any location on the globe given a G2S vector spherical harmonic coefficient set. The code employs an accurate numerical technique capable of handling square-root singularities. We investigate the seasonal variability of propagation characteristics over a five-year time series for two different stations within the International Monitoring System with the aim of understanding the capabilities of current working knowledge of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S54B..01P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S54B..01P"><span id="translatedtitle">Using large meteoroids as global <span class="hlt">infrasound</span> reference events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, C.; Ceranna, L.; LE Pichon, A.; Brown, P.</p> <p>2015-12-01</p> <p>The explosive fragmentation of large meteoroids entering the Earth's atmosphere is one of the strongest <span class="hlt">sources</span> of infrasonic waves and can be detected by <span class="hlt">infrasound</span> arrays all over the world. Pressure perturbations of the strongest bolide events were detected at distances of thousands of kilometers, while for the 2013 Chelyabinsk superbolide, arrivals at long orthodrome distances (above 20000 km) and after complete circumnavigations of the globe (up to 87000 km) were recorded. Influence parameters on the detection capability of a single <span class="hlt">infrasound</span> station on the one hand and of the complete global <span class="hlt">infrasound</span> network of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) are investigated within this study and applied to a number of strong bolide events of the past 15 years. Potential influences on <span class="hlt">infrasound</span> detection capability are due to the directivity of the acoustic <span class="hlt">source</span> energy emission, the long-range ducting via stratosphere and thermosphere and the diurnal change of meteorological parameters and noise conditions at the stations during the signal arrivals. Since <span class="hlt">infrasound</span> of large bolides has probably the most similar characteristics to an atmospheric nuclear explosion, it can be utilized as reference event for studies on the global performance of the International Monitoring System (IMS) of the CTBTO. Detections and non-detections of bolide <span class="hlt">infrasound</span> at the more than 40 operational IMS <span class="hlt">infrasound</span> stations are studied for the estimation of station and network performance and thus verification of nuclear test ban.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V33E..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V33E..05K"><span id="translatedtitle">Integrated video and <span class="hlt">infrasound</span> observations at Mount Erebus, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krzesni, D.; Johnson, J.; Kyle, P. R.</p> <p>2012-12-01</p> <p>Erebus volcano is ideally suited for <span class="hlt">infrasound</span> studies because it produces frequent, discrete, short-duration Strombolian eruptions that generate simple, high-amplitude (10^3 - 10^4 Pa-m), high signal-to-noise, acoustic pulses. Some explosions have been recorded by a video camera situated 300 m from the lava lake. Here we analyze the <span class="hlt">infrasound</span> signal recordings from 256 eruptions, 10 were accompanied by high-quality video. We have developed image processing scripts in MATLAB to measure the explosive expansion of eject in consecutive 30 fps video. An ellipse was fitted to the expanding surface, which begins as an intact bubble and then fragments into radially-projected ballistics. The volume of the magma bubble was estimated in each frame of the video and used to produce a synthetic <span class="hlt">infrasound</span> wave. We assumed an acoustic monopole point <span class="hlt">source</span> model where the volumetric acceleration was proportional to the radiated pressure waveform. In a comparison of synthetic and recorded <span class="hlt">infrasound</span> we find a consistent match in both frequency and amplitude. The synthetic <span class="hlt">infrasound</span> amplitude is generally greater than the amplitude of the observed <span class="hlt">infrasound</span>. This suggests some non-linear decay in acoustic energy between the fluid ejection <span class="hlt">source</span> and the <span class="hlt">infrasound</span> recording sites. The <span class="hlt">infrasound</span> signals were also analyzed to determine if a precursory pulse (or shoulder) in the waveforms, was related to distension of an unbroken magma bubble membrane prior to rupture. We examined the pressure slope (at the onset of an eruption) and the scaled asymmetry (of the bimodal pulses), and relate them to the initial magma overburden and <span class="hlt">source</span> overpressure respectively. For significantly asymmetric <span class="hlt">infrasound</span> pulses, with large rarefactions compared to initial compression, we speculate that rupture occurs for bubble slugs with very low overpressures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.7833N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.7833N"><span id="translatedtitle">A 868MHz-based wireless sensor network for <span class="hlt">ground</span> <span class="hlt">truthing</span> of soil moisture for a hyperspectral remote sensing campaign - design and preliminary results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Näthe, Paul; Becker, Rolf</p> <p>2014-05-01</p> <p>Soil moisture and plant available water are important environmental parameters that affect plant growth and crop yield. Hence, they are significant parameters for vegetation monitoring and precision agriculture. However, validation through ground-based soil moisture measurements is necessary for accessing soil moisture, plant canopy temperature, soil temperature and soil roughness with airborne hyperspectral imaging systems in a corresponding hyperspectral imaging campaign as a part of the INTERREG IV A-Project SMART INSPECTORS. At this point, commercially available sensors for matric potential, plant available water and volumetric water content are utilized for automated measurements with smart sensor nodes which are developed on the basis of open-<span class="hlt">source</span> 868MHz radio modules, featuring a full-scale microcontroller unit that allows an autarkic operation of the sensor nodes on batteries in the field. The generated data from each of these sensor nodes is transferred wirelessly with an open-<span class="hlt">source</span> protocol to a central node, the so-called "gateway". This gateway collects, interprets and buffers the sensor readings and, eventually, pushes the data-time series onto a server-based database. The entire data processing chain from the sensor reading to the final storage of data-time series on a server is realized with open-<span class="hlt">source</span> hardware and software in such a way that the recorded data can be accessed from anywhere through the internet. It will be presented how this open-<span class="hlt">source</span> based wireless sensor network is developed and specified for the application of <span class="hlt">ground</span> <span class="hlt">truthing</span>. In addition, the system's perspectives and potentials with respect to usability and applicability for vegetation monitoring and precision agriculture shall be pointed out. Regarding the corresponding hyperspectral imaging campaign, results from ground measurements will be discussed in terms of their contributing aspects to the remote sensing system. Finally, the significance of the wireless sensor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/900062','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/900062"><span id="translatedtitle"><span class="hlt">GROUND</span> <span class="hlt">TRUTH</span>, MAGNITUDE CALIBRATION AND REGIONAL PHASE PROPAGATION AND DETECTION IN THE MIDDLE EAST AND HORN OF AFRICA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nyblade, A; Adams, A; Brazier, R; Park, Y; Rodgers, A</p> <p>2006-07-10</p> <p>In this project, we are exploiting unique and open <span class="hlt">source</span> seismic data sets to improve seismic monitoring across the Middle East (including the Iranian Plateau, Zagros Mountains, Arabian Peninsula, Turkish Plateau, Gulf of Aqaba, Dead Sea Rift) and the Horn of Africa (including the northern part of the East African Rift, Afar Depression, southern Red Sea and Gulf of Aden). The data sets are being used to perform three related tasks. (1) We are determining moment tensors, moment magnitudes and <span class="hlt">source</span> depths for regional events in the magnitude 3.0 to 6.0 range. (2) These events are being used to characterize high-frequency (0.5-16 Hz) regional phase attenuation and detection thresholds, especially from events in Iran recorded at stations across the Arabian Peninsula. (3) We are collecting location <span class="hlt">ground</span> <span class="hlt">truth</span> at GT5 (local) and GT20 (regional) levels for seismic events with M > 2.5, including <span class="hlt">source</span> geometry information and <span class="hlt">source</span> depths. In the first phase of this project, seismograms from earthquakes in the Zagros Mountains recorded at regional distances have been inverted for moment tensors, and <span class="hlt">source</span> depths for the earthquakes have been determined via waveform matching. Early studies of the distribution of seismicity in the Zagros region found evidence for earthquakes in the upper mantle. But subsequent relocations of teleseismic earthquakes suggest that <span class="hlt">source</span> depths are generally much shallower, lying mainly within the upper crust. Nine events with magnitudes between 5 and 6 have been studied so far. <span class="hlt">Source</span> depths for six of the events are within the upper crust, and three are located within the lower crust. The uncertainty in the <span class="hlt">source</span> depths of the lower crustal events allows for the possibility that some of them may have even nucleated within the upper mantle. Eight events have thrust mechanisms and one has a strike-slip mechanism. We also report estimates of three-dimensional P- and S-wave velocity structure of the upper mantle beneath the Arabian</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/965952','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/965952"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span>, Magnitude Calibration and Regional Phase Propagation and Detection in the Middle East and Horn of Africa</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nyblade, A; Brazier, R; Adams, A; Park, Y; Rodgers, A; Al-Amri, A</p> <p>2007-07-08</p> <p>In this project, we are exploiting several seismic data sets to improve U.S. operational capabilities to monitor for low yield nuclear tests across the Middle East (including the Iranian Plateau, Zagros Mountains, Arabian Peninsula, Turkish Plateau, Gulf of Aqaba, Dead Sea Rift) and the Horn of Africa (including the northern part of the East African Rift, Afar Depression, southern Red Sea and Gulf of Aden). The data sets are being used to perform three related tasks. (1) We are determining moment tensors, moment magnitudes and <span class="hlt">source</span> depths for regional events in the magnitude 3.0 to 6.0 range. (2) These events are being used to characterize high-frequency (0.5-16 Hz) regional phase attenuation and detection thresholds, especially from events in Iran recorded at stations across the Arabian Peninsula. (3) We are collecting location <span class="hlt">ground</span> <span class="hlt">truth</span> at GT5 (local) and GT20 (regional) levels for seismic events with M > 2.5, including <span class="hlt">source</span> geometry information and <span class="hlt">source</span> depths. Towards meeting these objectives, seismograms from earthquakes in the Zagros Mountains recorded at regional distances have been inverted for moment tensors, which have then been used to create synthetic seismograms to determine the <span class="hlt">source</span> depths of the earthquakes via waveform matching. The <span class="hlt">source</span> depths have been confirmed by modeling teleseismic depth phases recorded on GSN and IMS stations. Early studies of the distribution of seismicity in the Zagros region found evidence for earthquakes in the upper mantle. But subsequent relocations of teleseismic earthquakes suggest that <span class="hlt">source</span> depths are generally much shallower, lying mainly within the upper crust. All of the regional events studied so far nucleated within the upper crust, and most of the events have thrust mechanisms. The <span class="hlt">source</span> mechanisms for these events are being used to characterize high-frequency (0.5-16 Hz) regional phase attenuation and detection thresholds for broadband seismic stations in the Arabian Peninsula, including IMS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoJI.198..495C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoJI.198..495C"><span id="translatedtitle"><span class="hlt">Infrasound</span> signals from the underground nuclear explosions of North Korea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, Il-Young; Park, Junghyun; Kim, Inho; Kim, Tae Sung; Lee, Hee-Il</p> <p>2014-07-01</p> <p>We investigated the <span class="hlt">infrasound</span> signals from seismic ground motions induced by North Korea's underground nuclear explosions, including the recent third explosion on 2013 February 12. For the third explosion, the epicentral <span class="hlt">infrasound</span> signals were detected not only by three <span class="hlt">infrasound</span> network stations (KSGAR, ULDAR and YAGAR) in South Korea but also by two nearby International Monitoring System <span class="hlt">infrasound</span> stations, IS45 and IS30. The detectability of the signals was limited at stations located on the relatively east side of the epicentre, with large azimuth deviations due to very favourable atmospheric conditions for eastward propagation at stratospheric height in 2013. The stratospheric wind direction was the reverse of that when the second explosion was conducted in 2009 May. The <span class="hlt">source</span> location of the epicentral <span class="hlt">infrasound</span> with wave parameters determined at the multiple stations has an offset by about 16.6 km from the reference seismic location. It was possible to determine the infrasonic location with moderate accuracy by the correction of the azimuth deviation due to the eastward winds in the stratosphere. In addition to the epicentral infrasonic signals, diffracted <span class="hlt">infrasound</span> signals were observed from the second underground nuclear explosion in 2009. The exceptional detectability of the diffracted <span class="hlt">infrasound</span> was a consequence of the temporal formation of a thin atmospheric inversion layer over the ocean surface when the event occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812871B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812871B"><span id="translatedtitle">Contribution of the <span class="hlt">infrasound</span> technology to characterize large scale atmospheric disturbances and impact on <span class="hlt">infrasound</span> monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanc, Elisabeth; Le Pichon, Alexis; Ceranna, Lars; Pilger, Christoph; Charlton Perez, Andrew; Smets, Pieter</p> <p>2016-04-01</p> <p>The International Monitoring System (IMS) developed for the verification of the Comprehensive nuclear-Test-Ban Treaty (CTBT) provides a unique global description of atmospheric disturbances generating <span class="hlt">infrasound</span> such as extreme events (e.g. meteors, volcanoes, earthquakes, and severe weather) or human activity (e.g. explosions and supersonic airplanes). The analysis of the detected signals, recorded at global scales and over near 15 years at some stations, demonstrates that large-scale atmospheric disturbances strongly affect <span class="hlt">infrasound</span> propagation. Their time scales vary from several tens of minutes to hours and days. Their effects are in average well resolved by the current model predictions; however, accurate spatial and temporal description is lacking in both weather and climate models. This study reviews recent results using the <span class="hlt">infrasound</span> technology to characterize these large scale disturbances, including (i) wind fluctuations induced by gravity waves generating <span class="hlt">infrasound</span> partial reflections and modifications of the <span class="hlt">infrasound</span> waveguide, (ii) convection from thunderstorms and mountain waves generating gravity waves, (iii) stratospheric warming events which yield wind inversions in the stratosphere, (iv)planetary waves which control the global atmospheric circulation. Improved knowledge of these disturbances and assimilation in future models is an important objective of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project. This is essential in the context of the future verification of the CTBT as enhanced atmospheric models are necessary to assess the IMS network performance in higher resolution, reduce <span class="hlt">source</span> location errors, and improve characterization methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060024664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060024664"><span id="translatedtitle">Comparisons of <span class="hlt">Ground</span> <span class="hlt">Truth</span> and Remote Spectral Measurements of the FORMOSAT and ANDE Spacecrafts</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>JorgensenAbercromby, Kira; Hamada, Kris; Okada, Jennifer; Guyote, Michael; Barker, Edwin</p> <p>2006-01-01</p> <p>Determining the material type of objects in space is conducted using laboratory spectral reflectance measurements from common spacecraft materials and comparing the results to remote spectra. This past year, two different <span class="hlt">ground-truth</span> studies commenced. The first, FORMOSAT III, is a Taiwanese set of six satellites to be launched in March 2006. The second is ANDE (Atmospheric Neutral Density Experiment), a Naval Research Laboratory set of two satellites set to launch from the Space Shuttle in November 2006. Laboratory spectra were obtained of the spacecraft and a model of the anticipated spectra response was created for each set of satellites. The model takes into account phase angle and orientation of the spacecraft relative to the observer. Once launched, the spacecraft are observed once a month to determine the space aging effects of materials as deduced from the remote spectra. Preliminary results will be shown of the FORMOSAT III comparison with laboratory data and remote data while results from only the laboratory data will be shown for the ANDE spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950039070&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950039070&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtruth"><span id="translatedtitle">The <span class="hlt">ground-truth</span> problem for satellite estimates of rain rate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>North, Gerald R.; Valdes, Juan B.; Eunho, HA; Shen, Samuel S. P.</p> <p>1994-01-01</p> <p>In this paper a scheme is proposed to use a point raingage to compare contemporaneous measurements of rain rate from a single-field-of-view (FOV) estimate based on a satellite remote sensor such as a microwave radiometer. Even in the ideal case the measurements are different because one is at a point and the other is an area average over the field of view. Also the point gage will be located randomly inside the field of view on different overpasses. A space-time spectral formalism is combined with a simple stochastic rain field to find the mean-square deviations between the two systems. It is found that by combining about 60 visits of the satellite to the <span class="hlt">ground-truth</span> site, the expected error can be reduced to about 10% of the standard deviation of the fluctuations of the systems alone. This seems to be a useful level of tolerance in terms of isolating and evaluating typical biases that might be contaminating retrieval algorithms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SPIE.8018E..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SPIE.8018E..05K"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> methods for optical cross-section modeling of biological aerosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kalter, J.; Thrush, E.; Santarpia, J.; Chaudhry, Z.; Gilberry, J.; Brown, D. M.; Brown, A.; Carter, C. C.</p> <p>2011-05-01</p> <p>Light detection and ranging (LIDAR) systems have demonstrated some capability to meet the needs of a fastresponse standoff biological detection method for simulants in open air conditions. These systems are designed to exploit various cloud signatures, such as differential elastic backscatter, fluorescence, and depolarization in order to detect biological warfare agents (BWAs). However, because the release of BWAs in open air is forbidden, methods must be developed to predict candidate system performance against real agents. In support of such efforts, the Johns Hopkins University Applied Physics Lab (JHU/APL) has developed a modeling approach to predict the optical properties of agent materials from relatively simple, Biosafety Level 3-compatible bench top measurements. JHU/APL has fielded new <span class="hlt">ground</span> <span class="hlt">truth</span> instruments (in addition to standard particle sizers, such as the Aerodynamic particle sizer (APS) or GRIMM aerosol monitor (GRIMM)) to more thoroughly characterize the simulant aerosols released in recent field tests at Dugway Proving Ground (DPG). These instruments include the Scanning Mobility Particle Sizer (SMPS), the Ultraviolet Aerodynamic Particle Sizer (UVAPS), and the Aspect Aerosol Size and Shape Analyser (Aspect). The SMPS was employed as a means of measuring smallparticle concentrations for more accurate Mie scattering simulations; the UVAPS, which measures size-resolved fluorescence intensity, was employed as a path toward fluorescence cross section modeling; and the Aspect, which measures particle shape, was employed as a path towards depolarization modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/806536','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/806536"><span id="translatedtitle">MTI <span class="hlt">Ground</span> <span class="hlt">Truth</span> Collection Ivanpah Dry Lake Bed, California, May, July, and August 2002</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>David L. Hawley</p> <p>2002-10-01</p> <p>A multi-agency collaboration successfully completed a series of <span class="hlt">ground</span> <span class="hlt">truth</span> measurements at the Ivanpah Dry Lake bed during FY 2002. Four collection attempts were made: two in May, one in July, and one in August. The objective was to collect ground-based measurements and airborne data during Multispectral Thermal Imager satellite overpasses. The measurements were to aid in the calibration of the satellite data and in algorithm validation. The Remote Sensing Laboratory, Las Vegas, Nevada; the National Aeronautics and Space Administration; Los Alamos National Laboratory; and the University of Arizona participated in the effort. Field instrumentation included a sun photometer on loan from the University of Arizona and the Remote Sensing Laboratory's radiosonde weather balloon, weather station, thermal infrared radiometers, and spectral radiometer. In addition, three reflectance panels were deployed; certain tests used water baths set at two different temperatures. Local weather data as well as sky photography were collected. May presented several excellent days; however, it was later learned that tasking for the satellite was not available. A combination of cloud cover, wind, and dusty conditions limited useful data collections to two days, August 28 and 29. Despite less-than- ideal weather conditions, the data for the Multispectral Thermal Imager calibration were obtained. A unique set of circumstances also allowed data collection during overpasses of the LANDSAT7 and ASTER satellites.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160008889','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160008889"><span id="translatedtitle">Comparing Eyewitness-Derived Trajectories of Bright Meteors to <span class="hlt">Ground</span> <span class="hlt">Truth</span> Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moser, D. E.</p> <p>2016-01-01</p> <p>The NASA Meteoroid Environment Office (MEO) is the only US government agency tasked with analyzing meteors of public interest. When queried about a meteor observed over the United States, the MEO must respond with a characterization of the trajectory, orbit, and size within a few hours. Using observations from meteor networks like the NASA All Sky Fireball Network or the Southern Ontario Meteor Network, such a characterization is often easy. If found, casual recordings from the public and stationary web cameras can be used to roughly analyze a meteor if the camera's location can be identified and its imagery calibrated. This technique was used with great success in the analysis of the Chelyabinsk meteorite fall. But if the event is outside meteor network coverage, if an insufficient number of videos are found, or if the imagery cannot be geolocated or calibrated, a timely assessment can be difficult if not impossible. In this situation, visual reports made by eyewitnesses may be the only resource available. This has led to the development of a tool to quickly calculate crude meteor trajectories from eyewitness reports made to the American Meteor Society. The output is illustrated in Figure 1. A description of the tool, example case studies, and a comparison to <span class="hlt">ground</span> <span class="hlt">truth</span> data observed by the NASA All Sky Fireball Network will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740021574','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740021574"><span id="translatedtitle">A new device for acquiring <span class="hlt">ground</span> <span class="hlt">truth</span> on the absorption of light by turbid waters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Klemas, V. (Principal Investigator); Srna, R.; Treasure, W.</p> <p>1974-01-01</p> <p>The author has identified the following significant results. A new device, called a Spectral Attenuation Board, has been designed and tested, which enables ERTS-1 sea truth collection teams to monitor the attenuation depths of three colors continuously, as the board is being towed behind a boat. The device consists of a 1.2 x 1.2 meter flat board held below the surface of the water at a fixed angle to the surface of the water. A camera mounted above the water takes photographs of the board. The resulting film image is analyzed by a micro-densitometer trace along the descending portion of the board. This yields information on the rate of attenuation of light penetrating the water column and the Secchi depth. Red and green stripes were painted on the white board to approximate band 4 and band 5 of the ERTS MSS so that information on the rate of light absorption by the water column of light in these regions of the visible spectrum could be concurrently measured. It was found that information from a red, green, and white stripe may serve to fingerprint the composition of the water mass. A number of these devices, when automated, could also be distributed over a large region to provide a cheap method of obtaining valuable satellite <span class="hlt">ground</span> <span class="hlt">truth</span> data at present time intervals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/752199','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/752199"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> measurements plan for the Multispectral Thermal Imager (MTI) satellite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Garrett, A.J.</p> <p>2000-01-03</p> <p>Sandia National Laboratories (SNL), Los Alamos National Laboratory (LANL), and the Savannah River Technology Center (SRTC) have developed a diverse group of algorithms for processing and analyzing the data that will be collected by the Multispectral Thermal Imager (MTI) after launch late in 1999. Each of these algorithms must be verified by comparison to independent surface and atmospheric measurements. SRTC has selected 13 sites in the continental U.S. for <span class="hlt">ground</span> <span class="hlt">truth</span> data collections. These sites include a high altitude cold water target (Crater Lake), cooling lakes and towers in the warm, humid southeastern US, Department of Energy (DOE) climate research sites, the NASA Stennis satellite Validation and Verification (V and V) target array, waste sites at the Savannah River Site, mining sites in the Four Corners area and dry lake beds in the southwestern US. SRTC has established mutually beneficial relationships with the organizations that manage these sites to make use of their operating and research data and to install additional instrumentation needed for MTI algorithm V and V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA111957','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA111957"><span id="translatedtitle">Antarctic Atmospheric <span class="hlt">Infrasound</span>.</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1981-11-30</p> <p>A summary is given of the project chronology and the reports describing our research in Antarctic Atmospheric <span class="hlt">infrasound</span>. Analysis of selected infrasonic signals is discussed and a list is given of all infrasonic waves received on the digital system with correlation coefficient greater than 0.6. (Author)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2948P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2948P"><span id="translatedtitle">Detection and interpretation of seismoacoustic events at German <span class="hlt">infrasound</span> stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, Christoph; Koch, Karl; Ceranna, Lars</p> <p>2016-04-01</p> <p>Three <span class="hlt">infrasound</span> arrays with collocated or nearby installed seismometers are operated by the Federal Institute for Geosciences and Natural Resources (BGR) as the German National Data Center (NDC) for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). <span class="hlt">Infrasound</span> generated by seismoacoustic events is routinely detected at these <span class="hlt">infrasound</span> arrays, but air-to-ground coupled acoustic waves occasionally show up in seismometer recordings as well. Different natural and artificial <span class="hlt">sources</span> like meteoroids as well as industrial and mining activity generate infrasonic signatures that are simultaneously detected at microbarometers and seismometers. Furthermore, many near-surface <span class="hlt">sources</span> like earthquakes and explosions generate both seismic and infrasonic waves that can be detected successively with both technologies. The combined interpretation of seismic and acoustic signatures provides additional information about the origin time and location of remote <span class="hlt">infrasound</span> events or about the characterization of seismic events distinguishing man-made and natural origins. Furthermore, seismoacoustic studies help to improve the modelling of <span class="hlt">infrasound</span> propagation and ducting in the atmosphere and allow quantifying the portion of energy coupled into ground and into air by seismoacoustic <span class="hlt">sources</span>. An overview of different seismoacoustic <span class="hlt">sources</span> and their detection by German <span class="hlt">infrasound</span> stations as well as some conclusions on the benefit of a combined seismoacoustic analysis are presented within this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S14A..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S14A..02D"><span id="translatedtitle"><span class="hlt">Infrasound</span> Studies at the USArray (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Groot-Hedlin, C. D.</p> <p>2013-12-01</p> <p>Many surface and atmospheric <span class="hlt">sources</span>, both natural and anthropogenic, have generated <span class="hlt">infrasound</span> signals that have been recorded on USArray transportable array (TA) seismometers at ranges up to thousands of kilometers. Such <span class="hlt">sources</span>, including surface explosions, large bolides, mining events, and a space shuttle, have contributed to an understanding of <span class="hlt">infrasound</span> propagation. We show examples of several atmospheric <span class="hlt">sources</span> recorded at the TA. We first used USArray data to investigate <span class="hlt">infrasound</span> signals from the space shuttle 'Atlantis'. Inclement weather in Florida forced the shuttle to land at Edwards Air Force Base in southern California on June 22, 2007, passing near three <span class="hlt">infrasound</span> stations and several hundred seismic stations in northern Mexico, southern California, and Nevada. The high signal-to-noise ratio, broad receiver coverage, and Atlantis' positional information allowed us to test <span class="hlt">infrasound</span> propagation modeling capabilities through the atmosphere to hundreds of kilometers range from the shuttle's path. Shadow zones and arrival times were predicted by tracing rays launched at right angles to the conical shock front surrounding the shuttle through a standard climatological model as well as a global ground to space model. Both models predict alternating regions of high and low ensonification to the NW, in line with observations. However, <span class="hlt">infrasound</span> energy was detected tens of kilometers beyond the predicted zones of ensonification, possibly due to uncertainties in stratospheric wind speeds. The models also predict increasing waveform complexity with increasing distance, in line with observations. Several hundreds of broadband seismic stations in the U.S. Pacific Northwest recorded acoustic to seismic coupled signals from a large meteor that entered the atmosphere above northeastern Oregon on 19 February 2008. The travel times of the first arriving energy are consistent with a terminal explosion <span class="hlt">source</span> model, suggesting that the large size of the explosion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28113570','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28113570"><span id="translatedtitle">On Solving the Problem of Identifying Unreliable Sensors Without a Knowledge of the <span class="hlt">Ground</span> <span class="hlt">Truth</span>: The Case of Stochastic Environments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yazidi, Anis; Oommen, B John; Goodwin, Morten</p> <p>2016-04-28</p> <p>The purpose of this paper is to propose a solution to an extremely pertinent problem, namely, that of identifying unreliable sensors (in a domain of reliable and unreliable ones) without any knowledge of the <span class="hlt">ground</span> <span class="hlt">truth</span>. This fascinating paradox can be formulated in simple terms as trying to identify stochastic liars without any additional information about the truth. Though apparently impossible, we will show that it is feasible to solve the problem, a claim that is counter-intuitive in and of itself. One aspect of our contribution is to show how redundancy can be introduced, and how it can be effectively utilized in resolving this paradox. Legacy work and the reported literature (for example, in the so-called weighted majority algorithm) have merely addressed assessing the reliability of a sensor by comparing its reading to the <span class="hlt">ground</span> <span class="hlt">truth</span> either in an online or an offline manner. Unfortunately, the fundamental assumption of revealing the <span class="hlt">ground</span> <span class="hlt">truth</span> cannot be always guaranteed (or even expected) in many real life scenarios. While some extensions of the Condorcet jury theorem [9] can lead to a probabilistic guarantee on the quality of the fused process, they do not provide a solution to the unreliable sensor identification problem. The essence of our approach involves studying the agreement of each sensor with the rest of the sensors, and not comparing the reading of the individual sensors with the <span class="hlt">ground</span> <span class="hlt">truth</span>-as advocated in the literature. Under some mild conditions on the reliability of the sensors, we can prove that we can, indeed, filter out the unreliable ones. Our approach leverages the power of the theory of learning automata (LA) so as to gradually learn the identity of the reliable and unreliable sensors. To achieve this, we resort to a team of LA, where a distinct automaton is associated with each sensor. The solution provided here has been subjected to rigorous experimental tests, and the results presented are, in our opinion, both novel and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70157111','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157111"><span id="translatedtitle"><span class="hlt">Ground-truthing</span> electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnson, Cordell; Swarzenski, Peter W.; Richardson, Christina M.; Smith, Christopher G.; Kroeger, Kevin D.; Ganguli, Priya M.</p> <p>2015-01-01</p> <p>Rigorous <span class="hlt">ground-truthing</span> at each field site showed that multi-channel electrcial resistivity techniques can reproduce the scales and dynamics of a seepage field when such data are correctly collected, and when the model inversions are tuned to field site characteristics. Such information can provide a unique perspective on the scales and dynamics of exchange processes within a coastal aquifer—information essential to scientists and resource managers alike.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714122A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714122A"><span id="translatedtitle"><span class="hlt">Infrasound</span> ray tracing models for real events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Averbuch, Gil; Applbaum, David; Price, Colin; Ben Horin, Yochai</p> <p>2015-04-01</p> <p>'s height or the sprite's most energetic part. Even though atmospheric wind has a strong influence on <span class="hlt">infrasound</span> wave propagation, our estimation is that for high altitude <span class="hlt">sources</span>, extreme weather in the troposphere below has low impact on the trajectories of the waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SPIE.8318E..1IA','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SPIE.8318E..1IA"><span id="translatedtitle">A systematic review of automated melanoma detection in dermatoscopic images and its <span class="hlt">ground</span> <span class="hlt">truth</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Abder-Rahman A.; Deserno, Thomas M.</p> <p>2012-02-01</p> <p>Malignant melanoma is the third most frequent type of skin cancer and one of the most malignant tumors, accounting for 79% of skin cancer deaths. Melanoma is highly curable if diagnosed early and treated properly as survival rate varies between 15% and 65% from early to terminal stages, respectively. So far, melanoma diagnosis is depending subjectively on the dermatologist's expertise. Computer-aided diagnosis (CAD) systems based on epiluminescense light microscopy can provide an objective second opinion on pigmented skin lesions (PSL). This work systematically analyzes the evidence of the effectiveness of automated melanoma detection in images from a dermatoscopic device. Automated CAD applications were analyzed to estimate their diagnostic outcome. Searching online databases for publication dates between 1985 and 2011, a total of 182 studies on dermatoscopic CAD were found. With respect to the systematic selection criterions, 9 studies were included, published between 2002 and 2011. Those studies formed databases of 14,421 dermatoscopic images including both malignant "melanoma" and benign "nevus", with 8,110 images being available ranging in resolution from 150 x 150 to 1568 x 1045 pixels. Maximum and minimum of sensitivity and specificity are 100.0% and 80.0% as well as 98.14% and 61.6%, respectively. Area under the receiver operator characteristics (AUC) and pooled sensitivity, specificity and diagnostics odds ratio are respectively 0.87, 0.90, 0.81, and 15.89. So, although that automated melanoma detection showed good accuracy in terms of sensitivity, specificity, and AUC, but diagnostic performance in terms of DOR was found to be poor. This might be due to the lack of dermatoscopic image resources (<span class="hlt">ground</span> <span class="hlt">truth</span>) that are needed for comprehensive assessment of diagnostic performance. In future work, we aim at testing this hypothesis by joining dermatoscopic images into a unified database that serves as a standard reference for dermatology related research in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5387712','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5387712"><span id="translatedtitle"><span class="hlt">Ground-truthing</span> 6. 5-kHz side scan sonographs: What are we really imaging</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gardner, J.V.; Field, M.E.; Lee, H.; Edwards, B.E. ); Masson, D.G.; Kenyon, N. ); Kidd, R.B. )</p> <p>1991-04-10</p> <p>A 1,000-km{sup 2} area on the distal lobe of Monterey Fan shows a digitate pattern of juxtaposed high and low backscatter on GLORIA side scan sonographs. This area was investigated using stereo photography, high-resolution seismic profiles, and measurements of physical properties of cores to quantitatively evaluate the causes of backscatter from the 6.5-kHz side scan sonar. Stereo photography and bottom video were used to determine that the sediment-water interface typically has a bed roughness less than 10 cm over the entire <span class="hlt">ground</span> <span class="hlt">truth</span> area; consequently, bed roughness is not a significant contributor to the sonar backscatter. Vertical-incidence 3.5-kHz profiles reveal that high-backscatter areas allow less penetration and have slightly more relief than low-backscatter areas. Closely spaced measurements of {rho} wave velocity, density, and grain size made on transponder-navigated cores are used to investigate the geoacoustic properties of the sediment with the aid of a numerical model. The model results demonstrate that the sediment-water interface is, in most cases, acoustically transparent to the sonar energy and that most or all of the energy is refracted into the sediment to depths of at least a few meters rather than scattered from the surface. In this area, thick (up to 50 cm) sand deposits with thin interbeds of silty clay correlate with lower backscatter than do silty clay deposits with thin interbeds of sand. This suggests that volume inhomogeneities and complex constructive and destructive interferences caused by the subsurface volume inhomogeneities within the top few meters of the sediment ultimately modulate the intensity of backscatter. Although 6.5-kHz sonographs appear easy to interpret in a conventional and simplistic manner, caution should be used when interpreting lithofacies from backscatter intensities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015P%26SS..119..194O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..119..194O"><span id="translatedtitle">Sunrise-driven movements of dust on the Moon: Apollo 12 <span class="hlt">Ground-truth</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>O'Brien, Brian J.; Hollick, Monique</p> <p>2015-12-01</p> <p>The first sunrise after Apollo 12 astronauts left the Moon caused dust storms across the site where rocket exhausts had disrupted about 2000 kg of smooth fine dust. The next few sunrises started progressively weaker dust storms, and the Eastern horizon brightened, adding to direct sunlight for half an hour. These <span class="hlt">Ground</span> <span class="hlt">truth</span> measurements were made 100 cm above the surface by the 270 g Apollo 12 Dust Detector Experiment we invented in 1966. Dust deposited on the horizontal solar cell during two lunar days after the first sunrise was almost 30% of the total it then measured over 6 years. The vertical east-facing solar cell measured horizon brightening on 14 of the first 17 lunations, with none detected on the following 61 Lunar Days. Based on over 2 million such measurements we propose a new qualitative model of sunrise-driven transport of individual dust particles freed by Apollo 12 activities from strong particle-to-particle cohesive forces. Each sunrise caused sudden surface charging which, during the first few hours, freshly mobilised and lofted the dust remaining free, microscopically smoothing the disrupted local areas. Evidence of reliability of measurements includes consistency among all 6 sensors in measurements throughout an eclipse. We caution Google Lunar XPrize competitors and others planning missions to the Moon and large airless asteroids that, after a spacecraft lands, dust hazards may occur after each of the first few sunrises. Mechanical problems in its first such period stranded Chinese lunar rover Yutu in 2014, although we would not claim yet that the causes were dust. On the other hand, sunrise-driven microscopic smoothing of disturbed areas may offer regular natural mitigations of dust consequences of mining lunar resources and reduce fears that many expeditions might cause excessive fine dust globally around the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005SPIE.5794..233H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005SPIE.5794..233H"><span id="translatedtitle">Identification of buried landmines using electromagnetic induction spectroscopy: evaluation of a blind test against <span class="hlt">ground</span> <span class="hlt">truth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Haoping; San Filipo, Bill; Norton, Steve; Won, I. J.</p> <p>2005-06-01</p> <p>The Geophex GEM-3 sensor was tested at a government test site comprised of 980 1-m squares containing buried landmines and clutter (metallic debris). Electromagnetic (EM) induction spectroscopy (EMIS) was used to discriminate between the landmines and clutter items. Receiver-operator characteristics (ROC) were constructed based on the results of the analysis. Approximately 92% of the landmines were correctly identified as such, with a false alarm rate of 12%. In this report, we present a comparison of our identification results against the <span class="hlt">ground</span> <span class="hlt">truth</span>. The EMIS method works well for high-metal mines for which the misfit threshold can be easily established, yielding a correct declaration in all cases without false alarms. For medium-metal mines, even though the misfit differences between the mines and clutter are not as clear as those for the high-metal mines, these mines were still identified at very low false alarm rates with the GEM-3 sensor. The low-metal mines may be discriminated from clutter if they yield reliable signals, but often at a much higher false alarm rate. The primary reason for this is that the EM signals from the low-metal mines are intrinsically weak and thus more subject to distortion by noise. There are several possibilities for improving the low-metal mine identification, including (1) increasing the upper limit of the frequency band to obtain a stronger signal and better defined spectra; (2) decreasing the size of the sensing head to further localize the region of sensitivity of the sensor; (3) displaying the spectral curves and performing the identification in real time to allow operator inspection of the spectral match; and (4) defining a generalized misfit that incorporates signal amplitude and possibly other spectral features such as the quadrature peak.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121...95S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121...95S"><span id="translatedtitle">A global <span class="hlt">ground</span> <span class="hlt">truth</span> view of the lunar air pressure tide L2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schindelegger, Michael; Dobslaw, Henryk</p> <p>2016-01-01</p> <p>A comprehensive model of the lunar air pressure tide L2 is developed on the basis of 2315 <span class="hlt">ground</span> <span class="hlt">truth</span> estimates from land barometers and moored buoys. Regional-scale features of the tide and its seasonal modulations are well resolved by the in situ scatter and gridded to a 2° mesh through multiquadric interpolation. The resulting climatologies serve as an independent standard to validate the lunar semidiurnal tidal signal that is present in ERA-Interim reanalysis products despite the absence of L2-related gravitational forcing mechanisms in the prescribed model physics. Inconsistencies between the reanalysis solution of the barometric lunar tide and its empirical account are generally small, yet when averaged over the period 1979-2010, ERA-Interim underestimates the 100 μbar open ocean tidal amplitude in the Tropics by up to 20 μbar and produces times of peak pressure that are too early by 10 lunar minutes. Large-amplitude features of the reanalysis tide off the coast of Alaska, the eastern U.S., and Great Britain are evidently spurious, introduced to the analysis system by assimilating marine pressure data at an invariant reference surface instead of properly accounting for vertical sensor movements associated with the M2 ocean tide. Additionally, a credible L2 signal is documented for the ERA-20C pilot reanalysis of the twentieth century. The fact that this model rests upon input data from mere surface observations provides an unambiguous indication that the lunar tidal oscillation in atmospheric analysis systems is closely tied to the assimilation of conventional pressure measurements from stations and marine objects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA176804','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA176804"><span id="translatedtitle">Antarctic Atmospheric <span class="hlt">Infrasound</span>.</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1986-11-01</p> <p>system. These are microbaroms, aurural infrasonic waves, mountain associated <span class="hlt">infrasound</span>, Mount Erebus eruptive events, and signals related to large...array. Mount Erebus is an active volcano located only fifteen miles from the Windless Bight array. Frequent mini-eruptions from the lava lake at the...MAX, Velocity MIN & MAX, and Start & Stop. To produce a listing of all events that were caused by Mount Erebus on the tape: Choose the T array, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.7161C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7161C"><span id="translatedtitle"><span class="hlt">Infrasound</span> signals coupled from an underwater explosion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, I.-Y.; Kim, T. S.; Lee, H.-I.</p> <p>2012-04-01</p> <p>On 26 March 2010, a South Korean warship, Cheoanham, was sunken down offshore of an island, Bakryeong, in the Yellow Sea, South Korea. In the island that is near to the incident site, were a seismo-acoustic array and a broadband seismic station in operation. These stations recorded clear seismic and infrasonic signals associated with the warship-sinking. In addition, five <span class="hlt">infrasound</span> arrays being operated in the inland of South Korea also detected the <span class="hlt">infrasound</span> signals propagated up to 348 km from the <span class="hlt">source</span>. We studied the seismic and infrasonic signatures from the event for the determination of exact <span class="hlt">source</span> location and explanation of coupling phenomena among three different media; sea, solid earth and atmosphere. For the accurate <span class="hlt">source</span> localization we fused all the available seismo-acoustic information of arrival time and azimuth estimates of coupled seismic and infrasonic signals. The calculated location is nearly coincident with the event location reported by the Civilian Military Joint Investigation Group, which shows seismo-acoustic location is much better than those calculated with just seismic or infrasonic dataset. The relationship between explosion depth and charge was constrained with the period of the observed infrasonic signals. The attenuated amplitude of <span class="hlt">infrasound</span> signal was corrected to estimate the perturbed air pressure at <span class="hlt">source</span> location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1331426','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1331426"><span id="translatedtitle">USGS VDP <span class="hlt">Infrasound</span> Sensor Evaluation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Slad, George William; Merchant, Bion J.</p> <p>2016-10-01</p> <p>Sandia National Laboratories has tested and evaluated two <span class="hlt">infrasound</span> sensors, the model VDP100 and VDP250, built in-house at the USGS Cascades Volcano Observatory. The purpose of the <span class="hlt">infrasound</span> sensor evaluation was to determine a measured sensitivity, self-noise, dynamic range and nominal transfer function. Notable features of the VDP sensors include novel and durable construction and compact size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120015657','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120015657"><span id="translatedtitle">Using Apollo Sites and Soils to Compositionally <span class="hlt">Ground</span> <span class="hlt">Truth</span> Diviner Lunar Radiometer Observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenhagen, Benjamin T.; Lucey, P. G.; Song, E.; Thomas, I R.; Bowles, N. E.; DonaldsonHanna, K. L.; Allen, C.; Foote, E. J.; Paige, D .A.</p> <p>2012-01-01</p> <p>Apollo landing sites and returned soils afford us a unique opportunity to "<span class="hlt">ground</span> <span class="hlt">truth</span>" Diviner Lunar Radiometer compositional observations, which are the first global, high resolution , thermal infrared measurements of an airless body. The Moon is the most accessible member of the most abundant class of solar system objects, which includes Mercury, asteroids, and icy satellites. And the Apollo samples returned from the Moon are the only extraterrestrial samples with known spatial context. Here we compare Diviner observations of Apollo landing sites and compositional and spectral laboratory measurements of returned Apollo soils. Diviner, onboard NASA's Lunar Reconnaissance Orbiter, has three spectral channels near 8 micron that were designed to characterize the mid-infrared emissivity maximum known as the Christiansen feature (CF), a well-studied indicator of silicate mineralogy. It has been observed that thermal infrared spectra measured in simulated lunar environment (SLE) are significantly altered from spectra measured under terrestrial or martian conditions, with enhanced CF contrast and shifted CF position relative to other spectral features. Therefore only thermal emission experiments conducted in SLE are directly comparable to Diviner data. With known compositions, Apollo landing sites and soils are important calibration points for the Diviner dataset, which includes all six Apollo sites at approximately 200 m spatial resolution. Differences in measured CFs caused by composition and space weathering are apparent in Diviner data. Analyses of Diviner observations and SLE measurements for a range of Apollo soils show good agreement, while comparisons to thermal reflectance measurements under ambient conditions do not agree well, which underscores the need for SLE measurements and validates our measurement technique. Diviner observations of Apollo landing sites are also correlated with geochemical measurements of Apollo soils from the Lunar Sample Compendium</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006SPIE.6360E..0DH','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SPIE.6360E..0DH"><span id="translatedtitle">Implementation of a <span class="hlt">ground</span> <span class="hlt">truth</span> process for development of a submerged aquatic vegetation (SAV) mapping protocol using hyperspectral imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hall, Carlton R.; Bostater, Charles R., Jr.; Virnstein, Robert W.</p> <p>2006-09-01</p> <p>Protocol development for science based mapping of submerged aquatic vegetation (SAV) requires comprehensive <span class="hlt">ground</span> <span class="hlt">truth</span> data describing the full range of variability observed in the target. The Indian River Lagoon, Florida, extends along 250 km of the east central Florida coast adjacent to the Atlantic Ocean. The lagoon crosses the transition zone between the Caribbean and Carolinian zoogeographic provinces making it highly diverse. For large scale mapping and management of SAV four common and three uncommon species of seagrass (Tracheophyta) and three broad groups of macroalgae; red algae (Rhodophyta), green algae (Chlorophyta), and brown algae (Phaeophyta) are recognized. Based on technical and cost limitations we established twenty, 7-10 km long flight transects for collection of 1.2 m2 spatial resolution hyperspectral imagery covering the length of the lagoon. Emphasis was placed on the area near the Sebastian River and adjacent Sebastian Inlet. Twenty six 40 m long <span class="hlt">ground</span> <span class="hlt">truth</span> transects were established in the lagoon using 1 m2 white panels to mark each transect end. Each transect target was located in the field using high precision GPS. Transects were positioned to cover a range of depths, SAV densities, mixed and monotypic species beds, water quality conditions and general sediment types. A 3 m wide by 30 m long grid was centered on each transect to avoid spectral influences of the white targets. Water depth, species of seagrasses, estimates of vegetation cover percentage, estimates of epiphytic density, and measured canopy height were made for each 1 m2 (n=90). This target based grid arrangement allows for identification and extraction of pixel based hyperspectral signatures corresponding to individual <span class="hlt">ground</span> <span class="hlt">truth</span> grid cells without significant concern for rectification and registration error.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A23A0181M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A23A0181M"><span id="translatedtitle">Mid-Pacific <span class="hlt">Ground-Truth</span> Data For Validation of the CrIMSS Sensor Suite Aboard Suomi-NPP</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mollner, A. K.; Wessel, J.; Gaab, K. M.; Cardoza, D. M.; LaLumondiere, S. D.; Karuza, P.; Caponi, D.; Lotshaw, W. T.; Nalli, N. R.; Reale, T.; Divakarla, M.; Gambacorta, A.; Barnet, C.; Maddy, E. S.; Tan, C.; Xiong, X.; Porter, O.</p> <p>2013-12-01</p> <p>The Aerospace Transportable Lidar System 2 (ATLS-2) provides <span class="hlt">ground</span> <span class="hlt">truth</span> humidity and temperature data for the testing and evaluation of instruments aboard environmental satellites. The Aerospace <span class="hlt">ground-truth</span> data consist of collocated state-of-the art lidar and radiosonde observations (RAOBs). The lidar system consists of a pulsed UV transmitter, 36-inch collection telescope, and detection channels for water Raman, nitrogen Raman, and Rayleigh/Mie scattering. All channels are separated into two altitude bins to improve the dynamic range of the system. Dedicated balloon-borne radiosondes are Vaisala RS-92, processed with the current version of the Digicora-III software. The synergy between the Raman lidar data and radiosonde data produce high accuracy, quality-controlled vertical profiles of humidity (0 - 20 km) and temperature (0 - 60 km). Starting in May 2012, The Aerospace Corporation has exercised ATLS-2 to collect dedicated <span class="hlt">ground</span> <span class="hlt">truth</span> data sets in support of calibration and validation (cal/val) efforts for the Cross-track Infrared and Microwave Sounding Suite (CrIMSS) aboard the Suomi-National Polar-orbiting Partnership (S-NPP) satellite. Data sets are collected from the Pacific Missile Range Facility (PMRF) on the west coast of Kauai and are timed to be coincident with S-NPP overpasses. The Aerospace PMRF datasets complement the ensemble of similar datasets collected from DOE Atmospheric Radiation Measurement (ARM) and NOAA Aerosols and Ocean Science Expedition (AEROSE) sites, which are compared to CrIMSS Environmental Data Records (EDRs) by the NOAA/NESDIS/STAR cal/val team for validation of algorithm performance and algorithm improvement. In addition to providing the only dedicated CrIMSS data in the mid-pacific, The Aerospace Corporation was the first site to provide <span class="hlt">ground</span> <span class="hlt">truth</span> data to the EDR cal/val team. As a result, ATLS-2 data sets served as the initial benchmarks for EDR performance testing. Details of the ATLS-2 system and data products as well</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813157M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813157M"><span id="translatedtitle">Long-range <span class="hlt">infrasound</span> monitoring of eruptive volcanoes.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchetti, Emanuele; Innocenti, Lorenzo; Ulivieri, Giacomo; Lacanna, Giorgio; Ripepe, Maurizio</p> <p>2016-04-01</p> <p>The efficient long-range propagation in the atmosphere makes <span class="hlt">infrasound</span> of active volcanoes extremely promising and opens new perspectives for volcano monitoring at large scale. In favourable propagation conditions, long-range <span class="hlt">infrasound</span> observations can be used to track the occurrence and the duration of volcanic eruptions also at remote non-monitored volcanoes, but its potential to infer volcanic eruptive <span class="hlt">source</span> term is still debated. We present results of comparing five years of <span class="hlt">infrasound</span> of eruptive activity at Mt.Etna volcano (Italy) recorded both at local (~5 km) and at regional distances (~600 km) from the <span class="hlt">source</span>. <span class="hlt">Infrasound</span> of lava fountains at Etna volcano, occurring in between 2010 and 2015, are analysed in terms of the local and regional wavefield record, and by comparing to all available volcanic <span class="hlt">source</span> terms (i.e. plume height and mass eruption rates). Besides, the potential of near real-time notification of ongoing volcanic activity at Etna volcano at a regional scale is investigated. In particular we show how long range <span class="hlt">infrasound</span>, in the case of Etna volcano, can be used to promptly deliver eruption notification and reliability is constrained by the results of the local array. This work is performed in the framework of the H2020 ARISE2 project funded by the EU in the period 2015-2018.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMAE13A0366A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMAE13A0366A"><span id="translatedtitle"><span class="hlt">Infra-sound</span> Signature of Lightning</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arechiga, R. O.; Badillo, E.; Johnson, J.; Edens, H. E.; Rison, W.; Thomas, R. J.</p> <p>2012-12-01</p> <p>We have analyzed thunder from over 200 lightning flashes to determine which part of thunder comes from the gas dynamic expansion of portions of the rapidly heated lightning channel and which from electrostatic field changes. Thunder signals were recorded by a ~1500 m network of 3 to 4 4-element microphone deployed in the Magdalena mountains of New Mexico in the summers of 2011 and 2012. The higher frequency <span class="hlt">infra-sound</span> and audio-range portion of thunder is thought to come from the gas dynamic expansion, and the electrostatic mechanism gives rise to a signature <span class="hlt">infra-sound</span> pulse peaked at a few Hz. More than 50 signature <span class="hlt">infra-sound</span> pulses were observed in different portions of the thunder signal, with no preference towards the beginning or the end of the signal. Detection of the signature pulse occurs sometimes only for one array and sometimes for several arrays, which agrees with the theory that the pulse is highly directional (i.e., the recordings have to be in a specific position with respect to the cloud generating the pulse to be able to detect it). The detection of these pulses under quiet wind conditions by different acoustic arrays corroborates the electrostatic mechanism originally proposed by Wilson [1920], further studied by Dessler [1973] and Few [1985], observed by Bohannon [1983] and Balachandran [1979, 1983], and recently analyzed by Pasko [2009]. Pasko employed a model to explain the electrostatic-to-acoustic energy conversion and the initial compression waves in observed infrasonic pulses, which agrees with the observations we have made. We present thunder samples that exhibit signature <span class="hlt">infra-sound</span> pulses at different times and acoustic <span class="hlt">source</span> reconstruction to demonstrate the beaming effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B41D0464C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B41D0464C"><span id="translatedtitle">UAS-Borne Photogrammetry for Surface Topographic Characterization: A <span class="hlt">Ground-Truth</span> Baseline for Future Change Detection and Refinement of Scaled Remotely-Sensed Datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coppersmith, R.; Schultz-Fellenz, E. S.; Sussman, A. J.; Vigil, S.; Dzur, R.; Norskog, K.; Kelley, R.; Miller, L.</p> <p>2015-12-01</p> <p>While long-term objectives of monitoring and verification regimes include remote characterization and discrimination of surficial geologic and topographic features at sites of interest, <span class="hlt">ground</span> <span class="hlt">truth</span> data is required to advance development of remote sensing techniques. Increasingly, it is desirable for these ground-based or ground-proximal characterization methodologies to be as nimble, efficient, non-invasive, and non-destructive as their higher-altitude airborne counterparts while ideally providing superior resolution. For this study, the area of interest is an alluvial site at the Nevada National Security Site intended for use in the <span class="hlt">Source</span> Physics Experiment's (Snelson et al., 2013) second phase. <span class="hlt">Ground-truth</span> surface topographic characterization was performed using a DJI Inspire 1 unmanned aerial system (UAS), at very low altitude (< 5-30m AGL). 2D photographs captured by the standard UAS camera payload were imported into Agisoft Photoscan to create three-dimensional point clouds. Within the area of interest, careful installation of surveyed ground control fiducial markers supplied necessary targets for field collection, and information for model georectification. The resulting model includes a Digital Elevation Model derived from 2D imagery. It is anticipated that this flexible and versatile characterization process will provide point cloud data resolution equivalent to a purely ground-based LiDAR scanning deployment (e.g., 1-2cm horizontal and vertical resolution; e.g., Sussman et al., 2012; Schultz-Fellenz et al., 2013). In addition to drastically increasing time efficiency in the field, the UAS method also allows for more complete coverage of the study area when compared to ground-based LiDAR. Comparison and integration of these data with conventionally-acquired airborne LiDAR data from a higher-altitude (~ 450m) platform will aid significantly in the refinement of technologies and detection capabilities of remote optical systems to identify and detect</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H53G1504S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H53G1504S"><span id="translatedtitle">Groundwater storage change in the Ngadda Catchment of the Lake Chad Basin using GRACE and <span class="hlt">ground</span> <span class="hlt">truth</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skaskevych, A.; Lee, J.</p> <p>2013-12-01</p> <p>The present study is to analyze groundwater storage variations in the Ngadda Catchment located in the southwestern edge of Lake Chad Basin using Gravity Recovery and Climate Experiment (GRACE) data. We collected monthly total water storage data from GRACE and monthly soil moisture data from Global Land Data Assimilation System (GLDAS) for the period of 2005 - 2009 with the spatial resolution of 1 and 0.25 degrees. We assumed surface water contributions to be negligible in the study area. The estimated groundwater storage changes were compared to the <span class="hlt">ground</span> <span class="hlt">truth</span> groundwater depth data collected in 2005 and 2009. The challenge of the present study is sparseness of the <span class="hlt">ground</span> <span class="hlt">truth</span> data in space and time. The study area is one of the data poor regions in the world due to the limited accessibility to the area. Different geostatistical techniques such as Kriging, Thiessen polygons, and Bayesian updating were applied to overcome such sparseness and modeling uncertainty under different scales and resolution. The study shows a significant increase of groundwater storage in the Ngadda catchment during the study period. Uncertainty is significant though depending on the size of the model and modeling technique. The study discusses advantages of using remote sensing data in data poor regions and how geostatistical techniques can be applied to deal with modeling uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA569899','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569899"><span id="translatedtitle"><span class="hlt">Infrasound</span> Sensor Calibration and Response</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-09-01</p> <p>functions with faster rise times. SUMMARY We have documented past work on the determination of the calibration constant of the LANL <span class="hlt">infrasound</span> sensor...Monitoring Technologies 735 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated...National Laboratory ( LANL ) has operated an <span class="hlt">infrasound</span> sensor calibration chamber that operates over a frequency range of 0.02 to 4 Hz. This chamber has</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8364B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8364B"><span id="translatedtitle">Use of the IMS <span class="hlt">infrasound</span> network for global atmospheric studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanc, Elisabeth; Le Pichon, Alexis; Ceranna, Lars; Farges, Thomas</p> <p>2010-05-01</p> <p>The development of the <span class="hlt">Infrasound</span> International Monitoring System (IMS), used for the verification of the Comprehensive Test Ban Treaty, represents a powerful tool to measure permanently, at a global scale and over large periods of time, the disturbances of the atmosphere. The network is mostly sensitive to <span class="hlt">infrasound</span> in the range 0.02 to 5 Hz, but it also measures gravity waves at lower frequencies and tidal waves. Measurements with the IMS <span class="hlt">infrasound</span> network provide both the state of the atmospheric wave guide and of the atmospheric waves which can be used to study the dynamics of the atmosphere. The first way is to study the variability of <span class="hlt">infrasound</span> from quasi continuous <span class="hlt">sources</span> such as ocean swells or volcanoes in relation with changes in large scale atmospheric structures. Since <span class="hlt">infrasound</span> propagate in the stratosphere and mesosphere, atmospheric parameters which affect the <span class="hlt">infrasound</span> propagation can be investigated from ground measurements of <span class="hlt">infrasound</span>. Azimuth changes of <span class="hlt">infrasound</span> from volcanis eruption were used to retrieve mesospheric zonal winds. The amplitude fluctuations of <span class="hlt">infrasound</span> from ocean swells represent planetary waves which modulate the atmospheric wave guide. Fluctuations are much larger in Northern hemispheres than in Southern hemisphere, because the amplitude of planetary waves is larger in Northern hemisphere where continental areas are more important. <span class="hlt">Infrasound</span> monitoring also revealed anomalies at a seasonal scale in Antarctica or at the scale of several days in Arctic regionsin relation with Sudden Stratospheric Warming. The second way is the direct observation of large scale gravity waves. These waves, mainly produced in the troposphere, propagate upwards and break in the stratosphere producing a chaotic forcing of the stratosphere. This is at the origin of a slow and large scale motion in which air masses are driven upward and poleward from the tropical lower stratosphere. In polar regions, they are pushed downward producing</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51C2690R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2690R"><span id="translatedtitle">Characteristics and Applications of a High Performance, Miniaturized, <span class="hlt">Infrasound</span> Sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rothman, J. L.; Marriott, D. A.</p> <p>2015-12-01</p> <p><span class="hlt">Infrasound</span> Sensors have been used for many years to monitor a large number of geophysical phenomena and manmade <span class="hlt">sources</span>. Due to their large size and power consumption these sensors have typically been deployed in fixed arrays, portable arrays have required trucks to transport the sensors and support equipment. A high performance, miniaturized, <span class="hlt">infrasound</span> microphone has been developed to enable mobile <span class="hlt">infrasound</span> measurements that would otherwise be impractical. The new device is slightly larger than a hockey puck, weighs 200g, and consumes less than 150mW. The sensitivity is 0.4V/Pa and self noise at 1Hz is less than 0.63μPa²/Hz. The characteristics were verified using a calibrator tracable to the Los Alamos calibration chamber. Field tests have demonstrated the performance is comparable to a Chaparral model 25. Applications include man portable arrays, mobile installations, and UAV based measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780007606','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780007606"><span id="translatedtitle">Procedures for gathering <span class="hlt">ground</span> <span class="hlt">truth</span> information for a supervised approach to a computer-implemented land cover classification of LANDSAT-acquired multispectral scanner data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Joyce, A. T.</p> <p>1978-01-01</p> <p>Procedures for gathering <span class="hlt">ground</span> <span class="hlt">truth</span> information for a supervised approach to a computer-implemented land cover classification of LANDSAT acquired multispectral scanner data are provided in a step by step manner. Criteria for determining size, number, uniformity, and predominant land cover of training sample sites are established. Suggestions are made for the organization and orientation of field team personnel, the procedures used in the field, and the format of the forms to be used. Estimates are made of the probable expenditures in time and costs. Examples of <span class="hlt">ground</span> <span class="hlt">truth</span> forms and definitions and criteria of major land cover categories are provided in appendixes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714341A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714341A"><span id="translatedtitle">Study of IDC <span class="hlt">infrasound</span> REB solutions using Egyptian National Seismic Network data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Sherif M.; Polich, Paul</p> <p>2015-04-01</p> <p> infragenic <span class="hlt">sources</span> within Egypt and regional surroundings, and benchmark the detection capability of the ENSN by its concurrence with IMS <span class="hlt">infrasound</span> data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800019173','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800019173"><span id="translatedtitle">The GSFC Mark-2 three band hand-held radiometer. [thematic mapper for <span class="hlt">ground</span> <span class="hlt">truth</span> data collection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tucker, C. J.; Jones, W. H.; Kley, W. A.; Sundstrom, G. J.</p> <p>1980-01-01</p> <p>A self-contained, portable, hand-radiometer designed for field usage was constructed and tested. The device, consisting of a hand-held probe containing three sensors and a strap supported electronic module, weighs 4 1/2 kilograms. It is powered by flashlight and transistor radio batteries, utilizes two silicon and one lead sulfide detectors, has three liquid crystal displays, sample and hold radiometric sampling, and its spectral configuration corresponds to LANDSAT-D's thematic mapper bands. The device was designed to support thematic mapper <span class="hlt">ground-truth</span> data collection efforts and to facilitate 'in situ' ground-based remote sensing studies of natural materials. Prototype instruments were extensively tested under laboratory and field conditions with excellent results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770010606','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770010606"><span id="translatedtitle">A procedure used for a <span class="hlt">ground</span> <span class="hlt">truth</span> study of a land use map of North Alabama generated from LANDSAT data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Downs, S. W., Jr.; Sharma, G. C.; Bagwell, C.</p> <p>1977-01-01</p> <p>A land use map of a five county area in North Alabama was generated from LANDSAT data using a supervised classification algorithm. There was good overall agreement between the land use designated and known conditions, but there were also obvious discrepancies. In ground checking the map, two types of errors were encountered - shift and misclassification - and a method was developed to eliminate or greatly reduce the errors. Randomly selected study areas containing 2,525 pixels were analyzed. Overall, 76.3 percent of the pixels were correctly classified. A contingency coefficient of correlation was calculated to be 0.7 which is significant at the alpha = 0.01 level. The land use maps generated by computers from LANDSAT data are useful for overall land use by regional agencies. However, care must be used when making detailed analysis of small areas. The procedure used for conducting the <span class="hlt">ground</span> <span class="hlt">truth</span> study together with data from representative study areas is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790013470','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790013470"><span id="translatedtitle">SAGE <span class="hlt">ground</span> <span class="hlt">truth</span> plan: Correlative measurements for the Stratospheric Aerosol and Gas Experiment (SAGE) on the AEM-B satellite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, P. B. (Editor); Cunnold, D. M.; Grams, G. W.; Laver, J.; Mccormick, M. P.; Mcmaster, L. R.; Murcray, D. G.; Pepin, T. J.; Perry, T. W.; Planet, W. G.</p> <p>1979-01-01</p> <p>The <span class="hlt">ground</span> <span class="hlt">truth</span> plan is outlined for correlative measurements to validate the Stratospheric Aerosol and Gas Experiment (SAGE) sensor data. SAGE will fly aboard the Applications Explorer Mission-B satellite scheduled for launch in early 1979 and measure stratospheric vertical profiles of aerosol, ozone, nitrogen dioxide, and molecular extinction between 79 N and 79 S. latitude. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. In addition, an overview of the SAGE expected instrument performance and data inversion results are presented. Various atmospheric models representative of stratospheric aerosols and ozone are used in the SAGE and correlative sensor analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT........67B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT........67B"><span id="translatedtitle"><span class="hlt">Infrasound</span> from ground to space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bowman, Daniel Charles</p> <p></p> <p>Acoustic detector networks are usually located on the Earth's surface. However, these networks suffer from shortcomings such as poor detection range and pervasive wind noise. An alternative is to deploy acoustic sensors on high altitude balloons. In theory, such platforms can resolve signals arriving from great distances, acquire others that never reach the surface at all, and avoid wind noise entirely. This dissertation focuses on scientific advances, instrumentation, and analytical techniques resulting from the development of such sensor arrays. Results from <span class="hlt">infrasound</span> microphones deployed on balloon flights in the middle stratosphere are described, and acoustic <span class="hlt">sources</span> such as the ocean microbarom and building ventilation systems are discussed. Electromagnetic noise originating from the balloon, flight system, and other payloads is shown to be a pervasive issue. An experiment investigating acoustic sensor calibration at low pressures is presented, and implications for high altitude recording are considered. Outstanding challenges and opportunities in sound measurement using sensors embedded in the free atmosphere are outlined. Acoustic signals from field scale explosions designed to emulate volcanic eruptions are described, and their generation mechanisms modeled. Wave forms recorded on sensors suspended from tethered helium balloons are compared with those detected on ground stations during the experiment. Finally, the Hilbert-Huang transform, a high time resolution spectral analysis method for nonstationary and nonlinear time series, is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1221711','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1221711"><span id="translatedtitle">Hyperion 5113/A <span class="hlt">Infrasound</span> Sensor Evaluation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Merchant, Bion John</p> <p>2015-09-01</p> <p>Sandia National Laboratories has tested and evaluated an <span class="hlt">infrasound</span> sensor, the 5113/A manufactured by Hyperion. These <span class="hlt">infrasound</span> sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the <span class="hlt">infrasound</span> sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, and dynamic range. The 5113/A <span class="hlt">infrasound</span> sensor is a new revision of the 5000 series intended to meet the <span class="hlt">infrasound</span> application requirements for use in the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=299746','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=299746"><span id="translatedtitle">Methods for improving accuracy and extending results beyond periods covered by traditional <span class="hlt">ground-truth</span> in remote sensing classification of a complex landscape</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Successful development of approaches to quantify impacts of diverse landuse and associated agricultural management practices on ecosystem services is frequently limited by lack of historical and contemporary landuse data. We hypothesized that recent <span class="hlt">ground</span> <span class="hlt">truth</span> data could be used to extrapolate pre...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51F..04A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51F..04A"><span id="translatedtitle">Global <span class="hlt">Infrasound</span> Association Based on Probabilistic Clutter Categorization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arora, N. S.; Mialle, P.</p> <p>2015-12-01</p> <p>The IDC collects waveforms from a global network of <span class="hlt">infrasound</span> sensors maintained by the IMS, and automatically detects signal onsets and associates them to form event hypotheses. However, a large number of signal onsets are due to local clutter <span class="hlt">sources</span> such as microbaroms (from standing waves in the oceans), waterfalls, dams, gas flares, surf (ocean breaking waves) etc. These <span class="hlt">sources</span> are either too diffuse or too local to form events. Worse still, the repetitive nature of this clutter leads to a large number of false event hypotheses due to the random matching of clutter at multiple stations. Previous studies, for example [1], have worked on categorization of clutter using long term trends on detection azimuth, frequency, and amplitude at each station. In this work we continue the same line of reasoning to build a probabilistic model of clutter that is used as part of NET-VISA [2], a Bayesian approach to network processing. The resulting model is a fusion of seismic, hydro-acoustic and <span class="hlt">infrasound</span> processing built on a unified probabilistic framework. Notes: The attached figure shows all the unassociated arrivals detected at IMS station I09BR for 2012 distributed by azimuth and center frequency. (The title displays the bandwidth of the kernel density estimate along the azimuth and frequency dimensions).This plot shows multiple micro-barom <span class="hlt">sources</span> as well as other <span class="hlt">sources</span> of <span class="hlt">infrasound</span> clutter. A diverse clutter-field such as this one is quite common for most IMS <span class="hlt">infrasound</span> stations, and it highlights the dangers of forming events without due consideration of this <span class="hlt">source</span> of noise. References: [1] <span class="hlt">Infrasound</span> categorization Towards a statistics-based approach. J. Vergoz, P. Gaillard, A. Le Pichon, N. Brachet, and L. Ceranna. ITW 2011 [2] NET-VISA: Network Processing Vertically Integrated Seismic Analysis. N. S. Arora, S. Russell, and E. Sudderth. BSSA 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9062L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9062L"><span id="translatedtitle">Observed and predicted performance of the global IMS <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Ceranna, L.; Landes, M.</p> <p>2012-04-01</p> <p>The International Monitoring System (IMS) <span class="hlt">infrasound</span> network is being deployed to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Global-scale analyses of data recorded by this network indicate that the detection capability exhibits strong spatio-temporal variations. Previous studies estimated radiated acoustic <span class="hlt">source</span> energy from remote <span class="hlt">infrasound</span> observations using empirical yield-scaling relations, which account for the along-path stratospheric winds. Although the empirical wind correction reduces the variance in the explosive energy versus pressure relationship, large error remains in the yield estimates. Numerical modeling techniques are now widely employed to investigate the role of different factors describing atmospheric <span class="hlt">infrasound</span> <span class="hlt">sources</span> and propagation. Here we develop a theoretical attenuation relation from a large set of numerical simulations using the Parabolic Equation method. This relation accounts for the effects of the <span class="hlt">source</span> frequency; geometrical spreading and dissipation; and realistic atmospheric specifications on the pressure wave attenuation. Compared with previous studies, the derived attenuation relation incorporates a more realistic physical description of <span class="hlt">infrasound</span> propagation. By incorporating real ambient noise information at the receivers, we obtain the minimum detectable <span class="hlt">source</span> amplitude in the frequency band of interest for detecting explosions. Empirical relations between the <span class="hlt">source</span> spectrum and explosion yield are used to infer detection thresholds in tons of TNT equivalent. In the context of future verification of the CTBT, the obtained attenuation relation provides a more realistic picture of the spatio-temporal variability of the IMS network performance. The attenuation relation could also be used in the design and maintenance of an arbitrary <span class="hlt">infrasound</span> monitoring network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814503A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814503A"><span id="translatedtitle">Global <span class="hlt">Infrasound</span> Association Based on Probabilistic Clutter Categorization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arora, Nimar; Mialle, Pierrick</p> <p>2016-04-01</p> <p>The IDC advances its methods and continuously improves its automatic system for the <span class="hlt">infrasound</span> technology. The IDC focuses on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold by identifying ways to refine signal characterization methodology and association criteria. An objective of this study is to reduce the number of associated <span class="hlt">infrasound</span> arrivals that are rejected from the automatic bulletins when generating the reviewed event bulletins. Indeed, a considerable number of signal detections are due to local clutter <span class="hlt">sources</span> such as microbaroms, waterfalls, dams, gas flares, surf (ocean breaking waves) etc. These <span class="hlt">sources</span> are either too diffuse or too local to form events. Worse still, the repetitive nature of this clutter leads to a large number of false event hypotheses due to the random matching of clutter at multiple stations. Previous studies, for example [1], have worked on categorization of clutter using long term trends on detection azimuth, frequency, and amplitude at each station. In this work we continue the same line of reasoning to build a probabilistic model of clutter that is used as part of NETVISA [2], a Bayesian approach to network processing. The resulting model is a fusion of seismic, hydroacoustic and <span class="hlt">infrasound</span> processing built on a unified probabilistic framework. References: [1] <span class="hlt">Infrasound</span> categorization Towards a statistics based approach. J. Vergoz, P. Gaillard, A. Le Pichon, N. Brachet, and L. Ceranna. ITW 2011 [2] NETVISA: Network Processing Vertically Integrated Seismic Analysis. N. S. Arora, S. Russell, and E. Sudderth. BSSA 2013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2490P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2490P"><span id="translatedtitle">Explosion <span class="hlt">Source</span> Location Study Using Collocated Acoustic and Seismic Networks in Israel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinsky, V.; Gitterman, Y.; Arrowsmith, S.; Ben-Horin, Y.</p> <p>2013-12-01</p> <p>We explore a joined analysis of seismic and infrasonic signals for improvement in automatic monitoring of small local/regional events, such as construction and quarry blasts, military chemical explosions, sonic booms, etc. using collocated seismic and infrasonic networks recently build in Israel (ISIN) in the frame of the project sponsored by the Bi-national USA-Israel Science Foundation (BSF). The general target is to create an automatic system, which will provide detection, location and identification of explosions in real-time or close-to-real time manner. At the moment the network comprises 15 stations hosting a microphone and seismometer (or accelerometer), operated by the Geophysical Institute of Israel (GII), plus two infrasonic arrays, operated by the National Data Center, Soreq: IOB in the South (Negev desert) and IMA in the North of Israel (Upper Galilee),collocated with the IMS seismic array MMAI. The study utilizes a <span class="hlt">ground-truth</span> data-base of numerous Rotem phosphate quarry blasts, a number of controlled explosions for demolition of outdated ammunitions and experimental surface explosions for a structure protection research, at the Sayarim Military Range. A special event, comprising four military explosions in a neighboring country, that provided both strong seismic (up to 400 km) and <span class="hlt">infrasound</span> waves (up to 300 km), is also analyzed. For all of these events the <span class="hlt">ground-truth</span> coordinates and/or the results of seismic location by the Israel Seismic Network (ISN) have been provided. For automatic event detection and phase picking we tested the new recursive picker, based on Statistically optimal detector. The results were compared to the manual picks. Several location techniques have been tested using the <span class="hlt">ground-truth</span> event recordings and the preliminary results obtained have been compared to the <span class="hlt">ground-truth</span> locations: 1) a number of events have been located as intersection of azimuths estimated using the wide-band F-K analysis technique applied to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930016609&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930016609&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtruth"><span id="translatedtitle">Geographic information system for fusion and analysis of high-resolution remote sensing and <span class="hlt">ground</span> <span class="hlt">truth</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz</p> <p>1992-01-01</p> <p>We seek to combine high-resolution remotely sensed data with models and <span class="hlt">ground</span> <span class="hlt">truth</span> measurements, in the context of a Geographical Information System, integrated with specialized image processing software. We will use this integrated system to analyze the data from two Case Studies, one at a bore Al forest site, the other a tropical forest site. We will assess the information content of the different components of the data, determine the optimum data combinations to study biogeophysical changes in the forest, assess the best way to visualize the results, and validate the models for the forest response to different radar wavelengths/polarizations. During the 1990's, unprecedented amounts of high-resolution images from space of the Earth's surface will become available to the applications scientist from the LANDSAT/TM series, European and Japanese ERS-1 satellites, RADARSAT and SIR-C missions. When the Earth Observation Systems (EOS) program is operational, the amount of data available for a particular site can only increase. The interdisciplinary scientist, seeking to use data from various sensors to study his site of interest, may be faced with massive difficulties in manipulating such large data sets, assessing their information content, determining the optimum combinations of data to study a particular parameter, visualizing his results and validating his model of the surface. The techniques to deal with these problems are also needed to support the analysis of data from NASA's current program of Multi-sensor Airborne Campaigns, which will also generate large volumes of data. In the Case Studies outlined in this proposal, we will have somewhat unique data sets. For the Bonanza Creek Experimental Forest (Case I) calibrated DC-8 SAR data and extensive <span class="hlt">ground</span> <span class="hlt">truth</span> measurement are already at our disposal. The data set shows documented evidence to temporal change. The Belize Forest Experiment (Case II) will produce calibrated DC-8 SAR and AVIRIS data, together with</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19105754','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19105754"><span id="translatedtitle">Science results from a Mars drilling simulation (Río Tinto, Spain) and <span class="hlt">ground</span> <span class="hlt">truth</span> for remote science observations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bonaccorsi, Rosalba; Stoker, Carol R</p> <p>2008-10-01</p> <p>Science results from a field-simulated lander payload and post-mission laboratory investigations provided "<span class="hlt">ground</span> <span class="hlt">truth</span>" to interpret remote science observations made as part of the 2005 Mars Astrobiology Research and Technology Experiment (MARTE) drilling mission simulation. The experiment was successful in detecting evidence for life, habitability, and preservation potential of organics in a relevant astrobiological analogue of Mars. SCIENCE RESULTS: Borehole 7 was drilled near the Río Tinto headwaters at Peña de Hierro (Spain) in the upper oxidized remnant of an acid rock drainage system. Analysis of 29 cores (215 cm of core was recovered from 606 cm penetrated depth) revealed a matrix of goethite- (42-94%) and hematite-rich (47-87%) rocks with pockets of phyllosilicates (47-74%) and fine- to coarse-grained loose material. Post-mission X-ray diffraction (XRD) analysis confirmed the range of hematite:goethite mixtures that were visually recognizable (approximately 1:1, approximately 1:2, and approximately 1:3 mixtures displayed a yellowish-red color whereas 3:1 mixtures displayed a dark reddish-brown color). Organic carbon was poorly preserved in hematite/goethite-rich materials (C(org) <0.05 wt %) beneath the biologically active organic-rich soil horizon (C(org) approximately 3-11 wt %) in contrast to the phyllosilicate-rich zones (C(org) approximately 0.23 wt %). <span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> VS. REMOTE SCIENCE ANALYSIS: Laboratory-based analytical results were compared to the analyses obtained by a Remote Science Team (RST) using a blind protocol. Ferric iron phases, lithostratigraphy, and inferred geologic history were correctly identified by the RST with the exception of phyllosilicate-rich materials that were misinterpreted as weathered igneous rock. Adenosine 5'-triphosphate (ATP) luminometry, a tool available to the RST, revealed ATP amounts above background noise, i.e., 278-876 Relative Luminosity Units (RLUs) in only 6 cores, whereas organic carbon was detected in all</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S53B1985E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S53B1985E"><span id="translatedtitle"><span class="hlt">Infrasound</span> analysis of I18DK, northwest Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evers, L. G.; Weemstra, C.</p> <p>2010-12-01</p> <p>Within the scope of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), four methods are used to verify the treaty. One of these methods is based on the detection of <span class="hlt">infrasound</span> waves generated by a nuclear explosion. Seismological, hydroacoustical and radionuclide measurements are also applied. The International Monitoring System (IMS) will consist of 60 <span class="hlt">infrasound</span> stations of which 35 stations are currently operational. Data obtained from an <span class="hlt">infrasound</span> station situated on the northwestern shoreline of Greenland is analyzed. This station is operated by Denmark and labeled as I18DK. I18DK is situated in an area which receives an ever increasing attention from a geophysical perspective. I18DK has continuously been operational from April 2003 and onwards. The IMS station is an <span class="hlt">infrasound</span> array with an aperture of about 1200 meters, where air-pressure fluctuations are recorded by eight microbarometers at a sample-rate of 20 Hz. The infrasonic recordings are filtered between 0.1 & 1.0 and 1.0 & 6.0 Hz. The slowness grid is searched for two different configurations in the higher frequency band. Once using all 8 stations and once only taking into account the 5 center stations. Several different <span class="hlt">source</span> types are known to generate <span class="hlt">infrasound</span>, for example, calving of icebergs and glaciers, explosions, earthquakes, oceanic wave-wave interaction, volcanic eruptions and aurora. The challenge is to distinguish between these different <span class="hlt">source</span> types and use the outcome of the array analysis to better understand these phenomena. The rate of occurrence of icequakes, the calving of glaciers and the variation in extent of the sea ice in this area is of interest in relation to global warming. The processing results of the 1 to 6 Hz band seem to show dominating back-azimuths related to these <span class="hlt">sources</span>. The glaciers south of I18DK produce significant <span class="hlt">infrasound</span> during summer time. As well, a direct link can be found between the number of warm days in a year and the number of <span class="hlt">infrasound</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMNH31C3877T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMNH31C3877T"><span id="translatedtitle">Assessing and optimizing <span class="hlt">infrasound</span> network performance: application to remote volcano monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tailpied, D.; LE Pichon, A.; Marchetti, E.; Kallel, M.; Ceranna, L.</p> <p>2014-12-01</p> <p><span class="hlt">Infrasound</span> is an efficient monitoring technique to remotely detect and characterize explosive <span class="hlt">sources</span> such as volcanoes. Simulation methods incorporating realistic <span class="hlt">source</span> and propagation effects have been developed to quantify the detection capability of any network. These methods can also be used to optimize the network configuration (number of stations, geographical location) in order to reduce the detection thresholds taking into account seasonal effects in <span class="hlt">infrasound</span> propagation. Recent studies have shown that remote <span class="hlt">infrasound</span> observations can provide useful information about the eruption chronology and the released acoustic energy. Comparisons with near-field recordings allow evaluating the potential of these observations to better constrain <span class="hlt">source</span> parameters when other monitoring techniques (satellite, seismic, gas) are not available or cannot be made. Because of its regular activity, the well-instrumented Mount Etna is in Europe a unique natural repetitive <span class="hlt">source</span> to test and optimize detection and simulation methods. The closest <span class="hlt">infrasound</span> station part of the International Monitoring System is located in Tunisia (IS48). In summer, during the downwind season, it allows an unambiguous identification of signals associated with Etna eruptions. Under the European ARISE project (Atmospheric dynamics InfraStructure in Europe, FP7/2007-2013), experimental arrays have been installed in order to characterize <span class="hlt">infrasound</span> propagation in different ranges of distance and direction. In addition, a small-aperture array, set up on the flank by the University of Firenze, has been operating since 2007. Such an experimental setting offers an opportunity to address the societal benefits that can be achieved through routine <span class="hlt">infrasound</span> monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDM13009R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDM13009R"><span id="translatedtitle">Interactions between intermittent gravity waves and <span class="hlt">infrasounds</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ribstein, Bruno; Millet, Christophe; Lott, Francois; de La Camara, Alvaro</p> <p>2016-11-01</p> <p>Even though the accuracy of atmospheric specifications is constantly improving, it is well known that the main part of gravity waves is still yet not resolved in the available data. In most <span class="hlt">infrasound</span> modeling studies, the unresolved gravity wave field is often represented as a deterministic field that is superimposed on a given average background state. Direct observations in the lower stratosphere show, however, that the gravity wave field is very intermittent, and is often dominated by rather well defined wave packets. In this study we sample the gravity wave spectrum by launching few monochromatic waves and choose their properties stochastically to mimic the intermittency. The statistics of acoustic signals are computed by decomposing the original signal into a sum of modal pulses. Owing to the disparity of the gravity and acoustic lengthscales, the interaction can be described using a multiplescale analysis and the appropriate amplitude evolution equation involves certain random terms that are related to the gravity wave <span class="hlt">sources</span>. More specifically, it is shown how the unpredictable low level small-scale dynamics triggers multiple random stratospheric waveguides in which high frequency <span class="hlt">infrasound</span> components can propagate efficiently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT........27O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT........27O"><span id="translatedtitle">Characterization and diagnostic methods for geomagnetic auroral <span class="hlt">infrasound</span> waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oldham, Justin J.</p> <p></p> <p>Infrasonic perturbations resulting from auroral activity have been observed since the 1950's. In the last decade advances in infrasonic microphone sensitivity, high latitude sensor coverage, time series analysis methods and computational efficiency have elucidated new types of auroral <span class="hlt">infrasound</span>. Persistent periods of infrasonic activity associated with geomagnetic sub-storms have been termed geomagnetic auroral <span class="hlt">infrasound</span> waves [GAIW]. We consider 63 GAIW events recorded by the Fairbanks, AK infrasonic array I53US ranging from 2003 to 2014 and encompassing a complete solar cycle. We make observations of the acoustic features of these events alongside magnetometer, riometer, and all-sky camera data in an effort to quantify the ionospheric conditions suitable for <span class="hlt">infrasound</span> generation. We find that, on average, the generation mechanism for GAIW is confined to a region centered about ~60 0 longitude east of the anti-Sun-Earth line and at ~770 North latitude. We note furthermore that in all cases considered wherein imaging riometer data are available, that dynamic regions of heightened ionospheric conductivity periodically cross the overhead zenith. Consistent features in concurrent magnetometer conditions are also noted, with irregular oscillations in the horizontal component of the field ubiquitous in all cases. In an effort to produce ionosphere based <span class="hlt">infrasound</span> free from the clutter and unknowns typical of geophysical observations, an experiment was undertaken at the High Frequency Active Auroral Research Program [HAARP] facility in 2012. Infrasonic signals appearing to originate from a <span class="hlt">source</span> region overhead were observed briefly on 9 August 2012. The signals were observed during a period when an electrojet current was presumed to have passed overhead and while the facilities radio transmitter was periodically heating the lower ionosphere. Our results suggest dynamic auroral electrojet currents as primary <span class="hlt">sources</span> of much of the observed <span class="hlt">infrasound</span>, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4392711','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4392711"><span id="translatedtitle">Semi-automatic <span class="hlt">ground</span> <span class="hlt">truth</span> generation using unsupervised clustering and limited manual labeling: Application to handwritten character recognition</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vajda, Szilárd; Rangoni, Yves; Cecotti, Hubert</p> <p>2015-01-01</p> <p>For training supervised classifiers to recognize different patterns, large data collections with accurate labels are necessary. In this paper, we propose a generic, semi-automatic labeling technique for large handwritten character collections. In order to speed up the creation of a large scale <span class="hlt">ground</span> <span class="hlt">truth</span>, the method combines unsupervised clustering and minimal expert knowledge. To exploit the potential discriminant complementarities across features, each character is projected into five different feature spaces. After clustering the images in each feature space, the human expert labels the cluster centers. Each data point inherits the label of its cluster’s center. A majority (or unanimity) vote decides the label of each character image. The amount of human involvement (labeling) is strictly controlled by the number of clusters – produced by the chosen clustering approach. To test the efficiency of the proposed approach, we have compared, and evaluated three state-of-the art clustering methods (k-means, self-organizing maps, and growing neural gas) on the MNIST digit data set, and a Lampung Indonesian character data set, respectively. Considering a k-nn classifier, we show that labeling manually only 1.3% (MNIST), and 3.2% (Lampung) of the training data, provides the same range of performance than a completely labeled data set would. PMID:25870463</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V53E3154B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V53E3154B"><span id="translatedtitle">A 3-D view of field-scale fault-zone cementation from geologically <span class="hlt">ground-truthed</span> electrical resistivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barnes, H.; Spinelli, G. A.; Mozley, P.</p> <p>2015-12-01</p> <p>Fault-zones are an important control on fluid flow, affecting groundwater supply, hydrocarbon/contaminant migration, and waste/carbon storage. However, current models of fault seal are inadequate, primarily focusing on juxtaposition and entrainment effects, despite the recognition that fault-zone cementation is common and can dramatically reduce permeability. We map the 3D cementation patterns of the variably cemented Loma Blanca fault from the land surface to ~40 m depth, using electrical resistivity and induced polarization (IP). The carbonate-cemented fault zone is a region of anomalously low normalized chargeability, relative to the surrounding host material. Zones of low-normalized chargeability immediately under the exposed cement provide the first <span class="hlt">ground-truth</span> that a cemented fault yields an observable IP anomaly. Low-normalized chargeability extends down from the surface exposure, surrounded by zones of high-normalized chargeability, at an orientation consistent with normal faults in the region; this likely indicates cementation of the fault zone at depth, which could be confirmed by drilling and coring. Our observations are consistent with: 1) the expectation that carbonate cement in a sandstone should lower normalized chargeability by reducing pore-surface area and bridging gaps in the pore space, and 2) laboratory experiments confirming that calcite precipitation within a column of glass beads decreases polarization magnitude. The ability to characterize spatial variations in the degree of fault-zone cementation with resistivity and IP has exciting implications for improving predictive models of the hydrogeologic impacts of cementation within faults.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoRL..40.3517L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.3517L"><span id="translatedtitle">Determining olivine composition of basaltic dunes in Gale Crater, Mars, from orbit: Awaiting <span class="hlt">ground</span> <span class="hlt">truth</span> from Curiosity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lane, Melissa D.; Christensen, Philip R.</p> <p>2013-07-01</p> <p>successful landing of the Mars Science Laboratory Curiosity rover in Gale Crater, Mars, presents a rare opportunity for validation of a spectral index developed for determining olivine chemistry from orbital midinfrared remote-sensing data. Here, a spectral index is developed using laboratory emissivity data of 13 synthetic Mg-Fe olivines. Utilizing this spectral index, a prediction of olivine composition (~Fo55 ± 5) is made from orbital data for a NE-SW trending dune field near the Curiosity rover. This dune field will be crossed during the mission as the rover travels toward a ~5 km-high sediment stack (Mount Sharp) that contains orbitally detected clays and sulfates. Curiosity can use its instrument suite (ChemMin, Alpha Particle X-ray Spectrometer, ChemCam) when it reaches the dunes to verify or refute the olivine-chemistry prediction presented here. The ability to validate the developed spectral index using the rover's <span class="hlt">ground-truth</span> instruments will strengthen olivine-chemistry mapping across the Martian surface using this spectral index.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19268708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19268708"><span id="translatedtitle">On the construction of a <span class="hlt">ground</span> <span class="hlt">truth</span> framework for evaluating voxel-based diffusion tensor MRI analysis methods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Hecke, Wim; Sijbers, Jan; De Backer, Steve; Poot, Dirk; Parizel, Paul M; Leemans, Alexander</p> <p>2009-07-01</p> <p>Although many studies are starting to use voxel-based analysis (VBA) methods to compare diffusion tensor images between healthy and diseased subjects, it has been demonstrated that VBA results depend heavily on parameter settings and implementation strategies, such as the applied coregistration technique, smoothing kernel width, statistical analysis, etc. In order to investigate the effect of different parameter settings and implementations on the accuracy and precision of the VBA results quantitatively, <span class="hlt">ground</span> <span class="hlt">truth</span> knowledge regarding the underlying microstructural alterations is required. To address the lack of such a gold standard, simulated diffusion tensor data sets are developed, which can model an array of anomalies in the diffusion properties of a predefined location. These data sets can be employed to evaluate the numerous parameters that characterize the pipeline of a VBA algorithm and to compare the accuracy, precision, and reproducibility of different post-processing approaches quantitatively. We are convinced that the use of these simulated data sets can improve the understanding of how different diffusion tensor image post-processing techniques affect the outcome of VBA. In turn, this may possibly lead to a more standardized and reliable evaluation of diffusion tensor data sets of large study groups with a wide range of white matter altering pathologies. The simulated DTI data sets will be made available online (http://www.dti.ua.ac.be).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EP%26S...65..109C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EP%26S...65..109C"><span id="translatedtitle"><span class="hlt">Infrasound</span> associated with the deep M 7.3 northeastern China earthquake of June 28, 2002</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, Il-Young; Kim, Geunyoung; Pichon, Alexis Le</p> <p>2013-02-01</p> <p>On 28 June, 2002, a deep-focus (566 km) earthquake with a moment magnitude of 7.3 occurred in the China-Russia-North Korea border region. Despite its deep focus, the earthquake produced an <span class="hlt">infrasound</span> signal that was observed by the remote <span class="hlt">infrasound</span> array (CHNAR), 682 km from the epicenter, in South Korea. Coherent <span class="hlt">infrasound</span> signals were detected sequentially at the receiver, with different arrival times and azimuths indicating that the signals were generated both near the epicenter and elsewhere. On the basis of the azimuth, arrival time measurements, and atmospheric ray simulation results, the <span class="hlt">source</span> area of the infrasonic signals that arrived earlier were located along the eastern coastal areas of North Korea and Russia, whereas later signals were <span class="hlt">sourced</span> throughout Japan. The geographically-constrained, and discrete, distribution of the <span class="hlt">sources</span> identified is explained by <span class="hlt">infrasound</span> propagation effects caused by a westward zonal wind that was active when the event occurred. The amplitude of the deep quake's signal was equivalent to that of a shallow earthquake with a magnitude of approximately 5. This study expands the breadth of seismically-associated <span class="hlt">infrasound</span> to include deep earthquakes, and also supports the possibility that <span class="hlt">infrasound</span> measurements could help determine the depth of earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PApGe.174..865Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PApGe.174..865Z"><span id="translatedtitle">Using Hilbert-Huang Transform (HHT) to Extract <span class="hlt">Infrasound</span> Generated by the 2013 Lushan Earthquake in China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, X.; Xu, Q.; Liu, H. X.</p> <p>2017-03-01</p> <p>We applied the Hilbert-Huang transform (HHT) method to extract the <span class="hlt">infrasound</span> generated by the 2013 Lushan earthquake and its following aftershocks in China from a nearly continuous <span class="hlt">infrasound</span> recode made 130 km from the earthquake epicenter. An improved STA/LTA algorithm was adopted for detecting the ambient infrasonic events from the data record. A powerful processing technique for non-stationary signal, the HHT, was applied to extract the significant intrinsic mode functions (IMFs) of the infrasonic signal associated with the earthquakes. The features of the extracted IMFs, such as the dominant frequency, the maximum amplitude and the spectral entropy, were investigated using Hilbert spectral analysis. Regression analysis between the maximum amplitude in the <span class="hlt">infrasound</span> spectra and the magnitudes of the earthquakes was carried out to verify the <span class="hlt">source</span> of the <span class="hlt">infrasound</span> events detected. The results demonstrated that the HHT method could successfully identify the <span class="hlt">infrasound</span> related to the earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44..143Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44..143Y"><span id="translatedtitle">Volcanic eruption volume flux estimations from very long period <span class="hlt">infrasound</span> signals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamada, Taishi; Aoyama, Hiroshi; Nishimura, Takeshi; Iguchi, Masato; Hendrasto, Muhamad</p> <p>2017-01-01</p> <p>We examine very long period infrasonic signals accompanying volcanic eruptions near active vents at Lokon-Empung volcano in Indonesia, Aso, Kuchinoerabujima, and Kirishima volcanoes in Japan. The excitation of the very long period pulse is associated with an explosion, the emerging of an eruption column, and a pyroclastic density current. We model the excitation of the <span class="hlt">infrasound</span> pulse, assuming a monopole <span class="hlt">source</span>, to quantify the volume flux and cumulative volume of erupting material. The <span class="hlt">infrasound</span>-derived volume flux and cumulative volume can be less than half of the video-derived results. A largely positive correlation can be seen between the <span class="hlt">infrasound</span>-derived volume flux and the maximum eruption column height. Therefore, our result suggests that the analysis of very long period volcanic <span class="hlt">infrasound</span> pulses can be helpful in estimating the maximum eruption column height.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1213302','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1213302"><span id="translatedtitle">Hyperion 5113/GP <span class="hlt">Infrasound</span> Sensor Evaluation.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Merchant, Bion J.</p> <p>2015-08-01</p> <p>Sandia National Laboratories has tested and evaluated an <span class="hlt">infrasound</span> sensor, the 5113/GP manufactured by Hyperion. These <span class="hlt">infrasound</span> sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the <span class="hlt">infrasound</span> sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, and seismic sensitivity. These sensors are being evaluated prior to deployment by the U.S. Air Force.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2489H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2489H"><span id="translatedtitle"><span class="hlt">Infrasound</span> Observations of the Massive Landslide at Bingham Canyon Copper Mine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hale, J. M.; Arrowsmith, S.; Burlacu, R.; Hayward, C.; Pankow, K. L.</p> <p>2013-12-01</p> <p>On 10 April 2013 approximately 55 million m3 of rock collapsed from the northeastern wall of the approximately one-kilometer deep open-pit Bingham Canyon copper mine near Salt Lake City, Utah, generating clear seismic and <span class="hlt">infrasound</span> signals. The material released in two sudden rock avalanches separated in time by about 1.5 hours. The magnitudes for the two slides were determined to be ML 2.5 and 2.4 and MSW 5.0 and 4.9, respectively. Seismic signals with durations approaching two minutes from both rock avalanches were recorded on stations of the University of Utah (UU) regional seismic network and other networks at distances of ~6 to greater than 400 km. In addition, the first event was recorded on seven UU <span class="hlt">infrasound</span> arrays at distances of ~13 - 400 km and the second at five <span class="hlt">infrasound</span> arrays between ~57 and 400 km distance. Comparison of the seismograms from the two slides show differences in the long-period energy. There are also clear differences in the <span class="hlt">infrasound</span> observations. For example, at the closest array recording both slides, the duration of the <span class="hlt">infrasound</span> signal for the first slide is much longer than for the second slide. In addition, <span class="hlt">infrasound</span> attributed to the first rock avalanche resulted in multiple arrival observations at the three most distant arrays, while only one array had multiple arrivals for the latter event. For the five <span class="hlt">infrasound</span> arrays, with detections for both rock avalanches, we look for signal differences by cataloging duration, amplitude, azimuth, dominant period, correlation coefficients, group and trace velocity. In addition, propagation modeling through ground-to-space (G2S) profiles will be performed to determine if atmospheric differences can account for the varying <span class="hlt">infrasound</span> observations, and the <span class="hlt">source</span> of the <span class="hlt">infrasound</span> signal will be located using the Bayesian Infrasonic <span class="hlt">Source</span> Location procedure. With a wealth of geophysical data we aim to determine if the seismic and <span class="hlt">infrasound</span> signals have a common <span class="hlt">source</span> and if the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1165050','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1165050"><span id="translatedtitle">MB3a <span class="hlt">Infrasound</span> Sensor Evaluation.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Merchant, Bion J.; McDowell, Kyle D.</p> <p>2014-11-01</p> <p>Sandia National Laboratories has tested and evaluated a new <span class="hlt">infrasound</span> sensor, the MB3a, manufactured by Seismo Wave. These <span class="hlt">infrasound</span> sensors measure pressure output by a methodology developed by researchers at the French Alternative Energies and Atomic Energy Commission (CEA) and the technology was recently licensed to Seismo Wave for production and sales. The purpose of the <span class="hlt">infrasound</span> sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, seismic sensitivity, and self- calibration ability. The MB3a <span class="hlt">infrasound</span> sensors are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51D2705W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2705W"><span id="translatedtitle">Dynamic Modeling of <span class="hlt">Infrasound</span> Generation from Vulcanian Explosions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watson, L. M.; Dunham, E. M.</p> <p>2015-12-01</p> <p>Volcano <span class="hlt">infrasound</span> provides a complementary view of volcanic processes to seismic waves, as the atmosphere exhibits contrasting wave propagation characteristics to the crust. Potential benefits include a more uniform velocity structure, shorter wavelengths enabling better spatial resolution, and lower attenuation improving remote monitoring capabilities. Recent work on volcano <span class="hlt">infrasound</span> has employed kinematic <span class="hlt">source</span> descriptions, in terms of such quantities as mass flux for a monopole point <span class="hlt">source</span>. Such descriptions are quite useful for the inverse problem of inferring mass flux from <span class="hlt">infrasound</span> data. In this study, we introduce a dynamic <span class="hlt">source</span> model incorporating the physical processes that determine how the cloud of eruptive gas and ash expands outward to generate the <span class="hlt">infrasound</span> signal. Our dynamic <span class="hlt">source</span> model could ultimately be coupled to an unsteady conduit flow model, providing a means to infer more details of the eruption process from recorded <span class="hlt">infrasound</span> signals. Our model describes a vulcanian eruption where mass is ejected into the atmosphere forming a cloud of gas and ash. Infrasonic acoustic waves are generated by the expansion of the cloud. The model goes beyond linear acoustics by accounting for nonlinear terms in the compressible Euler equations for the surrounding atmosphere. The model presently consists of a system of nonlinear ordinary differential equations, expressing the balance of mass, momentum, and energy, that can be solved for the evolution of the radius of the cloud and pressure and temperature within it. Entrainment and heat exchange with the surrounding atmospheric air can be accounted for. Our analysis is inspired by similar models of underwater explosions (Gilmore, 1952) and seismic air-guns (Ziolkowski, 1970). We aim to use the model to investigate how acoustic signals change when volcano properties, such as vent geometry, are varied. Our longer-term goal is to couple the atmospheric <span class="hlt">infrasound</span> model presented here to an unsteady</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15005407','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15005407"><span id="translatedtitle">Grid-Search Location Methods for <span class="hlt">Ground-Truth</span> Collection from Local and Regional Seismic Networks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schultz, C A; Rodi, W; Myers, S C</p> <p>2003-07-24</p> <p>The objective of this project is to develop improved seismic event location techniques that can be used to generate more and better quality reference events using data from local and regional seismic networks. Their approach is to extend existing methods of multiple-event location with more general models of the errors affecting seismic arrival time data, including picking errors and errors in model-based travel-times (path corrections). Toward this end, they are integrating a grid-search based algorithm for multiple-event location (GMEL) with a new parameterization of travel-time corrections and new kriging method for estimating the correction parameters from observed travel-time residuals. Like several other multiple-event location algorithms, GMEL currently assumes event-independent path corrections and is thus restricted to small event clusters. The new parameterization assumes that travel-time corrections are a function of both the event and station location, and builds in <span class="hlt">source</span>-receiver reciprocity and correlation between the corrections from proximate paths as constraints. The new kriging method simultaneously interpolates travel-time residuals from multiple stations and events to estimate the correction parameters as functions of position. They are currently developing the algorithmic extensions to GMEL needed to combine the new parameterization and kriging method with the simultaneous location of events. The result will be a multiple-event location method which is applicable to non-clustered, spatially well-distributed events. They are applying the existing components of the new multiple-event location method to a data set of regional and local arrival times from Nevada Test Site (NTS) explosions with known origin parameters. Preliminary results show the feasibility and potential benefits of combining the location and kriging techniques. They also show some preliminary work on generalizing of the error model used in GMEL with the use of mixture</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22818588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22818588"><span id="translatedtitle">Verification of retail food outlet location data from a local health department using <span class="hlt">ground-truthing</span> and remote-sensing technology: assessing differences by neighborhood characteristics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rossen, Lauren M; Pollack, Keshia M; Curriero, Frank C</p> <p>2012-09-01</p> <p>Obtaining valid and accurate data on community food environments is critical for research evaluating associations between the food environment and health outcomes. This study utilized <span class="hlt">ground-truthing</span> and remote-sensing technology to validate a food outlet retail list obtained from an urban local health department in Baltimore, Maryland in 2009. Ten percent of outlets (n=169) were assessed, and differences in accuracy were explored by neighborhood characteristics (96 census tracts) to determine if discrepancies were differential or non-differential. Inaccuracies were largely unrelated to a variety of neighborhood-level variables, with the exception of number of vacant housing units. Although remote-sensing technologies are a promising low-cost alternative to direct observation, this study demonstrated only moderate levels of agreement with <span class="hlt">ground-truthing</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.4572A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4572A"><span id="translatedtitle"><span class="hlt">Infrasound</span> research at Kola Regional Seismological Centre, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asming, Vladimir; Kremenetskaya, Elena</p> <p>2013-04-01</p> <p>A small-aperture <span class="hlt">infrasound</span> array has been installed in Kola Peninsula, Russia 17 km far from the town of Apatity in the year 2000. It comprises 3 Chaparral V microbarographs placed closely to the APA seismic array sensors and equipped with pipe wind reducing filters. The data are digitized at the array site and transmitted in real time to a processing center in Apatity. To search for <span class="hlt">infrasound</span> events (arrivals of coherent signals) a beamforming-style detector has been developed. Now it works in near real time. We analyzed the detecting statistics for different frequency bands. Most man-made events are detected in 1-5 Hz band, microbaromes are typically detected in 0.2-1 Hz band. In lower frequencies we record mostly a wind noise. A data base of samples of <span class="hlt">infrasound</span> signals of different natures has been collected. It contains recordings of microbaromes, industrial and military explosions, airplane shock waves, <span class="hlt">infrasound</span> of airplanes, thunders, rocket launches and reentries, bolides etc. The most distant signals we have detected are associated with Kursk Magnetic Anomaly explosions (1700 km far from Apatity). We implemented an algorithm for association of <span class="hlt">infrasound</span> signals and preliminary location of <span class="hlt">infrasound</span> events by several arrays. It was tested with Apatity data together with data of Sweden - Finnish <span class="hlt">infrasound</span> network operated by the Institute of Space Physics in Umea (Sweden). By agreement with NORSAR we have a real-time access to the data of Norwegian experimental <span class="hlt">infrasound</span> installation situated in Karasjok (North Norway). Currently our detection and location programs work both with Apatity and Norwegian data. The results are available in Internet. Finnish militaries routinely destroy out-of-date weapon in autumns at the same compact site in North Finland. This is a great <span class="hlt">source</span> of repeating <span class="hlt">infrasound</span> signals of the same magnitude and origin. We recorded several hundreds of such explosions. The signals have been used for testing our location routines</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V41E..07F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V41E..07F"><span id="translatedtitle"><span class="hlt">Infrasound</span> and SO2 Observations of the 2011 Explosive Eruption of Nabro Volcano, Eritrea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fee, D.; Carn, S. A.; Prata, F.</p> <p>2011-12-01</p> <p>Nabro volcano, Eritrea erupted explosively on 12 June 2011 and produced near continuous emissions and <span class="hlt">infrasound</span> until mid-July. The eruption disrupted air traffic and severely affected communities in the region. Although the eruption was relatively ash-poor, it produced significant SO2 emissions, including: 1) the highest SO2 column ever retrieved from space (3700 DU), 2) >1.3 Tg SO2 mass on 13 June, and 3) >2 Tg of SO2 for the entire eruption, one of the largest eruptive SO2 masses produced since the 1991 eruption of Mt. Pinatubo. Peak emissions reached well into the stratosphere (~19 km). Although the 12 June eruption was preceded by significant seismicity and clearly detected by satellite sensors, Nabro volcano is an understudied volcano that lies in a remote region with little ground-based monitoring. The Nabro eruption also produced significant <span class="hlt">infrasound</span> signals that were recorded by two <span class="hlt">infrasound</span> arrays: I19DJ (Djibouti, 264 km) and I32KE (Kenya, 1708 km). The I19DJ <span class="hlt">infrasound</span> array detected the eruption with high signal-noise and provides the most detailed eruption chronology available, including eruption onset, duration, changes in intensity, etc. As seen in numerous other studies, sustained low frequency <span class="hlt">infrasound</span> from Nabro is coincident with high-altitude emissions. Unexpectedly, the eruption also produced hundreds of short-duration, impulsive explosion signals, in addition to the sustained infrasonic jetting signals more typical of subplinian-plinian eruptions. These explosions are variable in amplitude, duration, and often cluster in groups. Here we present: 1) additional analyses, classification, and <span class="hlt">source</span> estimation of the explosions, 2) <span class="hlt">infrasound</span> propagation modeling to determine acoustic travel times and propagation paths, 3) detection and characterization of the SO2 emissions using the Ozone Monitoring Instrument (OMI) and Spin Enhanced Visible and Infra-Red Instrument (SEVIRI), and 4) a comparison between the relative <span class="hlt">infrasound</span> energy and</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA528730','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA528730"><span id="translatedtitle"><span class="hlt">Infrasound</span> Detection of Rocket Launches</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2000-09-01</p> <p>were examined for 14 VAFB launches in 1999 at SGAR (680 km) and DLIAR (1300 km). Detections were seen for a Titan IVB launched 5/22/99 and a Delta II...size. Upper atmospheric wind conditions should have been favorable for several of the detections, however noise levels were often high at SGAR and...phase velocities are consistent with stratospheric propagation and nominal <span class="hlt">infrasound</span> travel times to SGAR (2340 s) and DLIAR (4440 s). The signals were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S31B1727T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S31B1727T"><span id="translatedtitle">Application of a New <span class="hlt">Infrasound</span> Sensor Technology in a Long Range <span class="hlt">Infrasound</span> Propagation Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Talmadge, C. L.; Waxler, R.; Hetzer, C. H.; Kleniert, D. E., Jr.; Dillion, K.; Assink, J.; Aydin, A.</p> <p>2009-12-01</p> <p>A low-cost ruggedized <span class="hlt">infrasound</span> sensor has been developed at the NCPA laboratory of the University of Mississippi for outdoor <span class="hlt">infrasound</span> measurements. This sensor has similar performance characteristics to other "standard" <span class="hlt">infrasound</span> sensors, such as the Chaparral 50. A total of 50 sensors were constructed for this experiment, of which 42 were deployed on the Nevada and Utah desert for a period of four months. A long-range <span class="hlt">infrasound</span> propagation experiment using these sensors was performed during the summer and fall of 2009. <span class="hlt">Source</span> sizes varied in size from 4, 20 and 80 equivalent tons of TNT. The blasts were carried out typically on the Monday of each week in the afternoon, and were part of a scheduled demolition of first, second and third stages of trident missiles. In addition to a <span class="hlt">source</span> capture location 23-km south of the site of the blasts, a series of 8 5-element arrays are located to the west of the blast location, at approximate ranges of 180 through 250 km in 10-km steps. Each array consisted of elements at -150-m, -50-m, 0-m, 50-m and 150-m relative to the center of the array along an east-west direction, and all microphones were equipped with 4 50-ft porous hoses connected to the microphone manifold for wind noise suppression. The signals from the microphones were digitized using GPS-synchronized, 24-bit DAQ systems. A Westerly direction for the deployment of the microphones was motivated by the presence of a strong stratospheric duct that persists through the summer months in the northern hemisphere at these latitudes. In this paper, we will discuss feasibility issues related the design of the NCPA microphone that makes possible deployments on these on large scales. Signal to noise issues related to temperature and wind fluctuations will also be discussed. Future plans include a larger scale deployment of several hundred microphones during 2010. We will discuss how the lessons learned from this series of measurements impacts that future deployment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/761837','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/761837"><span id="translatedtitle"><span class="hlt">Infrasound</span> Sensor Models and Evaluations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>KROMER,RICHARD P.; MCDONALD,TIMOTHY S.</p> <p>2000-07-31</p> <p>Sandia National Laboratories has continued to evaluate the performance of <span class="hlt">infrasound</span> sensors that are candidates for use by the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty Organization. The performance criteria against which these sensors are assessed are specified in ``Operational Manual for <span class="hlt">Infra-sound</span> Monitoring and the International Exchange of <span class="hlt">Infrasound</span> Data''. This presentation includes the results of efforts concerning two of these sensors: (1) Chaparral Physics Model 5; and (2) CEA MB2000. Sandia is working with Chaparral Physics in order to improve the capability of the Model 5 (a prototype sensor) to be calibrated and evaluated. With the assistance of the Scripps Institution of Oceanography, Sandia is also conducting tests to evaluate the performance of the CEA MB2000. Sensor models based on theoretical transfer functions and manufacturer specifications for these two devices have been developed. This presentation will feature the results of coherence-based data analysis of signals from a huddle test, utilizing several sensors of both types, in order to verify the sensor performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7501G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7501G"><span id="translatedtitle">IPLOR performance in detecting <span class="hlt">infrasound</span> from volcanic eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghica, Daniela; Popa, Mihaela</p> <p>2016-04-01</p> <p>Plostina <span class="hlt">infrasound</span> array (IPLOR) is located in the central part of Romania, in Vrancea region, its current configuration consisting of 6 elements equipped with Chaparral Physics sensors deployed over a 2.5 km aperture. The array detectability observed after processing of more than 6 years of data has shown that IPLOR is more effective in measuring mainly <span class="hlt">infrasound</span> signals produced by natural and anthropogenic impulsive <span class="hlt">sources</span>. This can be explained by the sensors' characteristics (frequency response, dynamic range) and the large aperture of array. Among the types of events observed with IPLOR, an emphasis can be given to the Mt. Etna volcanic eruptions as one of the powerful <span class="hlt">infrasound</span> <span class="hlt">source</span> recorded by the array. Located at about 1320 km distance from volcano, the array has proved efficient in observing both large and small eruptions. In case of the most large eruptive episodes occurred lately (April and October 2013, December 2015), long duration infrasonic signals were detected, the initial impulsive signature of the volcanic explosion being followed by a long train of irregular waves with smaller amplitudes and higher frequency, extended over periods ranging from 6 hours to more than three days (in December 2015). For the purpose of assessing the IPLOR performance in detecting Etna eruptions, the signal interactive analysis was performed using WinPMCC, CEA/DASE version of PMCC software. The <span class="hlt">infrasound</span> detections obtained were plotted in function of back-azimuth, velocity and frequency, showing that the detectability is dependent both on the diurnal variations of the noise around the array (during the night the human activity diminishes) and on the seasonally dependent stratospheric winds (westward propagation during summer and eastward propagation during winter). In case of the Etna eruptive episodes detected by IPLOR, the back azimuth observed is in good agreement with the expected value (230o), i.e. an average value of 232±2o could be resolved. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6684J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6684J"><span id="translatedtitle">Could the IMS <span class="hlt">Infrasound</span> Stations Support a Global Network of Small Aperture Seismic Arrays?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>J, Gibbons, Steven; Kværna, Tormod; Mykkeltveit, Svein</p> <p>2015-04-01</p> <p> find such added capabilities valuable from a national perspective. In addition, the seismic recordings may also help to identify the <span class="hlt">sources</span> of <span class="hlt">infrasound</span> signals with consequences for improved event screening and evaluating models of <span class="hlt">infrasound</span> propagation and atmospheric properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023012','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023012"><span id="translatedtitle"><span class="hlt">Infrasound</span> and the avian navigational map</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hagstrum, J.T.</p> <p>2001-01-01</p> <p>Birds can accurately navigate over hundreds to thousands of kilometres, and use celestial and magnetic compass senses to orient their flight. How birds determine their location in order to select the correct homeward bearing (map sense) remains controversial, and has been attributed to their olfactory or magnetic senses. Pigeons can hear <span class="hlt">infrasound</span> down to 0??05 Hz, and an acoustic avian map is proposed consisting of infrasonic cues radiated from steep-sided topographic features. The <span class="hlt">source</span> of these infrasonic signals is microseisms continuously generated by interfering oceanic waves. Atmospheric processes affecting the infrasonic map cues can explain perplexing experimental results from pigeon releases. Moreover, four recent disrupted pigeon races in Europe and the north-eastern USA intersected infrasonic shock waves from the Concorde supersonic transport. Having an acoustic map might also allow clock-shifted birds to test their homeward progress and select between their magnetic and solar compasses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFMPP43C..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMPP43C..02H"><span id="translatedtitle">Geological "<span class="hlt">Ground</span> <span class="hlt">Truth</span>" of Sea-level Highstand Events During Warm Interglaciations (MIS 11 and 5e): Taking the Punch out of Proxy Precision</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hearty, P. J.</p> <p>2005-12-01</p> <p>High-resolution sea-level records for marine isotope stages (MIS) 11 and 5e from coastal outcrops in Bahamas, Bermuda, Hawaii, and Western Australia provide physical confirmation of extreme ice-melting events during Pleistocene interglacials. Field evidence indicates MIS 11 sea level rose in a series of oscillations to c. +20 m, while that of MIS 5e reached its maximum of +6-10 m. Because these were brief events (100s yrs), their true magnitude is generally muted or obscured in deep-sea oxygen isotope records; generally averaged over thousands of years by the combined effects of sampling, bioturbation, and sedimentation rates. Further unresolvable variables such as temperature and salinity further cloud the isotope proxy record. Thus, the tangible rock record is of greatest importance in understanding the nature of these extreme events. Geomorphology, sedimentary structures, taphonomy of and dating of organisms, and petrology provide <span class="hlt">ground</span> <span class="hlt">truth</span> at field sites. Sea-level highstands preserve terraces and benches by erosion and subsequent deposition of sub- and intertidal sediments. Fenestral porosity is a measure of intertidal wetting and drying of sand, while decimetre-scale, high-angle cross beds of poorly-sorted sand and gravel indicate shallow subtidal conditions. In situ coral heads describe similar subtidal conditions. Delicate, sometimes partially articulated skeletons of birds and reptiles in sea caves reveal a protected shoreline. An early generation of isopachous, fibrous cement verifies the presence of marine phreatic water over a sustained period of time. These features, often misinterpreted (McMurtry, 2004, AGU Fall Meeting, OS21E-06), categorically exclude emplacement by tsunami waves. Oceanic isotope records cannot produce an equivalent level of resolution of short, extreme events via (in terms of age, duration, rates of sea-level and ice-volume changes), thus shifting the `burden of proof' to proxy methods to identify such events. In our quest to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711518T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711518T"><span id="translatedtitle">Assessing and optimizing <span class="hlt">infrasound</span> network performance: application to remote volcano monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tailpied, Dorianne; Le Pichon, Alexis; Marchetti, Emanuele; Ceranna, Lars; Pilger, Christopher</p> <p>2015-04-01</p> <p>Interest in <span class="hlt">infrasound</span> propagation studies has been revived since the Comprehensive nuclear Test Ban Treaty (CTBT) was adopted in 1996. The International Monitoring System (IMS) is designed to ensure compliance with the CTBT by detecting and locating explosions in the world using at least 2 stations. Even not yet fully established, the <span class="hlt">infrasound</span> network already allows studies on a global scale as it has demonstrated to be a major asset to remotely identify and analyze geophysical events such as volcanoes. Simulation methods incorporating realistic <span class="hlt">source</span> and propagation effects have been developed to quantify the detection capability of this network. These methods can also be used to optimize the network configuration (number of stations, geographical location) in order to reduce the detection thresholds taking into account seasonal effects in <span class="hlt">infrasound</span> propagation. Recent studies have shown that remote <span class="hlt">infrasound</span> observations can provide useful information about eruption chronology and the released acoustic energy. Comparisons with near-field recordings allow evaluating the potential of these observations to better constrain <span class="hlt">source</span> parameters when other monitoring techniques (satellite, seismic, gas) are not available or cannot be made. Because of its regular activity, the well-instrumented Mount Etna is in Europe a unique natural repetitive <span class="hlt">source</span> to test and optimize detection and simulation methods. In summer, during the downwind season, its eruptions are quasi-permanently detected by IS48 in Tunisia, the closest <span class="hlt">infrasound</span> station part of the IMS. Under the European ARISE project (Atmospheric dynamics InfraStructure in Europe, FP7/2007-2013), experimental arrays have been installed in order to characterize <span class="hlt">infrasound</span> propagation in different ranges of distance and direction. Such an experimental setting offers an opportunity to address the societal benefits that can be achieved through routine <span class="hlt">infrasound</span> monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A31A0042S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0042S"><span id="translatedtitle">Simulation and Analysis of <span class="hlt">Infrasound</span> Generated by Convective Storms and Tornadoes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schecter, D.; Nicholls, M.</p> <p>2011-12-01</p> <p>Observational studies have shown that severe storms can emit abnormally strong, sustained <span class="hlt">infrasound</span> in the 0.5-5 Hz frequency range. There is reason to believe that the infrasonic emissions come from developing and mature tornadoes, but some ambiguity remains in the interpretation of the data. It is fair to say that we do not yet fully understand the conditions for which a vortex signal is discernible from the <span class="hlt">infrasound</span> of non-tornadic <span class="hlt">sources</span> within a storm. There is a pressing need to advance our fundamental understanding of the different mechanisms that generate <span class="hlt">infrasound</span> in atmospheric convection. To this end, numerical modeling may be the best method of investigation. We are exploring this avenue of research with a customized version of the Regional Atmospheric Modeling System (c-RAMS). Previous studies have established the basic credibility of c-RAMS for simulating acoustic phenomena. More recently, we have developed a convenient method for diagnosing the primary <span class="hlt">sources</span> of <span class="hlt">infrasound</span> in complex storm simulations. The method is based on a generalization of Lighthill's acoustic analogy, and is aptly illustrated in the context of a simulated cumulonimbus. Applying the diagnostic method to this system, we find that the 0.1-1 Hz <span class="hlt">infrasound</span> of diabatic processes in the hail-to-rain transition layer dominates that of turbulent wind fluctuations covering the entire storm. We have also used c-RAMS to investigate the <span class="hlt">infrasound</span> of tornadoes created by artificial buoyancy forcing in a dry, rotational environment. The simulated tornadoes have realistic structure, but their cores are typically quiet in the frequency range of interest. In other words, we find that dry fluctuations of the vortex core may not provide a robust <span class="hlt">source</span> of discernible <span class="hlt">infrasound</span>. Apparent deficiencies of earlier theories that predicted otherwise will be addressed. This work was supported by NSF grant AGS-0832320.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2491M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2491M"><span id="translatedtitle">Analysis of <span class="hlt">infrasound</span> waves generated by the May 2012 earthquake sequence in Northen Italy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchetti, E.; Ripepe, M.; Le Pichon, A.; Lacanna, G.; Piccinini, D.</p> <p>2013-12-01</p> <p>In May 2012 a 5.9 ML earthquake occurred in Northern Italy with the sequence of major quakes (Ml>5.4) clearly felt in Northern and Central Italy. Almost 2000 earthquakes, with local magnitude ranging between 1 and 5.9, were recorded in one month, and were typically associated with shallow (<10 km) inverse faults. We present analysis of pressure waves generated by these earthquakes and recorded at epicentral distances of ~200 km southward, at the large (1.4 km) aperture AMT array in Central Italy, and of ~300 km westward, at the small (130 m) aperture CHA array, operating in the northwestern Italian Alps mostly for snow avalanche monitoring. <span class="hlt">Infrasound</span> is recorded for events with varying magnitude (Ml >4) and depth (5-15 km), and appears to be composed both of epicentral <span class="hlt">infrasound</span>, produced at the <span class="hlt">source</span>, and secondary <span class="hlt">infrasound</span>, produced by the shaking of topography around the <span class="hlt">source</span>. The robust <span class="hlt">infrasound</span> dataset and the optimal recording condition, with downwind propagation to the CHA array, allow to carefully investigate the origin of the infrasonic radiation. Back-propagation of infrasonic detections points to a maximum <span class="hlt">infrasound</span> radiation along an extended area in the PO valley. The relationship between infrasonic emission and earthquake <span class="hlt">source</span> parameters such as magnitude, depth, focal mechanism and directivity, are analyzed for small-to-moderate magnitude earthquakes. Given the large distance among IMS infrasonic arrays, the relationship between <span class="hlt">infrasound</span> and earthquakes is not well documented yet and mainly restricted to ML>7 earthquake, and thus still debated. Accordingly, the present study, that integrates within the FP7 ARISE design study project (Atmospheric dynamics Research InfraStructure in Europe), represents a good opportunity to investigate such a topic given the robust seismological constraints and optimal <span class="hlt">infrasound</span> records.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMED43F..04P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMED43F..04P"><span id="translatedtitle">Remote Sensing across the Globe: Best Practices in Bringing Together Satellite Imagery, Telecommunications and <span class="hlt">Ground-Truth</span> Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Probst, R.; Walker, C. E.; Martin, C.; Dorame, B.; Ochoa, H.; Orellana, D.; Isbell, D. M.; Pompea, S. M.</p> <p>2006-12-01</p> <p>A special student-to-student videoconference was held mid-May 2006 between students in Tucson, Arizona and La Serena, Chile, the headquarters for the north and south offices of the National Optical Astronomy Observatory (NOAO). Fifty participants at each location reported on a remote-sensing activity conducted by hundreds of students during February, March and April, 2006. The students became acquainted with the geography and geology of their area using Landsat satellite remote sensing imaging. The Tucson students then analyzed images of La Serena and students from Chile analyzed images of Tucson. Since top-down satellite views may not provide complete information, students from one country emailed students from the other country and requested them to be human "rovers," taking local pictures of areas under question to establish <span class="hlt">ground-truth</span>. Student reaction to the project was unequivocally positive. "The remote sensing project was one of the most fun things in my junior year. I learned how to use a map of La Serena, Chile. I learned about the electromagnetic spectrum, used to form false color images. It was incredible for us Latino students to use our Spanish language to e-mail students in Chile", said Bisbail Dorame, student coordinator for the project at Howenstine High School in Tucson. The success of this cross-cultural program has motivated NOAO outreach staff to broaden the project to schools in other countries, coordinated by students as their service-learning project. To facilitate this effort, a special, yet generic, worksheet is being developed. The worksheet can be by teachers to include local landmarks and geographical features. Once completed and tested, the worksheet will be placed on the NOAO website, along with Landsat7 satellite images for different areas around the world. In 2007, the program will be expanded to examine the surface of Mars using Google Mars and NASA images. NOAO is operated by the Association of Universities for Research in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMIN53B1739B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMIN53B1739B"><span id="translatedtitle"><span class="hlt">Ground-Truthing</span> Moderate Resolution Satellite Imagery with Near-Surface Canopy Images in Hawai'i's Tropical Cloud Forests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bergstrom, R.; Miura, T.; Lepczyk, C.; Giambelluca, T. W.; Nullet, M. A.; Nagai, S.</p> <p>2012-12-01</p> <p>Phenological studies are gaining importance globally as the onset of climate change is impacting the timing of green up and senescence in forest canopies and agricultural regions. Many studies use and analyze land surface phenology (LSP) derived from satellite vegetation index time series (VI's) such as those from Moderate Resolution Imaging Spectroradiometer (MODIS) to monitor changes in phenological events. Seasonality is expected in deciduous temperate forests, while tropical regions are predicted to show more static reflectance readings given their stable and steady state. Due to persistent cloud cover and atmospheric interference in tropical regions, satellite VI time series are often subject to uncertainties and thus require near surface vegetation monitoring systems for <span class="hlt">ground-truthing</span>. This study has been designed to assess the precision of MODIS phenological signatures using above-canopy, down-looking digital cameras installed on flux towers on the Island of Hawai'i. The cameras are part of the expanding Phenological Eyes Network (PEN) which has been implementing a global network of above-canopy, hemispherical digital cameras for forest and agricultural phenological monitoring. Cameras have been installed at two locations in Hawaii - one on a flux tower in close proximity to the Thurston Lave Tube (HVT) in Hawai'i Volcanoes National Park and the other on a weather station in a section of the Hawaiian Tropical Experimental Forest in Laupaphoehoe (LEF). HVT consists primarily of a single canopy species, ohi'a lehua (Metrosideros polymorpha), with an understory of hapu'u ferns (Cibotium spp), while LEF is similarly comprised with an additional dominant species, Koa (Acacia Koa), included in the canopy structure. Given these species' characteristics, HVT is expected to show little seasonality, while LEF has the potential to deviate slightly during periods following dry and wet seasons. MODIS VI time series data are being analyzed and will be compared to images</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ASAJ..115..253S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..115..253S"><span id="translatedtitle">Uncertainties associated with parameter estimation in atmospheric <span class="hlt">infrasound</span> arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szuberla, Curt A. L.; Olson, John V.</p> <p>2004-01-01</p> <p>This study describes a method for determining the statistical confidence in estimates of direction-of-arrival and trace velocity stemming from signals present in atmospheric <span class="hlt">infrasound</span> data. It is assumed that the signal <span class="hlt">source</span> is far enough removed from the <span class="hlt">infrasound</span> sensor array that a plane-wave approximation holds, and that multipath and multiple <span class="hlt">source</span> effects are not present. Propagation path and medium inhomogeneities are assumed not to be known at the time of signal detection, but the ensemble of time delays of signal arrivals between array sensor pairs is estimable and corrupted by uncorrelated Gaussian noise. The method results in a set of practical uncertainties that lend themselves to a geometric interpretation. Although quite general, this method is intended for use by analysts interpreting data from atmospheric acoustic arrays, or those interested in designing and deploying them. The method is applied to <span class="hlt">infrasound</span> arrays typical of those deployed as a part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFD.H4004T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.H4004T"><span id="translatedtitle">Characterization of Atmospheric <span class="hlt">Infrasound</span> for Improved Weather Monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Threatt, Arnesha; Elbing, Brian</p> <p>2016-11-01</p> <p>Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUD MAP) is a multi-university collaboration focused on development and implementation of unmanned aircraft systems (UAS) and integration with sensors for atmospheric measurements. A primary objective for this project is to create and demonstrate UAS capabilities needed to support UAS operating in extreme conditions, such as a tornado producing storm system. These storm systems emit <span class="hlt">infrasound</span> (acoustic signals below human hearing, <20 Hz) up to 2 hours before tornadogenesis. Due to an acoustic ceiling and weak atmospheric absorption, <span class="hlt">infrasound</span> can be detected from distances in excess of 300 miles. Thus <span class="hlt">infrasound</span> could be used for long-range, passive monitoring and detection of tornadogenesis as well as directing UAS resources to high-decision-value-information. To achieve this the infrasonic signals with and without severe storms must be understood. This presentation will report findings from the first CLOUD MAP field demonstration, which acquired infrasonic signals while simultaneously sampling the atmosphere with UAS. Infrasonic spectra will be shown from a typical calm day, a continuous <span class="hlt">source</span> (pulsed gas-combustion torch), singular events, and UAS flights as well as localization results from a controlled <span class="hlt">source</span> and multiple microphones. This work was supported by NSF Grant 1539070: CLOUD MAP - Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRD..115.0L10F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRD..115.0L10F"><span id="translatedtitle">Characterization of the 2008 Kasatochi and Okmok eruptions using remote <span class="hlt">infrasound</span> arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fee, David; Steffke, Andrea; Garces, Milton</p> <p>2010-01-01</p> <p>The 2008 Plinian eruptions of Kasatochi and Okmok volcanoes were recorded by six remote International Monitoring System <span class="hlt">infrasound</span> arrays. High-amplitude <span class="hlt">infrasound</span> at these stations, combined with remote sensing, permits insight into important volcanic <span class="hlt">source</span> parameters, such as origin times, durations, and <span class="hlt">source</span> characteristics. <span class="hlt">Infrasound</span> from the 7-8 August Kasatochi eruption consists of three well-defined eruption pulses, with the first two steam-rich and the last ash-rich. Pulse 2 is the most energetic and impulsive. Okmok produced over 9 h of continuous <span class="hlt">infrasound</span> on 12-13 July. Acoustic propagation modeling for the Okmok eruption and first Kasatochi pulse predict thermospheric ducting and origin times consistent with seismic and satellite observations. However, theoretical acoustic origin times of pulses 2-3 are predicted to occur ˜15 min earlier than the seismic. Stratospheric ducting for these later pulses provides more consistent origin times. Although both volcanoes ejected ash into the stratosphere (>15 km), Kasatochi produced higher amplitude <span class="hlt">infrasound</span> than Okmok. Previous studies have shown sustained <span class="hlt">infrasound</span> with frequencies <0.5 Hz is indicative of high-altitude ash emissions. Kasatochi and Okmok recordings are consistent with this, as stratospheric emissions evident in satellite imagery are correlated with sustained 0.01-0.5 Hz <span class="hlt">infrasound</span>. Further, the acoustic spectrum shape resembles the spectrum from man-made jets, suggesting a self-similar noise generation mechanism proposed in earlier work. Although uncertainties exist, observations and propagation modeling from Kasatochi suggest self-similarity is apparent at long distances (>2000 km) and does not seem to be appreciably affected by changes in ash content between the eruption pulses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.1592B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.1592B"><span id="translatedtitle"><span class="hlt">Infrasound</span> absorption by atmospheric clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baudoin, Michael; Coulouvrat, Francois; Thomas, Jean-Louis</p> <p>2010-05-01</p> <p>A model is developed for the absorption of <span class="hlt">infrasound</span> by atmospheric clouds made of a suspension of liquid water droplets within a gaseous mixture of water vapor and air. The model is based on the work of D.A. Gubaidullin and R.I. Nigmatulin [Int. J. Multiphase Flow, 26, 207-228, 2000], which is applied to atmospheric clouds. Three physical mechanisms are included : unsteady viscous drag associated with momentum transfers due to the translation of water droplets, unsteady thermal transfers between the liquid and gaseous phases, and mass transfers due to the evaporation or condensation of the water phase. For clouds, in the infrasonic frequency range, phase changes are the dominant mechanisms (around 1 Hz), while viscous and heat transfers become significant only around 100 Hz. Mass transfers involve two physical effects : evaporation and condensation of the water phase at the droplet surface, and diffusion of the water vapor within the gaseous phase. The first one is described through the Hertz-Knudsen-Langmuir theory based on kinetic theory. It involves a little known coefficient known as coefficient of accommodation. The second one is the classical Fick diffusion. For clouds, and unless the coefficient of accommodation is very small (far from the generally recommended value is close to one), diffusion is the main limiting effects for mass transfers. In a second stage, the sound and <span class="hlt">infrasound</span> absorption is evaluated for various typical clouds up to about 4 km altitude. Above this altitude, the ice content of clouds is dominant compared to their water content, and the present model is not applicable. Cloud thickness, water content, and droplets size distribution are shown to be the major factors influencing the <span class="hlt">infrasound</span> absorption. A variety of clouds have been analyzed. In most cases, it is shown that <span class="hlt">infrasound</span> absorption within clouds is several orders larger than classical absorption (due to molecular relaxation of nitrogen and oxygen molecules in presence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/303950','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/303950"><span id="translatedtitle"><span class="hlt">Infrasound</span> workshop for CTBT monitoring: Proceedings</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Christie, D.; Whitaker, R.</p> <p>1998-11-01</p> <p>It is expected that the establishment of new <span class="hlt">infrasound</span> stations in the global IMS network by the Provisional Technical Secretariat of the CTBTO in Vienna will commence in the middle of 1998. Thus, decisions on the final operational design for IMS <span class="hlt">infrasound</span> stations will have to be made within the next 12 months. Though many of the basic design problems have been resolved, it is clear that further work needs to be carried out during the coming year to ensure that IMS <span class="hlt">infrasound</span> stations will operate with maximum capability in accord with the specifications determined during the May 1997 PrepCom Meeting. Some of the papers presented at the Workshop suggest that it may be difficult to design a four-element <span class="hlt">infrasound</span> array station that will reliably detect and locate <span class="hlt">infrasound</span> signals at all frequencies in the specified range from 0.02 to 4.0 Hz in all noise environments. Hence, if the basic design of an <span class="hlt">infrasound</span> array is restricted to four array elements, the final optimized design may be suited only to the detection and location of signals in a more limited pass-band. Several participants have also noted that the reliable discrimination of <span class="hlt">infrasound</span> signals could be quite difficult if the detection system leads to signal distortion. Thus, it has been emphasized that the detection system should not, if possible, compromise signal fidelity. This report contains the workshop agenda, a list of participants, and abstracts and viewgraphs from each presentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24437743','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24437743"><span id="translatedtitle">Modeling propagation of <span class="hlt">infrasound</span> signals observed by a dense seismic network.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chunchuzov, I; Kulichkov, S; Popov, O; Hedlin, M</p> <p>2014-01-01</p> <p>The long-range propagation of <span class="hlt">infrasound</span> from a surface explosion with an explosive yield of about 17.6 t TNT that occurred on June 16, 2008 at the Utah Test and Training Range (UTTR) in the western United States is simulated using an atmospheric model that includes fine-scale layered structure of the wind velocity and temperature fields. Synthetic signal parameters (waveforms, amplitudes, and travel times) are calculated using parabolic equation and ray-tracing methods for a number of ranges between 100 and 800 km from the <span class="hlt">source</span>. The simulation shows the evolution of several branches of stratospheric and thermospheric signals with increasing range from the <span class="hlt">source</span>. <span class="hlt">Infrasound</span> signals calculated using a G2S (ground-to-space) atmospheric model perturbed by small-scale layered wind velocity and temperature fluctuations are shown to agree well with recordings made by the dense High Lava Plains seismic network located at an azimuth of 300° from UTTR. The waveforms of calculated <span class="hlt">infrasound</span> arrivals are compared with those of seismic recordings. This study illustrates the utility of dense seismic networks for mapping an <span class="hlt">infrasound</span> field with high spatial resolution. The parabolic equation calculations capture both the effect of scattering of <span class="hlt">infrasound</span> into geometric acoustic shadow zones and significant temporal broadening of the arrivals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.V51E2085J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.V51E2085J"><span id="translatedtitle">Eruptions of Mount Erebus Volcano Constrained with <span class="hlt">Infrasound</span>, Video, and Doppler Radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, J. B.; Jones, K. R.; Aster, R.; Kyle, P.; McIntosh, W.; Gerst, A.</p> <p>2008-12-01</p> <p>Co-eruptive <span class="hlt">infrasound</span> recorded within several km of volcanoes can provide effective constraints on atmospheric accelerations or momentum exchange in the vicinity of active volcanic vents. These atmospheric perturbations can be induced by impulsive gas injection into the atmosphere (i.e., eruptive explosions), by deflection of a solid or fluid lava surface, or through a superposition of these effects. The "simple" lava lake bubble-bursting eruptions of Mount Erebus Volcano (Antarctica) provide an ideal test bed for multi- disciplinary observations of volcanic <span class="hlt">infrasound</span> because of proximal (within few hundred meters) deployment of microphones and line-of-sight viewing geometry of cameras and radar to the vent. Erebus video observations provide timing constraints on the <span class="hlt">infrasound</span> generation mechanisms, which include both pre- eruptive distension of the lava lake surface and gas expansion and jetting following large explosive bubble bursts. Network <span class="hlt">infrasound</span> recordings are used to quantify the time history of explosive gas flux and cumulative yield (>103 kg of gas in ~0.5 s), which is corroborated by the video and Doppler radar observations. <span class="hlt">Infrasound</span> records from a three-station network also show azimuthal variations, which can be attributed to non-isotropic components of the acoustic wavefield radiated during eruption. We model Erebus gas bubble bursts as a combination of symmetric gas expansion (monopole <span class="hlt">source</span>) and gas jetting (dipole <span class="hlt">source</span>) and corroborate this explosive asymmetry with video and Doppler radar observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010BGD.....7.3227K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010BGD.....7.3227K"><span id="translatedtitle">Towards <span class="hlt">ground-truthing</span> of spaceborne estimates of above-ground biomass and leaf area index in tropical rain forests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Köhler, P.; Huth, A.</p> <p>2010-05-01</p> <p>The canopy height of forests is a key variable which can be obtained using air- or spaceborne remote sensing techniques such as radar interferometry or lidar. If new allometric relationships between canopy height and the biomass stored in the vegetation can be established this would offer the possibility for a global monitoring of the above-ground carbon content on land. In the absence of adequate field data we use simulation results of a tropical rain forest growth model to propose what degree of information might be generated from canopy height and thus to enable <span class="hlt">ground-truthing</span> of potential future satellite observations. We here analyse the correlation between canopy height in a tropical rain forest with other structural characteristics, such as above-ground biomass (AGB) (and thus carbon content of vegetation) and leaf area index (LAI). The process-based forest growth model FORMIND2.0 was applied to simulate (a) undisturbed forest growth and (b) a wide range of possible disturbance regimes typically for local tree logging conditions for a tropical rain forest site on Borneo (Sabah, Malaysia) in South-East Asia. It is found that for undisturbed forest and a variety of disturbed forests situations AGB can be expressed as a power-law function of canopy height h (AGB=a·hb) with an r2~60% for a spatial resolution of 20 m×20 m (0.04 ha, also called plot size). The regression is becoming significant better for the hectare wide analysis of the disturbed forest sites (r2=91%). There seems to exist no functional dependency between LAI and canopy height, but there is also a linear correlation (r2~60%) between AGB and the area fraction in which the canopy is highly disturbed. A reasonable agreement of our results with observations is obtained from a comparison of the simulations with permanent sampling plot data from the same region and with the large-scale forest inventory in Lambir. We conclude that the spaceborne remote sensing techniques have the potential to</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814368J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814368J"><span id="translatedtitle">Estimation of snowpack matching <span class="hlt">ground-truth</span> data and MODIS satellite-based observations by using regression kriging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Juan Collados-Lara, Antonio; Pardo-Iguzquiza, Eulogio; Pulido-Velazquez, David</p> <p>2016-04-01</p> <p>The estimation of Snow Water Equivalent (SWE) is essential for an appropriate assessment of the available water resources in Alpine catchment. The hydrologic regime in these areas is dominated by the storage of water in the snowpack, which is discharged to rivers throughout the melt season. An accurate estimation of the resources will be necessary for an appropriate analysis of the system operation alternatives using basin scale management models. In order to obtain an appropriate estimation of the SWE we need to know the spatial distribution snowpack and snow density within the Snow Cover Area (SCA). Data for these snow variables can be extracted from in-situ point measurements and air-borne/space-borne remote sensing observations. Different interpolation and simulation techniques have been employed for the estimation of the cited variables. In this paper we propose to estimate snowpack from a reduced number of <span class="hlt">ground-truth</span> data (1 or 2 campaigns per year with 23 observation point from 2000-2014) and MODIS satellite-based observations in the Sierra Nevada Mountain (Southern Spain). Regression based methodologies has been used to study snowpack distribution using different kind of explicative variables: geographic, topographic, climatic. 40 explicative variables were considered: the longitude, latitude, altitude, slope, eastness, northness, radiation, maximum upwind slope and some mathematical transformation of each of them [Ln(v), (v)^-1; (v)^2; (v)^0.5). Eight different structure of regression models have been tested (combining 1, 2, 3 or 4 explicative variables). Y=B0+B1Xi (1); Y=B0+B1XiXj (2); Y=B0+B1Xi+B2Xj (3); Y=B0+B1Xi+B2XjXl (4); Y=B0+B1XiXk+B2XjXl (5); Y=B0+B1Xi+B2Xj+B3Xl (6); Y=B0+B1Xi+B2Xj+B3XlXk (7); Y=B0+B1Xi+B2Xj+B3Xl+B4Xk (8). Where: Y is the snow depth; (Xi, Xj, Xl, Xk) are the prediction variables (any of the 40 variables); (B0, B1, B2, B3) are the coefficients to be estimated. The ground data are employed to calibrate the multiple regressions. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA081792','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA081792"><span id="translatedtitle">The Effects of High Level <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1980-02-01</p> <p>Ohreshold of such effects may be as low as 150 dl] for the chinchillas . .’The chinchilla is prob.ably more sensitive to <span class="hlt">infrasound</span> than humans. There...several minutes (7 Hz). For these short times, no damage to the tympanic membrane or middle ear system occurred. However, the chinchilla results do...Johnson, D. L., "Exposure of Four Chinchillas to <span class="hlt">Infrasound</span>," Research Memo dated Mar 1976, AMRL, WPAFB OH. 8. Tonndorf, J., "The Influence of Service on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2720S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2720S"><span id="translatedtitle">Extensions of the framework for evaluation of crater detection algorithms: new <span class="hlt">ground</span> <span class="hlt">truth</span> catalogue with 57633 craters, additional subsystems and evaluations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salamunićcar, Goran</p> <p></p> <p>Crater detection algorithms' (CDAs) applications range from approximating the age of a planetary surface and autonomous landing to planets and asteroids to advanced statistical analyses [ASR, 33, 2281-2287]. A large amount of work on CDAs has already been published. However, problems arise when evaluation results of some new CDA have to be compared with already published evaluation results. The Framework for Evaluation of Crater Detection Algorithms (FECDA) was recently proposed as an initial step for solving the problem of objective evaluation of CDAs [ASR, in press, doi:10.1016/j.asr.2007.04.028]. The framework includes: (1) a definition of the measure for differences between craters; (2) test-field topography based on the 1/64° MOLA data; (3) the <span class="hlt">Ground</span> <span class="hlt">Truth</span> (GT) catalogue wherein each of 17582 impact craters is aligned with MOLA data and confirmed with catalogues by N. G. Barlow et al. and J. F. Rodionova et al.; (4) selection of methodology for training and testing; and (5) a Free-response Receiver Operating Characteristics (F-ROC) curves as a way to measure CDA performance. Recently, the GT catalogue with 17582 craters has been improved using cross-analysis. The result is a more complete GT catalogue with 18711 impact craters [7thMars abstract 3067]. Once this is done, the integration with Barlow, Rodionova, Boyce, Kuzmin and the catalogue from our previous work has been completed by merging. The result is even more complete GT catalogue with 57633 impact craters [39thLPS abstract 1372]. All craters from the resulting GT catalogue have been additionally registered, using 1/128° MOLA data as bases, with 1/256° THEMIS-DIR, 1/256° MDIM and 1/256° MOC data-sets. Thanks to that, the GT catalogue can also be used with these additional subsystems, so the FECDA can be extended with them. Part of the FECDA is also the Craters open-<span class="hlt">source</span> C++ project. It already contains a number of implemented CDAs [38thLPS abstract 1351, 7thMars abstract 3066, 39thLPS abstracts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.A13D0246H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.A13D0246H"><span id="translatedtitle">Experimental <span class="hlt">Infrasound</span> Studies in Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herrin, E. T.; Negraru, P. T.; Golden, P.; Williams, A.</p> <p>2009-12-01</p> <p>An experimental propagation study was carried out in Nevada in June 2009 on Julian days 173-177. During this field experiment we deployed 16 single channel digital <span class="hlt">infrasound</span> recorders to monitor the munitions disposal activities near Hawthorne, NV. The sensors were deployed in a single line and placed approximately 12 km apart at distances ranging from 2 to 177 km. A four element semi-permanent <span class="hlt">infrasound</span> array named FNIAR was installed approximately 154 km north of the detonation site in line with the individual temporary recorders. Tropospheric arrivals were observed during all days of the experiment, but during day 176 the observed arrivals had very large amplitudes. A large signal was observed at 58 km from the detonation site with amplitude as large as 4 Pascals, while at 94 km no signal was observed. At FNIAR the amplitude of the tropospheric arrival was 1 Pascal. During this day meteorological data acquired in the propagation path showed a strong jet stream to the north. On day 177 we were not able to identify tropospheric arrivals beyond 34 km, but at stations beyond 152 km we observed stratospheric arrivals. Continuous monitoring of these signals at FNIAR shows that stratospheric arrivals are the most numerous. In a two month period, from 06/15/2009 to 08/15/2009 there were 35 operational days at the Hawthorne disposal facility resulting in 212 explosions with known origin times. Based on the celerity values there were 115 explosions that have only stratospheric arrivals (celerities of 300-275 m/s), 72 explosions with both tropospheric (celerities above 330 m/s) and stratospheric arrivals, 20 explosions that were not detected and five explosions that have only tropospheric arrivals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/976405','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/976405"><span id="translatedtitle">Large meteoroid detection using the global IMS <span class="hlt">infrasound</span> system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>ReVelle, D. O.</p> <p>2002-01-01</p> <p>Numerous signals will be routinely detected using the 60 array, global IMS (International Monitoring System) <span class="hlt">infrasound</span> network. Infrasonic signals are sub-audible quasi longitudinal, atmospheric waves in the frequency band from about 10 Hz to -5 minutes in period (limited by human acoustic audibility in the high frequency limit and by the wave-guide acoustic cut-off frequency and the Brunt Vaisalla frequency in the low frequency limit) These small amplitude waves are a natural subset of the well-known atmospheric acoustic-gravity wave regime which has been identified from the linearized equations of geophysical fluid mechanics in the flat earth approximation, neglecting the earth's rotation, etc. For the IMS network the instrumental pressure sensor response was chosen to range from -4 to 0.02 Hz. These are ground-based arrays of typically 4 to 9 sensors with separations of about 1-2 km between the array elements. Examples of naturally occurring impulsive <span class="hlt">sources</span> of <span class="hlt">infrasound</span> include volcanic eruptions, earthquakes, bolides (large meteor-fireballs entering the atmospheric at very high speeds up to -300 times faster than ground-level sound waves), microbaroms (the 'voice of the sea' due to the interaction of atmospheric storms and surface ocean waves) and the supersonic motion of the auroral electrojet at about 100 km altitude (auroral infrasonic waves), etc. In this paper we will briefly summarize our current state of knowledge of <span class="hlt">infrasound</span> signals from bolides. This summary will include the generation of the signals at the complex, quasi-cylindrical line <span class="hlt">source</span>, to the refraction and diffraction of the propagating waves by the middle atmospheric and tropospheric temperature and wind systems and finally, the detection of the signals and their interpretation by inferring the <span class="hlt">source</span> properties, Le., <span class="hlt">source</span> altitude, blast radius (see below) and the <span class="hlt">source</span> energy, etc. In addition, we will use <span class="hlt">infrasound</span> from energetic bolides to estimate the expected steady state</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19206769','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19206769"><span id="translatedtitle"><span class="hlt">Infrasound</span> induced instability by modulation of condensation process in the atmosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Naugolnykh, Konstantin; Rybak, Samuil</p> <p>2008-12-01</p> <p>A sound wave in supersaturated water vapor can modulate both the process of heat release caused by condensation, and subsequently, as a result, the resonance interaction of sound with the modulated heat release provides sound amplification. High-intensity atmospheric perturbations such as cyclones and thunderstorms generate <span class="hlt">infrasound</span>, which is detectable at large distances from the <span class="hlt">source</span>. The wave-condensation instability can lead to variation in the level of <span class="hlt">infrasound</span> radiation by a developing cyclone, and this can be as a precursor of these intense atmospheric events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615343C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615343C"><span id="translatedtitle"><span class="hlt">Infrasound</span> emission generated by wind turbines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ceranna, Lars; Pilger, Christoph</p> <p>2014-05-01</p> <p>Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for <span class="hlt">infrasound</span> recording systems. Such systems are equipped with highly sensitive micro pressure sensors, which are accurately measuring acoustic signals in a frequency range inaudible to humans. At <span class="hlt">infrasound</span> station IGADE, north of Bremen, a constantly increasing background noise has been observed throughout the years since its installation in 2005. The spectral peaks are reflecting well the blade passing harmonics, which vary with prevailing wind speeds. Overall, a decrease is noted for the <span class="hlt">infrasound</span> array's detection capability. This aspect is particularly important for the other two sites of the German <span class="hlt">infrasound</span> stations I26DE in the Bavarian Forest and I27DE in Antarctica, because plans for installing wind turbines near these locations are being under discussion. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and have to meet stringent specifications with respect to infrasonic background noise. Therefore data obtained during a field experiment with mobile micro-barometer stations for measuring the infrasonic pressure level of a single horizontal-axis wind turbine have been revisited. The results of this experiment successfully validate a theoretical model which estimates the generated sound pressure level of wind turbines and makes it possible to specify the minimum allowable distance between wind turbines and <span class="hlt">infrasound</span> stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned <span class="hlt">infrasound</span> stations outside the determined disturbance range can be found, which will be presented; and vice versa, the model calculations' results for fixing the minimum distance for wind turbines planned for installation in the vicinity of an existing <span class="hlt">infrasound</span> array.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T53C..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T53C..03M"><span id="translatedtitle">Up-Scaling Field Observations to <span class="hlt">Ground</span> <span class="hlt">Truth</span> Seismic Interpretations and Test Dynamic Models of Deep Water Rifted Margins: What are the Challenges?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manatschal, G.; Nirrengarten, M.; Epin, M. E.</p> <p>2015-12-01</p> <p>Recent advances on the study of rifted margins resulted from the development of new, high-resolution seismic imaging methods and dynamic modelling that enable to image the crustal scale structure of rifted margins and experiment under what conditions they formed. However, both the used parameter space as well as the seismic interpretations and model results need to be <span class="hlt">ground</span> <span class="hlt">truth</span> by direct observations and data. In the case of deep-water rifted margins, the problem is that drill hole data is expensive, rare and only available from a handful of examples worldwide. In contrast, remnants preserving kilometre-scale outcrops of former deep-water rifted margins have been described from the Alps and the Pyrenees in Western Europe. These large-scale outcrops provide a direct access to mantle and crustal rocks and the associated sedimentary sequences and magmatic additions. The combination of world-class outcrops, classical, field-based mapping and analytical methods can provide the missing data that is necessary to calibrate and test dynamic models as well as to <span class="hlt">ground</span> <span class="hlt">truth</span> seismic interpretations. In my presentation I will use observations and data from key outcrops from the most distal fossil Alpine Tethys margins exposed in SE Switzerland with the aim to describe the deformation processes and conditions during final rifting and to test rift modes (semi-ductile flow vs. brittle poly-phase faulting). I will in particular focus on the way strain is distributed and the bulk rheology evolves during hyper-extension and mantle exhumation and compare the observations with model results and seismic interpretations. Up-and down scaling observations/data and bridging multiple spatial and temporal scales is a key to understand the large-scale extensional processes that are at the origin of the formation of hyper-extend and exhumed mantle domains. The major challenge is to understand how the learnings obtained from the well-documented examples in the Alps and Pyrenees can be used</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23952568','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23952568"><span id="translatedtitle">Reduction of <span class="hlt">infrasounds</span> in machines with hydrostatic drive.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kudźma, Zygmunt; Stosiak, Michał</p> <p>2013-01-01</p> <p>Some hazards posed by the operation of hydraulic systems, connected with low-frequency vibrations and noise are presented. Special attention is focused on <span class="hlt">infrasounds</span>. The <span class="hlt">sources</span> of low-frequency vibrations and noise and ways of reducing them are indicated. An original solution ensuring the effective reduction of vibrations and noise in a wide frequency range, i.e., a wide-band damper of pressure fluctuations, also performing the function of an acoustic filter, is proposed. The effectiveness of the damper was confirmed by the results of laboratory tests and tests carried out on engineering machines working in real conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20561575','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20561575"><span id="translatedtitle">Responses of the ear to low frequency sounds, <span class="hlt">infrasound</span> and wind turbines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Salt, Alec N; Hullar, Timothy E</p> <p>2010-09-01</p> <p>Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external <span class="hlt">sources</span>, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that <span class="hlt">infrasound</span> presented at an amplitude below what is audible has no influence on the ear. In this review, we consider possible ways that low frequency sounds, at levels that may or may not be heard, could influence the function of the ear. The inner ear has elaborate mechanisms to attenuate low frequency sound components before they are transmitted to the brain. The auditory portion of the ear, the cochlea, has two types of sensory cells, inner hair cells (IHC) and outer hair cells (OHC), of which the IHC are coupled to the afferent fibers that transmit "hearing" to the brain. The sensory stereocilia ("hairs") on the IHC are "fluid coupled" to mechanical stimuli, so their responses depend on stimulus velocity and their sensitivity decreases as sound frequency is lowered. In contrast, the OHC are directly coupled to mechanical stimuli, so their input remains greater than for IHC at low frequencies. At very low frequencies the OHC are stimulated by sounds at levels below those that are heard. Although the hair cells in other sensory structures such as the saccule may be tuned to infrasonic frequencies, auditory stimulus coupling to these structures is inefficient so that they are unlikely to be influenced by airborne <span class="hlt">infrasound</span>. Structures that are involved in endolymph volume regulation are also known to be influenced by <span class="hlt">infrasound</span>, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to <span class="hlt">infrasound</span>. In most cases, the inner ear's responses to <span class="hlt">infrasound</span> can be considered normal, but they could be associated with unfamiliar sensations or subtle changes in physiology. This raises the possibility that exposure to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9637E..1ZS','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9637E..1ZS"><span id="translatedtitle">Derivation from the Landsat 7 NDVI and <span class="hlt">ground</span> <span class="hlt">truth</span> validation of LAI and interception storage capacity for wetland ecosystems in Biebrza Valley, Poland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suliga, Joanna; Chormański, Jarosław; Szporak-Wasilewska, Sylwia; Kleniewska, Małgorzata; Berezowski, Tomasz; van Griensven, Ann; Verbeiren, Boud</p> <p>2015-10-01</p> <p>Wetlands are very valuable areas because they provide a wide range of ecosystems services therefore modeling of wetland areas is very relevant, however, the most widely used hydrological models were developed in the 90s and usually are not adjusted to simulate wetland conditions. In case of wetlands including interception storage into the model's calculation is even more challenging, because literature data hardly exists. This study includes the computation of interception storage capacity based on Landsat 7 image and <span class="hlt">ground</span> <span class="hlt">truthing</span> measurements conducted in the Biebrza Valley, Poland. The method was based on collecting and weighing dry, wet and fully saturated samples of sedges. During the experiments measurements of fresh/dry biomass and leaf area index (LAI) were performed. The research was repeated three times during the same season (May, June and July 2013) to observe temporal variability of parameters. <span class="hlt">Ground</span> <span class="hlt">truthing</span> measurements were used for the validating estimation of parameters derived from images acquired in a similar period as the measurements campaigns. The use of remote sensing has as major advantage of being able to obtain an area covering spatially and temporally distributed estimate of the interception storage capacity. Results from this study proved that interception capacity of wetlands vegetation is changing considerably during the vegetation season (temporal variability) and reaches its maximum value when plants are fully developed. Different areas depending on existing plants species are characterized with different values of interception capacity (spatial variability). This research frames within the INTREV and HiWET projects, funded respectively by National Science Centre (NCN) in Poland and BELSPO STEREO III.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ASAJ..115.2594P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..115.2594P"><span id="translatedtitle">Numerical modeling of <span class="hlt">infrasound</span> propagation at very long distance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piserchia, Pierre-Franck; Roche, Roger</p> <p>2004-05-01</p> <p>Compliance with the CTBT in the atmosphere will be monitored by a world-wide network of <span class="hlt">infrasound</span> stations consisting of 60 stations equipped with microbarographs in order to measure small changes in the air pressure in the frequency range 0.02 to 4 Hz. They are characterized by a good sensitivity, and by a large dynamic. By the application of array techniques, it is possible to determine the direction of pressure pulses caused by small explosions in the atmosphere, as well as shock waves caused by supersonic aircraft or meteorites. To take into account the nonlinear phenomena at the <span class="hlt">source</span> and during the propagation, we are developing a numerical approach to solve the Euler nonlinear equation. In a first step, in the linear domain, this method is compared with two other numerical modeling approaches based on the ray tracing technique and the parabolic approach. In our test case, the <span class="hlt">source</span> is on the ground and generates a 1-Pa pressure pulse centered at the frequency of 0.1 Hz. We considered an <span class="hlt">infrasound</span> propagation over a distance of 500 km and an atmosphere height of 200 km. In a further step, the <span class="hlt">source</span> level will be increased to study nonlinear phenomena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51C2688O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2688O"><span id="translatedtitle">Inferring atmospheric weather conditions in volcanic environments using <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortiz, H. D.; Johnson, J. B.; Ruiz, M. C.</p> <p>2015-12-01</p> <p>We use <span class="hlt">infrasound</span> produced by Tungurahua Volcano (Ecuador) to infer local time-varying atmospheric conditions, which can be used to improve gas flux measurements and tephra dispersal modeling. Physical properties of the atmosphere, including wind and temperature (which controls adiabatic sound speed), can be quantified by studying the travel times of acoustic waves produced during volcanic activity. The travel times between Tungurahua's vent and five <span class="hlt">infrasound</span> stations located in a network configuration over an area of 90 km2 were used in this study. We are able to quantify the arrival time differences of acoustic waves for ten unique station pairs and use this information to model the average speed of sound between <span class="hlt">source</span> and receiver. To identify what parameters best fit the observed arrival times, we perform a grid search for a homogeneous two-dimensional wind velocity as well as for air temperature. Due to travel time dependence on the specific path taken by waves, we account for topography using a 5 meter resolution digital elevation model of Tungurahua. To investigate the time-varying atmospheric structure we use data recorded at Tungurahua volcano, during a strombolian eruptive phase in August 2012, however the methodology can be applied to continuous network <span class="hlt">infrasound</span> data collected since July 2006 as part of the Japanese-Ecuadorian Cooperation Project: "Enhancement of the Volcano Monitoring Capacity in Ecuador". We propose that the computation of wind velocities will help to improve gas flux measurements that are based on remote sensing techniques like Differential Optical Absorption Spectroscopy (DOAS), resulting in better estimates of sulfur fluxes that can then be related to magma fluxing into the volcanic system. Further, wind field quantification close to the volcano can improve numerical models that are used to forecast tephra deposits, thereby helping to mitigate their effect on inhabitants, infrastructure, livestock, and crops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S11B1736B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S11B1736B"><span id="translatedtitle"><span class="hlt">Infrasound</span> monitoring, acoustic-gravity waves and global atmospheric dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blanc, E.; Le Pichon, A.; Ceranna, L.; Farges, T.</p> <p>2008-12-01</p> <p>For the verification of the Comprehensive nuclear Test Ban Treaty, the International Monitoring System has been developed. As part of this system, the <span class="hlt">infrasound</span> network provides an unique opportunity to monitor continuously pressure waves in the atmosphere. Such infrasonic waves propagate in the channel formed by the temperature and wind gradients of the atmosphere. Long term observations provide information about the evolution of the propagation conditions and then of atmospheric parameters. The monitoring of continuous <span class="hlt">sources</span>, as ocean swell, gives the characteristics of the stratospheric wave channel submitted to stratospheric warming effects. Large scale gravity waves, which are also observed by the network, produce a forcing of the stratosphere at low and middle latitudes and long-lived changes in the stratospheric circulation towards high latitudes, leading to fluctuations in the strength of the polar vortex. These fluctuations move down to the lower stratosphere with possible effects on the tropospheric temperature. Gravity wave monitoring in Antarctica reveals a gravity wave system probably related to the wind effect over mountains. At mid latitudes an additional main <span class="hlt">sources</span> of disturbances is the thunderstorm activity. The <span class="hlt">infrasound</span> monitoring system allows a better knowledge of the atmospheric wave systems and of the dynamics of the atmosphere. In return this better knowledge of the wave systems allow a better identification of the possible explosion signals in the background of the atmospheric waves and then to improve the discrimination methods</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.5922G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.5922G"><span id="translatedtitle">Evolution of the CTBTO <span class="hlt">Infrasound</span> Technology Roadmap</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garces, Milton; Haralabus, Georgios; Noack, Patrick; Grenard, Patrick</p> <p>2013-04-01</p> <p>The CTBTO's nuclear explosion monitoring program needs to maintain its effectiveness and ensure its long-term relevance to the verification regime. The aims of its <span class="hlt">Infrasound</span> Technology Roadmap (ITR) are to (1) establish a clear way forwards in accordance with the overall CTBTO nuclear monitoring vision, (2) couple scientific work with technology management, and (3) build upon existing technological accomplishments and project them into near-future technical targets. This ITR has a time horizon of seven years, and its activities are closely aligned to the Provisional Technical Secretariat's Technology Foresight Program, which extends its perspective to 20+ years. Phase 1 of the Roadmap effort requested input from the international <span class="hlt">infrasound</span> community through the Request for Contributions released on 15 November 2012 (RFC R1). A set of metrics were selected to lend fairness, accountability, and scientific integrity to the evaluation of technical topics. The RFC was an inclusive, participatory effort inviting individual scientists to identify and assess technologies and procedures that can be infused into the IMS to meet its monitoring requirements and help evolve technology to achieve a reliable, sustainable and trustworthy monitoring system. We received over 680 individual topic evaluations from 52 members of the international <span class="hlt">infrasound</span> community, with a 93% response rate. We present the statistical results from our survey as well as the highlights of the draft <span class="hlt">Infrasound</span> Technology Roadmap Document.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA569459','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569459"><span id="translatedtitle"><span class="hlt">Infrasound</span> Signal Characteristics from Small Earthquakes</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-09-01</p> <p>by many groups, e.g., McKenna et al. (2007), Che et al. (2002), and Sorrells et al. (1997). These studies show that <span class="hlt">infrasound</span> detections can be...L. Zoback, and D. D. Blackwell, Eds. Boulder, CO: Geol. Soc. Am. Sorrells , G. G., E. Herrin, and J. L. Bonner (1997). Construction of regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA569389','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569389"><span id="translatedtitle"><span class="hlt">Infrasound</span> Signal Characteristics from Small Earthquakes</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-09-01</p> <p><span class="hlt">infrasound</span> from surface explosions ( Sorrells et al., 1997; Che et al., 2002; and McKenna et al., 2007) with the work identifying the importance of path...M. L., Blackwell, and D. D., Eds., Geological Society of America, Boulder, CO, pp. 185–228. Sorrells , G. G., E. Herrin, and J. L. Bonner (1997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S14A..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S14A..07M"><span id="translatedtitle">Unraveling Structural <span class="hlt">Infrasound</span>: understanding the science for persistent remote monitoring of critical infrastructure (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McKenna, S. M.; Diaz-Alvarez, H.; McComas, S.; Costley, D.; Whitlow, R. D.; Jordan, A. M.; Taylor, O.</p> <p>2013-12-01</p> <p>In 2006, the Engineer Research and Development Center (ERDC) began a program designed to meet the capability gap associated with remote assessment of critical infrastructure. This program addresses issues arising from the use of geophysical techniques to solve engineering problems through persistent monitoring of critical infrastructure using <span class="hlt">infrasound</span>. In the original 2006-2009 study of a railroad bridge in Ft. Leonard Wood, MO, the fundamental modes of motion of the structure were detected at up to 30 km away, with atmospheric excitation deemed to be the <span class="hlt">source</span> driver. Follow-on research focused on the mechanically driven modes excited by traffic, with directional acoustic emanations. The success of the Ft. Wood ambient excitation study resulted in several subsequent programs to push the boundaries of this new technique for standoff assessment, discussed herein. Detection of scour and river system health monitoring are serious problems for monitoring civil infrastructure, from both civilian and military perspectives. Knowledge of overall system behavior over time is crucial for assessment of bridge foundations and barge navigation. This research focuses on the same steel-truss bridge from the Ft. Wood study, and analyzes 3D and 2D substructure models coupled with the superstructure reaction loads to assess the modal deformations within the <span class="hlt">infrasound</span> bandwidth and the correlation to scour of embedment material. The Urban <span class="hlt">infrasound</span> program is <span class="hlt">infrasound</span> modeling, data analysis, and sensor research leading to the detection, classification and localization of threat activities in complex propagation environments. Three seismo-acoustic arrays were deployed on rooftops across the Southern Methodist University campus in Dallas, Texas, to characterize the urban <span class="hlt">infrasound</span> environment. Structural <span class="hlt">sources</span> within 15 km of the arrays have been identified through signal processing and confirmed through acoustical models. <span class="hlt">Infrasound</span> is also being studied as a means of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1413368J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1413368J"><span id="translatedtitle">The Eyjafjallajökull 2010 eruptions: Correlation study of volcanic tremor and <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonsdottir, K.; Bean, C.; Vogfjord, K.; Ripepe, M.</p> <p>2012-04-01</p> <p>Volcanic far-field seismic tremor recorded at 7-20 km from the Eyjafjallajökull 2010 eruptions is investigated. Over a two months period, two very different eruptions occurred separated by 9 km and two days; an effusive flank eruption and later a highly explosive summit eruption. We observed high amplitude seismic tremor during the explosive eruption while the flank eruption produced very low amplitude tremor. <span class="hlt">Infrasound</span> data collected for a few days during the summit eruption, as well as other data including plume height is also compared to the seismic tremor amplitude. We find that tremor amplitude does not scale with the plume height. However, in line with similar studies, the <span class="hlt">infrasound</span> data, characterized by pressure pulses from the volcanic explosions, is seen to correlate temporally (0.55-0.6) with the seismic tremor data, characterized by repeating low frequency events. A high correlation in amplitude (0.8) is also found between these datasets. The analysis reveals a time lag of 15-20 seconds, where seismic low frequency events are seen prior to the <span class="hlt">infrasound</span> events. This is consistent with co-located seismic tremor and <span class="hlt">infrasound</span> <span class="hlt">sources</span> at the eruptive crater, and a surface wave velocity of 1350-1500 m/s. Singlestation three component analyses (undertaken for several stations) of the seismic low frequency events further confirms that they contain Rayleigh wave energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA516178','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA516178"><span id="translatedtitle"><span class="hlt">Infrasound</span> Signals from Ground-Motion <span class="hlt">Sources</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2008-09-01</p> <p>reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions...information if it does not display a currently valid OMB control number. 1 . REPORT DATE SEP 2008 2. REPORT TYPE 3. DATES COVERED 00-00-2008 to 00-00...zone calculation (Figure 1 ), where the input velocity data were from the modeled accelerations for the Tortugas event in hole U3gg. In the CAVEAT</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BoLMe.159..185C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BoLMe.159..185C"><span id="translatedtitle"><span class="hlt">Infrasound</span> as a Detector of Local and Remote Turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuxart, J.; Tatrai, D.; Weidinger, T.; Kircsi, A.; Józsa, J.; Kiss, M.</p> <p>2016-05-01</p> <p><span class="hlt">Infrasound</span> measurements are used to detect seismic waves and a large effort is devoted to eliminating the turbulence-related <span class="hlt">infrasound</span> signal, usually considered as noise. Here we take a complementary approach, investigating whether <span class="hlt">infrasound</span> can provide information on atmospheric turbulence. Microphone measurements of <span class="hlt">infrasound</span> from an experimental campaign in Hungary in 2013 are used, together with data from a nearby sonic anemometer and a sodar. The comparison of <span class="hlt">infrasound</span> integrated spectral energy to turbulent kinetic energy from the sonic provides a good match when turbulence is present near the ground. Moreover, on stable nights when the surface layer is strongly stratified and with turbulence absent, microphones sometimes recorded <span class="hlt">infrasound</span> when the sodar showed a low-level jet above the surface inversion, indicating that microphones may be used as detectors of elevated turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..12114651Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..12114651Z"><span id="translatedtitle">A study of National Lightning Detection Network responses to natural lightning based on <span class="hlt">ground</span> <span class="hlt">truth</span> data acquired at LOG with emphasis on cloud discharge activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Y.; Rakov, V. A.; Tran, M. D.; Nag, A.</p> <p>2016-12-01</p> <p>The U.S. National Lightning Detection Network (NLDN) detection efficiency (DE) and classification accuracy (CA) for cloud discharge (IC) activity (identified here by a sequence of non-return-stroke-type electric field pulses not accompanied by channels to ground) were evaluated using optical and electric field data acquired at the LOG (Lightning Observatory in Gainesville), Florida. Our <span class="hlt">ground</span> <span class="hlt">truth</span> "IC events" include 26 "isolated IC events" (complete IC flashes), 58 "IC events before first return stroke," and 69 "IC events after first return stroke." For the total of 153 IC events, 33% were detected by the NLDN, and the classification accuracy was 86%. For complete IC flashes, the detection efficiency and classification accuracy were 73% and 95%, respectively, and the average number of NLDN-reported cloud pulses was 2.9 per detected event. For 24 preliminary breakdown pulse trains in CG flashes, the detection efficiency and classification accuracy were 46% and 82%, respectively. We have additionally estimated the DE and CA for return strokes in CG flashes. Irrespective of stroke order and polarity, the DE was 92% (339/367), and the CA was also 92% (312/339). The DEs for negative first and subsequent strokes were 98% and 90%, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRG..112.4S09T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRG..112.4S09T"><span id="translatedtitle">Comparing different methods for assessing <span class="hlt">ground</span> <span class="hlt">truth</span> of rover data analysis for the 2005 season of the Life in the Atacama Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, G. W.; Peate, I. Ukstins; Nakamoto, J.; Pudenz, E.; Glasgow, J.; Bretthauer, J.; Cabrol, N.; Wettergreen, D.; Grin, E.; Coppin, P.; Dohm, J. M.; Piatek, J. L.; Warren-Rhodes, K.; Hock, A. N.; Weinstein, S.; Fisher, G.; Diaz, G. Chong; Cockell, C.; Marinangeli, L.; Minkley, N.; Moersch, J.; Ori, G. G.; Smith, T.; Stubb, K.; Wagner, M.; Waggoner, A. S.</p> <p>2007-12-01</p> <p>The scientific success of a remote exploration rover mission depends on the right combination of technology, teamwork and scientific insight. In order to quantitatively evaluate the success of a rover field trial, it is necessary to assess the accuracy of scientific interpretations made during the field test. This work compares three structured approaches to assessing the <span class="hlt">ground</span> <span class="hlt">truth</span> of scientific findings from a science team conducting a remote investigation of a locale using an autonomous rover. For the first approach, independent assessment, the daily science summaries were analyzed and reduced to a series of 1082 factual statements, which were treated as hypotheses. An independent scientist traveled to the field area to assess these hypotheses. For the second approach, guided self-study, the mission scientists themselves traveled to the field area and evaluated their own scientific interpretations. The third approach, discrepancy investigation, searched for the root causes of differences between the scientific interpretations made in the control room and those made in the field. The independent investigation provided sensitive, quantitative data, but suffered from the lack of context and continuity developed in the mission control room. The guided evaluation benefited from the context of the mission, but lacked clarity and consistency. The discrepancy investigation provided insight into the root causes behind the discrepancies, but was expensive and time consuming. The independent investigation method yielded particularly compelling results, but each method offers advantages and a comprehensive rover field trial assessment should include a combination of all three.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S54B..08L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S54B..08L"><span id="translatedtitle">Seismic generated <span class="hlt">infrasounds</span> on Telluric Planets: Modeling and comparisons between Earth, Venus and Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lognonne, P. H.; Rolland, L.; Karakostas, F. G.; Garcia, R.; Mimoun, D.; Banerdt, W. B.; Smrekar, S. E.</p> <p>2015-12-01</p> <p>Earth, Venus and Mars are all planets in which <span class="hlt">infrasounds</span> can propagate and interact with the solid surface. This leads to <span class="hlt">infrasound</span> generation for internal <span class="hlt">sources</span> (e.g. quakes) and to seismic waves generations for atmospheric <span class="hlt">sources</span> (e.g. meteor, impactor explosions, boundary layer turbulences). Both the atmospheric profile, surface density, atmospheric wind and viscous/attenuation processes are however greatly different, including major differences between Mars/Venus and Earth due to the CO2 molecular relaxation. We present modeling results and compare the seismic/acoustic coupling strength for Earth, Mars and Venus. This modeling is made through normal modes modelling for models integrating the interior, atmosphere, both with realistic attenuation (intrinsic Q for solid part, viscosity and molecular relaxation for the atmosphere). We complete these modeling, made for spherical structure, by integration of wind, assuming the later to be homogeneous at the scale of the <span class="hlt">infrasound</span> wavelength. This allows us to compute either the Seismic normal modes (e.g. Rayleigh surface waves), or the acoustic or the atmospheric gravity modes. Comparisons are done, for either a seismic <span class="hlt">source</span> or an atmospheric <span class="hlt">source</span>, on the amplitude of expected signals as a function of distance and frequency. Effects of local time are integrated in the modeling. We illustrate the Rayleigh waves modelling by Earth data (for large quakes and volcanoes eruptions). For Venus, very large coupling can occur at resonance frequencies between the solid part and atmospheric part of the planet through <span class="hlt">infrasounds</span>/Rayleigh waves coupling. If the atmosphere reduced the Q (quality coefficient) of Rayleigh waves in general, the atmosphere at these resonance soffers better propagation than Venus crust and increases their Q. For Mars, Rayleigh waves excitations by atmospheric burst is shown and discussed for the typical yield of impacts. The new data of the Nasa INSIGHT mission which carry both seismic and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A31A0049L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0049L"><span id="translatedtitle">Incorporating numerical modelling into estimates of the detection capability of the IMS <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Ceranna, L.</p> <p>2011-12-01</p> <p>To monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a dedicated International Monitoring System (IMS) is being deployed. Recent global scale observations recorded by this network confirm that its detection capability is highly variable in space and time. Previous studies estimated the radiated <span class="hlt">source</span> energy from remote observations using empirical yield-scaling relations which account for the along-path stratospheric winds. Although the empirical wind correction reduces the variance in the explosive energy versus pressure relationship, strong variability remains in the yield estimate. Today, numerical modelling techniques provide a basis to better understand the role of different factors describing the <span class="hlt">source</span> and the atmosphere that influence propagation predictions. In this study, the effects of the <span class="hlt">source</span> frequency and the stratospheric wind speed are simulated. In order to characterize fine-scale atmospheric structures which are excluded from the current atmospheric specifications, model predictions are further enhanced by the addition of perturbation terms. Thus, a theoretical attenuation relation is developed from massive numerical simulations using the Parabolic Equation method. Compared with previous studies, our approach provides a more realistic physical description of <span class="hlt">infrasound</span> propagation. We obtain a new relation combining a near-field and far-field term which account for the effects of both geometrical spreading and dissipation on the pressure wave attenuation. By incorporating real ambient <span class="hlt">infrasound</span> noise at the receivers which significantly limits the ability to detect and identify signals of interest, the minimum detectable <span class="hlt">source</span> amplitude can be derived in a broad frequency range. Empirical relations between the <span class="hlt">source</span> spectrum and the yield of explosions are used to infer detection thresholds in tons of TNT equivalent. In the context of the future verification of the CTBT, the obtained attenuation relation quantifies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/957399','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/957399"><span id="translatedtitle">IMPROVED <span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> IN SOUTHERN ASIA USING IN-COUNTRY DATA, ANALYST WAVEFORM REVIEW, AND ADVANCED ALGORITHMS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Engdahl, Eric, R.; Bergman, Eric, A.; Myers, Stephen, C.; Ryall, Floriana</p> <p>2009-06-19</p> <p> respective errors. This is a significant advance, as outliers and future events with apparently anomalous depths can be readily identified and, if necessary, further investigated. The patterns of reliable focal depth distributions have been interpreted in the context of Middle Eastern active tectonics. Most earthquakes in the Iranian continental lithosphere occur in the upper crust, less than about 25-30 km in depth, with the crustal shortening produced by continental collision apparently accommodated entirely by thickening and distributed deformation rather than by subduction of crust into the mantle. However, intermediate-depth earthquakes associated with subducted slab do occur across the central Caspian Sea and beneath the Makran coast. A multiple-event relocation technique, specialized to use different kinds of near-<span class="hlt">source</span> data, is used to calibrate the locations of 24 clusters containing 901 events drawn from the seismicity catalog. The absolute locations of these clusters are fixed either by comparing the pattern of relocated earthquakes with mapped fault geometry, by using one or more cluster events that have been accurately located independently by a local seismic network or aftershock deployment, by using InSAR data to determine the rupture zone of shallow earthquakes, or by some combination of these near-<span class="hlt">source</span> data. This technique removes most of the systematic bias in single-event locations done with regional and teleseismic data, resulting in 624 calibrated events with location uncertainties of 5 km or better at the 90% confidence level (GT590). For 21 clusters (847 events) that are calibrated in both location and origin time we calculate empirical travel times, relative to a standard 1-D travel time model (ak135), and investigate event to station travel-time anomalies as functions of epicentral distance and azimuth. Substantial travel-time anomalies are seen in the Iran region which make accurate locations impossible unless observing stations are at very short</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMPP22C..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMPP22C..03P"><span id="translatedtitle">Archaeological Evidence for Abrupt Cimate Change: Results from Satellite Imagery Analysis and Subsequent <span class="hlt">Ground-Truthing</span> in the El-Manzalah Region, Northeast Egyptian Delta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parcak, S. H.</p> <p>2003-12-01</p> <p>The abrupt global climate changes recorded at 8.2, 5.2 and 4.2 ka BP caused a wide range of transformations within ancient societies, including the focus of this study: ancient Egypt . In the case of the climatic changes that occurred at 4.2 ka BP, scholars have debated hotly the events surrounding the "collapse" of the Old Kingdom. Despite such studies into the Old Kingdom's "collapse", there have been insufficient regional settlement pattern studies in Egypt to augment hypotheses concerning the mechanisms behind the cultural transformations that occurred at the end of the Old Kingdom. Utilizing a combination of satellite imagery analysis and subsequent <span class="hlt">ground-truthing</span> techniques over a broad region in the East Delta, this study aims to reconstruct pharaonic settlement distributions in relation to the changing northeast delta topography, river courses, marshlands, and coastline. Although geo-political and religious factors played varying roles in settlement patterns, this study overlies the economic and environmental components behind the settlement of individual sites and areas. For instance, prior to the formation of the Manzala lagoon, beginning in the 4th century AD, the Mendesian branch of the Nile flowed past Mendes and its satellite, maritime port at Tell Tebilla: As early as the Old Kingdom, Tell Tebilla provided an ideal location for the formation of a town, being well-located to exploit both riverine and maritime transportation routes through trade, and regional floral and faunal resources from hunting, fishing, cultivation and animal husbandry. Key factors such as long-term fluctuations in precipitation, flood levels, and river courses, can affect dramatically the fortunes of individual settlements, areas, and regions, resulting in the decline and abandonment of some sites and the foundation and flourishing of other sites, especially within marginal regions. The Egyptian delta represents an ideal region for studying the impacts of climatic changes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27782589','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27782589"><span id="translatedtitle">Acoustic buffeting by <span class="hlt">infrasound</span> in a low vibration facility.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>MacLeod, B P; Hoffman, J E; Burke, S A; Bonn, D A</p> <p>2016-09-01</p> <p>Measurement instruments and fabrication tools with spatial resolution on the atomic scale require facilities that mitigate the impact of vibration <span class="hlt">sources</span> in the environment. One approach to protection from vibration in a building's foundation is to place the instrument on a massive inertia block, supported on pneumatic isolators. This opens the questions of whether or not a massive floating block is susceptible to acoustic forces, and how to mitigate the effects of any such acoustic buffeting. Here this is investigated with quantitative measurements of vibrations and sound pressure, together with finite element modeling. It is shown that a particular concern, even in a facility with multiple acoustic enclosures, is the excitation of the lowest fundamental acoustic modes of the room by <span class="hlt">infrasound</span> in the low tens of Hz range, and the efficient coupling of the fundamental room modes to a large inertia block centered in the room.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87i3901M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87i3901M"><span id="translatedtitle">Acoustic buffeting by <span class="hlt">infrasound</span> in a low vibration facility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacLeod, B. P.; Hoffman, J. E.; Burke, S. A.; Bonn, D. A.</p> <p>2016-09-01</p> <p>Measurement instruments and fabrication tools with spatial resolution on the atomic scale require facilities that mitigate the impact of vibration <span class="hlt">sources</span> in the environment. One approach to protection from vibration in a building's foundation is to place the instrument on a massive inertia block, supported on pneumatic isolators. This opens the questions of whether or not a massive floating block is susceptible to acoustic forces, and how to mitigate the effects of any such acoustic buffeting. Here this is investigated with quantitative measurements of vibrations and sound pressure, together with finite element modeling. It is shown that a particular concern, even in a facility with multiple acoustic enclosures, is the excitation of the lowest fundamental acoustic modes of the room by <span class="hlt">infrasound</span> in the low tens of Hz range, and the efficient coupling of the fundamental room modes to a large inertia block centered in the room.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/629378','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/629378"><span id="translatedtitle"><span class="hlt">Infrasound</span> records from U.S. atmospheric tests</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chael, E.P.; Lohr, R.D.</p> <p>1998-07-01</p> <p>The United States conducted over 100 atmospheric nuclear tests at the Nevada Test Site from 1951 through 1962. Some of the earliest tests caused unexpected damage, primarily broken glass and cracked plaster, in Las Vegas and other surrounding communities. To address this problem, Sandia initiated a program to monitor and predict the pressure waves around NTS. <span class="hlt">Infrasound</span> recording systems were developed, then field for all tests beginning with Operation Buster in October 1951. Investigators soon discovered that near-surface temperature inversions and wind profiles caused the damaging pressures in Las Vegas. A typical test was recorded at about a dozen stations from the Control Point on NTS to as far away as Pasadena, CA. In addition, some tests in the South Pacific were monitored, as well as numerous chemical explosions. Strip charts recorded signals in the frequency band from 0.05 to 30 Hz, and the paper tapes were achieved at Sandia in the early 1970s. The NTS events ranged in yield from below 1 ton to 74 kilotons; <span class="hlt">source</span> altitudes varied from near ground level (including some cratering experiments) to as high as 11 km. The resulting data contain a wealth of information on the <span class="hlt">source</span> function, yield scaling and regional propagation of <span class="hlt">infrasound</span> signals from atmospheric explosions. The renewed interest in infrasonic monitoring for CTBT verification has prompted the authors to exhume some of the archived records. The authors plan to digitize the signals from several tests and evaluate their applicability to CTBT issues. In addition, they will collect any existing parametric measurements for these records (arrival times, amplitudes, etc.). All data will be converted to CSS database format and made available to the research community. If appropriate, the resulting information could also be included in the Knowledge Base under development for CTBT monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JASTP..80..208E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JASTP..80..208E"><span id="translatedtitle"><span class="hlt">Infrasound</span> production by bolides: A global statistical study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ens, T. A.; Brown, P. G.; Edwards, W. N.; Silber, E. A.</p> <p>2012-05-01</p> <p>We have examined a dataset consisting of 71 bolides detected by satellite sensors, which provide energy and location estimates, with simultaneous measurements of the same events on 143 distinct waveforms. These bolides have total <span class="hlt">source</span> energies ranging from 0.02 kt TNT equivalent yield to ≈20 kt and probable diameters of order a few meters on average. We find that it is possible to detect large events with energies of ≈20 kt or more globally. Infrasonic detections of these events for stratospheric arrivals have ranges between 350-17,000 km and show clear wind-related amplitude modifications. We find that our period-yield relations are virtually identical to that found from AFTAC nuclear test data with the most robust period-yield correlation found for those events having multiple station averaged periods. We have also found empirical expressions relating maximum expected detection range for <span class="hlt">infrasound</span> as a function of energy and low and high frequency cut-off as a function of energy. Our multi-variate fits suggest that 1/2 > yield-scaling is most appropriate for long range bolide <span class="hlt">infrasound</span> measurements with a distance scaling exponent of ≈1.1 best representing the data. Our best-fit wind correction exponent is a factor of ≈3 smaller than found by previous studies which we suggest may indicate a decrease in the value of k with range. We find that the integral acoustic efficiency for bolides is ≥0.01% with a best lower limit estimate nearer 0.1%. Finally, we conclude that a range independent atmosphere implementation of the normal-mode approach to simulate bolide amplitudes is ineffective at large ranges due to the large change in atmospheric conditions along <span class="hlt">source</span>-receiver paths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.V23D2122M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V23D2122M"><span id="translatedtitle">Effects of topography and atmospheric structure on volcano <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcillo, O. E.; Johnson, J. B.</p> <p>2009-12-01</p> <p>Proper interpretation of infrasonic waves produced by volcanic explosions requires understanding of weather and topographic effects. We have studied <span class="hlt">infrasound</span> produced by two different volcanoes (Kilauea and Tungurahua) to determine the influence of topographic and atmospheric conditions on the infrasonic records corresponding to several weeks of eruptive activity. This analysis is necessary to understand and correct for phase and amplitude responses in order to properly perform waveform modeling. For instance, these corrections are necessary to obtain a better estimate of volume flux from the volcanic vent. The first case study is a dataset acquired during June of 2008 at Kilauea volcano in Hawaii, focused on the active Halemaumau Vent. Several days of infrasonic tremor were recorded by a 3-station <span class="hlt">infrasound</span> network. These records show a strong influence of wind and topography in one of the three stations of the network. This station was located 2370 m from the vent, at a comparable distance to the other stations, but line of sight to the vent was obstructed by a 50-meter high crater edge, which introduced diffraction effects. Periods when wind blew in the vent-station direction are correlated with increase in infrasonic energy in the 0.5 - 1 Hz bandwidth. The second case focuses on a campaign conducted in June 2009 at Tungurahua Volcano, Ecuador. This study implemented two infrasonic arrays located on the flanks of the volcano 6000m north of the vent and on the flanks of an adjacent hill, 11,500m northeast. Compared to the proximal array a distinctive attenuation is evident at certain frequencies (0.5-1.5 Hz) at the distal array. This degree of attenuation is time-variant and is mostly likely related to changing atmospheric structure. An alternative explanation for the apparent spectral differences between near and far stations (and their evolution over time) is a complex (and changing) <span class="hlt">source</span> geometry due to non-compact <span class="hlt">sources</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhDT.......174L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhDT.......174L"><span id="translatedtitle">Neural network approach to classification of <span class="hlt">infrasound</span> signals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Dong-Chang</p> <p></p> <p>As part of the International Monitoring Systems of the Preparatory Commissions for the Comprehensive Nuclear Test-Ban Treaty Organization, the <span class="hlt">Infrasound</span> Group at the University of Alaska Fairbanks maintains and operates two <span class="hlt">infrasound</span> stations to monitor global nuclear activity. In addition, the group specializes in detecting and classifying the man-made and naturally produced signals recorded at both stations by computing various characterization parameters (e.g. mean of the cross correlation maxima, trace velocity, direction of arrival, and planarity values) using the in-house developed weighted least-squares algorithm. Classifying commonly observed low-frequency (0.015--0.1 Hz) signals at out stations, namely mountain associated waves and high trace-velocity signals, using traditional approach (e.g. analysis of power spectral density) presents a problem. Such signals can be separated statistically by setting a window to the trace-velocity estimate for each signal types, and the feasibility of such technique is demonstrated by displaying and comparing various summary plots (e.g. universal, seasonal and azimuthal variations) produced by analyzing <span class="hlt">infrasound</span> data (2004--2007) from the Fairbanks and Antarctic arrays. Such plots with the availability of magnetic activity information (from the College International Geophysical Observatory located at Fairbanks, Alaska) leads to possible physical <span class="hlt">sources</span> of the two signal types. Throughout this thesis a newly developed robust algorithm (sum of squares of variance ratios) with improved detection quality (under low signal to noise ratios) over two well-known detection algorithms (mean of the cross correlation maxima and Fisher Statistics) are investigated for its efficacy as a new detector. A neural network is examined for its ability to automatically classify the two signals described above against clutter (spurious signals with common characteristics). Four identical perceptron networks are trained and validated (with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAP...116q3109D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAP...116q3109D"><span id="translatedtitle">Detection of volcanic <span class="hlt">infrasound</span> with a ring laser interferometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunn, Robert W.; Hosman, Ashley R.</p> <p>2014-11-01</p> <p>Over the last 15 years, large horizontally mounted ring lasers have been used to study numerous geophysical phenomena. This paper provides examples of the sensitivity of large active ring laser interferometers to far field <span class="hlt">infrasound</span> emissions from explosive volcanic eruptions. Volcanic <span class="hlt">infrasound</span> is reported from representative eruptions of volcanoes Kelut (Kelud), Klyuchevskaya (Kliuchevskoi), Puyehua, Santa Maria, Sakurajima, and Tungurahua. The detected <span class="hlt">infrasound</span> frequencies are in basic agreement with the far field air wave frequencies from the 1980 eruption of Mount St. Helens and the 1991 eruption of Mount Pinatubo. Cavities of large horizontally mounted active ring lasers contain two counter-propagating waves that in the presence Earth's rotation become traveling waves of slightly different frequencies. The Sagnac or beat frequency due to the difference in the traveling wave frequencies is modulated by geophysical phenomena, in this case volcanic <span class="hlt">infrasound</span>. Signatures of the <span class="hlt">infrasound</span> are found in the frequency modulated side bands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830017020&hterms=Excess+attenuation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DExcess%2Battenuation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830017020&hterms=Excess+attenuation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DExcess%2Battenuation"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> for oceanic rainfall</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dorman, C. E.</p> <p>1981-01-01</p> <p>Communications systems operating at frequencies in excess of 10 GHz are degraded significantly by rainfall. To provide the information needed for design of these millimeter wave systems, rain attentuation models were developed and data bases of propagation related information were accumulated. These data bases were developed based on the signal level measurements of geostationary satellite beacons at selected frequencies. Groundbased radar reflection measurements were able to develop data bases for system design. The rain attenuation models allow accurate correlation between the rain rate and the attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4688P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4688P"><span id="translatedtitle">Capability of the CTBT <span class="hlt">infrasound</span> stations detecting the 2013 Russian fireball</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; Le Pichon, Alexis; Mialle, Pierrick; Garces, Milton</p> <p>2015-04-01</p> <p>The explosive fragmentation of the 2013 Chelyabinsk meteorite generated a large airburst with an equivalent yield of 500 kT TNT. It is the most energetic event recorded by the <span class="hlt">infrasound</span> component of the CTBT-IMS, globally detected by 20 out of 42 operational stations. This study performs a station-by-station estimation of the IMS detection capability to explain <span class="hlt">infrasound</span> detections and non-detections from short to long distances, using the Chelyabinsk meteorite as global reference event. Investigated parameters influencing the detection capability are the directivity of the line <span class="hlt">source</span> signal, the ducting of acoustic energy and the individual noise conditions at each station. Findings include a clear detection preference for stations perpendicular to the meteorite trajectory, even over large distances. Only a weak influence of stratospheric ducting is observed for this low-frequency case. Furthermore, a strong dependence on the diurnal variability of background noise levels at each station is observed, favoring nocturnal detections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2923251','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2923251"><span id="translatedtitle">Responses of the ear to low frequency sounds, <span class="hlt">infrasound</span> and wind turbines</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Salt, Alec N.; Hullar, Timothy E.</p> <p>2010-01-01</p> <p>Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external <span class="hlt">sources</span>, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that <span class="hlt">infrasound</span> presented at an amplitude below what is audible has no influence on the ear. In this review, we consider possible ways that low frequency sounds, at levels that may or may not be heard, could influence the function of the ear. The inner ear has elaborate mechanisms to attenuate low frequency sound components before they are transmitted to the brain. The auditory portion of the ear, the cochlea, has two types of sensory cells, inner hair cells (IHC) and outer hair cells (OHC), of which the IHC are coupled to the afferent fibers that transmit “hearing” to the brain. The sensory stereocilia (“hairs”) on the IHC are “fluid coupled” to mechanical stimuli, so their responses depend on stimulus velocity and their sensitivity decreases as sound frequency is lowered. In contrast, the OHC are directly coupled to mechanical stimuli, so their input remains greater than for IHC at low frequencies. At very low frequencies the OHC are stimulated by sounds at levels below those that are heard. Although the hair cells in other sensory structures such as the saccule may be tuned to infrasonic frequencies, auditory stimulus coupling to these structures is inefficient so that they are unlikely to be influenced by airborne <span class="hlt">infrasound</span>. Structures that are involved in endolymph volume regulation are also known to be influenced by <span class="hlt">infrasound</span>, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to <span class="hlt">infrasound</span>. In most cases, the inner ear’s responses to <span class="hlt">infrasound</span> can be considered normal, but they could be associated with unfamiliar sensations or subtle changes in physiology. This raises the possibility that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030928','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030928"><span id="translatedtitle">The case for <span class="hlt">infrasound</span> as the long-range map cue in avian navigation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hagstrum, J.T.</p> <p>2007-01-01</p> <p>Of the various 'map' and 'compass' components of Kramer's avian navigational model, the long-range map component is the least well understood. In this paper atmospheric <span class="hlt">infrasounds</span> are proposed as the elusive longrange cues constituting the avian navigational map. Although <span class="hlt">infrasounds</span> were considered a viable candidate for the avian map in the 1970s, and pigeons in the laboratory were found to detect sounds at surprisingly low frequencies (0.05 Hz), other tests appeared to support either of the currently favored olfactory or magnetic maps. Neither of these hypotheses, however, is able to explain the full set of observations, and the field has been at an impasse for several decades. To begin, brief descriptions of infrasonic waves and their passage through the atmosphere are given, followed by accounts of previously unexplained release results. These examples include 'release-site biases' which are deviations of departing pigeons from the homeward bearing, an annual variation in homing performance observed only in Europe, difficulties orienting over lakes and above temperature inversions, and the mysterious disruption of several pigeon races. All of these irregularities can be consistently explained by the deflection or masking of infrasonic cues by atmospheric conditions or by other infrasonic <span class="hlt">sources</span> (microbaroms, sonic booms), respectively. A <span class="hlt">source</span> of continuous geographic <span class="hlt">infrasound</span> generated by atmosphere-coupled microseisms is also proposed. In conclusion, several suggestions are made toward resolving some of the conflicting experimental data with the pigeons' possible use of infrasonic cues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/961863','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/961863"><span id="translatedtitle">Evaluation of <span class="hlt">Infrasound</span> and Strobe Lights to Elicit Avoidance Behavior in Juvenile Salmon and Char.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mueller, Robert, P.; Neitzel, Duane A.; Amidan, Brett G.</p> <p>1999-02-01</p> <p>Experimental tests were conducted using hatchery reared and wild juvenile chinook salmon Oncorhynchus tshawytscha, eastern brook trout Salvelinus fontinalis, and rainbow trout O. mykiss to determine specific behavior responses to <span class="hlt">infrasound</span> (<20 Hz) and flashing strobe lights. Caged fish were acclimated in a static test tank and their behavior was recorded using low light cameras. Species specific behavior was characterized by measuring movements of the fish within the cage as well as observing startle and habituation responses. Wild chinook salmon (40-45 mm) and hatchery reared chinook salmon (45-50mm) exhibited avoidance responses when initially exposed to a 10 Hz volume displacement <span class="hlt">source</span>. Rainbow and eastern brook trout (25-100 mm) did not respond with avoidance or other behaviors to <span class="hlt">infrasound</span>. Habituation to the <span class="hlt">infrasound</span> <span class="hlt">source</span> was evident for chinook salmon during repeated exposures. Wild and hatchery chinook displayed a higher proportion of movement during the initial exposures to <span class="hlt">infrasound</span> when the acclimation period in the test tank was 2-3 h as compared to a 12-15 h acclimation period. A flashing strobe light produced higher and more consistent movement rates in wild chinook (60% of the tests); hatchery reared chinook salmon (50%) and rainbow trout (80%). No measurable movement or other responses was observed for eastern brook trout. Little if any habituation was observed during repeated exposures to strobe lights. Results from this study indicate that consistent repeatable responses can be elicited from some fish using high intensity strobe lights under a controlled laboratory testing. The specific behaviors observed in these experiments might be used to predict how fish might react to low frequency sound and strobe lights in a screening facility. Because sub-yearling salmonids and resident species are susceptible from becoming entrained at water diversion structures we conducted tests in conjunction with our evaluation of juvenile fish screening</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9515S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9515S"><span id="translatedtitle">Comparison of seismic and <span class="hlt">infrasound</span> wave fields generated by snow avalanches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suriñach, Emma; Tapia, Mar; Pérez-Guillén, Cristina; Khazaradze, Giorgi; Roig, Pere</p> <p>2016-04-01</p> <p>Snow avalanches are a <span class="hlt">source</span> of waves that are transmitted through the ground and the air. These wave fields are detected by seismic and <span class="hlt">infrasound</span> sensors. During the winter seasons 2008 -2016, a good quality database of avalanches was obtained at the VdlS test site with an accurate instrumentation. These avalanches were both natural and artificially triggered and were of varying types and sizes. Distances involved were 0.5 -3 km. Seismic signals were acquired using three seismometers (3-components, 1Hz) spaced 600 m apart along the avalanche track. One <span class="hlt">infrasound</span> sensor (0.1Hz) and one seismometer (3-components, 1Hz) were placed one next to the other with a common base of time on the slope opposite the path. The database obtained enables us to compare the different signals generated. Differences in the frequency content and shape of the signals depending on the type and size of the avalanche are detected. A clear evolution of the recorded seismic signals along the path is observed. The cross correlation of the <span class="hlt">infrasound</span> and seismic signals generated by the avalanches allows us to determine different characteristics for powder, transitional and wet avalanches concerning their wave fields. The joint analysis of <span class="hlt">infrasound</span> and seismic waves enables us to obtain valuable information about the internal parts of the avalanche as a <span class="hlt">source</span> of each wave field. This study has repercussions on avalanche dynamics and on the selection of the appropriate avalanche detection system. This study is supported by the Spanish Ministry of Science and Innovation project CHARMA: CHAracterization and ContRol of MAss Movements. A Challenge for Geohazard Mitigation (CGL2013-40828-R), and RISKNAT group (2014GR/1243).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8524B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8524B"><span id="translatedtitle">Contribution of <span class="hlt">Infrasound</span> to IDC Reviewed Event Bulletin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bittner, Paulina; Polich, Paul; Gore, Jane; Ali, Sherif Mohamed; Medinskaya, Tatiana; Mialle, Pierrick</p> <p>2016-04-01</p> <p>Until 2003 two waveform technologies, i.e. seismic and hydroacoustic were used to detect and locate events included in the International Data Centre (IDC) Reviewed Event Bulletin (REB). The first atmospheric event was published in the REB in 2003 but <span class="hlt">infrasound</span> detections could not be used by the Global Association (GA) Software due to the unmanageable high number of spurious associations. Offline improvements of the automatic processing took place to reduce the number of false detections to a reasonable level. In February 2010 the <span class="hlt">infrasound</span> technology was reintroduced to the IDC operations and has contributed to both automatic and reviewed IDC bulletins. The primary contribution of <span class="hlt">infrasound</span> technology is to detect atmospheric events. These events may also be observed at seismic stations, which will significantly improve event location. Examples of REB events, which were detected by the International Monitoring System (IMS) <span class="hlt">infrasound</span> network were fireballs (e.g. Bangkok fireball, 2015), volcanic eruptions (e.g. Calbuco, Chile 2015) and large surface explosions (e.g. Tjanjin, China 2015). Query blasts and large earthquakes belong to events primarily recorded at seismic stations of the IMS network but often detected at the <span class="hlt">infrasound</span> stations. Presence of <span class="hlt">infrasound</span> detection associated to an event from a mining area indicates a surface explosion. Satellite imaging and a database of active mines can be used to confirm the origin of such events. This presentation will summarize the contribution of 6 years of <span class="hlt">infrasound</span> data to IDC bulletins and provide examples of events recorded at the IMS <span class="hlt">infrasound</span> network. Results of this study may help to improve location of small events with observations on <span class="hlt">infrasound</span> stations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/ceap/?cid=stelprdb1186080','USGSPUBS'); return false;" href="http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/ceap/?cid=stelprdb1186080"><span id="translatedtitle">Application of <span class="hlt">ground-truth</span> for classification and quantification of bird movements on migratory bird habitat initiative sites in southwest Louisiana: final report</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Barrow, Wylie C.; Baldwin, Michael J.; Randall, Lori A.; Pitre, John; Dudley, Kyle J.</p> <p>2013-01-01</p> <p>This project was initiated to assess migrating and wintering bird use of lands enrolled in the Natural Resources Conservation Service’s (NRCS) Migratory Bird Habitat Initiative (MBHI). The MBHI program was developed in response to the Deepwater Horizon oil spill in 2010, with the goal of improving/creating habitat for waterbirds affected by the spill. In collaboration with the University of Delaware (UDEL), we used weather surveillance radar data (Sieges 2014), portable marine radar data, thermal infrared images, and visual observations to assess bird use of MBHI easements. Migrating and wintering birds routinely make synchronous flights near dusk (e.g., departure during migration, feeding flights during winter). Weather radars readily detect birds at the onset of these flights and have proven to be useful remote sensing tools for assessing bird-habitat relations during migration and determining the response of wintering waterfowl to wetland restoration (e.g., Wetlands Reserve Program lands). However, <span class="hlt">ground-truthing</span> is required to identify radar echoes to species or species group. We designed a field study to <span class="hlt">ground-truth</span> a larger-scale, weather radar assessment of bird use of MBHI sites in southwest Louisiana. We examined seasonal bird use of MBHI fields in fall, winter, and spring of 2011-2012. To assess diurnal use, we conducted total area surveys of MBHI sites in the afternoon, collecting data on bird species composition, abundance, behavior, and habitat use. In the evenings, we quantified bird activity at the MBHI easements and described flight behavior (i.e., birds landing in, departing from, circling, or flying over the MBHI tract). Our field sampling captured the onset of evening flights and spanned the period of collection of the weather radar data analyzed. Pre- and post-dusk surveys were conducted using a portable radar system and a thermal infrared camera. Landbirds, shorebirds, and wading birds were commonly found on MBHI fields during diurnal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24116535','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24116535"><span id="translatedtitle">Frequency-wavenumber processing for <span class="hlt">infrasound</span> distributed arrays.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Costley, R Daniel; Frazier, W Garth; Dillion, Kevin; Picucci, Jennifer R; Williams, Jay E; McKenna, Mihan H</p> <p>2013-10-01</p> <p>The work described herein discusses the application of a frequency-wavenumber signal processing technique to signals from rectangular <span class="hlt">infrasound</span> arrays for detection and estimation of the direction of travel of <span class="hlt">infrasound</span>. Arrays of 100 sensors were arranged in square configurations with sensor spacing of 2 m. Wind noise data were collected at one site. Synthetic <span class="hlt">infrasound</span> signals were superposed on top of the wind noise to determine the accuracy and sensitivity of the technique with respect to signal-to-noise ratio. The technique was then applied to an impulsive event recorded at a different site. Preliminary results demonstrated the feasibility of this approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2504C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2504C"><span id="translatedtitle">On the fingerprint of ssw events in <span class="hlt">infrasound</span> recordings at IMS stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ceranna, L.; Le Pichon, A.; Pilger, C.; Ross, O.</p> <p>2013-12-01</p> <p>It has been recently shown that sudden stratospheric warming (ssw) events have an impact on the detection of coherent infrasonic waves at dedicated arrays (e.g., Evers & Siegmund, 2009). During ssw events the polar vortex of prevailing stratospheric westerly winds in a winter hemisphere abruptly slows down or even reverses its direction along with an increase of stratospheric temperatures up to several tens of °C. Since <span class="hlt">infrasound</span> arrays are mostly recording signals ducted in stratospheric wave-guides, such antennas are sensitive to changes in effective sound speed profiles - temperature plus wind speed in direction of propagation. Considering continuous infrasonic waves emitted by ocean swell (microbaroms), volcanoes or even anthropogenic <span class="hlt">sources</span> as flares, a gap or a change in the back-azimuth of these detected signals can be observed at arrays. For the compliances with the verification of the Comprehensive Nuclear-Test-Ban Treaty a global network of 60 <span class="hlt">infrasound</span> stations is under construction as a part of the International Monitoring System (IMS); whereas 45 have already been installed. Analysis of waveform data recorded at these stations has demonstrated the capability of <span class="hlt">infrasound</span> as a supplementary tool for remote sensing of the atmosphere. In our study we compare the re-analysis, using PMCC, of more than five years of continuous data at all available sites (see Matoza et al., 2013) with atmospheric descriptions provided by the EMCWF. We present a synoptic view of the fingerprint of ssw events in detection of coherent signals at IMS <span class="hlt">infrasound</span> stations both on northern and southern hemisphere, covering the full latitude range from Antarctica to Greenland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9628C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9628C"><span id="translatedtitle">On the fingerprint of ssw events in <span class="hlt">infrasound</span> recordings at IMS stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ceranna, Lars; Pilger, Christoph; Ross, Ole; Le Pichon, Alexis</p> <p>2013-04-01</p> <p>It has been recently shown that sudden stratospheric warming (ssw) events have an impact on the detection of coherent infrasonic waves at dedicated arrays (e.g., Evers & Siegmund, 2009). During ssw events the polar vortex of prevailing stratospheric westerly winds in a winter hemisphere abruptly slows down or even reverses its direction along with an increase of stratospheric temperatures up to several tens of °C. Since <span class="hlt">infrasound</span> arrays are mostly recording signals ducted in stratospheric wave-guides, such antennas are sensitive to changes in effective sound speed profiles - temperature plus wind speed in direction of propagation. Considering continuous infrasonic waves emitted by ocean swell (microbaroms), volcanoes or even anthropogenic <span class="hlt">sources</span> as flares, a gap or a change in the back-azimuth of these detected signals can be observed at arrays. For the compliances with the verification of the Comprehensive Nuclear-Test-Ban Treaty a global network of 60 <span class="hlt">infrasound</span> stations is under construction as a part of the International Monitoring System (IMS); whereas 45 have already been installed. Analysis of waveform data recorded at these stations has demonstrated the capability of <span class="hlt">infrasound</span> as a supplementary tool for remote sensing of the atmosphere. In our study we compare the re-analysis, using PMCC, of more than five years of continuous data at all available sites (see Matoza et al., 2013) with atmospheric descriptions provided by the EMCWF. We present a synoptic view of the fingerprint of ssw events in detection of coherent signals at IMS <span class="hlt">infrasound</span> stations both on northern and southern hemisphere, covering the full latitude range from Antarctica to Greenland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70034757','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70034757"><span id="translatedtitle"><span class="hlt">Infrasound</span> from the 2007 fissure eruptions of Kīlauea Volcano, Hawai'i</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fee, D.; Garces, M.; Orr, T.; Poland, M.</p> <p>2011-01-01</p> <p>Varied acoustic signals were recorded at Kīlauea Volcano in mid-2007, coincident with dramatic changes in the volcano's activity. Prior to this time period, Pu'u 'Ō'ō crater produced near-continuous infrasonic tremor and was the primary <span class="hlt">source</span> of degassing and lava effusion at Kīlauea. Collapse and draining of Pu'u 'Ō'ō crater in mid-June produced impulsive infrasonic signals and fluctuations in infrasonic tremor. Fissure eruptions on 19 June and 21 July were clearly located spatially and temporally using <span class="hlt">infrasound</span> arrays. The 19 June eruption from a fissure approximately mid-way between Kīlauea's summit and Pu'u 'O'o produced <span class="hlt">infrasound</span> for ~30 minutes-the only observed geophysical signal associated with the fissure opening. The <span class="hlt">infrasound</span> signal from the 21 July eruption just east of Pu'u 'Ō'ō shows a clear azimuthal progression over time, indicative of fissure propagation over 12.9 hours. The total fissure propagation rate is relatively slow at 164 m/hr, although the fissure system ruptured discontinuously. Individual fissure rupture times are estimated using the acoustic data combined with visual observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V52C..08P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V52C..08P"><span id="translatedtitle">Regional Localization with the Hawaii Island <span class="hlt">Infrasound</span> Network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perttu, A. B.; Garces, M. A.; Thelen, W. A.</p> <p>2013-12-01</p> <p>The Big Island of Hawaii is home to an extensive network of <span class="hlt">infrasound</span> arrays, with additional arrays in Maui and Kauai. Four of the six Hawaii arrays are focused on Kilauea volcano. This project examines several methods for estimating <span class="hlt">source</span> location, onset time, duration, and <span class="hlt">source</span> energetics from regional infrasonic signals, with an emphasis on improving signal characterization. Diverse persistent natural and anthropogenic regional <span class="hlt">sources</span> provide a data set for addressing localization with the Hawaii network. Explosions at the Pohakuloa Training Area, rock falls within the Halema'uma'u vent, and a repetitive unknown signal off the coast of Maui supply transient signals with known and unknown locations. In addition, Halema'uma'u and Pu'u O'o vents both produce infrasonic tremor with known locations. Well-constrained signal discrimination and characterization is essential for good location results. This paper presents progress in signal processing, feature extraction, and event association with standardized, self-similar, logarithmic time-frequency multiresolution algorithms. The Infrasonic Energy, Nth Octave (INFERNO) energy estimation suite of Garces (2013) is used in conjunction with the PMCC4 array processing algorithm to extract standardized signal features and parameters for improved regional association, localization, and <span class="hlt">source</span> characterization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..120.8828C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..120.8828C"><span id="translatedtitle">Study of the wind velocity-layered structure in the stratosphere, mesosphere, and lower thermosphere by using <span class="hlt">infrasound</span> probing of the atmosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chunchuzov, I.; Kulichkov, S.; Perepelkin, V.; Popov, O.; Firstov, P.; Assink, J. D.; Marchetti, E.</p> <p>2015-09-01</p> <p>The wind velocity structure in the upper stratosphere, mesosphere, and lower thermosphere (MLT) is studied with the recently developed method of <span class="hlt">infrasound</span> probing of the atmosphere. The method is based on the effect of <span class="hlt">infrasound</span> scattering from highly anisotropic wind velocity and temperature inhomogeneities in the middle and upper atmosphere. The scattered <span class="hlt">infrasound</span> field propagates in the acoustic shadow zones, where it is detected by microbarometers. The vertical profiles of the wind velocity fluctuations in the upper stratosphere (30-52 km) and MLT (90-140 km) are retrieved from the waveforms and travel times of the <span class="hlt">infrasound</span> signals generated by explosive <span class="hlt">sources</span> such as volcanoes and surface explosions. The fine-scale wind-layered structure in these layers was poorly observed until present time by other remote sensing methods, including radars and satellites. It is found that the MLT atmospheric layer (90-102 km) can contain extremely high vertical gradients of the wind velocity, up to 10 m/s per 100 m. The effect of a fine-scale wind velocity structure on the waveforms of <span class="hlt">infrasound</span> signals is studied. The vertical wave number spectra of the retrieved wind velocity fluctuations are obtained for the upper stratosphere. Despite the difference in the locations of the explosive <span class="hlt">sources</span> all the obtained spectra show the existence of high vertical wave number spectral tail with a -3 power law decay. The obtained spectral characteristics of the wind fluctuations are necessary for improvement of gravity wave drag parameterizations for numerical weather forecast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714513Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714513Y"><span id="translatedtitle">ASTERIA: A Balloon-Borne Experiment for <span class="hlt">Infrasound</span> Detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Young, Eliot; Wahl, Kerry; Ballard, Courtney; Daugherty, Emily; Dullea, Connor; Garner, Kyle; Heaney, Martin; Thom, Ian; Von Hendy, Michael; Young, Emma; Diller, Jed; Dischner, Zach; Drob, Douglas; Boslough, Mark; Brown, Peter</p> <p>2015-04-01</p> <p>ASTERIA (Aloft Stratospheric Testbed for Experimental Research on Infrasonic Activity) is a small (<20 kg) payload designed to measure <span class="hlt">infrasound</span> disturbances from a balloon-borne platform at altitudes near 60,000 ft (~20 km). A balloon platform is expected to have two advantages over ground-based <span class="hlt">infrasound</span> stations: a relatively benign wind environment and exposure to higher signal strengths within a stratospheric duct. ASTERIA's nominal sensitivity requirements are to measure waves between 0.1 to 20 Hz at the 0.1 Pa level with signal-to-noise ratios of 5 or better. At the time of this writing, we have tested wave sensors based on the differential pressure transducers recently flown by Bowman et al. (2014) on a NASA/HASP (High Altitude Student Payload); our modified pressure sensor was tested in a NOAA piston-bellows facility in Boulder, CO. Our goal of characterizing 0.1 Pa amplitude waves requires that combined noise <span class="hlt">sources</span> are below the the 0.02 Pa rms level. ASTERIA carries five differential transducers with port inlets arranged a diamond-like pattern (one zenith- and one nadir-facing port, plus three horizontal ports equally spaced in azimuth). Baffling for these sensors is a hybrid of perforated tubing and porous barriers, as described in Hedlin (2014). Other noise <span class="hlt">sources</span> of concern include the electronic amplification of the transducer voltages and low-frequency pressure waves caused by pendulum or twisting modes of the payload. We will report on our plans to characterize and reduce these noise <span class="hlt">sources</span>. The ASTERIA payload is intended to fly on long-duration super-pressure balloons for intervals of ~100 days. We plan to conduct an experiment in the summer or fall of 2015 in which a calibrated disturbance is set off and detected simultaneously from stratospheric ASTERIA payloads and ground-based stations. References: 1) Bowman et al. 2014, "Balloons over Volcanoes Scientific Report," HASP 2014 final report. 2) Hedlin 2003, "Infrasonic Wind-noise Reduction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010BGeo....7.2531K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010BGeo....7.2531K"><span id="translatedtitle">Towards <span class="hlt">ground-truthing</span> of spaceborne estimates of above-ground life biomass and leaf area index in tropical rain forests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Köhler, P.; Huth, A.</p> <p>2010-08-01</p> <p>The canopy height h of forests is a key variable which can be obtained using air- or spaceborne remote sensing techniques such as radar interferometry or LIDAR. If new allometric relationships between canopy height and the biomass stored in the vegetation can be established this would offer the possibility for a global monitoring of the above-ground carbon content on land. In the absence of adequate field data we use simulation results of a tropical rain forest growth model to propose what degree of information might be generated from canopy height and thus to enable <span class="hlt">ground-truthing</span> of potential future satellite observations. We here analyse the correlation between canopy height in a tropical rain forest with other structural characteristics, such as above-ground life biomass (AGB) (and thus carbon content of vegetation) and leaf area index (LAI) and identify how correlation and uncertainty vary for two different spatial scales. The process-based forest growth model FORMIND2.0 was applied to simulate (a) undisturbed forest growth and (b) a wide range of possible disturbance regimes typically for local tree logging conditions for a tropical rain forest site on Borneo (Sabah, Malaysia) in South-East Asia. In both undisturbed and disturbed forests AGB can be expressed as a power-law function of canopy height h (AGB = a · hb) with an r2 ~ 60% if data are analysed in a spatial resolution of 20 m × 20 m (0.04 ha, also called plot size). The correlation coefficient of the regression is becoming significant better in the disturbed forest sites (r2 = 91%) if data are analysed hectare wide. There seems to exist no functional dependency between LAI and canopy height, but there is also a linear correlation (r2 ~ 60%) between AGB and the area fraction of gaps in which the canopy is highly disturbed. A reasonable agreement of our results with observations is obtained from a comparison of the simulations with permanent sampling plot (PSP) data from the same region and with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNS43B..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNS43B..02P"><span id="translatedtitle">Archaeogeophysical data acquisition and analysis at Tel Burna, Israel: a valuable opportunity for ongoing <span class="hlt">ground-truth</span> investigation and collaboration (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pincus, J. A.</p> <p>2013-12-01</p> <p>, acquired in a zigzag east-west direction, proceeding south. The area extended from the present excavation border to the north and east. The following paper will discuss the method of data acquisition, post-processing, and analysis of the results. The final conclusions of the survey show a continuation of several key walls to the east, a valuable sub-surface tracing of the limestone bedrock, and the limit to which the archaeological material is present spatially in Area B to the north. These results play a major role in determining where to focus excavation efforts in the 2014 excavation season. This unique collaboration with the archaeological team and ongoing opportunity for archaeological <span class="hlt">ground-truthing</span> will be documented and published as the site develops. As there is a limited presence of such data within the corpus of published archaeogeophysical research, we look forward to further investigations at the site in the coming years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4832704Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4832704Y"><span id="translatedtitle">Balloon-Borne <span class="hlt">Infrasound</span> Detection of Energetic Bolide Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Young, Eliot F.; Ballard, Courtney; Klein, Viliam; Bowman, Daniel; Boslough, Mark</p> <p>2016-10-01</p> <p><span class="hlt">Infrasound</span> is usually defined as sound waves below 20 Hz, the nominal limit of human hearing. <span class="hlt">Infrasound</span> waves propagate over vast distances through the Earth's atmosphere: the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization) has 48 installed <span class="hlt">infrasound</span>-sensing stations around the world to detect nuclear detonations and other disturbances. In February 2013, several CTBTO <span class="hlt">infrasound</span> stations detected <span class="hlt">infrasound</span> signals from a large bolide that exploded over Chelyabinsk, Russia. Some stations recorded signals that had circumnavigated the Earth, over a day after the original event. The goal of this project is to improve upon the sensitivity of the CTBTO network by putting microphones on small, long-duration super-pressure balloons, with the overarching goal of studying the small end of the NEO population by using the Earth's atmosphere as a witness plate.A balloon-borne <span class="hlt">infrasound</span> sensor is expected to have two advantages over ground-based stations: a lack of wind noise and a concentration of <span class="hlt">infrasound</span> energy in the "stratospheric duct" between roughly 5 - 50 km altitude. To test these advantages, we have built a small balloon payload with five calibrated microphones. We plan to fly this payload on a NASA high-altitude balloon from Ft Sumner, NM in August 2016. We have arranged for three large explosions to take place in Socorro, NM while the balloon is aloft to assess the sensitivity of balloon-borne vs. ground-based <span class="hlt">infrasound</span> sensors. We will report on the results from this test flight and the prospects for detecting/characterizing small bolides in the stratosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AAS...21540503P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AAS...21540503P"><span id="translatedtitle">Can Gamma Ray Bursts be Detected Using <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmer, Jahi; McGruder, C.; Hetzer, C.</p> <p>2010-01-01</p> <p>CAN GAMMA RAY BURST BE DETECTED USING <span class="hlt">INFRASOUND</span> <span class="hlt">Infrasound</span> has been used to detect sonic disturbances in earth's atmosphere caused by terrestrial events such as earthquakes and lightning. It may be possible to detect celestial events such as Gamma Ray Bursts (GRB's) through this method. We have searched for GRB's which are known to have caused ionospheric disturbances in infrasonic data. None of the selected GRB's were found to be associated with infrasonic disturbances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH23D1550M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH23D1550M"><span id="translatedtitle">IDC <span class="hlt">infrasound</span> analysis of the 15 February 2013 Chelyabinsk fireball</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mialle, P.; Bittner, P.; Brown, D.; Polich, P.; Gore, J.</p> <p>2013-12-01</p> <p>The first atmospheric event built only from <span class="hlt">infrasound</span> arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 45 <span class="hlt">infrasound</span> stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. In early 2010 the IDC began routine automatic processing of <span class="hlt">infrasound</span> data reviewed by interactive analysis; the detected and located events are now systematically included in the REB. This study focuses on a major infragenic event that occurred in February 2013 and was thoroughly analyzed at the IDC. On February 15 a fireball in the Chelyabinsk region (Russia) was observed generating <span class="hlt">infrasound</span> waves that were recorded by 20 <span class="hlt">infrasound</span> IMS stations globally spread from Greenland to Antarctica. Chronology of the analysis and specificities of this event will be introduced. This event is the largest ever recorded by the <span class="hlt">infrasound</span> component of the IMS network. Related seismic observations were also found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V23C4812M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4812M"><span id="translatedtitle">Large Bubble Growth Quantified By Video and <span class="hlt">Infrasound</span> at Mount Erebus, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, A. J. C.; Johnson, J. B.</p> <p>2014-12-01</p> <p>Mount Erebus lava lake eruptions exhibit many characteristic strombolian attributes including the ascent of a large gas slug(s) through the magma column followed by its expansion and bursting at the surface. Strombolian explosions correspond to pressurized large (>10 m radius) bubbles, which distend the lava lake surface before bursting within a few tenths of a second thus generating infrasonic impulses followed by decaying oscillations. We quantify the dynamics of bubble evolution using <span class="hlt">infrasound</span> and time synchronized video data recording at ~30 FPS. Video footage is used to synthesize pressure time series during eruptions assuming a simple acoustic <span class="hlt">source</span>. These synthetic pressure records are directly compared to <span class="hlt">infrasound</span> pressure records collected at two sites located ~300 m from the lava lake <span class="hlt">source</span>. A scaled relationship exists between <span class="hlt">infrasound</span> and video derived pressures where video generally overestimates the volumetrically expanding <span class="hlt">source</span>. This scaling is due to the image processing routine, which tracks and models the ejection of ballistics during eruption as an expanding hemisphere and not necessarily the expansion of a translucent gas <span class="hlt">source</span> that is not directly visible with optical imagery. Using both data sets, we describe Erebus lava lake eruptions in three phases with smooth distension of spherical cap (P1), followed by membrane fragmentation and violent gas expulsion (P2) and finally a contraction of the volumetric gas <span class="hlt">source</span> due to an initial over-expansion followed by re-equilibration. (P3). Specifically, P3 is identified by decaying oscillations of the pressure record which has been well modeled in laboratory experiments but never described at Erebus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25920837','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25920837"><span id="translatedtitle">The stratospheric arrival pair in <span class="hlt">infrasound</span> propagation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Waxler, Roger; Evers, Läslo G; Assink, Jelle; Blom, Phillip</p> <p>2015-04-01</p> <p>The ideal case of a deep and well-formed stratospheric duct for long range <span class="hlt">infrasound</span> propagation in the absence of tropospheric ducting is considered. A canonical form, that of a pair of arrivals, for ground returns of impulsive signals in a stratospheric duct is determined. The canonical form is derived from the geometrical acoustics approximation, and is validated and extended through full wave modeling. The full caustic structure of the field of ray paths is found and used to determine phase relations between the contributions to the wavetrain from different propagation paths. Finally, comparison with data collected from the 2005 fuel gas depot explosion in Buncefield, England is made. The correspondence between the theoretical results and the observations is shown to be quite good.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRD..117.5121L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRD..117.5121L"><span id="translatedtitle">Incorporating numerical modeling into estimates of the detection capability of the IMS <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Ceranna, L.; Vergoz, J.</p> <p>2012-03-01</p> <p>To monitor compliance with the Comprehensive Nuclear-Test ban Treaty (CTBT), a dedicated International Monitoring System (IMS) is being deployed. Recent global scale observations recorded by this network confirm that its detection capability is highly variable in space and time. Previous studies estimated the radiated <span class="hlt">source</span> energy from remote observations using empirical yield-scaling relations which account for the along-path stratospheric winds. Although the empirical wind correction reduces the variance in the explosive energy versus pressure relationship, strong variability remains in the yield estimate. Today, numerical modeling techniques provide a basis to better understand the role of different factors describing the <span class="hlt">source</span> and the atmosphere that influence propagation predictions. In this study, the effects of the <span class="hlt">source</span> frequency and the stratospheric wind speed are simulated. In order to characterize fine-scale atmospheric structures which are excluded from the current atmospheric specifications, model predictions are further enhanced by the addition of perturbation terms. A theoretical attenuation relation is thus developed from massive numerical simulations using the Parabolic Equation method. Compared with previous studies, our approach provides a more realistic physical description of long-range <span class="hlt">infrasound</span> propagation. We obtain a new relation combining a near-field and a far-field term, which account for the effects of both geometrical spreading and absorption. In the context of the future verification of the CTBT, the derived attenuation relation quantifies the spatial and temporal variability of the IMS <span class="hlt">infrasound</span> network performance in higher resolution, and will be helpful for the design and prioritizing maintenance of any arbitrary <span class="hlt">infrasound</span> monitoring network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090009968','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090009968"><span id="translatedtitle">Sub-Surface Windscreen for the Measurement of Outdoor <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shams, Qamar A.; Burkett, Cecil G., Jr.; Comeaux, Toby; Zuckerwar, Allan J.; Weistroffer, George R.</p> <p>2008-01-01</p> <p>A windscreen has been developed that features two advantages favorable for the measurement of outdoor <span class="hlt">infrasound</span>. First, the sub-surface location, with the top of the windscreen flush with the ground surface, minimizes the mean velocity of the impinging wind. Secondly, the windscreen material (closed cell polyurethane foam) has a sufficiently low acoustic impedance (222 times that of air) and wall thickness (0.0127 m) to provide a transmission coefficient of nearly unity over the infrasonic frequency range (0-20 Hz). The windscreen, a tightly-sealed box having internal dimensions of 0.3048 x 0.3048 x 0.3556 m, contains a microphone, preamplifier, and a cable feed thru to an external power supply. Provisions are made for rain drainage and seismic isolation. A three-element array, configured as an equilateral triangle with 30.48 m spacing and operating continuously in the field, periodically receives highly coherent signals attributed to emissions from atmospheric turbulence. The time delays between infrasonic signals received at the microphones permit determination of the bearing and elevation of the <span class="hlt">sources</span>, which correlate well with locations of pilot reports (PIREPS) within a 320 km radius about the array. The test results are interpreted to yield spectral information on infrasonic emissions from clear air turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAP...120l3109D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAP...120l3109D"><span id="translatedtitle">Detection of atmospheric <span class="hlt">infrasound</span> with a ring laser interferometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunn, Robert W.; Meredith, John A.; Lamb, Angela B.; Kessler, Elijah G.</p> <p>2016-09-01</p> <p>In this paper, the results from using a large active ring laser interferometer as an <span class="hlt">infrasound</span> detector are presented. On April 27, 2014, an EF4 tornado struck Central Arkansas and passed within 21 km of the ring laser interferometer. The tornado resulted in 16 fatalities and millions of dollars in damage. Using the ring laser to study the tornado <span class="hlt">infrasound</span> produced results that qualitatively agree with several findings from a long-term study of weather generated <span class="hlt">infrasound</span> by the National Oceanic and Atmospheric Administration. A Fast Fourier Transform of the ring laser output revealed a coherent frequency of approximately 0.94 Hz that lasted during the life of the storm. The 0.94 Hz frequency was initially observed 30 min before the funnel was reported on the ground. <span class="hlt">Infrasound</span> signatures from four separate tornadoes are presented. In each case, coherent <span class="hlt">infrasound</span> was detected at least 30 min before the tornado was reported on the ground. Examples of the detection of distant coherent acoustic-gravity waves from volcanoes and typhoons are also presented. In addition, buoyancy waves were recorded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15..476T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15..476T"><span id="translatedtitle">Remote <span class="hlt">infrasound</span> monitoring of Mount Etna: Observed and predicted network detection capability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tailpied, Dorianne; Le Pichon, Alexis; Marchetti, Emanuele; Ripepe, Maurizio; Kallel, Mohamed; Ceranna, Lars</p> <p>2013-04-01</p> <p>Volcanic eruptions are unique and valuable calibrating <span class="hlt">sources</span> of infrasonic waves worldwide detected by the International Monitoring System (IMS) of the Comprehensive nuclear Test Ban Treaty Organization (CTBTO) and other experimental stations. Building a comprehensive database of volcanic signals is likely to help the scientific community to better characterize eruptive sequences and may help to prevent eruption disasters while on a longer term mitigate the impact of ash clouds on aviation. In this study, we assess the detection capability of the existing <span class="hlt">infrasound</span> network to remotely detect the eruptive activity of Mount Etna with a high level of confidence, and predict the performance of the future ARISE infrastructure network (Atmospheric dynamics InfraStructure in Europe). This well-instrumented volcano offers a unique opportunity to validate attenuation models using multiyear near-and-far field recordings. The seasonal trend in the number of detections of Etna at the IS48 IMS station (Tunisia) is correlated to fine temporal fluctuations of the stratospheric waveguide structure. The modeling results are consistent with the observed detection capability of the existing network. In summer, during the downwind season, a minimum detectable amplitude of ~10 Pa at a reference distance of 1 km from the <span class="hlt">source</span> is predicted. In winter, when upwind propagation occurs, detection thresholds increase up to ~100 Pa. When adding four experimental arrays to the existing IMS network, thresholds decrease down to ~20 Pa in winter. The simulation results provide here a realistic description of long-range <span class="hlt">infrasound</span> propagation and allow predicting fine temporal fluctuations in the European <span class="hlt">infrasound</span> network performance with potential application for civil aviation safety.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1004382','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1004382"><span id="translatedtitle">Evaluation of Inter-Mountain Labs <span class="hlt">infrasound</span> sensors : July 2007.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hart, Darren M.</p> <p>2007-10-01</p> <p>Sandia National Laboratories has tested and evaluated three Inter Mountain Labs <span class="hlt">infrasound</span> sensors. The test results included in this report were in response to static and tonal-dynamic input signals. Most test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters; others were designed by Sandia specifically for <span class="hlt">infrasound</span> application evaluation and for supplementary criteria not addressed in the IEEE standards. The objective of this work was to evaluate the overall technical performance of the Inter Mountain Labs (IML) <span class="hlt">infrasound</span> sensor model SS. The results of this evaluation were only compared to relevant noise models; due to a lack of manufactures documentation notes on the sensors under test prior to testing. The tests selected for this system were chosen to demonstrate different performance aspects of the components under test.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20329823','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20329823"><span id="translatedtitle">Detecting blast-induced <span class="hlt">infrasound</span> in wind noise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Howard, Wheeler B; Dillion, Kevin L; Shields, F Douglas</p> <p>2010-03-01</p> <p>Current efforts seek to monitor and investigate such naturally occurring events as volcanic eruptions, hurricanes, bolides entering the atmosphere, earthquakes, and tsunamis by the <span class="hlt">infrasound</span> they generate. Often, detection of the <span class="hlt">infrasound</span> signal is limited by the masking effect of wind noise. This paper describes the use of a distributed array to detect <span class="hlt">infrasound</span> signals from four atmospheric detonations at White Sands Missile Range in New Mexico, USA in 2006. Three of the blasts occurred during times of low wind noise and were easily observed with array processing techniques. One blast was obscured by high wind conditions. The results of signal processing are presented that allowed localization of the blast-induced signals in the presence of wind noise in the array response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20649183','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20649183"><span id="translatedtitle">Tracking near-surface atmospheric conditions using an <span class="hlt">infrasound</span> network.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marcillo, O; Johnson, J B</p> <p>2010-07-01</p> <p>Continuous volcanic <span class="hlt">infrasound</span> signal was recorded on a three-microphone network at Kilauea in July 2008 and inverted for near-surface horizontal winds. Inter-station phase delays, determined by signal cross-correlation, vary by up to 4% and are attributable to variable atmospheric conditions. The results suggest two predominant weather regimes during the study period: (1) 6-9 m/s easterly trade winds and (2) lower-intensity 2-5 m/s mountain breezes from Mauna Loa. The results demonstrate the potential of using <span class="hlt">infrasound</span> for tracking local averaged meteorological conditions, which has implications for modeling plume dispersal and quantifying gas flux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S41B4487K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S41B4487K"><span id="translatedtitle">Seismo-acoustic Signals Recorded at KSIAR, the <span class="hlt">Infrasound</span> Array Installed at PS31</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, T. S.; Che, I. Y.; Jeon, J. S.; Chi, H. C.; Kang, I. B.</p> <p>2014-12-01</p> <p>One of International Monitoring System (IMS)'s primary seismic stations, PS31, called Korea Seismic Research Station (KSRS), was installed around Wonju, Korea in 1970s. It has been operated by US Air Force Technical Applications Center (AFTAC) for more than 40 years. KSRS is composed of 26 seismic sensors including 19 short period, 6 long period and 1 broad band seismometers. The 19 short period sensors were used to build an array with a 10-km aperture while the 6 long period sensors were used for a relatively long period array with a 40-km aperture. After KSRS was certified as an IMS station in 2006 by Comprehensive Nuclear Test Ban Treaty Organization (CTBTO), Korea Institute of Geoscience and Mineral Resources (KIGAM) which is the Korea National Data Center started to take over responsibilities on the operation and maintenance of KSRS from AFTAC. In April of 2014, KIGAM installed an <span class="hlt">infrasound</span> array, KSIAR, on the existing four short period seismic stations of KSRS, the sites KS05, KS06, KS07 and KS16. The collocated KSIAR changed KSRS from a seismic array into a seismo-acoustic array. The aperture of KSIAR is 3.3 km. KSIAR also has a 100-m small aperture <span class="hlt">infrasound</span> array at KS07. The <span class="hlt">infrasound</span> data from KSIAR except that from the site KS06 is being transmitted in real time to KIGAM with VPN and internet line. An initial analysis on seismo-acoustic signals originated from local and regional distance ranges has been performed since May 2014. The analysis with the utilization of an array process called Progressive Multi-Channel Correlation (PMCC) detected seismo-acoustic signals caused by various <span class="hlt">sources</span> including small explosions in relation to constructing local tunnels and roads. Some of them were not found in the list of automatic bulletin of KIGAM. The seismo-acoustic signals recorded by KSIAR are supplying a useful information for discriminating local and regional man-made events from natural events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.tmp..412T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.tmp..412T"><span id="translatedtitle">Assessing and optimizing the performance of <span class="hlt">infrasound</span> networks to monitor volcanic eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tailpied, Dorianne; Pichon, Alexis Le; Marchetti, Emanuele; Assink, Jelle; Vergniolle, Sylvie</p> <p>2016-10-01</p> <p>We propose a numerical modeling technique based on a frequency-dependent attenuation relation to assess, quantify and optimize the performance of any arbitrary <span class="hlt">infrasound</span> network to monitor explosive <span class="hlt">sources</span> such as volcanic eruptions. Simulations are further enhanced by including realistic <span class="hlt">sources</span> and propagation effects. We apply our approach to both hemispheres by considering the Euro-Mediterranean and the Eastern Australian regions. In these regions, we use quasi-permanent <span class="hlt">infrasound</span> signals from Mt. Etna recorded in Tunisia and from Mt. Yasur recorded in New Caledonia. These well-instrumented volcanoes offer a unique opportunity to validate our attenuation model. In particular, accurate comparisons between near and far-field recordings demonstrate the potential of the proposed methodology to remotely monitor volcanoes. A good agreement is found between modeled and observed results, especially when incorporating representative 10 m/s wind perturbations in the atmospheric specifications according to previous campaign measurements. To optimize the network layout in order to ensure the best monitoring of the volcanoes, we proceed through a grid search to find optimum locations of an additional array. We show that adding one array at an appropriate location in both regions under study could significantly improve detections half of the year. The application of the proposed methodology can provide in near real-time a realistic confidence level of volcanic eruption detections, useful to mitigate the risk of aircrafts encountering volcanic ash.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH21D..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH21D..06P"><span id="translatedtitle">2013 Russian Fireball Largest Ever Detected by CTBTO <span class="hlt">Infrasound</span> Sensors (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, C.; Ceranna, L.; Le Pichon, A.; Herry, P.; Brachet, N.; Mialle, P.; Brown, D.</p> <p>2013-12-01</p> <p>On 15 February 2013 at 03h20 UT, a large Earth impacting fireball disintegrated over the Ural Mountains near the city of Chelyabinsk. The bolide produced shock waves that blew out windows, injured hundreds of people and damaged buildings in many surrounding cities. Infrasonic waves generated by the explosion propagated over very long distances. The event was globally detected by 20 arrays part of the 44 operating <span class="hlt">infrasound</span> IMS (International Monitoring System) stations of the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). This fireball event provides a prominent milestone for studying, in detail, <span class="hlt">infrasound</span> propagation traveling twice around the globe for almost two days at distances larger than 80000 km. Therefore, its analysis offers a unique opportunity to calibrate detection and location methods and evaluate the global performance of the IMS network. The presentation will provide an overview on the global recordings and analyses. Moreover, in order to explain the detection capability of the overall operating IMS network, range-dependent propagation modeling considering both a point-like explosive <span class="hlt">source</span> and a line <span class="hlt">source</span> is performed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.208..437T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.208..437T"><span id="translatedtitle">Assessing and optimizing the performance of <span class="hlt">infrasound</span> networks to monitor volcanic eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tailpied, Dorianne; Le Pichon, Alexis; Marchetti, Emanuele; Assink, Jelle; Vergniolle, Sylvie</p> <p>2017-01-01</p> <p>We propose a numerical modeling technique based on a frequency-dependent attenuation relation to assess, quantify and optimize the performance of any arbitrary <span class="hlt">infrasound</span> network to monitor explosive <span class="hlt">sources</span> such as volcanic eruptions. Simulations are further enhanced by including realistic <span class="hlt">sources</span> and propagation effects. We apply our approach to both hemispheres by considering the Euro-Mediterranean and the Eastern Australian regions. In these regions, we use quasi-permanent <span class="hlt">infrasound</span> signals from Mt. Etna recorded in Tunisia and from Mt. Yasur recorded in New Caledonia. These well-instrumented volcanoes offer a unique opportunity to validate our attenuation model. In particular, accurate comparisons between near- and far-field recordings demonstrate the potential of the proposed methodology to remotely monitor volcanoes. A good agreement is found between modeled and observed results, especially when incorporating representative 10 m s-1 wind perturbations in the atmospheric specifications according to previous campaign measurements. To optimize the network layout in order to ensure the best monitoring of the volcanoes, we proceed through a grid search to find optimum locations of an additional array. We show that adding one array at an appropriate location in both regions under study could significantly improve detections half of the year. The application of the proposed methodology can provide in near real-time a realistic confidence level of volcanic eruption detections, useful to mitigate the risk of aircrafts encountering volcanic ash.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ASAJ..112.2380S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ASAJ..112.2380S"><span id="translatedtitle">Determination of uncertainty in the estimation of velocity and direction-of-arrival for atmospheric <span class="hlt">infrasound</span> signals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Szuberla, Curt A. L.; Olson, John V.</p> <p>2002-11-01</p> <p>Upon the detection of an atmospheric <span class="hlt">infrasound</span> signal, the problem of precisely estimating the signal's velocity (v) and direction-of-arrival (theta) arises. Multiple <span class="hlt">sources</span>, multipath, medium anisotropies, and other propagation effects can all degrade precision; however, uncertainty in the estimates of v and theta is fundamentally governed by array geometry and the estimation of time delays across the array. Typically, as in the Comprehensive Test Ban Treaty Organzation Provisional Technical Secretariat (CTBTO/PTS) specification for data from <span class="hlt">infrasound</span> stations, the Cramer-Rao lower bound is invoked to ascertain the uncertainties associated with v and theta. As this theoretical lower limit is often overly conservative, a more general, and useful, approach to calculate these uncertainties is developed. Examples of this uncertainty determination are presented for typical impulsive and continuous atmospheric <span class="hlt">infrasound</span> signals received at arrays in Windless Bight, Antarctica and Fairbanks, Alaska. Since the determination of v and theta serves as primary input to any propogation model, it is critical that uncertainties in these estimates be addressed. As an extension of this work, an interactive graphical tool is constructed to assist in the analysis of performance bounds for arbitrary array geometries and signal characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMNH51A1796H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMNH51A1796H"><span id="translatedtitle">Using <span class="hlt">Infrasound</span> and Machine Learning for Monitoring Plinian Volcanic Eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ham, F. M.; Iyengar, I.; Hambebo, B. M.; Garces, M. A.; Deaton, J.; Perttu, A.; Williams, B.</p> <p>2012-12-01</p> <p>Large plinian volcanic eruptions can inject a substantial amount of volcanic gas and ash into the stratosphere. This can present a severe hazard to commercial air traffic. A hazardous Icelandic volcanic ash-eruption was reported on April 14, 2010. This resulted in London's aviation authority to issue an alert that an ash plume was moving from an eruption in Iceland towards northwestern Europe. This eruption resulted in the closure of large areas of European airspace. Large plinian volcanic eruptions radiate infrasonic signals that can be detected by a global <span class="hlt">infrasound</span> array network. To reduce potential hazards for commercial aviation from volcanic ash, these <span class="hlt">infrasound</span> sensor arrays have been used to detect infrasonic signals released by sustained volcanic eruptions that can inject ash into the stratosphere at aircraft's cruising altitudes, typically in the order of 10km. A system that is capable of near, real-time eruption detection and discrimination of plinian eruptions from other natural phenomena that can produce <span class="hlt">infrasound</span> with overlapping spectral content (0.01 to 0.1 Hz) is highly desirable to provide ash-monitoring for commercial aviation. In the initial study, cepstral features were extracted from plinian volcanic eruptions and mountain associated wave <span class="hlt">infrasound</span> signals. These feature vectors were then used to train and test a two-module neural network classifier (radial basis function neural networks were used for each module). One module is dedicated to classifying plinian volcanic eruptions, the other mountain associated waves. Using an independent validation dataset, the classifier's correct classification rate was 91.5%. Then a different two-module neural network classifier was designed to discriminate between plinian volcanic eruptions and a collection of <span class="hlt">infrasound</span> signals that are not-of-interest but have spectral content that overlaps with the volcano signals. One module is again dedicated to classifying plinian volcanic eruptions, however, in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.7720T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.7720T"><span id="translatedtitle">Kernel-based machine learning techniques for <span class="hlt">infrasound</span> signal classification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tuma, Matthias; Igel, Christian; Mialle, Pierrick</p> <p>2014-05-01</p> <p><span class="hlt">Infrasound</span> monitoring is one of four remote sensing technologies continuously employed by the CTBTO Preparatory Commission. The CTBTO's <span class="hlt">infrasound</span> network is designed to monitor the Earth for potential evidence of atmospheric or shallow underground nuclear explosions. Upon completion, it will comprise 60 <span class="hlt">infrasound</span> array stations distributed around the globe, of which 47 were certified in January 2014. Three stages can be identified in CTBTO <span class="hlt">infrasound</span> data processing: automated processing at the level of single array stations, automated processing at the level of the overall global network, and interactive review by human analysts. At station level, the cross correlation-based PMCC algorithm is used for initial detection of coherent wavefronts. It produces estimates for trace velocity and azimuth of incoming wavefronts, as well as other descriptive features characterizing a signal. Detected arrivals are then categorized into potentially treaty-relevant versus noise-type signals by a rule-based expert system. This corresponds to a binary classification task at the level of station processing. In addition, incoming signals may be grouped according to their travel path in the atmosphere. The present work investigates automatic classification of <span class="hlt">infrasound</span> arrivals by kernel-based pattern recognition methods. It aims to explore the potential of state-of-the-art machine learning methods vis-a-vis the current rule-based and task-tailored expert system. To this purpose, we first address the compilation of a representative, labeled reference benchmark dataset as a prerequisite for both classifier training and evaluation. Data representation is based on features extracted by the CTBTO's PMCC algorithm. As classifiers, we employ support vector machines (SVMs) in a supervised learning setting. Different SVM kernel functions are used and adapted through different hyperparameter optimization routines. The resulting performance is compared to several baseline classifiers. All</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S54B..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S54B..06B"><span id="translatedtitle">High Altitude <span class="hlt">Infrasound</span> Measurements using Balloon-Borne Arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bowman, D. C.; Johnson, C. S.; Gupta, R. A.; Anderson, J.; Lees, J. M.; Drob, D. P.; Phillips, D.</p> <p>2015-12-01</p> <p>For the last fifty years, almost all <span class="hlt">infrasound</span> sensors have been located on the Earth's surface. A few experiments consisting of microphones on poles and tethered aerostats comprise the remainder. Such surface and near-surface arrays likely do not capture the full diversity of acoustic signals in the atmosphere. Here, we describe results from a balloon mounted <span class="hlt">infrasound</span> array that reached altitudes of up to 38 km (the middle stratosphere). The balloon drifted at the ambient wind speed, resulting in a near total reduction in wind noise. Signals consistent with tropospheric turbulence were detected. A spectral peak in the ocean microbarom range (0.12 - 0.35 Hz) was present on balloon-mounted sensors but not on static <span class="hlt">infrasound</span> stations near the flight path. A strong 18 Hz signal, possibly related to building ventilation systems, was observed in the stratosphere. A wide variety of other narrow band acoustic signals of uncertain provenance were present throughout the flight, but were absent in simultaneous recordings from nearby ground stations. Similar phenomena were present in spectrograms from the last balloon <span class="hlt">infrasound</span> campaign in the 1960s. Our results suggest that the infrasonic wave field in the stratosphere is very different from that which is readily detectable on surface stations. This has implications for modeling acoustic energy transfer between the lower and upper atmosphere as well as the detection of novel acoustic signals that never reach the ground. Our work provides valuable constraints on a proposed mission to detect earthquakes on Venus using balloon-borne <span class="hlt">infrasound</span> sensors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.2523P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.2523P"><span id="translatedtitle">CTBT <span class="hlt">infrasound</span> network performance to detect the 2013 Russian fireball event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; Le Pichon, Alexis; Mialle, Pierrick; Garcés, Milton A.</p> <p>2015-04-01</p> <p>The explosive fragmentation of the 2013 Chelyabinsk meteorite generated a large airburst with an equivalent yield of 500 kT TNT. It is the most energetic event recorded by the <span class="hlt">infrasound</span> component of the Comprehensive Nuclear-Test-Ban Treaty-International Monitoring System (CTBT-IMS), globally detected by 20 out of 42 operational stations. This study performs a station-by-station estimation of the IMS detection capability to explain <span class="hlt">infrasound</span> detections and nondetections from short to long distances, using the Chelyabinsk meteorite as global reference event. Investigated parameters influencing the detection capability are the directivity of the line <span class="hlt">source</span> signal, the ducting of acoustic energy, and the individual noise conditions at each station. Findings include a clear detection preference for stations perpendicular to the meteorite trajectory, even over large distances. Only a weak influence of stratospheric ducting is observed for this low-frequency case. Furthermore, a strong dependence on the diurnal variability of background noise levels at each station is observed, favoring nocturnal detections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MeScT..27b5018H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MeScT..27b5018H"><span id="translatedtitle">A dedicated pistonphone for absolute calibration of <span class="hlt">infrasound</span> sensors at very low frequencies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Wen; He, Longbiao; Zhang, Fan; Rong, Zuochao; Jia, Shushi</p> <p>2016-02-01</p> <p>Aimed at the absolute calibration of <span class="hlt">infrasound</span> sensors at very low frequencies, an upgraded and improved infrasonic pistonphone has been developed. The pistonphone was designed such that a very narrow clearance between the piston and its guide was realized based on an automatically-centered clearance-sealing structure, and a large volume rigid-walled chamber was also adopted, which improved the leakage time-constant of the chamber. A composite feedback control system was applied to the electromagnetic vibrator to control the precise motion of the piston. Performance tests and uncertainty analysis show that the leakage time-constant is so large, and the distortion of the sound pressure is so small, that the pistonphone can be used as a standard <span class="hlt">infrasound</span> <span class="hlt">source</span> in the frequency range from 0.001 Hz to 20 Hz. The low frequency property of the pistonphone has been verified through calibrating low frequency microphones. Comparison tests with the reciprocity method have shown that the pressure sensitivities from the pistonphone are not only reliable at common frequencies but also have smaller uncertainties at low frequencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..113.2246S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..113.2246S"><span id="translatedtitle">The use of an <span class="hlt">infrasound</span> microphone array to study wind noise spectra and correlation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shields, F. Douglas; Talmadge, Carrick</p> <p>2003-04-01</p> <p>A three dimensional array of <span class="hlt">infrasound</span> sensors of original design has been constructed and used to study wind generated pressure signals in the frequency range from 0.1 to 100 Hz. The ten sensors in each arm of the array are 2 feet apart. An ultrasonic anemometer ten feet off the ground was used to make simultaneous measurements of the three components of the wind velocity. Several sets of data have been taken in open fields with different ground cover. The data have been spectrally analyzed and, over a limited frequency range, the velocity and pressure variations found to obey the 5/3 and 7/3 power law that is expected for the inertial range. A study has also been made of the dependence of the correlation between the pressure signals and the sensor separation. The coherence of the pressure signals indicates that the convection velocity is nearly independent of frequency, and the correlation has an exponentially decaying sinusoidal dependence on the sensor separation. The array has also been used successfully to localize <span class="hlt">infrasound</span> <span class="hlt">sources</span>. [Work supported by the U.S. Army Armament Research Development and Engineering Center.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4821621K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4821621K"><span id="translatedtitle"><span class="hlt">Infrasound</span> as a Geophysical Probe Using Earth as a Venus Analog</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Komjathy, Attila; Cutts, James; Pauken, Michael; Kedar, Sharon; Smrekar, Suzanne</p> <p>2016-10-01</p> <p>JPL is in a process of developing an instrument to measure seismic activity on Venus by detecting infrasonic waves in the atmosphere. The overall objective of this research is to demonstrate the feasibility of using sensitive barometers to detect infrasonic signals from seismic and explosive activity on Venus from a balloon platform. Because of Venus' dense atmosphere, seismic signatures from even small quakes (magnitude ~3) are effectively coupled into the atmosphere. The seismic signals are known to couple about 60 times more efficiently into the atmosphere on Venus than on Earth. It was found that almost no attenuation below 80 km on Venus for frequency less than 1Hz. Whereas wind noise is a major <span class="hlt">source</span> of background noise for terrestrial infrasonic arrays, it is expected that a balloon platform, which drifts with winds will be capable of very sensitive measurements with low noise.In our research we will demonstrate and apply techniques for discriminating upward propagating waves from a seismic event by making measurements with two or more infrasonic sensors using very sensitive barometers on a tether deployed from the balloon in a series of earth-based tests. We will first demonstrate and validate the technique using an artificial <span class="hlt">infrasound</span> <span class="hlt">source</span> in a deployment from a hot air balloon on Earth and then extend it with longer duration flights in the troposphere and stratosphere.We will report results on the first flight experiment that will focus on using the barometer instruments on a tethered helium-filled balloon. The balloon flight will be conducted in the vicinity of a known seismic <span class="hlt">source</span> generated by a seismic hammer. Earlier tests conducted by Sandia National Laboratory demonstrated that this is a highly reproducible <span class="hlt">source</span> of seismic and acoustic energy using <span class="hlt">infrasound</span> sensors. The results of the experiments are intended to validate the two-barometer signal processing approach using a well-characterized point signal <span class="hlt">source</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1612014D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1612014D"><span id="translatedtitle">Looking for a correlation between <span class="hlt">infrasound</span> and volcanic gas in strombolian explosions by using high resolution UV spectroscopy and thermal imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Delle Donne, Dario; Tamburello, Giancarlo; Ripepe, Maurizio; Aiuppa, Alessandro</p> <p>2014-05-01</p> <p>According to the linear theory of sound, acoustic pressure propagating in a homogeneous atmosphere can be modelled in terms of the rate of change of a volumetric <span class="hlt">source</span>. At open-vent volcanoes, this acoustic <span class="hlt">source</span> process is commonly related to the explosive dynamics triggered by the rise, expansion and bursting of a gas slug at the magma free surface with the conduit. Just before an explosion, the magma surface will undergo deformation by the expanding gas slug. The deformation of the magma surface will then produce an equivalent displacement of the atmosphere, inducing a volumetric compression and generating an excess pressure that scales to the rate of volumetric change of the atmosphere displaced. Linear theory of sound thus predicts that pressure amplitude of infrasonic waves associated to volcanic explosions should be generated by the first time-derivative of the gas mass flux during the burst. In some cases a correlation between the first time-derivative and the SO2 mass flux has been found. However no clear correlation has yet been established between infrasonic amplitude and total ejected gas mass; therefore, the origin of <span class="hlt">infrasound</span> in volcanic systems remains matter of debate. In the framework of the FP7-ERC BRIDGE Project, we tested different possible hypotheses on the acoustic <span class="hlt">source</span> model, by correlating <span class="hlt">infrasound</span> with the total gas mass retrieved from high-resolution UV spectroscopy techniques (UV camera). Experiments were conducted at Stromboli volcano (Italy), where we also employed a thermal camera to measure the total fragments/gas mass. Both techniques allowed independent estimation of total mass flux of gas and fragments within the volcanic plume. During the experiments, explosions detected by the UV camera emitted between 2 and 55 kg SO2, corresponding to SO2 peak fluxes of 0.1-0.8 kg/s. SO2 mass was converted into a total (maximum) erupted gas of 1310 kg, which is generating a peak pressure of ~8 Pa recorded at ~450 m from the <span class="hlt">source</span> vent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/921719','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/921719"><span id="translatedtitle">Test definitions for the evaluation of <span class="hlt">infrasound</span> sensors.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kromer, Richard Paul; Hart, Darren M.; Harris, James Mark</p> <p>2007-07-01</p> <p>Most test methodologies referenced in this Test Definition and Test Procedures were designed by Sandia specifically for geophysical instrumentation evaluation. When appropriate, test instrumentation calibration is traceable to the National Institute for Standards Technology (NIST). The objectives are to evaluate the overall technical performance of the <span class="hlt">infrasound</span> sensor. The results of these evaluations can be compared to the manufacturer's specifications and any relevant application requirements or specifications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA519497','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA519497"><span id="translatedtitle"><span class="hlt">Infrasound</span> Monitoring of Local, Regional and Global Events</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-09-01</p> <p><span class="hlt">INFRASOUND</span> MONITORING OF LOCAL, REGIONAL AND GLOBAL EVENTS Stephen J. Arrowsmith and Douglas O. ReVelle Los Alamos National Laboratory Sponsored...State seismo-acoustic network and identify 206 local and regional infrasonic events in a dataset comprising 28 days of data. We detect multiple signals...from mining explosions at two sites in Washington State, including 5 events that were recorded in a regional seismic bulletin. We also automatically</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9696K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9696K"><span id="translatedtitle">Regional measurements of <span class="hlt">infrasound</span> signals from ARIANE-5 engine tests in Southern Germany</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koch, K.</p> <p>2012-04-01</p> <p>A well-controlled <span class="hlt">source</span> of repetitive <span class="hlt">infrasound</span> emissions was previously identified and has been related to development and acceptance tests of the European Space Agencies ARIANE-5 main engine. The propulsion testing facility of the German Aerospace Agency (DLR) near Heilbronn, Southern Germany, is a distance of about 320 km away from the International Monitoring System (IMS) station IS26 in east-southeasterly direction. In the past, signals associated with these propulsion tests could normally be detected at IS26 during winter months, but not during summer months, reflecting the changes in atmospheric conditions between winter and summer. Over the last year, DLR has prepared to conduct a series of seven propulsion tests which started in November 2011; with interim times between tests of 3-4 weeks it will last until late March or early April 2012. With mobile <span class="hlt">infrasound</span> recording equipment available at BGR we planned to record the infrasonic wavefield along the path to IS26 at regular distances starting as close as 20 km from the <span class="hlt">source</span>. Our aim is to study sound propagation from direct paths mainly involving the tropospheric layer through the "zone of silence" to distances close to IS26, where paths through stratospheric layers are followed. Preliminary results show that during the relevant winter season direct path propagation can be observed to some 40 km from the propulsion test <span class="hlt">source</span>, even at seismographic stations where the acoustic wave couples into the ground. The tests are also observed at IS26, and waveform duration and f-k-analysis confirm the signals to be associated with the GT-type propulsion tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S31B1725G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S31B1725G"><span id="translatedtitle">In-situ comparison calibration of <span class="hlt">infrasound</span> array elements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabrielson, T. B.</p> <p>2009-12-01</p> <p>A typical <span class="hlt">infrasound</span> array element consists of an infrasonic sensor connected to a multiple-pipe or porous-hose system for reduction of wind noise. While the frequency response of the sensor itself may be known, the wind-noise reduction system can modify that response. One approach to measuring the actual frequency response in situ is to perform a comparison calibration using ambient noise. The reference sensor must have a sufficiently low self noise and have a well characterized frequency response over the band of interest. In the cases presented here, three reference sensors are placed and summed to form a virtual reference at the geometric center of the pipe system. Under low-wind conditions, coherence between the virtual reference and the <span class="hlt">infrasound</span> element is typically greater than 0.8 from 0.01 to 8 Hz. Proper combination of auto- and cross-spectral averages over a several-hour period produces an estimate of the response of the <span class="hlt">infrasound</span> system relative to that of the virtual reference. Measured coherence and the consistency between the magnitude and the phase provide quality checks on the process. [Funded by the US Army Space and Missile Defense Command</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813030D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813030D"><span id="translatedtitle">Impact of mountain gravity waves on <span class="hlt">infrasound</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Damiens, Florentin; Lott, François; Millet, Christophe</p> <p>2016-04-01</p> <p>Linear theory of acoustic propagation is used to analyze how mountain waves can change the characteristics of <span class="hlt">infrasound</span> signals. The mountain wave model is based on the integration of the linear inviscid Taylor-Goldstein equation forced by a nonlinear surface boundary condition. For the acoustic propagation we solve the wave equation using the normal mode method together with the effective sound speed approximation. For large-amplitude mountain waves we use direct numerical simulations to compute the interactions between the mountain waves and the <span class="hlt">infrasound</span> component. It is shown that the mountain waves perturb the low level waveguide, which leads to significant acoustic dispersion. The mountain waves also impact the arrival time and spread of the signals substantially and can produce a strong absorption of the wave signal. To interpret our results we follow each acoustic mode separately and show which mode is impacted and how. We also show that the phase shift between the acoustic modes over the horizontal length of the mountain wave field may yield to destructive interferences in the lee side of the mountain, resulting in a new form of <span class="hlt">infrasound</span> absorption. The statistical relevance of those results is tested using a stochastic version of the mountain wave model and large enough sample sizes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.207.1432S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.207.1432S"><span id="translatedtitle">Characterization of absorption and non-linear effects in <span class="hlt">infrasound</span> propagation using an augmented Burgers' equation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sabatini, R.; Bailly, C.; Marsden, O.; Gainville, O.</p> <p>2016-12-01</p> <p>The long-range atmospheric propagation of explosion-like waves of frequency in the <span class="hlt">infrasound</span> range is investigated using non-linear ray theory. Simulations are performed for <span class="hlt">sources</span> of increasing amplitude on rays up to the lower thermosphere and for distances of hundreds of kilometres. A study of the attenuation of the waveforms observed at ground level induced by both the classical mechanisms and the vibrational relaxation of the molecules comprising the atmospheric gas is carried out. The relative importance of classical absorption and vibrational relaxation along the typical atmospheric propagation trajectories is assessed. Non-linear effects are highlighted as well and particular emphasis is placed on their strong interaction with absorption phenomena. A detailed description of the propagation model and of the numerical algorithm used in this work is first reported. Results are then discussed and the importance of the different mechanisms is clarified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S11B1731H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S11B1731H"><span id="translatedtitle"><span class="hlt">Infrasound</span> Sensor and Porous-Hose Filter Characterization Results</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hart, D. M.; Harris, J. M.</p> <p>2008-12-01</p> <p>The Ground-Based Nuclear Explosion Monitoring Research and Development (GNEM R&D) program at Sandia National Laboratories (SNL) is regarded as the primary center for unbiased expertise in testing and evaluation of geophysical sensors and instrumentation for nuclear explosion monitoring. Over the past year much of our work has focused in the area of <span class="hlt">infrasound</span> sensor characterization through the continuing development of an <span class="hlt">infrasound</span> sensor characterization test-bed. Our main areas of focus have been in new sensor characterization and understanding the effects of porous-hose filters for reducing acoustic background signals. Three <span class="hlt">infrasound</span> sensors were evaluated for characteristics of instrument response, linearity and self-noise. The sensors tested were Chaparral Physics model 2.5 low-gain, New Mexico Tech All-Sensor and the Inter-Mountain Labs model SS avalanche sensor. For the <span class="hlt">infrasound</span> sensors tested, the test results allow us to conclude that two of the three sensors had sufficiently quiet noise floor to be at or below the Acoustic low-noise model from 0.1 to 7 Hz, which make those sensors suitable to explosion monitoring. The other area of focus has been to understand the characteristics of porous-hose filters used at some monitoring sites. For this, an experiment was designed in which two <span class="hlt">infrasound</span> sensors were co- located. One sensor was connected to a typical porous-hose spatial filter consisting of eight individual hoses covering a 30m aperture and the second sensor was left open to unimpeded acoustic input. Data were collected for several days, power spectrum computed for two-hour windows and the relative gain of the porous-hose filters were estimated by dividing the power spectrum. The porous-hose filter appears to attenuate less than 3 dB (rel 1 Pa**2/Hz) below 0.1 Hz and as much as 25 dB at 1 Hz and between 20 to 10 dB above 10 Hz. Several more experiments will be designed to address the effects of different characteristics of the individual porous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2505L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2505L"><span id="translatedtitle">Upper atmospheric processes as measured by collocated Lidar, <span class="hlt">infrasound</span>, radiometer and airglow measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Blanc, E.; Assink, J. D.; Ceranna, L.; Pilger, C.; Ross, O.; Keckhut, P.; Hauchecorne, A.; Schmidt, C.; Bittner, M.; Wuest, S.; Rüfenacht, R.; Kaempfer, N.; Smets, P.</p> <p>2013-12-01</p> <p>To better initialize weather forecasting systems, a key challenge is to understand stratosphere-resolving climate models. The ARISE project (http://arise-project.eu/) aims to design a novel infrastructure integrating different atmospheric observation networks to accurately recover the vertical structure of the wind and temperature from the ground to the mesosphere. This network includes Lidar and mesospheric airglow observations, complemented by continuous <span class="hlt">infrasound</span> measurements. Together with additional ground-based wind radar system, such complementary techniques help to better describe the interaction between atmospheric layers from the ground to the mesosphere and the influence of large scale waves on the atmospheric dynamics. Systematic comparisons between these observations and the ECMWF upper wind and temperature models (http://www.ecmwf.int/) have been performed at the OHP site (Haute-Provence Observatory, France). The main results are outlined below. - Systematic comparisons between Lidar soundings (NDACC, http://ndacc-lidar.org/) and ECMWF highlight differences increasing with altitude. Below 50 km altitude, differences are as large as 20°K. In average, the temperature appears to be overestimated by ~5 m/s in the stratosphere and underestimated by ~10 m/s in the mesopause. - Comparisons with collocated <span class="hlt">infrasound</span> measurements provide additional useful integrated information about the structure of the stratospheric waveguide. Below 0.5 Hz, most <span class="hlt">infrasound</span> signals originate from ocean swells in the North Atlantic region. As expected, since most long-range propagating signals travel in the stratospheric waveguide, improved detection capability occurs downwind. Deviations from this trend are either related to short time-scale variability of the atmosphere (e.g., large-scale planetary waves, stratospheric warming effects), or can be explained by changes in the nature of the <span class="hlt">source</span>. We investigate possible correlation between unexpected propagation paths and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.A13D0253D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.A13D0253D"><span id="translatedtitle">Finite-difference time-domain modeling of <span class="hlt">infrasound</span> from pulsating auroras and comparison with recent experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Larquier, S.; Pasko, V. P.; Stenbaek-Nielsen, H. C.; Wilson, C. R.; Olson, J. V.</p> <p>2009-12-01</p> <p>Atmospheric infrasonic waves are acoustic waves with frequencies ranging from 0.02 to 10 Hz, slightly higher than the acoustic cut-off frequency (approximately 0.032 Hz), but lower than the audible frequencies (typically 20 Hz-15 kHz) [e.g., Blanc, Ann. Geophys., 3, 673, 1985]. A number of natural events have been identified as generating atmospheric <span class="hlt">infrasound</span>, such as volcanoes, tornadoes, avalanches, earthquakes [e.g., Bedard and Georges, Physics Today, S3, 32, 2000], ocean surfaces [e.g., Gossard and Hooke, Waves in the Atmosphere, Elsevier, 1975, Ch. 9], lightning [e.g., Assink et al., GRL, 35, L15802, 2008; Pasko, JGR, 114, D08205, 2009], or transient luminous events in the middle atmosphere termed sprites [e.g., Farges, Lightning: Principles, Instruments and Applications, H.D. Betz et al. (eds), Springer, 2009, Ch. 18]. The importance of <span class="hlt">infrasound</span> studies has been emphasized in the past ten years from the Comprehensive Nuclear-Test-Ban Treaty verification perspective [e.g., Le Pichon et al., JGR, 114, D08112, 2009]. A proper understanding of <span class="hlt">infrasound</span> propagation in the atmosphere is required for identification and classification of different infrasonic waves and their <span class="hlt">sources</span> [Drob et al., JGR, 108, D21, 4680, 2003]. The goal of the present work is to provide a quantitative interpretation and explanation of infrasonic signatures from pulsating auroras reported recently by Wilson et al. [GRL, 32, L14810, 2005]. The <span class="hlt">infrasound</span> signals observed with an infrasonic array at Fairbanks, Alaska had a mean amplitude of 0.05 Pa, a delay of about 5 minutes from the pulsating aurora, and an almost normal incidence on the ground plane [Wilson et al., 2005]. We employ a finite-difference time-domain (FDTD) model of <span class="hlt">infrasound</span> propagation in a realistic atmosphere. We use the absorption model of <span class="hlt">infrasound</span> introduced by Sutherland and Bass [J. Acoust. Soc. Am., 115, 1012, 2004]. Classical absorption mechanisms as well as molecular relaxation mechanisms are taken into</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1163495','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1163495"><span id="translatedtitle"><span class="hlt">Infrasound</span> Generation from the HH Seismic Hammer.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jones, Kyle Richard</p> <p>2014-10-01</p> <p>The HH Seismic hammer is a large, "weight-drop" <span class="hlt">source</span> for active <span class="hlt">source</span> seismic experiments. This system provides a repetitive <span class="hlt">source</span> that can be stacked for subsurface imaging and exploration studies. Although the seismic hammer was designed for seismological studies it was surmised that it might produce energy in the infrasonic frequency range due to the ground motion generated by the 13 metric ton drop mass. This study demonstrates that the seismic hammer generates a consistent acoustic <span class="hlt">source</span> that could be used for in-situ sensor characterization, array evaluation and surface-air coupling studies for <span class="hlt">source</span> characterization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V23C4817F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4817F"><span id="translatedtitle">Classification, Characterization, and Automatic Detection of Volcanic Explosion Complexity using <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fee, D.; Matoza, R. S.; Lopez, T. M.; Ruiz, M. C.; Gee, K.; Neilsen, T.</p> <p>2014-12-01</p> <p><span class="hlt">Infrasound</span> signals from volcanoes represent the acceleration of the atmosphere during an eruption and have traditionally been classified into two end members: 1) "explosions" consisting primarily of a high amplitude bi-polar pressure pulse that lasts a few to tens of seconds, and 2) "tremor" or "jetting" consisting of sustained, broadband <span class="hlt">infrasound</span> lasting for minutes to hours. However, as our knowledge and recordings of volcanic eruptions have increased, significant <span class="hlt">infrasound</span> signal diversity has been found. Here we focus on identifying and characterizing trends in volcano <span class="hlt">infrasound</span> data to help better understand eruption processes. We explore <span class="hlt">infrasound</span> signal metrics that may be used to quantitatively compare, classify, and identify explosive eruptive styles by systematic analysis of the data. We analyze <span class="hlt">infrasound</span> data from short-to-medium duration explosive events recorded during recent <span class="hlt">infrasound</span> deployments at Sakurajima Volcano, Japan; Karymsky Volcano, Kamchatka; and Tungurahua Volcano, Ecuador. Preliminary results demonstrate that a great variety of explosion styles and flow behaviors from these volcanoes can produce relatively similar bulk acoustic waveform properties, such as peak pressure and event duration, indicating that accurate classification of physical eruptive styles requires more advanced field studies, waveform analyses, and modeling. Next we evaluate the spectral and temporal properties of longer-duration tremor and jetting signals from large eruptions at Tungurahua Volcano; Redoubt Volcano, Alaska; Augustine Volcano, Alaska; and Nabro Volcano, Eritrea, in an effort to identify distinguishing <span class="hlt">infrasound</span> features relatable to eruption features. We find that unique transient signals (such as repeated shocks) within sustained <span class="hlt">infrasound</span> signals can provide critical information on the volcanic jet flow and exhibit a distinct acoustic signature to facilitate automatic detection. Automated detection and characterization of <span class="hlt">infrasound</span> associated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA570369','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA570369"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> in Building Human Security</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-11-01</p> <p>James Cricks , professor at the U.S. Army Command and General Staff College, non-state personae include “pillars of social power in the affected...nations, in- cluding religious groups and tribal leaders.”27 Cricks then asks, “Who could possibly be (or become) better 13 equipped within the...United States Civilian Agencies Cricks was likely aware that in 2008 Congress au- thorized the Civilian Response Corps (CRC) within the Department of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830015771&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830015771&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth"><span id="translatedtitle">AVE/VAS experiment: <span class="hlt">Ground</span> <span class="hlt">truth</span> network</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scoggins, J. R.</p> <p>1983-01-01</p> <p>The visible/infrared spin scan radiometer (VISSR) atmospheric sounder (VAS) rawinsonde field program is discussed. Specific items covered include: planning, personnel requirements and training, operational requirement and procedures, sounding times and dates, methods of data processing, data inventory, and status of data processing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA616431','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA616431"><span id="translatedtitle">SpinSat Mission <span class="hlt">Ground</span> <span class="hlt">Truth</span> Characterization</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2014-09-01</p> <p>launch via the SpaceX Falcon 9 CRS4 mission on 12 Sept 2014 and is to be deployed from the International Space Station (ISS) on 29 Sept. 2014. 2...ISS as part of the soft-stow cargo allotment on the SpaceX Dragon spacecraft launched by the SpaceX Falcon 9 two stage to orbit launch vehicle during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA......885S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA......885S"><span id="translatedtitle"><span class="hlt">Infrasound</span> from the September 24 2002 Vitim (Siberian) fireball</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shumilov, O. I.; Kasatkina, E. A.; Tereshchenko, E. D.; Kulichkov, S. N.; Raspopov, O. M.; Vasiljev, A. N.; Struev, A. G.</p> <p>2003-04-01</p> <p>On 24 September 2002, sensors aboard US Department Of Defence satellites detected the impact of a fireball at 16.49 UT near Bodaibo in Siberia (58.21 N, 113.46 E). Eyewitnesses described the fireball as a large bright star streaking across the sky, ending in bright flash and loud explosive noise. Ground shaking detonations were felt at a large distance (tens of kilometers). An array of microbarographs operated at Polar Geophysical Institute (PGI), Apatity (67.3 N, 33.3 E) recorded a pressure impulse with an amplitude of 45 dyn/cm^2 on September 24, 2002 at 22.20 UT, at a distance about of 4000 km from a fireball detection. The PGI microbarograph array consists of three spatially placed <span class="hlt">infrasound</span> detectors for measurements of atmospheric waves in the frequency band of 0.0001 - 1 Hz. The computer-aided system permits to get information with a frequency of five times per second. The time interval between the bolide observation and the detection of pressure impulse is consistent with an acoustic travel time from the location of fireball impact. Estimates were made of both the local <span class="hlt">infrasound</span> velocity and the direction of arrival of the signal. These values are in agreement with the travel velocity and the south azimuth. Estimates of the fireball mass from the radiated energy value agree with mass estimates calculated from the blast wave theory. These results seem to suppose the propagation of the <span class="hlt">infrasound</span> signal from the Vitim fireball through atmospheric acoustic wave guide. According to Brown et al. (Nature, V420, 294, 2002) estimations the Earth is hit on average annually by the Vitim-like meteorite. Collisions of large asteroids with our planet result in dramatic impacts that can lead to the Earth magnetic field reversals. This work was supported by EC (grant INTAS 97-31008) and RFBR (grant 01-05-64850).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812391A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812391A"><span id="translatedtitle"><span class="hlt">Infrasound</span> analysis using Fisher detector and Hough transform</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Averbuch, Gil; Assink, Jelle D.; Smets, Pieter S. M.; Evers, Läslo G.</p> <p>2016-04-01</p> <p>Automatic detection of <span class="hlt">infrasound</span> signals from the International Monitoring System (IMS) from the Comprehensive Nuclear-Test-Ban Treaty requires low rates of both false alarms and missed events. The Fisher detector is a statistical method used for detecting such infrasonic events. The detector aims to detect coherent signals after Beamforming is applied on the recordings. A detection is defined to be above a threshold value of Fisher ratio. The Fisher distribution for such a detection is affected by the SNR. While events with high Fisher ratio and SNR can easily be detected automatically, events with lower Fisher ratios and SNRs might be missed. The Hough transform is a post processing step. It is based on a slope-intercept transform applied to a discretely sampled data, with the goal of finding straight lines (in apparent velocity and back azimuth). Applying it on the results from the Fisher detector is advantageous in case of noisy data, which corresponds to low Fisher ratios and SNRs. Results of the Hough transform on synthetic data with SNR down to 0.7 provided a lower number of missed events. In this work, we will present the results of an automatic detector, based on both methods. Synthetic data with different lengths and SNRs are evaluated. Furthermore, continuous data from the IMS <span class="hlt">infrasound</span> station I18DK will be analyzed. We will compare the performances of both methods and investigate their ability in reducing the number of missed events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21895057','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21895057"><span id="translatedtitle">Sound, <span class="hlt">infrasound</span>, and sonic boom absorption by atmospheric clouds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baudoin, Michaël; Coulouvrat, François; Thomas, Jean-Louis</p> <p>2011-09-01</p> <p>This study quantifies the influence of atmospheric clouds on propagation of sound and <span class="hlt">infrasound</span>, based on an existing model [Gubaidulin and Nigmatulin, Int. J. Multiphase Flow 26, 207-228 (2000)]. Clouds are considered as a dilute and polydisperse suspension of liquid water droplets within a mixture of dry air and water vapor, both considered as perfect gases. The model is limited to low and medium altitude clouds, with a small ice content. Four physical mechanisms are taken into account: viscoinertial effects, heat transfer, water phase changes (evaporation and condensation), and vapor diffusion. Physical properties of atmospheric clouds (altitude, thickness, water content and droplet size distribution) are collected, along with values of the thermodynamical coefficients. Different types of clouds have been selected. Quantitative evaluation shows that, for low audible and <span class="hlt">infrasound</span> frequencies, absorption within clouds is several orders of magnitude larger than classical absorption. The importance of phase changes and vapor diffusion is outlined. Finally, numerical simulations for nonlinear propagation of sonic booms indicate that, for thick clouds, attenuation can lead to a very large decay of the boom at the ground level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/314136','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/314136"><span id="translatedtitle"><span class="hlt">Infrasound</span> from the El Paso super-bolide of October 9, 1997</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>ReVelle, D.O.; Whitaker, R.W.; Armstrong, W.T.</p> <p>1998-12-31</p> <p>During the noon hour on October 9, 1997 an extremely bright fireball ({approx}-21.5 in stellar magnitude putting it into the class of a super-bolide) was observed over western Texas with visual sightings from as far away as Arizona to northern Mexico and even in northern New Mexico over 300 miles away. This event produced tremendously loud sonic boom reports in the El Paso area. It was also detected locally by 4 seismometers which are part of a network of 5 seismic stations operated by the University of Texas at El Paso (UTEP). Subsequent investigations of the data from the six <span class="hlt">infrasound</span> arrays used by LANL (Los Alamos National Laboratory) and operated for the DOE (Department of Energy) as a part of the CTB (Comprehensive Test Ban) Research and Development program for the IMS (International Monitoring System) showed the presence of an infrasonic signal from the proper direction at the correct time for this super-bolide from two of the six arrays. Both the seismic and <span class="hlt">infrasound</span> recordings indicated that an explosion occurred in the atmosphere at <span class="hlt">source</span> heights from 28--30 km, having its epicenter slightly to the northeast of Horizon City, Texas. The signal characteristics, analyzed from {approx}0.1 to 5.0 Hz, include a total duration of {approx}4 min (at Los Alamos, LA) to >{approx}5 min at Lajitas, Texas, TXAR, another CTB IMS array operated by E. Herrin at Southern Methodist University (SMU) for a <span class="hlt">source</span> directed from LA toward {approx}171--180 deg and from TXAR of {approx}321-4 deg respectively from true north. The observed signal trace velocities (for the part of the recording with the highest cross-correlation) at LA ranged from 300--360 m/sec with a signal velocity of 0.30 {+-} 0.03 km/sec, implying a Stratospheric (S Type) ducted path. The dominant signal frequency at LA was from 0.20 to 0.80 Hz, with a peak near 0.3 Hz. These highly correlated signals at LA had a very large, peak to peak, maximum amplitude of 21.0 microbars (2.1 Pa). The analysis, using</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24606252','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24606252"><span id="translatedtitle">A study of <span class="hlt">infrasound</span> propagation based on high-order finite difference solutions of the Navier-Stokes equations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marsden, O; Bogey, C; Bailly, C</p> <p>2014-03-01</p> <p>The feasibility of using numerical simulation of fluid dynamics equations for the detailed description of long-range <span class="hlt">infrasound</span> propagation in the atmosphere is investigated. The two dimensional (2D) Navier Stokes equations are solved via high fidelity spatial finite differences and Runge-Kutta time integration, coupled with a shock-capturing filter procedure allowing large amplitudes to be studied. The accuracy of acoustic prediction over long distances with this approach is first assessed in the linear regime thanks to two test cases featuring an acoustic <span class="hlt">source</span> placed above a reflective ground in a homogeneous and weakly inhomogeneous medium, solved for a range of grid resolutions. An atmospheric model which can account for realistic features affecting acoustic propagation is then described. A 2D study of the effect of <span class="hlt">source</span> amplitude on signals recorded at ground level at varying distances from the <span class="hlt">source</span> is carried out. Modifications both in terms of waveforms and arrival times are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2014/1253/downloads/OFR2014-1253.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2014/1253/downloads/OFR2014-1253.pdf"><span id="translatedtitle">An analysis of three new <span class="hlt">infrasound</span> arrays around Kīlauea Volcano</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Thelen, Weston A.; Cooper, Jennifer</p> <p>2015-01-01</p> <p>A network of three new <span class="hlt">infrasound</span> station arrays was installed around Kīlauea Volcano between July 2012 and September 2012, and a preliminary analysis of open-vent monitoring has been completed by Hawaiian Volcano Observatory (HVO). <span class="hlt">Infrasound</span> is an emerging monitoring method in volcanology that detects perturbations in atmospheric pressure at frequencies below 20 Hz, which can result from volcanic events that are not always observed optically or thermally. Each array has the capability to detect various <span class="hlt">infrasound</span> events as small as 0.05 Pa as measured at the array site. The <span class="hlt">infrasound</span> monitoring network capabilities are demonstrated through case studies of rockfalls, pit collapses, and rise-fall cycles at Halema'uma'u Crater and Pu'u 'Ōʻō.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA581753','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA581753"><span id="translatedtitle">Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2013-04-01</p> <p>Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for <span class="hlt">Infrasound</span> by W.C. Kirkpatrick Alberts, II... Windshield and Microphone for <span class="hlt">Infrasound</span> W.C. Kirkpatrick Alberts, II, Stephen M. Tenney, and John M. Noble Sensors and Electron Devices Directorate...NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) April 2013 2. REPORT TYPE Final 3. DATES COVERED (From - To) Nov 2011–Jan</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70041411','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70041411"><span id="translatedtitle">Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with <span class="hlt">infrasound</span> and ground-couples airwaves</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David</p> <p>2012-01-01</p> <p>In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and <span class="hlt">infrasound</span> observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by <span class="hlt">infrasound</span> sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. <span class="hlt">Infrasound</span> and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic <span class="hlt">infrasound</span> and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow <span class="hlt">infrasound</span> to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in <span class="hlt">infrasound</span> monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EOSTr..94S..96S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EOSTr..94S..96S"><span id="translatedtitle">Tropical cyclone waves detected with <span class="hlt">infrasound</span> sensor array</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schultz, Colin</p> <p>2013-02-01</p> <p>The strong winds of a tropical cyclone whip up the sea surface, driving ocean waves a dozen meters high. When one such ocean wave runs into another wave that has an equal period but is traveling in the opposite direction, the interaction produces low-frequency sound waves that can be detected thousands of kilometers away. The <span class="hlt">infrasound</span> signals produced by interacting ocean surface waves—known as microbarom—have typical frequencies around 0.2 hertz. Researchers previously determined that as a hurricane travels along its track, early waves generated by the storm will interact with those generated later on, producing a strong microbarom signal in the storm's wake. Researchers also found, however, that microbarom signals are produced by regular surface ocean behavior, including swell, surface waves, and nontropical cyclone storms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70177896','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70177896"><span id="translatedtitle">Long period seismicity and very long period <span class="hlt">infrasound</span> driven by shallow magmatic degassing at Mount Pagan, Mariana Islands</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lyons, John; Haney, Matt; Werner, Cynthia A.; Kelly, Peter; Patrick, Matthew R.; Kern, Christoph; Trusdell, Frank A.</p> <p>2016-01-01</p> <p>Long period (LP) seismicity and very long period <span class="hlt">infrasound</span> (iVLP) were recorded during continuous degassing from Mount Pagan, Mariana Islands, in July 2013 to January 2014. The frequency content of the LP and iVLP events and delay times between the two arrivals were remarkably stable and indicate nearly co-located <span class="hlt">sources</span>. Using phase-weighted stacking over similar events to dampen noise, we find that the LP <span class="hlt">source</span> centroid is located 60 m below and 180 m west of the summit vent. The moment tensor reveals a volumetric <span class="hlt">source</span> modeled as resonance of a subhorizontal sill intersecting a dike. We model the seismoacoustic wavefields with a coupled earth-air 3-D finite difference code. The ratios of pressure to velocity measured at the <span class="hlt">infrasound</span> arrays are an order of magnitude larger than the synthetic ratios, so the iVLP is not the result of LP energy transmitting into the atmosphere at its epicenter. Based on crater shape and dimensions determined by structure from motion, we model the iVLP as acoustic resonance of an exponential horn. The <span class="hlt">source</span> of the continuous plume from gas analysis is shallow magmatic degassing, which repeatedly pressurized the dike-sill portion of the conduit over the 7 months of observation. Periodic gas release caused the geologically controlled sill to partially collapse and resonate, while venting of gas at the surface triggered resonance in the crater. LP degassing only accounts for ~12% of total degassing, indicating that most degassing is relatively aseismic and that multiple active pathways exist beneath the vent.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6206P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6206P"><span id="translatedtitle">The 2013 Chelyabinsk meteorite: global detection performance of the CTBTO <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, Christoph; Ceranna, Lars; Le Pichon, Alexis; Mialle, Pierrick; Garces, Milton</p> <p>2014-05-01</p> <p>The explosive fragmentation of the Chelyabinsk meteorite of 15 February 2013 over the Ural Mountains, Russia, generated a large airburst with an equivalent explosive yield of half a megaton of TNT. It is the most energetic event recorded by the <span class="hlt">infrasound</span> component of the International Monitoring System (IMS) network operated by the Comprehensive Nuclear-Test-Ban Treaty Organization. The event was detected by 20 out of 45 stations of the operational IMS network and propagation paths from the event to the stations ranged between 500 km and 87000 km, traveling more than twice around the globe. The current study in the framework of the ARISE project (http://arise-project.eu/) performs a detailed station-by-station estimation to address why infrasonic signals were clearly detected at some of the stations over very large distances whereas they were not detected at other stations at shorter distances. One potential explanation investigated within this study is the directivity of the signal energy radiated from the meteorite's line <span class="hlt">source</span>, where azimuth directions at stations perpendicular to the trajectory are favored compared to parallel directions. Another explanation might be different noise and data quality levels at each station, which not only depend on frequency and sensor response, but also on diurnal, seasonal and weather variability. The presentation will provide a station-dependent overview on these parameters compared to the detections of the meteorite event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4625S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4625S"><span id="translatedtitle"><span class="hlt">Infrasound</span> and seismic signals from Baikonur spaceport rocket launches recorded by Kazakh stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smirnov, Alexandr; Sokolova, Inna; Mikhailova, Natalya</p> <p>2015-04-01</p> <p>The monitoring network of the Institute of Geophysical Researches, Kazakhstan consists of 2 <span class="hlt">infrasound</span> arrays, 8 seismic arrays and 7 3C stations. 5 of these stations are a part of IMS CTBTO. The Institute of Geophysical Researches monitors round-the-clock many sorts of seismoacoustic events. Tens of rockets are launched every year from Baikonur spaceport located in Central Kazakhstan. Baikonur rockets fly over several regions of Kazakhstan. Kazakh monitoring stations record launches, rocket stage falls, satellite recovery and sometimes accidents. A catalog of events associated with such activity is built. Some waveform features are collected. The catalog also contains some kinematic and dynamic parameters of the events <span class="hlt">sources</span>. The signals from accidents of Dnepr rocket of July 26, 2006 and Proton rocket of September 5, 2007 and of July 2, 2013 were studied in details. Discrimination of the events associated with spaceport activity and its exclusion from seismic bulletins allows improving the bulletins quality. And in case of accident this information helps to estimate the event parameters and to start recovery procedures in proper time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4519F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4519F"><span id="translatedtitle"><span class="hlt">Infrasound</span> from lightning measured in Ivory Coast from 2004 to 2014</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farges, Thomas; Le Pichon, Alexis; Ceranna, Lars; Diawara, Adama</p> <p>2016-04-01</p> <p>It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. 80 % of the <span class="hlt">infrasound</span> stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes …). Some of the IMS stations are located where lightning activity is high (e.g. Africa, South America). These <span class="hlt">infrasound</span> stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in <span class="hlt">infrasound</span> array data processing over the past ten years makes such lightning studies possible. Assink et al. (2008) and Farges and Blanc (2010) show clearly that it is possible to measure lightning <span class="hlt">infrasound</span> from thunderstorms within 300 km. One-to-one correlation is possible when the thunderstorm is within about 75 km from the station. When the lightning flash occurs within 20 km, it is also possible to rebuild the 3D geometry of the discharges when the network size is less than 100 m (Arechiga et al., 2011; Gallin, 2014). An IMS <span class="hlt">infrasound</span> station has been installed in Ivory Coast since 2002. The lightning rate of this region is 10-20 flashes/km²/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study <span class="hlt">infrasound</span> data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 10 years of data (2005-2014). Correlation between <span class="hlt">infrasound</span> having a mean frequency higher than 1 Hz and lightning flashes detected by the World Wide Lightning Location Network (WWLLN) is systematically looked for. One-to-one correlation is obtained for flashes occurring within about 100 km. An exponential decrease of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-06-30/pdf/2010-15928.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-06-30/pdf/2010-15928.pdf"><span id="translatedtitle">75 FR 37742 - Addition of New Export Control Classification Number 6A981 Passive <span class="hlt">Infrasound</span> Sensors to the...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-06-30</p> <p>... Classification Number 6A981 Passive <span class="hlt">Infrasound</span> Sensors to the Commerce Control List of the Export Administration... Control List (CCL) to control passive <span class="hlt">infrasound</span> sensors because of their military and commercial utility... CONTACT: James Thompson, Sensors and Aviation Division, Bureau of Industry and Security, Telephone:...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5516A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5516A"><span id="translatedtitle">Merging <span class="hlt">Infrasound</span> and Electromagnetic Signals as a Means for Nuclear Explosion Detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashkenazy, Joseph; Lipshtat, Azi; Kesar, Amit S.; Pistinner, Shlomo; Ben Horin, Yochai</p> <p>2016-04-01</p> <p>The <span class="hlt">infrasound</span> monitoring network of the CTBT consists of 60 stations. These stations are capable of detecting atmospheric events, and may provide approximate location within time scale of a few hours. However, the nature of these events cannot be deduced from the <span class="hlt">infrasound</span> signal. More than two decades ago it was proposed to use the electromagnetic pulse (EMP) as a means of discriminating nuclear explosion from other atmospheric events. An EMP is a unique signature of nuclear explosion and is not detected from chemical ones. Nevertheless, it was decided to exclude the EMP technology from the official CTBT verification regime, mainly because of the risk of high false alarm rate, due to lightning electromagnetic pulses [1]. Here we present a method of integrating the information retrieved from the <span class="hlt">infrasound</span> system with the EMP signal which enables us to discriminate between lightning discharges and nuclear explosions. Furthermore, we show how spectral and other characteristics of the electromagnetic signal emitted from a nuclear explosion are distinguished from those of lightning discharge. We estimate the false alarm probability of detecting a lightning discharge from a given area of the <span class="hlt">infrasound</span> event, and identifying it as a signature of a nuclear explosion. We show that this probability is very low and conclude that the combination of <span class="hlt">infrasound</span> monitoring and EMP spectral analysis may produce a reliable method for identifying nuclear explosions. [1] R. Johnson, Unfinished Business: The Negotiation of the CTBT and the End of Nuclear Testing, United Nations Institute for Disarmament Research, 2009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSV...388..188P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSV...388..188P"><span id="translatedtitle">The influence of periodic wind turbine noise on <span class="hlt">infrasound</span> array measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pilger, Christoph; Ceranna, Lars</p> <p>2017-02-01</p> <p>Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for <span class="hlt">infrasound</span> recording systems. These systems are equipped with highly sensitive micro pressure sensors accurately measuring acoustic signals in a frequency range inaudible to the human ear. Ten years of data (2006-2015) from the <span class="hlt">infrasound</span> array IGADE in Northern Germany are analysed to quantify the influence of wind turbine noise on <span class="hlt">infrasound</span> recordings. Furthermore, a theoretical model is derived and validated by a field experiment with mobile micro-barometer stations. Fieldwork was carried out 2004 to measure the infrasonic pressure level of a single horizontal-axis wind turbine and to extrapolate the sound effect for a larger number of nearby wind turbines. The model estimates the generated sound pressure level of wind turbines and thus enables for specifying the minimum allowable distance between wind turbines and <span class="hlt">infrasound</span> stations for undisturbed recording. This aspect is particularly important to guarantee the monitoring performance of the German <span class="hlt">infrasound</span> stations I26DE in the Bavarian Forest and I27DE in Antarctica. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and thus have to meet stringent specifications with respect to infrasonic background noise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9531A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9531A"><span id="translatedtitle">First observations of sprites in the eastern Mediterranean using the Israeli <span class="hlt">infrasound</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Applbaum, David; Price, Colin; Ben Horin, Yochai; Yair, Yoav</p> <p>2014-05-01</p> <p>As outlined by Farges et al (2005) as part of the Sprite2003 campaign in Europe, sprites at close range (less than a few hundred km) exhibit a unique signal in <span class="hlt">infrasound</span>. This signal consists of an 'inverted chirp,' lasting up to several minutes and in which the higher frequencies arrive prior to the lower frequencies. The ILAN (Imaging of Lightning and Nocturnal Flashes) science team at Tel Aviv University maintains a database of optically observed sprites occurring within a few hundred kilometers of the Mediterranean coast of Israel. Using the observed azimuths of these sprites' locations with respect to the detectors, combined with an acoustic propagation model and the observed delays associated with propagation of the signals between the sprites and the <span class="hlt">infrasound</span> arrays, we present here observations of several sprites that are consistent with the observations made by Farges et al. These constitute the first observations of sprites made using the Israeli <span class="hlt">infrasound</span> network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoRL..40.3732L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.3732L"><span id="translatedtitle">The 2013 Russian fireball largest ever detected by CTBTO <span class="hlt">infrasound</span> sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, Alexis; Ceranna, Lars; Pilger, Christoph; Mialle, Pierrick; Brown, David; Herry, Pascal; Brachet, Nicolas</p> <p>2013-07-01</p> <p>15 February 2013, a large Earth-impacting fireball disintegrated over the Ural Mountains. This extraordinary event is, together with the 1908 Tunguska fireball, among the most energetic events ever instrumentally recorded. It generated <span class="hlt">infrasound</span> returns, after circling the globe, at distances up to ~85,000 km, and was detected at 20 infrasonic stations of the global International Monitoring System (IMS). For the first time since the establishment of the IMS <span class="hlt">infrasound</span> network, multiple arrivals involving waves that traveled twice round the globe have been clearly identified. A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kt of TNT equivalent. In the context of the future verification of the Comprehensive Nuclear-Test-Ban Treaty, this event provides a prominent milestone for studying in detail <span class="hlt">infrasound</span> propagation around the globe for almost 3 days as well as for calibrating the performance of the IMS network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860009830','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860009830"><span id="translatedtitle">Design of <span class="hlt">infrasound</span>-detection system via adaptive LMSTDE algorithm</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Khalaf, C. S.; Stoughton, J. W.</p> <p>1984-01-01</p> <p>A proposed solution to an aviation safety problem is based on passive detection of turbulent weather phenomena through their infrasonic emission. This thesis describes a system design that is adequate for detection and bearing evaluation of <span class="hlt">infrasounds</span>. An array of four sensors, with the appropriate hardware, is used for the detection part. Bearing evaluation is based on estimates of time delays between sensor outputs. The generalized cross correlation (GCC), as the conventional time-delay estimation (TDE) method, is first reviewed. An adaptive TDE approach, using the least mean square (LMS) algorithm, is then discussed. A comparison between the two techniques is made and the advantages of the adaptive approach are listed. The behavior of the GCC, as a Roth processor, is examined for the anticipated signals. It is shown that the Roth processor has the desired effect of sharpening the peak of the correlation function. It is also shown that the LMSTDE technique is an equivalent implementation of the Roth processor in the time domain. A LMSTDE lead-lag model, with a variable stability coefficient and a convergence criterion, is designed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ASAJ..115.2554P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..115.2554P"><span id="translatedtitle">The role of <span class="hlt">infrasounds</span> in maintaining whale herds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Payne, Roger S.</p> <p>2004-05-01</p> <p>For whales and dolphins a basic social unit is the herd. In several species, herds have been observed to maintain the same speed, direction, and membership overnight, and while swimming in waters of near-zero visibility-evidence that individuals can stay together using nonvisual cues. The most likely such cue is sound. If whale herds are held together with sound, yet we define herds as groups of whales seen moving together, then we are using visual criteria to judge what is an acoustic phenomenon, and our conclusions about a most basic unit of cetacean social structure, the herd, are at least incomplete, and, quite possibly, worthless. By calling herds, heards, we remind ourselves that sound controls herd size. We then consider that some whale <span class="hlt">infrasound</span> can propagate across deep water at useful intensities (even in today's ship-noise-polluted ocean) for thousands of kilometers. The distance to which blue and fin whale sounds propagate before falling below background noise is given, and the possible advantages these whales obtain from such sounds is explored. The conclusion is that by sharing information on food finds infrasonically, fin and blue whales may have developed a way to divide up the food resources of an entire ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001ASAJ..115.2554P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001ASAJ..115.2554P"><span id="translatedtitle">The role of <span class="hlt">infrasounds</span> in maintaining whale herds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Payne, Roger S.</p> <p>2001-05-01</p> <p>For whales and dolphins a basic social unit is the herd. In several species, herds have been observed to maintain the same speed, direction, and membership overnight, and while swimming in waters of near-zero visibility-evidence that individuals can stay together using nonvisual cues. The most likely such cue is sound. If whale herds are held together with sound, yet we define herds as groups of whales seen moving together, then we are using visual criteria to judge what is an acoustic phenomenon, and our conclusions about a most basic unit of cetacean social structure, the herd, are at least incomplete, and, quite possibly, worthless. By calling herds, heards, we remind ourselves that sound controls herd size. We then consider that some whale <span class="hlt">infrasound</span> can propagate across deep water at useful intensities (even in today's ship-noise-polluted ocean) for thousands of kilometers. The distance to which blue and fin whale sounds propagate before falling below background noise is given, and the possible advantages these whales obtain from such sounds is explored. The conclusion is that by sharing information on food finds infrasonically, fin and blue whales may have developed a way to divide up the food resources of an entire ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A43E..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A43E..06M"><span id="translatedtitle">Implementation and evaluation of an inexpensive low-power low-noise <span class="hlt">infrasound</span> sensor and its use in a dense sensor network around an active volcanic vent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcillo, O. E.; Johnson, J. B.; Hart, D. M.</p> <p>2011-12-01</p> <p>The development and evaluation of a low-cost <span class="hlt">infrasound</span> sensor, the infraNMT, and its use as part of a dense (45-element) sensor network around an active volcanic vent, are described. This sensor is based on a commercial micro-machined piezo-resistive differential pressure transducer that uses a mechanical high-pass filter to reject low-frequency out-band energy. The sensor features low noise, 2.02 mPa rms (0.5-2 Hz), 5.47 mPa RMS (0.1-20 Hz), or 5.62 mPa rms (0.05-20 Hz), flat response between 0.01 Hz to at least 40 Hz, inband sensitivity of 45.13 +/-0.23 μV/Pa, and nominal linear range of -124.5 to +124.5 Pa. The sensor consumes a minimum of 24 mW, and operates with voltages above 8V while drawing 3mA of current. The infraNMT specifications described above were independently verified using the <span class="hlt">infrasound</span> test chamber at the Sandia National Laboratories' Facility for Acceptance, Calibration, and Testing (SNL-FACT) and following procedures for comparison calibration against traceable reference stands in voltage and pressure. Due to the intended broad frequency response of this sensor the testing chamber was configured in a double reference sensor scheme. A well-characterized MB2000 micro-barometer (with a flat amplitude response between 0.01 and 8 Hz) and microphone (with a flat amplitude response above 8Hz) were used simultaneously in this double reference test configuration. The characteristics of the infraNMT, including small size, low power consumption, high dynamic range, and low cost, favor its use in array or network configurations for near <span class="hlt">source</span> and/or higher noise environments. This sensor has been used for <span class="hlt">infrasound</span> array studies associated with various <span class="hlt">sources</span>, including volcanic and chemical explosions, glacier earthquakes, and thunder. In this study we report on the Summer 2010 deployment of a network of 45 infraNMT sensors at Kilauea volcano to study the <span class="hlt">infrasound</span> generated by degassing of the active Halema'uma'u vent. For this experiment, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/878619','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/878619"><span id="translatedtitle"><span class="hlt">Source</span> and Propagation Characteristics of Explosive and Other Seismic <span class="hlt">Sources</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ni, X; Chan, W; Wagner, R; Walter, W R; Matzel, E M</p> <p>2005-07-14</p> <p>Understanding of the <span class="hlt">source</span> and propagation characteristics of seismic events of different types including earthquakes, explosions and mining-induced events is essential for successful discrimination of nuclear explosions. We are compiling a data set of mining related seismic events in east Eurasia. Natural earthquake data in the same region are also collected for comparison study between mining related events and earthquakes. The <span class="hlt">ground-truth</span> data set will provide a unique and valuable resource for monitoring research. We will utilize the data set to investigate the <span class="hlt">source</span> and propagation characteristics of seismic <span class="hlt">sources</span> of different types including mine blasts, tremors, collapses and earthquakes. We will use various seismological techniques including spectral analysis, and waveform modeling to conduct the investigation. The research will improve our understanding of the S-wave excitation and propagation characteristics of chemical explosions and other <span class="hlt">source</span> types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930063619&hterms=Geographical+information+system+raster+model&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGeographical%2Binformation%2Bsystem%2Braster%2Bmodel','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930063619&hterms=Geographical+information+system+raster+model&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGeographical%2Binformation%2Bsystem%2Braster%2Bmodel"><span id="translatedtitle">A system for verifying models and classification maps by extraction of information from a variety of data <span class="hlt">sources</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Norikane, L.; Freeman, A.; Way, J.; Okonek, S.; Casey, R.</p> <p>1992-01-01</p> <p>Recent updates to a geographical information system (GIS) called VICAR (Video Image Communication and Retrieval)/IBIS are described. The system is designed to handle data from many different formats (vector, raster, tabular) and many different <span class="hlt">sources</span> (models, radar images, <span class="hlt">ground</span> <span class="hlt">truth</span> surveys, optical images). All the data are referenced to a single georeference plane, and average or typical values for parameters defined within a polygonal region are stored in a tabular file, called an info file. The info file format allows tracking of data in time, maintenance of links between component data sets and the georeference image, conversion of pixel values to `actual' values (e.g., radar cross-section, luminance, temperature), graph plotting, data manipulation, generation of training vectors for classification algorithms, and comparison between actual measurements and model predictions (with <span class="hlt">ground</span> <span class="hlt">truth</span> data as input).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19045636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19045636"><span id="translatedtitle">Evaluation of <span class="hlt">infrasound</span> signals from the shuttle Atlantis using a large seismic network.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Groot-Hedlin, Catherine D; Hedlin, Michael A H; Walker, Kristoffer T; Drob, Douglas P; Zumberge, Mark A</p> <p>2008-09-01</p> <p>Inclement weather in Florida forced the space shuttle "Atlantis" to land at Edwards Air Force Base in southern California on June 22, 2007, passing near three <span class="hlt">infrasound</span> stations and several hundred seismic stations in northern Mexico, southern California, and Nevada. The high signal-to-noise ratio, broad receiver coverage, and Atlantis' positional information allow for the testing of <span class="hlt">infrasound</span> propagation modeling capabilities through the atmosphere to regional distances. Shadow zones and arrival times are predicted by tracing rays that are launched at right angles to the conical shock front surrounding the shuttle through a standard climatological model as well as a global ground to space model. The predictions and observations compare favorably over much of the study area for both atmospheric specifications. To the east of the shuttle trajectory, there were no detections beyond the primary acoustic carpet. <span class="hlt">Infrasound</span> energy was detected hundreds of kilometers to the west and northwest (NW) of the shuttle trajectory, consistent with the predictions of ducting due to the westward summer-time stratospheric jet. Both atmospheric models predict alternating regions of high and low ensonifications to the NW. However, <span class="hlt">infrasound</span> energy was detected tens of kilometers beyond the predicted zones of ensonification, possibly due to uncertainties in stratospheric wind speeds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S24B..04G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S24B..04G"><span id="translatedtitle">Estimation <span class="hlt">Source</span> Parameters of Large-Scale Chemical Surface Explosions and Recent Underground Nuclear Tests</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gitterman, Y.; Kim, S.; Hofstetter, R.</p> <p>2013-12-01</p> <p> spectra of teleseismic P-waves. For a <span class="hlt">ground-truth</span> explosion with a shallow <span class="hlt">source</span> depth (relatively to an earthquake), this phenomenon can be interpreted in terms of the interference between the down-going P-wave energy and the pP phase reflected from the Earth's surface. A similar effect was observed before at ISN stations for the Pakistan explosion (28.05.98) at a different frequency 1.7 Hz indicating the <span class="hlt">source</span>- and not site-effect. Based on the null frequency dependency on the near-surface acoustic velocity and the <span class="hlt">source</span> depth, the depth of the both North Korea tests was estimated ~2 km, different from the value ~1 km informed by USGS. This depth estimation is based only on several closely placed teleseismic ISN stations and should be verified at other local networks on similar directions and distances from the test site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3656933','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3656933"><span id="translatedtitle">Group Behavioural Responses of Atlantic Salmon (Salmo salar L.) to Light, <span class="hlt">Infrasound</span> and Sound Stimuli</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bui, Samantha; Oppedal, Frode; Korsøen, Øyvind J.; Sonny, Damien; Dempster, Tim</p> <p>2013-01-01</p> <p>Understanding species-specific flight behaviours is essential in developing methods of guiding fish spatially, and requires knowledge on how groups of fish respond to aversive stimuli. By harnessing their natural behaviours, the use of physical manipulation or other potentially harmful procedures can be minimised. We examined the reactions of sea-caged groups of 50 salmon (1331±364 g) to short-term exposure to visual or acoustic stimuli. In light experiments, fish were exposed to one of three intensities of blue LED light (high, medium and low) or no light (control). Sound experiments included exposure to <span class="hlt">infrasound</span> (12 Hz), a surface disturbance event, the combination of <span class="hlt">infrasound</span> and surface disturbance, or no stimuli. Groups that experienced light, <span class="hlt">infrasound</span>, and the combination of <span class="hlt">infrasound</span> and surface disturbance treatments, elicited a marked change in vertical distribution, where fish dived to the bottom of the sea-cage for the duration of the stimulus. Light treatments, but not sound, also reduced the total echo-signal strength (indicative of swim bladder volume) after exposure to light, compared to pre-stimulus levels. Groups in <span class="hlt">infrasound</span> and combination treatments showed increased swimming activity during stimulus application, with swimming speeds tripled compared to that of controls. In all light and sound treatments, fish returned to their pre-stimulus swimming depths and speeds once exposure had ceased. This work establishes consistent, short-term avoidance responses to these stimuli, and provides a basis for methods to guide fish for aquaculture applications, or create avoidance barriers for conservation purposes. In doing so, we can achieve the manipulation of group position with minimal welfare impacts, to create more sustainable practices. PMID:23691087</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GSL.....3...26C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GSL.....3...26C"><span id="translatedtitle"><span class="hlt">Infrasound</span> and seismic detections associated with the 7 September 2015 Bangkok fireball</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caudron, Corentin; Taisne, Benoit; Perttu, Anna; Garcés, Milton; Silber, Elizabeth A.; Mialle, Pierrick</p> <p>2016-12-01</p> <p>A bright fireball was reported at 01:43:35 UTC on September 7, 2015 at a height of ˜30 km above 14.5°N, 98.9°E near Bangkok, Thailand. It had a TNT yield equivalent of 3.9 kilotons (kt), making it the largest fireball detected in South-East Asia since the ˜50 kt 2009 Sumatra bolide. Infrasonic signals were observed at four <span class="hlt">infrasound</span> arrays that are part of the International Monitoring System (IMS) and one <span class="hlt">infrasound</span> array located in Singapore. Acoustic bearings and event origin times inferred from array processing are consistent with the eyewitness accounts. A seismic signal associated with this event was also likely recorded at station SRDT, in Thailand. An acoustic energy equivalent of 1.15 ± 0.24 kt is derived from the Singaporean acoustic data using the period of the peak energy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E6105K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E6105K"><span id="translatedtitle">Nanotube Aerogel Sheet Flutter for Actuation, Power Generation, and <span class="hlt">Infrasound</span> Detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E.; Baughman, Ray H.; Lee, Hong H.; Kim, Yong Hyup</p> <p>2014-08-01</p> <p>Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect <span class="hlt">infrasound</span> at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for <span class="hlt">infrasound</span> frequencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4135338','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4135338"><span id="translatedtitle">Nanotube Aerogel Sheet Flutter for Actuation, Power Generation, and <span class="hlt">Infrasound</span> Detection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E.; Baughman, Ray H.; Lee, Hong H.; Kim, Yong Hyup</p> <p>2014-01-01</p> <p>Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect <span class="hlt">infrasound</span> at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for <span class="hlt">infrasound</span> frequencies. PMID:25130708</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.6324J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.6324J"><span id="translatedtitle">Lahar <span class="hlt">infrasound</span> associated with Volcán Villarrica's 3 March 2015 eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Jeffrey B.; Palma, Jose L.</p> <p>2015-08-01</p> <p>The paroxysmal 2015 eruption of Volcán Villarrica (Chile) produced a 2.5 h long lahar, which descended more than 20 km within the Rio Correntoso/Turbio drainage and destroyed two small bridges. A three-element <span class="hlt">infrasound</span> array 10 km from the summit, and 4 km from the lahar's closest approach, was used to study the flow's progression. Array processing using cross-correlation lag times and semblance places constraints on the lahar's dynamics, including detection of an initial flow pulse that traveled from 2 to 12 km at an average speed of 38 m/s. Subsequently, the lahar signal evolved to a relatively stationary infrasonic tremor located 10 to 12 km from the vent and adjacent to a topographic notch, through which sound may have preferentially diffracted toward the recording site. This study demonstrates the powerful capabilities of <span class="hlt">infrasound</span> arrays for lahar study and suggests their potential application for future hazard monitoring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1362M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1362M"><span id="translatedtitle">Atmospheric <span class="hlt">infrasound</span> propagation modelling using the reflectivity method with a direct formulation of the wind effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maupin, Valerie; Näsholm, Sven Peter; Schweitzer, Johannes; Gibbons, Steven J.</p> <p>2016-04-01</p> <p>We recently advocated using the reflectivity method, also known as the wavenumber integration method or fast-field program, to model atmospheric <span class="hlt">infrasound</span> propagation at regional distances. The advantage of the reflectivity method is its ability to model the full wavefield, including diffractive effects with head waves and shadow zone arrivals, in a broad frequency range but still at a relatively low computational cost. Attenuation can easily be included, giving the possibility to analyse relative amplitudes and frequency content of the different arrivals. It has clear advantages compared with ray theory in terms of predicting phases considering the particular frequent occurrence of shadow zone arrivals in <span class="hlt">infrasound</span> observations. Its main limitation, at least in the traditional form of the method, lies in the fact that it can only handle range-independent models. We presented earlier some reflectivity method simulations of an observed accidental explosion in Norway. Wind intensity and direction are non-negligible parameters for <span class="hlt">infrasound</span> propagation and these are appropriately taken into account in most <span class="hlt">infrasound</span> ray-tracing codes. On the other hand, in the previous reflectivity simulations wind was taken into account only through the effective sound speed approximation where the horizontal projection of the wind field is added to the adiabatic sound speed profiles. This approximation is appropriate for dominantly horizontal propagation but can give incorrect arrival times and shadow zone locations for waves which have a significant portion of their propagation path at more vertical incidence, like thermospheric arrivals. We present here how we have modified the original reflectivity algorithm in order to take the wind into account in a more correct fashion, and how this improvement influences the synthetics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA590009','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA590009"><span id="translatedtitle">Detection Optimization of the Progressive Multi-Channel Correlation Algorithm Used in <span class="hlt">Infrasound</span> Nuclear Treaty Monitoring</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2013-03-01</p> <p>microbaroms, mountain associated waves, volcanic eruptions , auroras, earthquakes, rockets, and explosions [5] [6]. Examination of <span class="hlt">infrasound</span> dating...progressive search for distant sensors to add to initial sub- arrays, a PMCC pitfall more comprehensively addressed in Section 2.3. WinPMCC’s solution to this...the goal is to minimize the total number of false alarm and missed detection categorization decisions. Specifically, the solution to this approach</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.2009L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.2009L"><span id="translatedtitle">Dust devil signatures in <span class="hlt">infrasound</span> records of the International Monitoring System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lorenz, Ralph D.; Christie, Douglas</p> <p>2015-03-01</p> <p>We explore whether dust devils have a recognizable signature in <span class="hlt">infrasound</span> array records, since several Comprehensive Nuclear-Test-Ban Treaty verification stations conducting continuous measurements with microbarometers are in desert areas which see dust devils. The passage of dust devils (and other boundary layer vortices, whether dust laden or not) causes a local temporary drop in pressure: the high-pass time domain filtering in microbarometers results in a "heartbeat" signature, which we observe at the Warramunga station in Australia. We also observe a ~50 min pseudoperiodicity in the occurrence of these signatures and some higher-frequency <span class="hlt">infrasound</span>. Dust devils do not significantly degrade the treaty verification capability. The pipe arrays for spatial averaging used in <span class="hlt">infrasound</span> monitoring degrade the detection efficiency of small devils, but the long observation time may allow a useful census of large vortices, and thus, the high-sensitivity infrasonic array data from the monitoring network can be useful in studying columnar vortices in the lower atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1326653','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1326653"><span id="translatedtitle">Detection of regional <span class="hlt">infrasound</span> signals using array data: Testing, tuning, and physical interpretation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Park, Junghyun; Stump, Brian W.; Hayward, Chris; Arrowsmith, Stephen J.; Che, Il-Young; Drob, Douglas P.</p> <p>2016-07-14</p> <p>This work quantifies the physical characteristics of <span class="hlt">infrasound</span> signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to <span class="hlt">infrasound</span> data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in <span class="hlt">infrasound</span> detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1326653-detection-regional-infrasound-signals-using-array-data-testing-tuning-physical-interpretation','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1326653-detection-regional-infrasound-signals-using-array-data-testing-tuning-physical-interpretation"><span id="translatedtitle">Detection of regional <span class="hlt">infrasound</span> signals using array data: Testing, tuning, and physical interpretation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Park, Junghyun; Stump, Brian W.; Hayward, Chris; ...</p> <p>2016-07-14</p> <p>This work quantifies the physical characteristics of <span class="hlt">infrasound</span> signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to <span class="hlt">infrasound</span> data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonablymore » variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in <span class="hlt">infrasound</span> detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19045635','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19045635"><span id="translatedtitle">Finite-difference time-domain synthesis of <span class="hlt">infrasound</span> propagation through an absorbing atmosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Groot-Hedlin, C</p> <p>2008-09-01</p> <p>Equations applicable to finite-difference time-domain (FDTD) computation of <span class="hlt">infrasound</span> propagation through an absorbing atmosphere are derived and examined in this paper. It is shown that over altitudes up to 160 km, and at frequencies relevant to global <span class="hlt">infrasound</span> propagation, i.e., 0.02-5 Hz, the acoustic absorption in dB/m varies approximately as the square of the propagation frequency plus a small constant term. A second-order differential equation is presented for an atmosphere modeled as a compressible Newtonian fluid with low shear viscosity, acted on by a small external damping force. It is shown that the solution to this equation represents pressure fluctuations with the attenuation indicated above. Increased dispersion is predicted at altitudes over 100 km at <span class="hlt">infrasound</span> frequencies. The governing propagation equation is separated into two partial differential equations that are first order in time for FDTD implementation. A numerical analysis of errors inherent to this FDTD method shows that the attenuation term imposes additional stability constraints on the FDTD algorithm. Comparison of FDTD results for models with and without attenuation shows that the predicted transmission losses for the attenuating media agree with those computed from synthesized waveforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27475150','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27475150"><span id="translatedtitle">Detection of regional <span class="hlt">infrasound</span> signals using array data: Testing, tuning, and physical interpretation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Junghyun; Stump, Brian W; Hayward, Chris; Arrowsmith, Stephen J; Che, Il-Young; Drob, Douglas P</p> <p>2016-07-01</p> <p>This work quantifies the physical characteristics of <span class="hlt">infrasound</span> signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to <span class="hlt">infrasound</span> data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in <span class="hlt">infrasound</span> detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. This suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014acm..conf...63B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014acm..conf...63B"><span id="translatedtitle">Using the international monitoring system of seismic, <span class="hlt">infrasound</span>, and hydroacoustic sensors for global airburst detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, P.</p> <p>2014-07-01</p> <p>The impact of meter-sized objects with the Earth occurs every few weeks [1,2]. Most of these collisions result in airbursts, here defined as impacts where the meteoroid's initial kinetic energy is of order a small nuclear weapon (> 0.1 kilotons of TNT equivalent = 4.185×10^{11} J) and where this energy is fully deposited at high altitude in the atmosphere. Historically, the majority of these airbursts go undetected over oceans or remote land areas as dedicated fireball camera networks (eg.[ 3]) cover less than 1 % of the globe. Airbursts often produce meteorite falls and hence airburst data may yield pre-atmospheric orbits and physical properties for the impacting NEO providing context for recovered meteorite samples [4]. With the advent of more capable telescopic survey systems, pre-atmospheric detection of NEO-producing airbursts has become possible as evidenced by the impacts of 2014 AA and 2008 TC_3 [5]. Detection of ''terminal plungers'' is expected to become more common as projects such as ATLAS [6] become operational. This increases the need for instrumental data of the corresponding airburst, particularly its location and energy. Beginning in the late 1990s, a global network of seismic, <span class="hlt">infrasound</span>, and hydroacoustic sensors has been deployed globally to provide treaty verification for a nuclear test ban. This network is the International Monitoring System (IMS) overseen by Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) [7]. The IMS is a unique global resource for detection of explosions worldwide and in recent years shock waves from many airbursts [8] have been detected by the system. Data from the IMS permits airburst location, origin time and energy to be measured. In rare cases, <span class="hlt">source</span> heights, trajectories, and details of fragmentation may be obtained. Here the current capabilities of the IMS will be presented in the context of airburst detection and characterization. Empirical characteristics of the long-range sound produced by airbursts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JVGR..288...46D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JVGR..288...46D"><span id="translatedtitle">Comparing near-regional and local measurements of <span class="hlt">infrasound</span> from Mount Erebus, Antarctica: Implications for monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dabrowa, A. L.; Green, D. N.; Johnson, J. B.; Phillips, J. C.; Rust, A. C.</p> <p>2014-11-01</p> <p>Local (100 s of metres from vent) monitoring of volcanic <span class="hlt">infrasound</span> is a common tool at volcanoes characterized by frequent low-magnitude eruptions, but it is generally not safe or practical to have sensors so close to the vent during more intense eruptions. To investigate the potential and limitations of monitoring at near-regional ranges (10 s of km) we studied <span class="hlt">infrasound</span> detection and propagation at Mount Erebus, Antarctica. This site has both a good local monitoring network and an additional International Monitoring System <span class="hlt">infrasound</span> array, IS55, located 25 km away. We compared data recorded at IS55 with a set of 117 known Strombolian events that were recorded with the local network in January 2006. 75% of these events were identified at IS55 by an analyst looking for a pressure transient coincident with an F-statistic detection, which identifies coherent <span class="hlt">infrasound</span> signals. With the data from January 2006, we developed and calibrated an automated signal-detection algorithm based on threshold values of both the F-statistic and the correlation coefficient. Application of the algorithm across IS55 data for all of 2006 identified infrasonic signals expected to be Strombolian explosions, and proved reliable for indicating trends in eruption frequency. However, detectability at IS55 of known Strombolian events depended strongly on the local signal amplitude: 90% of events with local amplitudes > 25 Pa were identified at IS55, compared to only 26% of events with local amplitudes < 25 Pa. Event detection was also affected by considerable variation in amplitude decay rates between the local and near-regional sensors. Amplitudes recorded at IS55 varied between 3% and 180% of the amplitude expected assuming hemispherical spreading, indicating that amplitudes recorded at near-regional ranges to Erebus are unreliable indicators of event magnitude. Comparing amplitude decay rates with locally collected radiosonde data indicates a close relationship between recorded</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51C2700A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2700A"><span id="translatedtitle"><span class="hlt">Infrasound</span> and Seismic Recordings of a US Airstrike on an ISIS Car Bomb Factory on June 3, 2015</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aleqabi, G. I.; Ghalib, H. A. A.; Wysession, M. E.</p> <p>2015-12-01</p> <p>Concurrent <span class="hlt">infrasound</span> and seismic records of a jet airstrike in Iraq are presented. Media reports stated that US jets carried out a large airstrike on June 3, 2015, just after midnight local time, that targeted and destroyed an ISIS car bomb factory in Hawija, Iraq, just south of the city of Kirkuk, Iraq. The resulting explosion was felt within Kirkuk and at other locations as far as 34 km away from the Hawija factory. Seismic broadband stations located in northern Iraq, at a distance of about 160 km, show clear simultaneous signals of <span class="hlt">infrasound</span> waves on the seismometers as well as on collocated <span class="hlt">infrasound</span> equipment. From an analysis of the body waves, the Pg to Lg time difference is nearly ~20 sec, with a back azimuth of 250o to 260o, which is consistent with explosion location. The time difference between the Pg and <span class="hlt">infrasound</span> signals is just over 7 minutes, consistent with sound speed in the atmosphere. No clear Rg wave was observed. As was demonstrated by Aleqabi, Wysession, and Ghalib [2015, BSSA, in press], broadband seismic recordings are able to identify and distinguish between several different kinds of MOUT (military operations in urban terrain) and even determine the magnitudes of ordinance used in certain blasts. The addition of collocated <span class="hlt">infrasound</span> equipment provides additional constraints that can be used in the analysis of the size and form of the MOUT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21895058','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21895058"><span id="translatedtitle">In situ calibration of atmospheric-<span class="hlt">infrasound</span> sensors including the effects of wind-noise-reduction pipe systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gabrielson, Thomas B</p> <p>2011-09-01</p> <p>A worldwide network of more than 40 <span class="hlt">infrasound</span> monitoring stations has been established as part of the effort to ensure compliance with the Comprehensive Nuclear Test Ban Treaty. Each station has four to eight individual <span class="hlt">infrasound</span> elements in a kilometer-scale array for detection and bearing determination of acoustic events. The frequency range of interest covers a three-decade range-roughly from 0.01 to 10 Hz. A typical <span class="hlt">infrasound</span> array element consists of a receiving transducer connected to a multiple-inlet pipe network to average spatially over the short-wavelength turbulence-associated "wind noise." Although the frequency response of the transducer itself may be known, the wind-noise reduction system modifies that response. In order to understand the system's impact on detection and identification of acoustical events, the overall frequency response must be determined. This paper describes a technique for measuring the absolute magnitude and phase of the frequency response of an <span class="hlt">infrasound</span> element including the wind-noise-reduction piping by comparison calibration using ambient noise and a reference-microphone system. Measured coherence between the reference and the <span class="hlt">infrasound</span> element and the consistency between the magnitude and the phase provide quality checks on the process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.3867Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.3867Q"><span id="translatedtitle">Design of monitoring and early warning system for geo-hazards in Three Gorges reservoir area using <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiu, N.; Zeng, Z. X.; Yang, Y. C.</p> <p>2009-04-01</p> <p>With the progress of the Three Gorges Dam Project, geological disasters have become increasingly prominent. The reservoir area prone to landslides, collapses, cracks, and earthquake disaster because the complex terrain and geological conditions. It is of significance to monitor and foresee geo-hazards in the reservoir area. Here we introduce our design of monitoring and early warning system for geo-hazards in Three Gorges reservoir area using <span class="hlt">infrasound</span>. <span class="hlt">Infrasound</span> may be abnormal during geological disasters, such as debris and earthquake occurred. The formation a d movement of debris flow in its basin will generate <span class="hlt">infrasound</span>, and spread to the surrounding air medium. Velocity of <span class="hlt">infrasound</span> is much larger than that of debris flow, so we can monitor and forecast debris flow using <span class="hlt">infrasound</span>. The sudden vertical displacement brought about by earthquake will generate acoustic-gravity wave which can be observed in distance to monitor earthquake, especially to monitor earthquake precursors. So we try to monitor the geological disasters for the Three Gorges reservoir area in China by design a <span class="hlt">infrasound</span> array monitor system. This work is supported by Chinese "985 Project". The <span class="hlt">infrasound</span> monitor system is comprised of two observation stations arranged in Badong county inside the reservoir area and in Wuhan city, respectively. Each station has respectively arranged a kind of augmentable linear array in the form of quasi-uniform linear array and additional amending direction sensors. The linear array comprises eight sensors arranged in several different uniform intervals along a line. The amending direction sensor is situated at certain point in mid-perpendicular of linear array in order to reduce multiplicity in determine the direction of arrival. The sensors used in the system are CDC-2B capacitances infrasonic receiver which can observe frequency ranging 0~20Hz. The, measurement resolution is 750mV/LPa. Infrasonic wave signal collected by sensor is transferred from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51D2706S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2706S"><span id="translatedtitle">Characterizing Explosive Eruptions at Sakurajima Volcano, Japan, Using Seismic, <span class="hlt">Infrasound</span>, Lightning and Video Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, C. M.; Behnke, S. A.; Thomas, R. J.; Edens, H. E.; Cimarelli, C.; Cigala, V.; Van Eaton, A. R.; Iguchi, M.; Miki, D.; McNutt, S. R.</p> <p>2015-12-01</p> <p>The ability to determine volcanic ash plume characteristics from seismic and/or infrasonic records would enable increased accuracy in volcanic monitoring during times of low visibility. During May-June 2015 a field deployment of 6 <span class="hlt">infrasound</span> sensors, 2 seismometers, multiple cameras, and 10 Lightning Mapping Array (LMA) stations were deployed around Sakurajima Volcano in Japan. During one month of observations (13 May to 10 June) hundreds of explosive eruptions were observed with plume heights reaching 4.3 km above the vent. The plumes varied in duration, ash content, and physical form. The resulting explosions exhibited a variety of <span class="hlt">infrasound</span> waveforms including the classic long-period N shape as well as events with a mixture of high and low frequencies. For a subset of larger events, peak pressures ranged from 16 to 741 Pa at a distance of 3.6 km from the vent. The seismic signals are long period and emergent with no clear P or S-waves, although high frequency ground-coupled airwaves are visible in conjunction with the infrasonic record of some of the explosive eruptions. Peak ground displacements on the vertical component ranged from 2.1 to 183 um for the same subset of events. Volcanic lightning was both visually observed and recorded on the LMA stations. One of the goals of this project to determine if there are intrinsic relationships between ash plume characteristics, such as initial velocity or acceleration, ash grain size, texture, and composition, seismic and <span class="hlt">infrasound</span> waveforms, and the presence and type of volcanic lightning. The rich variety of observations provides a good opportunity to determine such relationships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.2446E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.2446E"><span id="translatedtitle">Complex monitoring and alert network for electromagnetic, <span class="hlt">infrasound</span>, acoustic seismotectonic phenomena</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>-Emilian Toader, Victorin; Moldovan, Iren-Adelina; Constantin, Ionescu</p> <p>2014-05-01</p> <p>The Romanian seismicity recorded in 2013 three important events: the largest seismic "silence", the shortest sequence of two earthquakes greater than 4.8R in less than 14 days after the "Romanian National Institute for Earth Physics" (NIEP) developed a digital network, and a very high crustal activity in Galati area. We analyze the variations of the telluric currents and local magnetic field, variations of the atmospheric electrostatic field, <span class="hlt">infrasound</span>, temperature, humidity, wind speed and direction, atmospheric pressure, variations in the earth crust with inclinometers and animal behavior. The general effect is the first high seismic energy discontinuity that could be a precursor factor. Since 1977 Romania did not register any important earthquake that would generate a sense of fear among the population. In parallel with the seismic network NIEP developed a magneto-telluric, bioseismic, VLF and acoustic network. A large frequency spectrum is covered for mechanical vibration, magnetic and electric field with ground and air sensors. Special software was designed for acquisition, analysis and real time alert using internet direct connection, web page, email and SMS. Many examples show the sensitivity of telluric current, <span class="hlt">infrasound</span>, acoustic records (from air-ground), and the effect of tectonic stress on the magnetic field or ground deformation. The next update of the multidisciplinary monitoring network will include measurement of ionization, radon emission, sky color, solar radiation and extension of <span class="hlt">infrasound</span> and VL/LF equipment. NOAA Space Weather satellites transmit solar activity magnetic field data, X ray flux, electron, and proton flux information useful for complex analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27369137','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27369137"><span id="translatedtitle">Analysis and modeling of <span class="hlt">infrasound</span> from a four-stage rocket launch.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blom, Philip; Marcillo, Omar; Arrowsmith, Stephen</p> <p>2016-06-01</p> <p><span class="hlt">Infrasound</span> from a four-stage sounding rocket was recorded by several arrays within 100 km of the launch pad. Propagation modeling methods have been applied to the known trajectory to predict infrasonic signals at the ground in order to identify what information might be obtained from such observations. There is good agreement between modeled and observed back azimuths, and predicted arrival times for motor ignition signals match those observed. The signal due to the high-altitude stage ignition is found to be low amplitude, despite predictions of weak attenuation. This lack of signal is possibly due to inefficient aeroacoustic coupling in the rarefied upper atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9450P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9450P"><span id="translatedtitle">On the use of <span class="hlt">infrasound</span> sensors for low frequency atmospheric studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ponceau, Damien; Marty, Julien; Koenig, Jean-Marc; Denis, Stéphane; Ulziibat, Munkhuu</p> <p>2010-05-01</p> <p>Most of infrasonic stations from International Monitoring System (IMS) of the Comprehensive Nuclear Test Organization (CTBTO) use absolute <span class="hlt">infrasound</span> sensors associated with acquisition units dedicated to geophysics. These sensors measure ambient atmospheric pressure over a frequency bandwidth from DC to tens of Hz, including the entire <span class="hlt">infrasound</span> frequency range. The reference cavity vacuum gives them an intrinsic thermal sensitivity much lower than that of differential <span class="hlt">infrasound</span> sensors such as microphones. Experience shows that this is especially interesting when low frequency pressure measurements are needed. Direct digitizing of such signals requires a dynamic range better than 145 dB over the frequency bandwidth of interest. Microbarometers were equipped with an additional output attenuating the very low frequencies with a simple first order high pass filter with a cutoff frequency of 0.01 Hz and a gain over its bandwidth of 20. This output has a dynamic range of about 108 dB easier to digitize. It is made from electronic components selected for their accuracy, their stability and insensitivity to environment. This is the "filtered output" which is generally used on the IMS. More and more scientific studies for civilian applications focus on low frequency signals affected by this filtering. This presentation discusses how the use of this filtered output affects data quality in this frequency range and how it is possible to exploit them. Microbarometer output stage has been modeled to estimate the noise induced by filtering and its influence on the infrasonic signals of interest. This presentation discusses how it is possible to compensate filter's influence to recover the "true" signals of interest. It explains how the operating principle of these sensors can minimize errors. Three stations consisting in four sensors were set up in Mongolia in order to record pressure variations produced by the total solar eclipse of the 1 August 2008. For each sensor, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060043601&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060043601&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dtruth"><span id="translatedtitle">MER vistas: <span class="hlt">ground-truth</span> for Earth-based radar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haldemann, Albert F.; Larsen, Kristopher W.; Jurgens, Raymond F.; Golombek, Matthew P.; Slade, Martin A.</p> <p>2004-01-01</p> <p>Earth-based delay-Doppler radar observations of Mars with four receiving stations were carried out during the Mars oppositions of 2001 and 2003 in support of Mars Exploration Rover landing site selection. This interferometric planetary radar technique has demonstrated radar mapping of Mars with a 5 km spatial resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100009427','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100009427"><span id="translatedtitle">LRO Diviner Soil Composition Measurements - Lunar Sample <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Allen, Carlton C.; Greenhagen, Benjamin T.; Paige, David A.</p> <p>2010-01-01</p> <p>The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter [1,2] includes three thermal infrared channels spanning the wavelength ranges 7.55-8.05 microns 8.10-8.40 microns, and 8.38-8.68 microns. These "8 micron" bands were specifically selected to measure the "Christiansen feature". The wavelength location of this feature, referred to herein as CF, is particularly sensitive to silicate minerals including plagioclase, pyroxene, and olivine the major crystalline components of lunar rocks and soil. The general trend is that lower CF values are correlated with higher silica content and higher CF values are correlated with lower silica content. In a companion abstract, Greenhagen et al. [3] discuss the details of lunar mineral identification using Diviner data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AAS...22934717N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AAS...22934717N"><span id="translatedtitle">Quantitative Morphology Measures in Galaxies: <span class="hlt">Ground-Truthing</span> from Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Narayanan, Desika T.; Abruzzo, Matthew W.; Dave, Romeel; Thompson, Robert</p> <p>2017-01-01</p> <p>The process of galaxy assembly is a prevalent question in astronomy; there are a variety of potentially important effects, including baryonic accretion from the intergalactic medium, as well as major galaxy mergers. Recent years have ushered in the development of quantitative measures of morphology such as the Gini coefficient (G), the second-order moment of the brightest quintile of a galaxy’s light (M20), and the concentration (C), asymmetry (A), and clumpiness (S) of galaxies. To investigate the efficacy of these observational methods at identifying major mergers, we have run a series of very high resolution cosmological zoom simulations, and coupled these with 3D Monte Carlo dust radiative transfer. Our methodology is powerful in that it allows us to “observe” the simulation as an observer would, while maintaining detailed knowledge of the true merger history of the galaxy. In this presentation, we will present our main results from our analysis of these quantitative morphology measures, with a particular focus on high-redshift (z>2) systems.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760020566','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760020566"><span id="translatedtitle">Soil-moisture <span class="hlt">ground</span> <span class="hlt">truth</span>, Hand County, South Dakota</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.</p> <p>1976-01-01</p> <p>Soil types were determined from the Soil Survey of Hand County, South Dakota. The soil types encountered on the soil moisture lines are summarized. The actual soil moisture data are presented. The data have been divided by range, township and section. The soil moisture data obtained in fields of winter wheat and spring wheat are briefly summarized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760023549','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760023549"><span id="translatedtitle">Soil-moisture <span class="hlt">ground</span> <span class="hlt">truth</span>, Hand County, South Dakota</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.</p> <p>1976-01-01</p> <p>Soil samples were taken in the field and carefully preserved in taped metal containers for later laboratory gravimetric analysis to determine soil-moisture content. The typical sampling pattern used in this mission is illustrated, and the soil types encountered on the soil-moisture lines are summarized. The actual soil-moisture data were tabulated by range, township and section. Soil-moisture data obtained in fields of winter wheat and spring wheat are briefly summarized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA570025','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA570025"><span id="translatedtitle">Development of Mine Explosion <span class="hlt">Ground</span> <span class="hlt">Truth</span> Smart Sensors</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-09-01</p> <p>interest. The two candidates are the GS11-D by Oyo Geospace that is used extensively in seismic monitoring of geothermal fields and the Sensor Nederland SM...Technologies 853 Figure 4. Our preferred sensors and processor for the GTMS. (a) Sensor Nederland SM-6 geophone with emplacement spike. (b</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA473142','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA473142"><span id="translatedtitle">Global <span class="hlt">Ground</span> <span class="hlt">Truth</span> Data Set with Waveform and Arrival Data</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-07-30</p> <p>the NW by 18 km toward the African-European plate boundary. Even though the error ellipses are small, no events are promoted to GT5...17 10381 Rotorua, New Zealand -37.993 176.664 5.5 22 19 10386 Kileaua South Flank, Hawaii 19.312 -155.267 9.5 104 56 10500 Spitak, Armenia 41.012...recorded by 361 regional and teleseismic stations. The dashed line represents the plate boundary between the Eurasian and Philippine Sea plates (Bird</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S23E..07B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S23E..07B"><span id="translatedtitle">The <span class="hlt">Ground</span> <span class="hlt">Truth</span> of Crustal Anisotropy from Receiver Functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bianchi, I.; Apoloner, M. T.; Qorbani, E.; Lloyd, S. M.; Gribovski, K.; Gerner, A.; Arneitz, P.; Jordakiev, P.; Bokelmann, G.</p> <p>2014-12-01</p> <p>As one of the rare observational tools for studying deformation and stress within the Earth, seismic anisotropy has been one of the focuses of geophysical studies over the last decade. Recently, in order to unravel the anisotropic properties of the crust, the teleseismic receiver functions (RFs) methodology has been largely applied. Effects of anisotropy on the RFs dataset were illustrated in more than one theoretical study, showing the strong backazimuthal dependence of RFs on the 3D characteristics of the traversed media. The use of teleseismic RFs has the advantage of not being affected by heterogeneous depth distribution of local earthquakes, since teleseismic rays sample the entire crust beneath the stations. The application of this technique anyway, needs to be critically assessed using a suitable field test. To test this technique, we need a crustal block where the underground structure is reasonably well-known, e.g., where there is extensive knowledge from local seismic experiments and drilling. Therefore a field test around the KTB (Kontinental Tiefbohrung) site in the Oberpfalz in Southeastern Germany, has been carried out to test the technique, and to compare with previous results from deep drilling, and high-frequency seismic experiments around the drill site. The investigated region has been studied extensively by local geophysical experiments. The deep borehole was placed into gneiss rocks of the Zone Erbendorf-Vohenstrauss. Drilling activity lasted from 1987 to 1994, and descended down to a depth of 9101 meters, sampling an alternating sequence of paragneiss and amphibolite, with metamorphism of upper amphibolite facies conditions, and ductile deformation produced a strong foliation of the rocks. The application of the RFs reveals strong seismic anisotropy in the upper crust related to the so-called Erbendorf body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA224857','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA224857"><span id="translatedtitle">ALP FOPEN Site Description and <span class="hlt">Ground</span> <span class="hlt">Truth</span> Summary</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1990-02-01</p> <p>is comprised of inactive phloem cells. The next layer, which is usually only several millimeters thick, is the phloem layer. The cells in this layer...The bark layer; 2. The outside of the phloem layer, just to the inside of the cortex. Because this layer is often less than .10 cm thick, the outer...xylem layer is also influencing the dielectric constant measurement; 3. The inside of the phloem layer. The phloem layer can often be clearly separated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1019341','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1019341"><span id="translatedtitle">Operational Assessment of CAS in COIN: Airing the <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-04-01</p> <p>might be excessively predisposed to organic fires. Such was the case during Anaconda, as a key lesson identified was the failure to include airmen...firing ordnance) might be optimal for a B-1 Bomber. This could be the case if an Army patrol is pinned in a valley based on SIGINT of enemy...build on practices adopted from service-oriented private industry rather than defense R&D constructs. The customer in this case is any ground commander</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvE..90f2805H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvE..90f2805H"><span id="translatedtitle">Community detection in networks: Structural communities versus <span class="hlt">ground</span> <span class="hlt">truth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hric, Darko; Darst, Richard K.; Fortunato, Santo</p> <p>2014-12-01</p> <p>Algorithms to find communities in networks rely just on structural information and search for cohesive subsets of nodes. On the other hand, most scholars implicitly or explicitly assume that structural communities represent groups of nodes with similar (nontopological) properties or functions. This hypothesis could not be verified, so far, because of the lack of network datasets with information on the classification of the nodes. We show that traditional community detection methods fail to find the metadata groups in many large networks. Our results show that there is a marked separation between structural communities and metadata groups, in line with recent findings. That means that either our current modeling of community structure has to be substantially modified, or that metadata groups may not be recoverable from topology alone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070030107','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070030107"><span id="translatedtitle">Remote and <span class="hlt">Ground</span> <span class="hlt">Truth</span> Spectral Measurement Comparisons of FORMOSAT III</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abercromby, Kira Jorgensen; Hamada, Kris; Guyote, Michael; Okada, Jennifer; Barker, Edwin</p> <p>2007-01-01</p> <p>FORMOSAT III are a set of six research satellites from Taiwan that were launched in April 2006. The satellites are in 800 km, 71 degree inclination orbits and separated by 24 degrees in ascending node. Laboratory spectral measurements were taken of outer surface materials on FORMOSAT III. From those measurements, a computer model was built to predict the spectral reflectance accounting for both solar phase angle and orientation of the spacecraft relative to the observer. However, materials exposed to the space environment have exhibited spectral changes including a darkening and a "reddening" of the spectra. This "reddening" is characterized by an increase in slope of the reflectance as the wavelength increases. Therefore, the model of pre-flight materials was augmented to include the presumed causative agent: space weathering effects. Remote data were collected on two of the six FORMOSAT satellites using the 1.6 meter telescope at the AMOS (Air Force Maui Optical and Supercomputing) site with the Spica spectrometer. Due to the separation in ascending node, observations were acquired of whichever one of the six satellites was visible on that specific night. Three nights of data were collected using the red (6000 - 9500 angstroms) filter and five nights of data were collected using the blue (3200 - 6600 angstroms) filter. A comparison of the data showed a good match to the pre-flight models for the blue filter region. The absorption feature near 5500 angstroms due to the copper colored Kapton multi-layer insulation (MLI) was very apparent in the remote samples and a good fit to the data was seen in all satellites observed. The features in the red filter regime agreed with the pre-flight model up through 7000 angstroms where the reddening begins and the slope of the remote sample increases. A comparison of the satellites showed similar features in the red and blue filter regions, i.e. the satellite surfaces were aging at the same rate. A comparison of the pre-flight model to the first month of remote measurements showed the amount by which the satellite had reddened. The second month of data observed a satellite at a higher altitude and was therefore, not compared to the first month. A third month of data was collected but of satellites at the lower altitude regime and can only be compared to the first month. One cause of the reddening that was ruled out in early papers was a possible calibration issue.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.4394B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4394B"><span id="translatedtitle">The IDC Seismic, Hydroacoustic and <span class="hlt">Infrasound</span> low and high noise models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, David; Brachet, Nicolas; Mialle, Pierrick; Lebras, Ronan</p> <p>2010-05-01</p> <p>The International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) in Vienna, Austria, is developing the capability to routinely determine the sensor noise levels for all Seismic, Hydroacoustic and <span class="hlt">Infrasound</span> (SHI) stations of the International Monitoring System (IMS) sending data to the IDC. This noise data can be used to provide state of health information to station maintenance personnel, and can be used in network detection capability analyses, and can also be used as a quality control measure in automatic processing. Station noise is being determined as a Power Spectral Density (PSD) using the Welch overlapping method. When PSD's for a given sensor are collected over time and considered together it is possible to generate a Probability Density Function (PDF) for the power spectra and determine low- and high-noise curves that bound the PDF. When used in data quality control applications warnings can be issued if the PSD for incoming data for a given sensor is not found to be bounded by the previously determined low and high noise models for that sensor. In this paper, low and high noise models will be presented for representative seismic, hydroacoustic and <span class="hlt">infrasound</span> stations, as well as preliminary global low and high noise models for each of these technologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51C2697P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2697P"><span id="translatedtitle">Detection of Regional <span class="hlt">Infrasound</span> Signals Using Array Data - Testing, Tuning, and Physical Interpretation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, J.; Stump, B. W.; Hayward, C.; Arrowsmith, S.; Che, I. Y.; Drob, D. P.</p> <p>2015-12-01</p> <p>In order to understand the impact environmental conditions have on <span class="hlt">infrasound</span> detection, an automated detector that accounts for both correlated and uncorrelated noise is run on data from a number of infrasonic arrays, all in a regional context. Data from six seismo-acoustic arrays in South Korea (BRDAR, CHNAR, KMPAR, KSGAR, TJIAR, and YPDAR), which are cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU), were used. An adaptive F-detector (AFD) (Arrowsmith et al., 2009) is applied that utilizes the F-statistic (Blandford, 1974) with an adaptive procedure that assesses variations in coherent noise in order to reduce false alarms. The adaptive procedure is characterized by the time dependent C-value that is found to depend on the weather conditions and local site effects. Arrays located on islands or near the coast produce noise power densities that are higher, consistent with both higher wind speeds as well as ocean wave contributions that vary seasonally. These results suggest that optimal detection processing requires careful characterization of background noise level and its relationship to enviornmental measures at individual arrays. This study also documents significant seasonal variations in <span class="hlt">infrasound</span> detections including daily time of occurrence, total number of detections, and phase velocity/azimuth estimates. These time-dependent effects in most part explained by atmospheric models across the Korean peninsula as described by Drob et al. (2003).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRD..119.8659A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRD..119.8659A"><span id="translatedtitle">Evaluation of wind and temperature profiles from ECMWF analysis on two hemispheres using volcanic <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Assink, J. D.; Pichon, A. Le; Blanc, E.; Kallel, M.; Khemiri, L.</p> <p>2014-07-01</p> <p>In this paper, we evaluate vertical wind and temperature profiles that are produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric analysis. The evaluation is carried out on both hemispheres: we make use of stratospheric <span class="hlt">infrasound</span> arrivals from Mount Etna (37°N) and Mount Yasur (22°S). The near-continuous, high activity of both volcanoes permits the study of stratospheric propagation along well-defined paths with a time resolution ranging from hours to multiple years. <span class="hlt">Infrasound</span> observables are compared to theoretical estimates obtained from acoustic propagation modeling using the ECMWF analysis. While a first-order agreement is found for both hemispheres, we report on significant discrepancies around some of the equinox periods and other intervals during which the atmosphere is in a state of transition and dynamical oscillations of the atmosphere dominate over the general circulation. We present an inversion study in which we make use of measured trace velocity estimates to estimate first-order effective sound speed model updates in a Bayesian framework. Deviations from the a priori models around the stratopause up to 10% (≈ 30 m s-1) are estimated. Such updates are in line with the results from comparisons between ECMWF analysis and observations from lidar and microwave Doppler spectroradiometer facilities that were colocated during the course of the 2012-2013 Atmospheric dynamics Research and InfraStructure in Europe (ARISE) measurement campaign.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1004164','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1004164"><span id="translatedtitle">Linear and Nonlinear <span class="hlt">Infrasound</span> Propagation to 1000 km</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2015-12-15</p> <p>to their average sea level values and the ambient temperature is set to 15oC, giving a static sound speed of 340 m/s. The <span class="hlt">source</span> is centered at an...alters the governing equations, but results in quantifiable dispersion characteristics. It is shown that this method leaves sound speeds and...2. Profiles of a) density, b) sound speed, and c) attenuation as a function of altitude -- 13 3. FDTD Pressure fluctuation snapshots, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.6614C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.6614C"><span id="translatedtitle">On the use of remote <span class="hlt">infrasound</span> and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caudron, Corentin; Taisne, Benoít; Garcés, Milton; Alexis, Le Pichon; Mialle, Pierrick</p> <p>2015-08-01</p> <p>The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and <span class="hlt">infrasound</span> sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and <span class="hlt">infrasound</span> events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by <span class="hlt">infrasound</span> sensors and up to 2300 km away on seismometers. A seismic event followed ˜12 minutes later and was recorded 7000 km away by seismometers. We estimate a volcanic intensity around 10.9, placing the 2014 Kelud eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. We demonstrate how remote <span class="hlt">infrasound</span> and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51D2702T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2702T"><span id="translatedtitle">On the use of remote <span class="hlt">infrasound</span> and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taisne, B.; Caudron, C.; Garces, M. A.; Mialle, P.; LE Pichon, A.</p> <p>2015-12-01</p> <p>The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and <span class="hlt">infrasound</span> sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and <span class="hlt">infrasound</span> events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by <span class="hlt">infrasound</span> sensors, and up to 2,300 km away on seismometers. A seismic event followed ~12 minutes later and was recorded 7,000 km away by seismometers. We estimate a volcanic intensity [Pyle,2000] around 10.9, placing the 2014 Kelud eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. We demonstrate how remote <span class="hlt">infrasound</span> and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA569462','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569462"><span id="translatedtitle">Sayarim <span class="hlt">Infrasound</span> Calibration Explosion: Near-<span class="hlt">Source</span> and Local Observations and Yield Estimation</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2010-09-01</p> <p>of large-scale explosions on soft soil (Adushkin and Khristoforov , 2004): R = 3.36W0.336; H = 1.78W0.316 , (1) where W is TNT equivalent... Khristoforov (2004). Craters of large-scale surface explosions, Combust, Explo. Shock Waves 40: 674–678. Bowman, J. R., H. Israelsson, G. Shields, M</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1213066R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1213066R"><span id="translatedtitle">Parallel Grid approach to solve Feature Selection problem in volcanic <span class="hlt">infrasound</span> signals classification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reitano, Danilo; Pistagna, Fabrizio; Russo, Gaetano; Valenti, Vincenzo</p> <p>2010-05-01</p> <p>The continuous monitoring of an active volcano, such as Mt. Etna (Sicily, Italy), represents one of the main tasks for the Italian National Institute of Geophysics and Volcanology (INGV), Catania Branch. Around the volcano summit area, four <span class="hlt">infrasound</span> sensors have been installed during the last recent years, which allow to acquire, real time waveforms that are subsequently stored on a server, located inside the INGV Control Room. A new method here introduced, based on Genetic Algorithms (GA), has been used to analyze the data coming from the remote <span class="hlt">infrasound</span> sensors stations. In particular, the acquired signals have been processed by a custom modular software: the first module allows the visual manipulation, filtering and, in order to optimize performances, resampling the data to better elaborate them. The second module, using an alghorithm (G. Russo, 2009 ) based on two different thresholds (upper and lower) and the standard deviation, is able to recognize and collect <span class="hlt">infrasound</span> events (IE) from the stored data. In the third step, the Green & Nueberg algorithm (2006) is used to correlate different families of IE and define the clusters nodes. Once a minimum number of families are characterized, they define the main features inside each cluster. Feature extraction process is a very complex algorithm due to the large number of requested correlations. In order to speed up the time needed to carry out so many simulations, the code has been deployed and executed on the Sicilian Grid infrastructure owned and managed by the Consorzio Cometa, a not-for-profit organisation including INGV among its members. The infrastructure, distributed across the Sicilian territory, is composed of 7 sites for a total of about 2000 CPU cores and more than 250 TB of storage. All the sites of the infrastructure are equipped with low latency Infiniband networks and are installed with MPI libraries. A complete workflow has been created from scratch to execute the various phases of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S53D..01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S53D..01L"><span id="translatedtitle">Long-Period Seismicity and Very-Long-Period <span class="hlt">Infrasound</span> Driven by Shallow Magmatic Degassing at Mount Pagan, Mariana Islands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lyons, J. J.; Haney, M. M.; Werner, C. A.; Kelly, P. J.; Patrick, M. R.; Kern, C.; Trusdell, F.</p> <p>2015-12-01</p> <p>Mount Pagan is the currently active vent on the north end of Pagan Volcano, Mariana Islands. A persistent degassing plume, LP seismicity, and VLP <span class="hlt">infrasound</span> (iVLP) have dominated activity since at least 2013, when ground-based geophysical sensors were first installed. Direct gas sampling with a Multi-GAS sensor indicates a plume generated by a shallow magmatic system. Here we present an analysis of coupled LP and iVLP events in order to reveal the details of their <span class="hlt">source</span> processes and how the signals are related to shallow magmatic degassing. The LP and iVLP waveform characteristics were highly stable from July 2013 - January 2014. Both events have durations of 5-20 s, occur every 1-2 minutes, and have emergent onsets. The LP events have a dominant frequency of 0.54 Hz, while the dominant frequency of the iVLP is 0.32 Hz. The delay times between the LP and iVLP arrivals show little variation during the 7-month study, indicating a stable, shallow, and nearly co-located <span class="hlt">source</span>. Full waveform inversion of a master LP event reveals a volumetric <span class="hlt">source</span> 60 m below and 180 m west of the summit vent. Inverting Green's functions of different geometric combinations results in a 2-crack model dominated by a subhorizontal crack intersecting a NW-SE trending dike. The extension of the modeled crack intersects the surface near the vent location. The nearly horizontal orientation of the dominant crack is likely controlled by the orientation of lava flows and pyroclastic deposits that are observed in the western wall of the cone at the LP depth. We propose that the LP seismicity is crack resonance triggered by collapse of the gas-charged upper conduit system following periodic venting. Measured and modeled pressure-velocity (P/Vz) ratios for the seismoacoustic events indicate that elastodynamic processes associated with the seismic LP cannot generate the iVLP. Thus, we model the iVLP as volume resonance of an exponential horn, based on the shape of the crater and the wavelength of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/116295','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/116295"><span id="translatedtitle">Reduction of swimming time in mice through interaction of <span class="hlt">infrasound</span> and alcohol.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lehmann, A G; Busnel, R G</p> <p>1979-09-01</p> <p>The effects of noise, alcohol, and the combination of the two were studied on muscular fatigue in several mouse strains to investigate a possible interaction between the two stresses. Muscular fatigue was measured by latency to submersion during a forced-swimming test. Animals were exposed to acoustic stimuli of fixed frequency and intensity for 2h preceding the test. Ethanol was administered orally from 30 min to 3h 30 min prior to testing. Alcohol doses and sound intensities were subliminal when administered separately. While no significant interaction occurred between alcohol and audible sound, the interaction between alcohol and <span class="hlt">infrasound</span> was highly significant indicating that their joint effects are more than merely additive. Blood alcohol measurements indicate that these interactive effects are prolonged for more than 2h after elimination of alcohol from the blood. Effects are similar in genetically deaf and hearing mice, implicating involvement of nonauditory pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRD..114.8112L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRD..114.8112L"><span id="translatedtitle">Assessing the performance of the International Monitoring System's <span class="hlt">infrasound</span> network: Geographical coverage and temporal variabilities</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Pichon, A.; Vergoz, J.; Blanc, E.; Guilbert, J.; Ceranna, L.; Evers, L.; Brachet, N.</p> <p>2009-04-01</p> <p>A global-scale analysis of detections made at all 36 currently operating International Monitoring System (IMS) <span class="hlt">infrasound</span> arrays confirms that the primary factor controlling signal detectability is the seasonal variability of the stratospheric zonal wind. At most arrays, ˜80% of the detections in the 0.2- to 2-Hz bandpass are associated with propagation downwind of the dominant stratospheric wind direction. Previous IMS <span class="hlt">infrasound</span> network performance models neglect the time- and site-dependent effects of both stratospheric meteorological variability and ambient noise models. In this study both effects are incorporated; we compare empirical and improved specifications of the stratospheric wind and include station-dependent wind noise models. Using a deterministic approach, the influence of individual model parameters on the network performance is systematically assessed. At frequencies of interest for detecting atmospheric explosions (0.2-2 Hz), the simulations predict that explosions equivalent to ˜500 t of TNT would be detected by at least two stations at any time of the year. The detection capability is best around January and July when stratospheric winds are strongest, compared to the equinox periods when zonal winds reduce and reverse. The model predicts that temporal fluctuations in the ground-to-stratosphere meteorological variables generate detection threshold variations on daily and seasonal timescales of ˜50 and ˜500 t, respectively. While the strong zonal winds lead to an improvement in detection capability, their highly directional nature leads to an increase in the location uncertainty owing to the decreased azimuthal separation of the detecting stations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4337M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4337M"><span id="translatedtitle">Ionosonde tracking of <span class="hlt">infrasound</span> wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel</p> <p>2015-04-01</p> <p>It is well known that atmospheric waves excited by intense earthquakes induce ionospheric disturbances. At remote distances greater than ~500 km, Rayleigh waves are the major <span class="hlt">source</span> of <span class="hlt">infrasounds</span> that propagate upward in the atmosphere. Acoustic waves interact with the ionospheric plasma through collision between neutral particles and ions. Ionospheric disturbances caused by Rayleigh waves near the low frequency part of the Airy phase (a period of several minutes) are detected as a change in the total electron content since the wavelength of induced acoustic waves in the thermosphere is comparable to the ionospheric slab thickness. On the other hand, Rayleigh waves near the high frequency part of the Airy phase (a period of several tens of seconds) cause distortion of ionogram traces characterized by a multiple cusp signature (MCS). The vertical separation of the ledge corresponding to each cusp is the wavelength of the <span class="hlt">infrasound</span> in the thermosphere. Thus, the MCS ionogram is considered to be a snapshot of the wave that propagates upward. We conducted rapid run operation of ionosonde with a frame rate of 1 min at Kazan, Russia. After the 2010 M8.8 Chile earthquake (epicentral distance was 15,162 km), ionospheric disturbances showing MCSs on ionograms were observed for several tens of minutes. The sound speed calculated by a model was 500~700 m/s at the height of the bottomside ionosphere and wavefronts should propagate 30~42 km upward during the intervals of ionograms, which is smaller than the bottomside depth of the ionosphere. The seismogram obtained at Obninsk near Moscow, Russia (epicentral distance was 14,369 km) recorded Rayleigh waves with a period of ~17 s responsible for the ionospheric disturbances showing MCS, when the plot was shifted by the time corresponding to the difference of epicentral distances between the two locations by assuming a Rayleigh wave speed of 3 km/s. The vertical wavelength of the acoustic waves launched by the Rayleigh waves was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.9200D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.9200D"><span id="translatedtitle">A study of volcanic eruption characteristics using <span class="hlt">infrasound</span> data recorded on the global IMS network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dabrowa, Amy; Green, David; Phillips, Jeremy; Rust, Alison</p> <p>2010-05-01</p> <p>Explosive volcanic eruptions have the capability to generate sound waves with infrasonic frequencies (<20Hz). As such waves can propagate over distances of thousands of kilometres within the atmosphere, they present an opportunity to remotely monitor volcanic eruptions and potentially constrain eruptive characteristics. Though most volcanoes in sensitive areas of the world are monitored individually, many volcanoes in remote locations are not monitored directly but can still pose a threat, especially to aviation. The growing International Monitoring System (IMS) network of <span class="hlt">infrasound</span> stations provides an opportunity to monitor these remote volcanoes. Currently comprising of 43 arrays, the network is designed to achieve global coverage for surface explosions equivalent to a few hundred tonnes of chemical explosive. In recent years work has been published on the detection of specific volcanic eruptions at IMS stations, primarily at regional ranges (< 1000 km from volcano to receiver). In contrast, work presented here looks to create a catalogue of volcanic eruptions that have been detected at IMS stations, with the aim of assessing the capability of the IMS network for use in global volcano monitoring. At this time 40 eruptive events at 19 volcanoes have been investigated from the period 2004 - 2009; however the work is on-going and it is planned to extend this catalogue. In total we document 61 individual detections that have been made on the IMS network. These range from Strombolian activity at Mount Erebus (Antarctica) recorded at a range of 25 km distance, to the Plinian eruption of Manam Volcano (Papua New Guinea) recorded at ranges of over 10,000 km distance. The observed signal frequencies for different eruptions range from less than 0.01 Hz to greater than 5 Hz, and in general, lower frequencies are generated by the larger eruptions. We provide examples of analyses for eruptions recorded at multiple stations (e.g., Manam, October 2004; Kasatochi, August 2008</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNG43A1679M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNG43A1679M"><span id="translatedtitle">Tree-cover and topography effects on local-<span class="hlt">infrasound</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McKenna, S. M.; Swearingen, M.; Ketcham, S.; White, M.</p> <p>2013-12-01</p> <p><span class="hlt">Infrasound</span> can propagate very long distances and remain at measurable levels. As a result <span class="hlt">infrasound</span> sensing is used for remote monitoring in many applications. At local ranges terrain relief is capable of scattering and blocking the propagation and assessment of the influence of the presence or absence of forests on the propagation of infrasonic signals is necessary. Because the wavelengths of interest are much larger than the scale of individual components, the forest is modeled as a porous material. This approximation is developed starting with the Relaxation model of porous materials. This representation is then incorporated into a Crank-Nicholson method parabolic equation solver to determine the relative impacts of the physical parameters of a forest (trunk size and basal area), the presence of gaps/trees in otherwise continuous forest/open terrain, and the effects of meteorology coupled with the porous layer. Finally, the simulations are compared to experimental data from a 10.9 kg blast propagated 14.5 km. Comparison to the experimental data shows that appropriate inclusion of a forest layer along the propagation path provides a closer fit to the data than solely changing the ground type across the frequency range from 1-30 Hz. Spatially discontinuous tree cover is a novel undertaking with forested volumes represented as a flow-resisting porous material. With only terrain topography but without tree cover, the model has conformity with measured signals, but addition of treecover properties does not significantly improve this conformity, though this result is consistent with theoretical expectations for the specific central Mississippi forest densities modeled. This study found that continuous tracts of forest produce some sound enhancement for frequencies below 25 Hz, and additional attenuation between 25-50 Hz. These effects are stronger for forests with higher densities of trees present and decrease as forest density decreases. At distances several</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V32A..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V32A..07L"><span id="translatedtitle">Investigating the tremor <span class="hlt">source</span> process at Fuego volcano, Guatemala through bench-scale analogue modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lyons, J. J.; Ichihara, M.; Lees, J. M.; Waite, G. P.</p> <p>2011-12-01</p> <p>The characteristic frequency content of harmonic tremor has made it an attractive tool for interpreting the <span class="hlt">source</span> mechanisms of shallow fluid flow and volcanic degassing, and models for the generation of harmonic tremor include flow-driven oscillation of volcanic conduits, resonance of fluid-filled cracks, vortex shedding off conduit irregularities, and periodic venting or degassing. However, the nonlinear nature and variability of the tremor signal complicates processing and interpretation, driving a robust debate about <span class="hlt">source</span> mechanisms. <span class="hlt">Infrasound</span> sensors deployed with seismometers are revealing that volcanoes also frequently radiate tremor signals into the atmosphere. This adds additional complexity to interpretations, but may also help constrain <span class="hlt">source</span> models through investigations of the conduit and vent conditions that allow simultaneous generation of seismic and <span class="hlt">infrasound</span> tremor. We recorded harmonic tremor at Fuego volcano, Guatemala in 2008 and 2009 with collocated broadband seismic and <span class="hlt">infrasound</span> sensors. Tremor was prevalent in both seismic records, but harmonic tremor occurs more frequently in the 2009 data, with continuous periods lasting up to 60 minutes. The seismic signal displays abundant frequency gliding and decreasing tremor amplitudes are most often associated with gliding to higher frequencies. Smooth upward shifts in frequency of 100-150% over tens to hundreds of seconds are common and accompany amplitude changes of an order of magnitude (100-10 μM/s). Infrasonic tremor occurs much less frequently and for shorter durations (10s of seconds), but almost always accompanies seismic tremor. A number of interesting characteristics distinguish the seismic and <span class="hlt">infrasound</span> tremor signals, including a shift in the most energetic peak frequency toward lower frequencies in the <span class="hlt">infrasound</span> tremor, fewer harmonics in the <span class="hlt">infrasound</span> signal, and occurrence of <span class="hlt">infrasound</span> tremor most often following larger explosions. We investigate the <span class="hlt">source</span> mechanisms of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1413076L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1413076L"><span id="translatedtitle">Characterization of volcanic activity using observations of <span class="hlt">infrasound</span>, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lopez, T.; Fee, D.; Prata, F.</p> <p>2012-04-01</p> <p>Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, with activity ranging from vigorous degassing, frequent ash emissions, and apparent vent sealing, all punctuated by daily to weekly explosive magmatic eruptions. Recent studies have highlighted the strengths in using complementary <span class="hlt">infrasound</span> measurements and remote volcanic emission measurements to characterize volcanic activity, with the potential to discriminate emission-type, approximate ash-cloud height, and estimate SO2 emission mass. Here we use coincident measurements of <span class="hlt">infrasound</span>, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only <span class="hlt">infrasound</span> data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1 - 5 minutes that either jet or roil out of the vent, by plumes from 500 - 1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1 - 3 minutes, and by plumes from 300 - 1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude <span class="hlt">infrasound</span> and occasionally visible shock</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51D2708R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2708R"><span id="translatedtitle">Frequency and Size of Strombolian Eruptions from the Phonolitic Lava Lake at Erebus Volcano, Antarctica: Insights from <span class="hlt">Infrasound</span> and Seismic Observations on Bubble Formation and Ascent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rotman, H. M. M.; Kyle, P. R.; Fee, D.; Curtis, A.</p> <p>2015-12-01</p> <p>Erebus, an active intraplate volcano on Ross Island, commonly produces bubble burst Strombolian explosions from a long-lived, convecting phonolitic lava lake. Persistent lava lakes are rare, and provide direct insights into their underlying magmatic system. Erebus phonolite is H2O-poor and contains ~30% anorthoclase megacrysts. At shallow depths lab measurements suggest the magma has viscosities of ~107 Pa s. This has implications for magma and bubble ascent rates through the conduit and into the lava lake. The bulk composition and matrix glass of Erebus ejecta has remained uniform for many thousands of years, but eruptive activity varies on decadal and shorter time scales. Over the last 15 years, increased activity took place in 2005-2007, and more recently in the 2013 austral summer. In the 2014 austral summer, new <span class="hlt">infrasound</span> sensors were installed ~700 m from the summit crater hosting the lava lake. These sensors, supplemented by the Erebus network seismic stations, recorded >1000 eruptions between 1 January and 7 April 2015, with an average <span class="hlt">infrasound</span> daily uptime of 9.6 hours. Over the same time period, the CTBT <span class="hlt">infrasound</span> station IS55, ~25 km from Erebus, detected ~115 of the >1000 locally observed eruptions with amplitude decreases of >100x. An additional ~200 eruptions were recorded during local <span class="hlt">infrasound</span> downtime. This represents an unusually high level of activity from the Erebus lava lake, and while instrument noise influences the minimum observable amplitude each day, the eruption <span class="hlt">infrasound</span> amplitudes may vary by ~3 orders of magnitude over the scale of minutes to hours. We use this heightened period of variable activity and associated seismic and acoustic waveforms to examine mechanisms for bubble formation and ascent, such as rise speed dependence and collapsing foam; repose times for the larger eruptions; and possible eruption connections to lava lake cyclicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1636...55F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1636...55F"><span id="translatedtitle"><span class="hlt">Source</span> detection in astronomical images by Bayesian model comparison</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frean, Marcus; Friedlander, Anna; Johnston-Hollitt, Melanie; Hollitt, Christopher</p> <p>2014-12-01</p> <p>The next generation of radio telescopes will generate exabytes of data on hundreds of millions of objects, making automated methods for the detection of astronomical objects ("<span class="hlt">sources</span>") essential. Of particular importance are faint, diffuse objects embedded in noise. There is a pressing need for <span class="hlt">source</span> finding software that identifies these <span class="hlt">sources</span>, involves little manual tuning, yet is tractable to calculate. We first give a novel image discretisation method that incorporates uncertainty about how an image should be discretised. We then propose a hierarchical prior for astronomical images, which leads to a Bayes factor indicating how well a given region conforms to a model of <span class="hlt">source</span> that is exceptionally unconstrained, compared to a model of background. This enables the efficient localisation of regions that are "suspiciously different" from the background distribution, so our method looks not for brightness but for anomalous distributions of intensity, which is much more general. The model of background can be iteratively improved by removing the influence on it of <span class="hlt">sources</span> as they are discovered. The approach is evaluated by identifying <span class="hlt">sources</span> in real and simulated data, and performs well on these measures: the Bayes factor is maximized at most real objects, while returning only a moderate number of false positives. In comparison to a catalogue constructed by widely-used <span class="hlt">source</span> detection software with manual post-processing by an astronomer, our method found a number of dim <span class="hlt">sources</span> that were missing from the "<span class="hlt">ground</span> <span class="hlt">truth</span>" catalogue.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5263K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5263K"><span id="translatedtitle">Exploring the "what if?" in geology through a RESTful open-<span class="hlt">source</span> framework for cloud-based simulation and analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klump, Jens; Robertson, Jess</p> <p>2016-04-01</p> <p>The spatial and temporal extent of geological phenomena makes experiments in geology difficult to conduct, if not entirely impossible and collection of data is laborious and expensive - so expensive that most of the time we cannot test a hypothesis. The aim, in many cases, is to gather enough data to build a predictive geological model. Even in a mine, where data are abundant, a model remains incomplete because the information at the level of a blasting block is two orders of magnitude larger than the sample from a drill core, and we have to take measurement errors into account. So, what confidence can we have in a model based on sparse data, uncertainties and measurement error? Our framework consist of two layers: (a) a <span class="hlt">ground-truth</span> layer that contains geological models, which can be statistically based on historical operations data, and (b) a network of RESTful synthetic sensor microservices which can query the <span class="hlt">ground-truth</span> for underlying properties and produce a simulated measurement to a control layer, which could be a database or LIMS, a machine learner or a companies' existing data infrastructure. <span class="hlt">Ground</span> <span class="hlt">truth</span> data are generated by an implicit geological model which serves as a host for nested models of geological processes as smaller scales. Our two layers are implemented using Flask and Gunicorn, which are open <span class="hlt">source</span> Python web application framework and server, the PyData stack (numpy, scipy etc) and Rabbit MQ (an open-<span class="hlt">source</span> queuing library). Sensor data is encoded using a JSON-LD version of the SensorML and Observations and Measurements standards. Containerisation of the synthetic sensors using Docker and CoreOS allows rapid and scalable deployment of large numbers of sensors, as well as sensor discovery to form a self-organized dynamic network of sensors. Real-time simulation of data <span class="hlt">sources</span> can be used to investigate crucial questions such as the potential information gain from future sensing capabilities, or from new sampling strategies, or the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18635163','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18635163"><span id="translatedtitle">The "Haunt" project: an attempt to build a "haunted" room by manipulating complex electromagnetic fields and <span class="hlt">infrasound</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>French, Christopher C; Haque, Usman; Bunton-Stasyshyn, Rosie; Davis, Rob</p> <p>2009-05-01</p> <p>Recent research has suggested that a number of environmental factors may be associated with a tendency for susceptible individuals to report mildly anomalous sensations typically associated with "haunted" locations, including a sense of presence, feeling dizzy, inexplicable smells, and so on. Factors that may be associated with such sensations include fluctuations in the electromagnetic field (EMF) and the presence of <span class="hlt">infrasound</span>. A review of such work is presented, followed by the results of the "Haunt" project in which an attempt was made to construct an artificial "haunted" room by systematically varying such environmental factors. Participants (N=79) were required to spend 50 min in a specially constructed chamber, within which they were exposed to <span class="hlt">infrasound</span>, complex EMFs, both or neither. They were informed in advance that during this period they might experience anomalous sensations and asked to record on a floor plan their location at the time of occurrence of any such sensations, along with a note of the time of occurrence and a brief description of the sensation. Upon completing the session in the experimental chamber, they were asked to complete three questionnaires. The first was an EXIT scale asking respondents to indicate whether or not they had experienced particular anomalous sensations. The second was the Australian Sheep-Goat Scale, a widely used measure of belief in and experience of the paranormal. The third was Persinger's Personal Philosophy Inventory, although only the items that constitute the Temporal Lobe Signs (TLS) Inventory sub-scale were scored. These items deal with psychological experiences typically associated with temporal lobe epilepsy but normally distributed throughout the general population. Although many participants reported anomalous sensations of various kinds, the number reported was unrelated to experimental condition but was related to TLS scores. The most parsimonious explanation for our findings is in terms of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..322..184M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..322..184M"><span id="translatedtitle">Strombolian surface activity regimes at Yasur volcano, Vanuatu, as observed by Doppler radar, infrared camera and <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meier, K.; Hort, M.; Wassermann, J.; Garaebiti, E.</p> <p>2016-08-01</p> <p>In late 2008 we recorded a continuous multi-parameter data set including Doppler radar, infrared and <span class="hlt">infrasound</span> data at Yasur volcano, Vanuatu. Our recordings cover a transition in explosive style from ash-rich to ash-free explosions followed again by a phase of high ash discharge. To assess the present paradigm of Strombolian behavior in this study we investigate the geophysical signature of these different explosive episodes and compare our results to observations at Stromboli volcano, Italy. To this end we characterize Yasur's surface activity in terms of material movement, temperature and excess pressure. The joint temporal trend in these data reveals smooth variations of surface activity and regime-like persistence of individual explosion forms over days. Analysis of all data types shows ash-free and ash-rich explosive styles similar to those found at Stromboli volcano. During ash-free activity low echo powers, high explosion velocities and high temperatures result from the movement of isolated hot ballistic clasts. In contrast, ash-rich episodes exhibit high echo powers, low explosion velocities and low temperatures linked to the presence of colder ash-rich plumes. Furthermore ash-free explosions cause high excess pressure signals exhibiting high frequencies opposed to low-amplitude, low-frequency signals accompanying ash-rich activity. To corroborate these findings we compare fifteen representative explosions of each explosive episode. Explosion onset velocities derived from Doppler radar and infrared camera data are in excellent agreement and consistent with overall observations in each regime. Examination of <span class="hlt">infrasound</span> recordings likewise confirms our observations, although a weak coupling between explosion velocity and excess pressure indicates changes in wave propagation. The overall trend in explosion velocity and excess pressure however demonstrates a general correlation between explosive style and explosion intensity, and points to stability of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1513933S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1513933S"><span id="translatedtitle">Spatial rainfall data in open <span class="hlt">source</span> environment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schuurmans, Hanneke; Maarten Verbree, Jan; Leijnse, Hidde; van Heeringen, Klaas-Jan; Uijlenhoet, Remko; Bierkens, Marc; van de Giesen, Nick; Gooijer, Jan; van den Houten, Gert</p> <p>2013-04-01</p> <p>Since January 2013 The Netherlands have access to innovative high-quality rainfall data that is used for watermanagers. This product is innovative because of the following reasons. (i) The product is developed in a 'golden triangle' construction - corporation between government, business and research. (ii) Second the rainfall products are developed according to the open-<span class="hlt">source</span> GPL license. The initiative comes from a group of water boards in the Netherlands that joined their forces to fund the development of a new rainfall product. Not only data from Dutch radar stations (as is currently done by the Dutch meteorological organization KNMI) is used but also data from radars in Germany and Belgium. After a radarcomposite is made, it is adjusted according to data from raingauges (<span class="hlt">ground</span> <span class="hlt">truth</span>). This results in 9 different rainfall products that give for each moment the best rainfall data. Specific knowledge is necessary to develop these kind of data. Therefore a pool of experts (KNMI, Deltares and 3 universities) participated in the development. The philosophy of the developers (being corporations) is that products like this should be developed in open <span class="hlt">source</span>. This way knowledge is shared and the whole community is able to make suggestions for improvement. In our opinion this is the only way to make real progress in product development. Furthermore the financial resources of government organizations are optimized. More info (in Dutch): www.nationaleregenradar.nl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ISPAr62W1..299K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ISPAr62W1..299K"><span id="translatedtitle">Open-<span class="hlt">Source</span> Digital Elevation Model (DEMs) Evaluation with GPS and LiDAR Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khalid, N. F.; Din, A. H. M.; Omar, K. M.; Khanan, M. F. A.; Omar, A. H.; Hamid, A. I. A.; Pa'suya, M. F.</p> <p>2016-09-01</p> <p>Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) are freely available Digital Elevation Model (DEM) datasets for environmental modeling and studies. The quality of spatial resolution and vertical accuracy of the DEM data <span class="hlt">source</span> has a great influence particularly on the accuracy specifically for inundation mapping. Most of the coastal inundation risk studies used the publicly available DEM to estimated the coastal inundation and associated damaged especially to human population based on the increment of sea level. In this study, the comparison between <span class="hlt">ground</span> <span class="hlt">truth</span> data from Global Positioning System (GPS) observation and DEM is done to evaluate the accuracy of each DEM. The vertical accuracy of SRTM shows better result against ASTER and GMTED10 with an RMSE of 6.054 m. On top of the accuracy, the correlation of DEM is identified with the high determination of coefficient of 0.912 for SRTM. For coastal zone area, DEMs based on airborne light detection and ranging (LiDAR) dataset was used as <span class="hlt">ground</span> <span class="hlt">truth</span> data relating to terrain height. In this case, the LiDAR DEM is compared against the new SRTM DEM after applying the scale factor. From the findings, the accuracy of the new DEM model from SRTM can be improved by applying scale factor. The result clearly shows that the value of RMSE exhibit slightly different when it reached 0.503 m. Hence, this new model is the most suitable and meets the accuracy requirement for coastal inundation risk assessment using open <span class="hlt">source</span> data. The suitability of these datasets for further analysis on coastal management studies is vital to assess the potentially vulnerable areas caused by coastal inundation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4379O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4379O"><span id="translatedtitle">An Offline-Online Android Application for Hazard Event Mapping Using WebGIS Open <span class="hlt">Source</span> Technologies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olyazadeh, Roya; Jaboyedoff, Michel; Sudmeier-Rieux, Karen; Derron, Marc-Henri; Devkota, Sanjaya</p> <p>2016-04-01</p> <p>Nowadays, Free and Open <span class="hlt">Source</span> Software (FOSS) plays an important role in better understanding and managing disaster risk reduction around the world. National and local government, NGOs and other stakeholders are increasingly seeking and producing data on hazards. Most of the hazard event inventories and land use mapping are based on remote sensing data, with little <span class="hlt">ground</span> <span class="hlt">truthing</span>, creating difficulties depending on the terrain and accessibility. Open <span class="hlt">Source</span> WebGIS tools offer an opportunity for quicker and easier <span class="hlt">ground</span> <span class="hlt">truthing</span> of critical areas in order to analyse hazard patterns and triggering factors. This study presents a secure mobile-map application for hazard event mapping using Open <span class="hlt">Source</span> WebGIS technologies such as Postgres database, Postgis, Leaflet, Cordova and Phonegap. The objectives of this prototype are: 1. An Offline-Online android mobile application with advanced Geospatial visualisation; 2. Easy Collection and storage of events information applied services; 3. Centralized data storage with accessibility by all the service (smartphone, standard web browser); 4. Improving data management by using active participation in hazard event mapping and storage. This application has been implemented as a low-cost, rapid and participatory method for recording impacts from hazard events and includes geolocation (GPS data and Internet), visualizing maps with overlay of satellite images, viewing uploaded images and events as cluster points, drawing and adding event information. The data can be recorded in offline (Android device) or online version (all browsers) and consequently uploaded through the server whenever internet is available. All the events and records can be visualized by an administrator and made public after approval. Different user levels can be defined to access the data for communicating the information. This application was tested for landslides in post-earthquake Nepal but can be used for any other type of hazards such as flood, avalanche</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMIN42A..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMIN42A..07M"><span id="translatedtitle">Using Citizen Science and Crowdsourcing via Aurorasaurus as a Near Real Time Data <span class="hlt">Source</span> for Space Weather Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacDonald, E.; Heavner, M.; Hall, M.; Tapia, A.; Lalone, N.; Clayon, J.; Case, N.</p> <p>2014-12-01</p> <p>Aurorasaurus is on the cutting edge of space science, citizen science, and computer science simultaneously with the broad goals to develop a real-time citizen science network, educate the general public about the northern lights, and revolutionize real-time space weather nowcasting of the aurora for the public. We are currently in the first solar maximum with social media, which enables the technological roots to connect users, citizen scientists, and professionals around a shared global, rare interest. We will introduce the project which has been in a prototype mode since 2012 and recently relaunched with a new mobile and web presence and active campaigns. We will showcase the interdisciplinary advancements which include a more educated public, disaster warning system applications, and improved real-time <span class="hlt">ground</span> <span class="hlt">truth</span> data including photographs and observations of the Northern Lights. We will preview new data which validates the proof of concept for significant improvements in real-time space weather nowcasting. Our aim is to provide better real-time notifications of the visibility of the Northern Lights to the interested public via the combination of noisy crowd-<span class="hlt">sourced</span> <span class="hlt">ground</span> <span class="hlt">truth</span> with noisy satellite-based predictions. The latter data are available now but are often delivered with significant jargon and uncertainty, thus reliable, timely interpretation of such forecasts by the public are problematic. The former data show real-time characteristic significant rises (in tweets for instance) that correlate with other non-real-time indices of auroral activity (like the Kp index). We will discuss the <span class="hlt">source</span> of 'noise' in each data <span class="hlt">source</span>. Using citizen science as a platform to provide a basis for deeper understanding is one goal; secondly we want to improve understanding of and appreciation for the dynamics and beauty of the Northern Lights by the public and scientists alike.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PCE....95..125G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PCE....95..125G"><span id="translatedtitle">Identification of blasting <span class="hlt">sources</span> in the Dobrogea seismogenic region, Romania using seismo-acoustic signals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghica, Daniela Veronica; Grecu, Bogdan; Popa, Mihaela; Radulian, Mircea</p> <p>2016-10-01</p> <p>In order to discriminate between quarry blasts and earthquakes observed in the Dobrogea seismogenic region, a seismo-acoustic analysis was performed on 520 events listed in the updated Romanian seismic catalogue from January 2011 to December 2012. During this time interval, 104 seismo-acoustic events observed from a distance between 110 and 230 km and backazimuth interval of 110-160° from the IPLOR <span class="hlt">infrasound</span> array were identified as explosions by associating with infrasonic signals. WinPMCC software for interactive analysis was applied to detect and characterize infrasonic signals in terms of backazimuth, speed and frequency content. The measured and expected values of both backazimuths and arrival times for the study events were compared in order to identify the <span class="hlt">sources</span> of <span class="hlt">infrasound</span>. Two predominant directions for seismo-acoustic <span class="hlt">sources</span>' aligning were observed, corresponding to the northern and central parts of Dobrogea, and these directions are further considered as references in the process of discriminating explosions from earthquakes. A predominance of high-frequency detections (above 1 Hz) is also observed in the <span class="hlt">infrasound</span> data. The strong influence of seasonally dependent stratospheric winds on the IPLOR detection capability limits the efficiency of the discrimination procedure, as proposed by this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910007377','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910007377"><span id="translatedtitle">Vehicular <span class="hlt">sources</span> in acoustic propagation experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George</p> <p>1990-01-01</p> <p>One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise <span class="hlt">sources</span> must be understood and characterized; the vehicle's location or '<span class="hlt">ground</span> <span class="hlt">truth</span>' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9727A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9727A"><span id="translatedtitle">Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground <span class="hlt">source</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Averbuch, Gil; Price, Colin</p> <p>2015-04-01</p> <p>Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground <span class="hlt">source</span>. G. Averbuch, C. Price Department of Geosciences, Tel Aviv University, Israel <span class="hlt">Infrasound</span> is one of the four Comprehensive Nuclear-Test Ban Treaty technologies for monitoring nuclear explosions. This technology measures the acoustic waves generated by the explosions followed by their propagation through the atmosphere. There are also natural phenomena that can act as an <span class="hlt">infrasound</span> <span class="hlt">sources</span> like sprites, volcanic eruptions and earthquakes. The <span class="hlt">infrasound</span> waves generated from theses phenomena can also be detected by the <span class="hlt">infrasound</span> arrays. In order to study the behavior of these waves, i.e. the physics of wave propagation in the atmosphere, their evolution and their trajectories, numerical methods are required. This presentation will deal with the evolution of acoustic waves generated by underground <span class="hlt">sources</span> (earthquakes and underground explosions). A 2D Spectral elements formulation for lithosphere-atmosphere coupling will be presented. The formulation includes the elastic wave equation for the seismic waves and the momentum, mass and state equations for the acoustic waves in a moving stratified atmosphere. The coupling of the two media is made by boundary conditions that ensures the continuity of traction and velocity (displacement) in the normal component to the interface. This work has several objectives. The first is to study the evolution of acoustic waves in the atmosphere from an underground <span class="hlt">source</span>. The second is to derive transmission coefficients for the energy flux with respect to the seismic magnitude and earth density. The third will be the generation of seismic waves from acoustic waves in the atmosphere. Is it possible?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22325302','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22325302"><span id="translatedtitle">SU-E-J-42: Customized Deformable Image Registration Using Open-<span class="hlt">Source</span> Software SlicerRT</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaitan, J Cifuentes; Chin, L; Pignol, J; Kirby, N; Pouliot, J; Lasso, A; Pinter, C; Fichtinger, G</p> <p>2014-06-01</p> <p>Purpose: SlicerRT is a flexible platform that allows the user to incorporate the necessary images registration and processing tools to improve clinical workflow. This work validates the accuracy and the versatility of the deformable image registration algorithm of the free open-<span class="hlt">source</span> software SlicerRT using a deformable physical pelvic phantom versus available commercial image fusion algorithms. Methods: Optical camera images of nonradiopaque markers implanted in an anatomical pelvic phantom were used to measure the <span class="hlt">ground-truth</span> deformation and evaluate the theoretical deformations for several DIR algorithms. To perform the registration, full and empty bladder computed tomography (CT) images of the phantom were obtained and used as fixed and moving images, respectively. The DIR module, found in SlicerRT, used a B-spline deformable image registration with multiple optimization parameters that allowed customization of the registration including a regularization term that controlled the amount of local voxel displacement. The virtual deformation field at the center of the phantom was obtained and compared to the experimental <span class="hlt">ground-truth</span> values. The parameters of SlicerRT were then varied to improve spatial accuracy. To quantify image similarity, the mean absolute difference (MAD) parameter using Hounsfield units was calculated. In addition, the Dice coefficient of the contoured rectum was evaluated to validate the strength of the algorithm to transfer anatomical contours. Results: Overall, SlicerRT achieved one of the lowest MAD values across the algorithm spectrum, but slightly smaller mean spatial errors in comparison to MIM software (MIM). On the other hand, SlicerRT created higher mean spatial errors than Velocity Medical Solutions (VEL), although obtaining an improvement on the DICE to 0.91. The large spatial errors were attributed to the poor contrast in the prostate bladder interface of the phantom. Conclusion: Based phantom validation, SlicerRT is capable of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/573309','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/573309"><span id="translatedtitle">Report on the test and evaluation of the Chaparral Physics Model 4.1.1 prototype microbarograph for CTBT <span class="hlt">infrasound</span> array application</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kromer, R.P.; McDonald, T.S.</p> <p>1998-01-01</p> <p>The Sandia National Laboratories has tested and evaluated the Chaparral Physics Model 4.1.1 prototype <span class="hlt">infrasound</span> sensor to CTBT specifications. The sensor was characterized by using a piston-phone chamber to set and measure sensor sensitivity. Multiple sensor side-by-side coherence analysis testing provided a measure of sensor relative gain and phase; sensor self-noise was computed using this technique. The performance of the sensor calibration circuitry was evaluated. Sensor performance was compared to CTBT specifications. The Chaparral sensor met or exceeded all CTBT specifications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMNH21D..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH21D..04S"><span id="translatedtitle">Seismoacoustic Signatures from Chelyabinsk Meteor Observed by the Kazakhstan Nuclear Explosion Monitoring Network (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smirnov, A.; Mikhailova, N.; Garces, M. A.</p> <p>2013-12-01</p> <p><span class="hlt">Infrasound</span> and seismic stations of the Kazakhstan Nuclear Explosion Monitoring network recorded high-fidelity seismoacoustic signatures from the Chelyabinsk meteor. <span class="hlt">Infrasound</span> array I31KZ in Aktyubinsk was the closest IMS <span class="hlt">infrasound</span> station to the <span class="hlt">source</span>. This station is in the Northwest Kazakhstan, approximately 520 km southward from the bolide blast. The propitious station position relative to the entry trajectory, coupled with calm weather during the event, permitted a detailed, broadband record of the bolide explosion. All eight I31KZ <span class="hlt">infrasound</span> array channels show an extremely strong broadband signal at 03:48 UTC and a duration of ~20 minutes. Array processing of the signal with PMCC4 shows that signal contains unprecedented detail on the <span class="hlt">source</span> characteristics. Another Kazakhstani <span class="hlt">infrasound</span> array in Kurchatov, Northeast Kazakhstan, also recorded the explosion signals. This is third closest <span class="hlt">infrasound</span> array to the <span class="hlt">source</span>. The second one is Russian array I43RU, Dubna. Epicentral distances are 1090 km for Dubna and 1300 km for Kurchatov. Traveltimes are 26 minutes for I31KZ Aktyubinsk and 66 minutes for the Kurchatov array. In addition to <span class="hlt">infrasound</span> arrays, Kazakhstani seismic arrays belonging to Institute of Geophysical Research also recorded the signals generated by the bolide. The epicentral seismic <span class="hlt">source</span> location corresponds to the pressure shock wave ground impact, and is under the meteor hypercenter. The seismic signal was recorded by Akbulak, Borovoe, Karatau and Makanchy arrays and other Kazakhstani seismic stations. Akbulak was the station nearest to epicenter, at a range of 630 km southward. The estimated origin time of the seismic event following the bolide explosion is 03:21:59.64 GMT. The difference between <span class="hlt">ground</span> <span class="hlt">truth</span> time 3:20:33 GMT provided by NASA and the seismic origin time is in reasonable agreement with the reported hypercenter altitude range of 25-30 km asl. The seismic event had a body wave magnitude of Mb 3.5, with energy class K 8</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008IJBm...52..553D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008IJBm...52..553D"><span id="translatedtitle">Atmospheric pressure fluctuations in the far <span class="hlt">infrasound</span> range and emergency transport events coded as circulatory system diseases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Didyk, L. A.; Gorgo, Yu. P.; Dirckx, J. J. J.; Bogdanov, V. B.; Buytaert, J. A. N.; Lysenko, V. A.; Didyk, N. P.; Vershygora, A. V.; Erygina, V. T.</p> <p>2008-09-01</p> <p>This study examines whether a relation exists between rapid atmospheric pressure fluctuations, attributed to the far <span class="hlt">infrasound</span> frequency range (APF), and a number of emergency transport events coded as circulatory system diseases (EEC). Over an entire year, the average integral amplitudes of APF in the range of periods from 3 s to 120 s over each hour (HA) were measured. Daily dynamics of HA averaged over the year revealed a wave shape with smooth increase from night to day followed by decrease from day to night. The total daily number of EEC within the city of Kiev, Ukraine, was related to the daily mean of HA (DHA) and to the ratio of HA averaged over the day time to HA averaged over the night time (Rdn), and was checked for confounding effects of classical meteorological variables through non-parametric regression algorithms. The number of EEC were significantly higher on days with high DHA (3.72 11.07 Pa, n = 87) compared to the low DHA (0.7 3.62 Pa, n = 260, p = 0.01), as well at days with low Rdn (0.21 1.64, n = 229) compared to the high Rdn (1.65 7.2, n = 118, p = 0.03). A difference between DHA and Rdn effects on the emergency events related to different categories of circulatory diseases points to a higher sensitivity of rheumatic and cerebro-vascular diseases to DHA, and ischaemic and hypertensive diseases to Rdn. Results suggest that APF could be considered as a meteorotropic factor capable of influencing circulatory system diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338604','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338604"><span id="translatedtitle">Health-Based Audible Noise Guidelines Account for <span class="hlt">Infrasound</span> and Low-Frequency Noise Produced by Wind Turbines</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Berger, Robert G.; Ashtiani, Payam; Ollson, Christopher A.; Whitfield Aslund, Melissa; McCallum, Lindsay C.; Leventhall, Geoff; Knopper, Loren D.</p> <p>2015-01-01</p> <p>Setbacks for wind turbines have been established in many jurisdictions to address potential health concerns associated with audible noise. However, in recent years, it has been suggested that <span class="hlt">infrasound</span> (IS) and low-frequency noise (LFN) could be responsible for the onset of adverse health effects self-reported by some individuals living in proximity to wind turbines, even when audible noise limits are met. The purpose of this paper was to investigate whether current audible noise-based guidelines for wind turbines account for the protection of human health, given the levels of IS and LFN typically produced by wind turbines. New field measurements of indoor IS and outdoor LFN at locations between 400 and 900 m from the nearest turbine, which were previously underrepresented in the scientific literature, are reported and put into context with existing published works. Our analysis showed that indoor IS levels were below auditory threshold levels while LFN levels at distances >500 m were similar to background LFN levels. A clear contribution to LFN due to wind turbine operation (i.e., measured with turbines on in comparison to with turbines off) was noted at a distance of 480 m. However, this corresponded to an increase in overall audible sound measures as reported in dB(A), supporting the hypothesis that controlling audible sound produced by normally operating wind turbines will also control for LFN. Overall, the available data from this and other studies suggest that health-based audible noise wind turbine siting guidelines provide an effective means to evaluate, monitor, and protect potential receptors from audible noise as well as IS and LFN. PMID:25759808</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25759808','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25759808"><span id="translatedtitle">Health-based audible noise guidelines account for <span class="hlt">infrasound</span> and low-frequency noise produced by wind turbines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Berger, Robert G; Ashtiani, Payam; Ollson, Christopher A; Whitfield Aslund, Melissa; McCallum, Lindsay C; Leventhall, Geoff; Knopper, Loren D</p> <p>2015-01-01</p> <p>Setbacks for wind turbines have been established in many jurisdictions to address potential health concerns associated with audible noise. However, in recent years, it has been suggested that <span class="hlt">infrasound</span> (IS) and low-frequency noise (LFN) could be responsible for the onset of adverse health effects self-reported by some individuals living in proximity to wind turbines, even when audible noise limits are met. The purpose of this paper was to investigate whether current audible noise-based guidelines for wind turbines account for the protection of human health, given the levels of IS and LFN typically produced by wind turbines. New field measurements of indoor IS and outdoor LFN at locations between 400 and 900 m from the nearest turbine, which were previously underrepresented in the scientific literature, are reported and put into context with existing published works. Our analysis showed that indoor IS levels were below auditory threshold levels while LFN levels at distances >500 m were similar to background LFN levels. A clear contribution to LFN due to wind turbine operation (i.e., measured with turbines on in comparison to with turbines off) was noted at a distance of 480 m. However, this corresponded to an increase in overall audible sound measures as reported in dB(A), supporting the hypothesis that controlling audible sound produced by normally operating wind turbines will also control for LFN. Overall, the available data from this and other studies suggest that health-based audible noise wind turbine siting guidelines provide an effective means to evaluate, monitor, and protect potential receptors from audible noise as well as IS and LFN.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH21D..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH21D..08M"><span id="translatedtitle">Completing a <span class="hlt">Ground</span> <span class="hlt">Truth</span> View of the Global Heliosphere: What Does IMAP Tell Us?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthaeus, W. H.</p> <p>2014-12-01</p> <p>Recent and planned advances in heliospheric research promise to provide for the first time a fairly complete picture of the processes that shape the Geospace environment and the Heliospheric envelope that defines the magnetic and plasma neighborhood of the Sun. The upcoming Solar Orbiter and Solar probe Plus missions will vastly extend our knowledge of the inner heliospheric drivers that impact the entire system. However to develop understanding of energy and particle transport that controls the Geospace plasma and radiation envirionment, it is necessary to maintain an accurate monitoring of the plasma and electromagnetic properties of the solar wind near 1 AU. To complete understanding of the Heliosphere we must also extend understanding of energy and plasma transport to regions beyond 1 AU and throughout the Heliosphere. This understanding will complete the connection between the the corona, the 1AU environment and the outer boundaries recently explored by the Voyagers and IBEX. This talk will focus on the linkages between inner heliosphere, the Geospace environment and the outer heliosphere, with an emphasis on what an L1 monitor such as IMAP can provde for the next decade of great discoveries in space physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA456341','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA456341"><span id="translatedtitle">Formation of <span class="hlt">Ground</span> <span class="hlt">Truth</span> Databases and Related Studies and Regional Seismic Monitoring Research</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2006-06-01</p> <p>Outpost, Alaska, USA Bolivia Charters Towers, Australia Davao, Philippines Bolivia Mount Kent, East Falkland Island Erkin-Sai, Kyrgyzstan...Anza, Calif. Domenigoni Valley Reservoir, California, USA Bolivia Dobmska, Czech Republic Mount Kent, East Falkland Island M S 2 ENH E r n...Moravsky Beroun, Czech Republic Mahe Island, SeycheUm Mount W i l q California, USA Nilore, Pakistan NaM, Peru Norilsk, Russia Obninsk, Russia</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160012386','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160012386"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truthing</span> Orbital Clay Mineral Observations with the APXS Onboard Mars Exploration Rover Opportunity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schroeder, C.; Gellert, R.; VanBommel, S.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. S.; Yen, A. S.</p> <p>2016-01-01</p> <p>NASA's Mars Exploration Rover Opportunity has been exploring approximately 22 km diameter Endeavour crater since 2011. Its rim segments predate the Hesperian-age Burns formation and expose Noachian-age material, which is associated with orbital Fe3+-Mg-rich clay mineral observations [1,2]. Moving to an orders of magnitude smaller instrumental field of view on the ground, the clay minerals were challenging to pinpoint on the basis of geochemical data because they appear to be the result of near-isochemical weathering of the local bedrock [3,4]. However, the APXS revealed a more complex mineral story as fracture fills and so-called red zones appear to contain more Al-rich clay minerals [5,6], which had not been observed from orbit. These observations are important to constrain clay mineral formation processes. More detail will be added as Opportunity is heading into her 10th extended mission, during which she will investigate Noachian bedrock that predates Endeavour crater, study sedimentary rocks inside Endeavour crater, and explore a fluid-carved gully. ESA's ExoMars rover will land on Noachian-age Oxia Planum where abundant Fe3+-Mg-rich clay minerals have been observed from orbit, but the story will undoubtedly become more complex once seen from the ground.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017LPICo1989.8148S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017LPICo1989.8148S"><span id="translatedtitle">A <span class="hlt">Ground</span> <span class="hlt">Truth</span>-Based Approach to Future Solar System Origins Research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stroud, R. M.</p> <p>2017-02-01</p> <p>To expand our understanding of how the solar system, and thus humanity itself, came into being, we must push forward the state-of-the-art in planetary materials analysis capabilities over the next three decades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4811005M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4811005M"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> of (sub-)micrometre cometary dust - Results of MIDAS onboard Rosetta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mannel, Thurid; Bentley, Mark; Schmied, Roland; Torkar, Klaus; Jeszenszky, Harald; Romsted, Jens; Levasseur-Regourd, A.; Weber, Iris; Jessberger, Elmar K.; Ehrenfreund, Pascale; Köberl, Christian; Havnes, Ove</p> <p>2016-10-01</p> <p>The investigation of comet 67P by Rosetta has allowed the comprehensive characterisation of pristine cometary dust particles ejected from the nucleus. Flying alongside the comet at distances as small as a few kilometres, and with a relative velocity of only centimetres per second, the Rosetta payload sampled almost unaltered dust. A key instrument to study this dust was MIDAS (the Micro-Imaging Dust Analysis System), a dedicated atomic force microscope that scanned the surfaces of hundreds of (sub-)micrometre sized particles in 3D with resolutions down to nanometres. This offers the unique opportunity to explore the morphology of smallest cometary dust and expand our current knowledge about cometary material.Here we give an overview of dust collected and analysed by MIDAS and highlight its most important features. These include the ubiquitous agglomerate nature of the dust, which is found at all size scales from the largest (>10 µm) through to the smallest (<1 µm) dust particles. The sub-units show characteristic sizes and shapes that are compared with model predictions for interstellar dust.Our findings constrain key parameters of the evolution of the early Solar System. We will discuss which dust growth model is favoured by the observed morphology and how the results restrict cometary formation. Finally, dust particles detected by MIDAS resemble primitive interplanetary dust which is a strong argument for a common cometary origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeoRL..39.3304K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeoRL..39.3304K"><span id="translatedtitle">Field experiment provides <span class="hlt">ground</span> <span class="hlt">truth</span> for surface nuclear magnetic resonance measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knight, Rosemary; Grunewald, Elliot; Irons, Trevor; Dlubac, Katherine; Song, Yiqiao; Bachman, Henry N.; Grau, Ben; Walsh, Dave; Abraham, Jared D.; Cannia, Jim</p> <p>2012-02-01</p> <p>The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governing the non-invasive Surface NMR (SNMR) technology. We acquired both SNMR data and logging NMR data at a field site, along with lithology information from drill cuttings. This allowed us to directly compare the NMR relaxation parameter measured during logging, T2, to the relaxation parameter T2* measured using the SNMR method. The latter can be affected by inhomogeneity in the magnetic field, thus obscuring the link between the NMR relaxation parameter and the hydraulic conductivity of the geologic material. When the logging T2 data were transformed to pseudo- T2* data, by accounting for inhomogeneity in the magnetic field and instrument dead time, we found good agreement with T2* obtained from the SNMR measurement. These results, combined with the additional information about lithology at the site, allowed us to delineate the physical mechanisms governing the SNMR measurement. Such understanding is a critical step in developing SNMR as a reliable geophysical method for the assessment of groundwater resources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001747','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001747"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> Mineralogy vs. Orbital Observations at the Bagnold Dune Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Achilles, C. N.; Downs, R. T.; Ming, D. W.; Rampe, E. B.; Morris, R. V.; Treiman, A. H.; Morrison, S. M.; Blake, D. F.; Vaniman, D. T.; Bristow, T. F.</p> <p>2017-01-01</p> <p>The Mars Science Laboratory (MSL) rover, Curiosity, is analyzing rock and sediments in Gale crater to provide in situ sedimentological, geochemical, and mineralogical assessments of the crater's geologic history. Curiosity's recent traverse through an active, basaltic eolian deposit, informally named the Bagnold Dunes, provided the opportunity for a multi-instrument investigation of the dune field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950009770','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950009770"><span id="translatedtitle">Chryse Planitia as a Mars Pathfinder landing site: The imperative of building on previous <span class="hlt">ground</span> <span class="hlt">truth</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crumpler, Larry S.</p> <p>1994-01-01</p> <p>Based on consideration of the geological characteristics of Chryse Planitia, the requirements for Mars Pathfinder landing sites, the nature of the mission, the scale of the observations to be made, and the need to build outward from previous experience, a new mission to Chryse Planitia offers several advantages that are difficult to ignore as well as offering a low-gamble/high-return mission scenario. Considering the need to ensure a successful mission, and to ensure the continued health of planetary exploration, the reasons for a new mission to Chryse Planitia are compelling. Results of 1:500,000 mapping, operational benefits of Chryse Planitia, science benefits of Chryse Planitia, and conclusions and site recommendations are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860007392&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860007392&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle">Requirements for sea surface temperature <span class="hlt">ground</span> <span class="hlt">truth</span> in the Indonesian region</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Penrose, J.</p> <p>1985-01-01</p> <p>The comparatively low density of ship and XBT observations in large areas of the Southern Hemisphere and the tropics limits the extent to which satellite SST estimates can be validated on a global basis. These limitations are discussed, and some recommendations for correction are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850008942&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850008942&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> for SIR-B images obtained by SIR system 8 impulse radar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ulriksen, P.; Ottersten, H.; Borg, C. G.; Axelsson, S.; Ekengren, B.</p> <p>1984-01-01</p> <p>Verification of suspected penetration by means of three dimensional information on the features in the SIR-B images will be investigated. The Great Alvar is a well documented area, especially in geology and ecology, and should provide a good opportunity to evaluate the data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=212384','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=212384"><span id="translatedtitle">Airborne multispectral remote sensing with <span class="hlt">ground</span> <span class="hlt">truth</span> for areawide pest management</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Scientists and engineers in areawide pest management programs have been developing, integrating, and evaluating multiple strategies and technologies into a systems approach for management of field crop insect pests. Remote sensing along with global positioning systems, geographic information system...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880040590&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880040590&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle">Techniques of <span class="hlt">ground-truth</span> measurements of desert-scrub structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ottermann, J.; Deering, D.; Eck, T.; Ringrose, S.</p> <p>1987-01-01</p> <p>Inversion of remote sensing data taken over a desert scrub surface in Texas with a multidirectionally viewing field radiometer, PARABOLA, yields the value of 0.12 for the protrusion parameter, s, (the projection on a vertical plane of plants per unit area) if isotropy (Lambert law) is assumed for the underlying soil. However, a significantly higher value of s, in the range 0.15 to 0.20, can be inferred if the soil is assumed anisotropic. It is concluded that in remote sensing of sparse vegetation, it is important to know the reflectance characteristics of the underlying soil. Other techniques that can be used to infer desert scrub vegetation structure include various photographic techniques, and measurements of reflected radiance from zenith for a range of solar elevation angles on a clear day.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760009508','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760009508"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> report 1975 Phoenix microwave experiment. [Joint Soil Moisture Experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blanchard, B. J.</p> <p>1975-01-01</p> <p>Direct measurements of soil moisture obtained in conjunction with aircraft data flights near Phoenix, Arizona in March, 1975 are summarized. The data were collected for the Joint Soil Moisture Experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830017021&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830017021&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dtruth"><span id="translatedtitle">Precipitation measurements for earth-space communications: Accuracy requirements and <span class="hlt">ground-truth</span> techniques</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ippolito, L. J.; Kaul, R.</p> <p>1981-01-01</p> <p>Rainfall which is regarded as one of the more important observations for the measurements of this most variable parameter was made continuously, across large areas and over the sea. Ships could not provide the needed resolution nor could available radars provide the needed breadth of coverage. Microwave observations from the Nimbus-5 satellite offered some hope. Another possibility was suggested by the results of many comparisons between rainfall and the clouds seen in satellite pictures. Sequences of pictures from the first geostationary satellites were employed and a general correspondence between rain and the convective clouds visible in satellite pictures was found. It was demonstrated that the agreement was best for growing clouds. The development methods to infer GATE rainfall from geostationary satellite images are examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780034338&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780034338&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtruth"><span id="translatedtitle">Optimal spatial sampling techniques for <span class="hlt">ground</span> <span class="hlt">truth</span> data in microwave remote sensing of soil moisture</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rao, R. G. S.; Ulaby, F. T.</p> <p>1977-01-01</p> <p>The paper examines optimal sampling techniques for obtaining accurate spatial averages of soil moisture, at various depths and for cell sizes in the range 2.5-40 acres, with a minimum number of samples. Both simple random sampling and stratified sampling procedures are used to reach a set of recommended sample sizes for each depth and for each cell size. Major conclusions from statistical sampling test results are that (1) the number of samples required decreases with increasing depth; (2) when the total number of samples cannot be prespecified or the moisture in only one single layer is of interest, then a simple random sample procedure should be used which is based on the observed mean and SD for data from a single field; (3) when the total number of samples can be prespecified and the objective is to measure the soil moisture profile with depth, then stratified random sampling based on optimal allocation should be used; and (4) decreasing the sensor resolution cell size leads to fairly large decreases in samples sizes with stratified sampling procedures, whereas only a moderate decrease is obtained in simple random sampling procedures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800038771&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800038771&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtruth"><span id="translatedtitle">Gulf stream <span class="hlt">ground</span> <span class="hlt">truth</span> project - Results of the NRL airborne sensors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcclain, C. R.; Chen, D. T.; Hammond, D. L.</p> <p>1980-01-01</p> <p>Results of an airborne study of the waves in the Gulf Stream are presented. These results show that the active microwave sensors (high-flight radar and wind-wave radar) provide consistent and accurate estimates of significant wave height and surface wind speed, respectively. The correlation between the wave height measurements of the high-flight radar and a laser profilometer is excellent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930071705&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930071705&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dtruth"><span id="translatedtitle">Comparison of land surface temperatures derived from satellite observations with <span class="hlt">ground</span> <span class="hlt">truth</span> during FIFE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sugita, M.; Brutsaert, W.</p> <p>1993-01-01</p> <p>Surface temperatures of the FIFE (First ISLSCP Field Experiment) experimental area derived from thermal infrared radiances recorded from different satellite platforms at different scales were compared with reference observations by means of infrared thermometers at ground stations distributed over the area. FIFE was conducted during late spring, summer and fall over an area of 15 km by 15 km in a hilly tall-grass prairie region in northeastern Kansas. The data available for this purpose were produced by AVHRR and TOVS instruments aboard NOAA-9 and NOAA-10, the TM instrument aboard Landsat-5, and VISSR instrument aboard GOES-7. The scales covered by these instruments span a wide range, namely between hundreds of meters (Landsat TM) and hundreds of kilometers (TOVS). The data are analyzed both with and without the application of an atmospheric correction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910021263','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910021263"><span id="translatedtitle">Design of the primary and secondary Pre-TRMM and TRMM <span class="hlt">ground</span> <span class="hlt">truth</span> sites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Garstang, Michael; Austin, Geoffrey; Cosgrove, Claire</p> <p>1991-01-01</p> <p>Results generated over six months are covered in five manuscripts: (1) estimates of rain volume over the Peninsula of Florida during the summer season based upon the Manually Digitized Radar data; (2) the diurnal characteristics of rainfall over Florida and over the near shore waters; (3) convective rainfall as measured over the east coast of central Florida; (4) the spatial and temporal variability of rainfall over Florida; and (5) comparisons between the land based radar and an optical raingage onboard an anchored buoy 50 km offshore.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760012446','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760012446"><span id="translatedtitle">Soils maps supplement to soil moisture <span class="hlt">ground</span> <span class="hlt">truth</span>, Lafayette, Indiana, site St. Charles, Missouri, site</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, E. B.; Olt, S. E.</p> <p>1975-01-01</p> <p>A compilation of soils information obtained as the result of a library search of data on the Lafayette, Indiana, site and St. Charles, Missouri, site is presented. Soils data for the Lafayette, Indiana, site are shown in Plates 1 and 2; and soils data for the St. Charles, Missouri, site are shown in Plates 3 and 4.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=64359&keyword=sensor+AND+natural&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78770758&CFTOKEN=17336127','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=64359&keyword=sensor+AND+natural&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78770758&CFTOKEN=17336127"><span id="translatedtitle">AN ASSESSMENT OF <span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> VARIABILITY USING A "VIRTUAL FIELD REFERENCE DATABASE"</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><br><br>A "Virtual Field Reference Database (VFRDB)" was developed from field measurment data that included location and time, physical attributes, flora inventory, and digital imagery (camera) documentation foy 1,01I sites in the Neuse River basin, North Carolina. The sampling f...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1611B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1611B"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span> and Application for the Anisotropic Receiver Functions Technique - Test site KTB: the installation campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bianchi, Irene; Anselmi, Mario; Apoloner, Maria-Theresia; Qorbani, Ehsan; Gribovszki, Katalin; Bokelmann, Götz</p> <p>2015-04-01</p> <p>The project at hand is a field test around the KTB (Kontinentale Tiefbohrung) site in the Oberpfalz, Southeastern Germany, at the northwestern edge of the Bohemian Massif. The region has been extensively studied through the analysis of several seismic reflection lines deployed around the drilling site. The deep borehole had been placed into gneiss rocks of the Zone Erbendorf-Vohenstrauss. Drilling activity lasted since 1987 to 1994, and it descends down to a depth of 9101 meters. In our experiment, we aim to recover structural information as well as anisotropy of the upper crust using the receiver function technique. This retrieved information will form the base for a comparison between the resulting anisotropy amount and orientation with information of rock samples from up to 9 km depth, and with earlier high-frequency seismic experiments around the drill site. For that purpose, we installed 9 seismic stations, and recorded seismicity continuously for two years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032693','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032693"><span id="translatedtitle">Field experiment provides <span class="hlt">ground</span> <span class="hlt">truth</span> for surface nuclear magnetic resonance measurement</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Knight, R.; Grunewald, E.; Irons, T.; Dlubac, K.; Song, Y.; Bachman, H.N.; Grau, B.; Walsh, D.; Abraham, J.D.; Cannia, J.</p> <p>2012-01-01</p> <p>The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governing the non-invasive Surface NMR (SNMR) technology. We acquired both SNMR data and logging NMR data at a field site, along with lithology information from drill cuttings. This allowed us to directly compare the NMR relaxation parameter measured during logging, T 2, to the relaxation parameter T 2 * measured using the SNMR method. The latter can be affected by inhomogeneity in the magnetic field, thus obscuring the link between the NMR relaxation parameter and the hydraulic conductivity of the geologic material. When the logging T 2 data were transformed to pseudo-T 2 * data, by accounting for inhomogeneity in the magnetic field and instrument dead time, we found good agreement with T 2 * obtained from the SNMR measurement. These results, combined with the additional information about lithology at the site, allowed us to delineate the physical mechanisms governing the SNMR measurement. Such understanding is a critical step in developing SNMR as a reliable geophysical method for the assessment of groundwater resources. Copyright 2012 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SPIE.8658E..18A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SPIE.8658E..18A"><span id="translatedtitle">WFST-based <span class="hlt">ground</span> <span class="hlt">truth</span> alignment for difficult historical documents with text modification and layout variations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al Azawi, Mayce; Liwicki, Marcus; Breuel, Thomas M.</p> <p>2013-01-01</p> <p>This work proposes several approaches that can be used for generating correspondences between real scanned books and their transcriptions which might have different modifications and layout variations, also taking OCR errors into account. Our approaches for the alignment between the manuscript and the transcription are based on weighted finite state transducers (WFST). In particular, we propose adapted WFSTs to represent the transcription to be aligned with the OCR lattices. The character-level alignment has edit rules to allow edit operations (insertion, deletion, substitution). Those edit operations allow the transcription model to deal with OCR segmentation and recognition errors, and also with the task of aligning with different text editions. We implemented an alignment model with a hyphenation model, so it can adapt the non-hyphenated transcription. Our models also work with Fraktur ligatures, which are typically found in historical Fraktur documents. We evaluated our approach on Fraktur documents from Wanderungen durch die Mark Brandenburg" volumes (1862-1889) and observed the performance of those models under OCR errors. We compare the performance of our model for three different scenarios: having no information about the correspondence at the word (i), line (ii), sentence (iii) or page (iv) level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA563743','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA563743"><span id="translatedtitle">Assessing the Impact of Information Channels on the Understanding of <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-06-01</p> <p>Ghost 1-6 Scout 2 Scout 2 Section Ghost 2-6 Engineers Engineer Company Commander Blacksmith 6 101 Scenario 2, Operations Order Unit: 3d...Scout 2 Scout 2 Section Ghost 2-6 Engineers Engineer Company Commander Blacksmith 6 105 APPENDIX H. SHIFT CHANGEOVER BRIEFS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=294392&keyword=library+AND+information+AND+science&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90746031&CFTOKEN=34416627','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=294392&keyword=library+AND+information+AND+science&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90746031&CFTOKEN=34416627"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truthing</span> the 'Conventional Wisdom' of Lead Corrosion Control Using Mineralogical Analysis</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>For drinking water distribution systems (DWDS) with lead-bearing plumbing materials some form of corrosion control is typically necessary, with the goal of mitigating lead release by forming adherent, stable corrosion scales composed of low-solubility mineral phases. Conventional...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=294391&keyword=library+AND+information+AND+science&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90746031&CFTOKEN=34416627','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=294391&keyword=library+AND+information+AND+science&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90746031&CFTOKEN=34416627"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truthing</span> the ‘Conventional Wisdom’ of Lead Corrosion Control Using Mineralogical Analysis</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>For drinking water distribution systems (DWDS) with lead-bearing plumbing materials some form of corrosion control is typically necessary, with the goal of mitigating lead release by forming adherent, stable corrosion scales composed of low-solubility mineral phases. Conventional...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA469462','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA469462"><span id="translatedtitle">Global <span class="hlt">Ground</span> <span class="hlt">Truth</span> Data Set with Waveform and Improved Arrival Data</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2006-09-29</p> <p>Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies Our next example (Figure 4) is from the south flank of Kilauea Volcano ...local network. Sb) c) -I w .15Ř’ *•S| -195.4’ - .. " -in’ 410 -1115 -IisA " l Figure 4. (a) RCA geometry for the Kilauea Volcano south flank, Hawaii...status all 56 events, including the two offshore events near the underwater volcano , Loihi, off the coast of Hawaii and more than 20 km outside the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED260912.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED260912.pdf"><span id="translatedtitle">Man and the Biosphere: <span class="hlt">Ground</span> <span class="hlt">Truthing</span> Coral Reefs for the St. John Island Biosphere Reserve.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Brody, Michael J.; And Others</p> <p></p> <p>Research on the coral species composition of St. John's reefs in the Virgin Islands was conducted through the School for Field Studies (SFS) Coral Reef Ecology course (winter 1984). A cooperative study program based on the United Nations Educational, Scientific, and Cultural Organization's (Unesco) program, Man and the Biosphere, was undertaken by…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940010708','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940010708"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> spectrometry and imagery of eruption clouds to maximize utility of satellite imagery</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rose, William I.</p> <p>1993-01-01</p> <p>Field experiments with thermal imaging infrared radiometers were performed and a laboratory system was designed for controlled study of simulated ash clouds. Using AVHRR (Advanced Very High Resolution Radiometer) thermal infrared bands 4 and 5, a radiative transfer method was developed to retrieve particle sizes, optical depth and particle mass involcanic clouds. A model was developed for measuring the same parameters using TIMS (Thermal Infrared Multispectral Scanner), MODIS (Moderate Resolution Imaging Spectrometer), and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). Related publications are attached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=computer+AND+network+AND+design&pg=3&id=ED548206','ERIC'); return false;" href="http://eric.ed.gov/?q=computer+AND+network+AND+design&pg=3&id=ED548206"><span id="translatedtitle">Inter-Vehicular Ad Hoc Networks: From the <span class="hlt">Ground</span> <span class="hlt">Truth</span> to Algorithm Design and Testbed Architecture</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Giordano, Eugenio</p> <p>2011-01-01</p> <p>Many of the devices we interact with on a daily basis are currently equipped with wireless connectivity. Soon this will be extended to the vehicles we drive/ride every day. Wirelessly connected vehicles will form a new kind of network that will enable a wide set of innovative applications ranging from enhanced safety to entertainment. To…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26430292','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26430292"><span id="translatedtitle">Objective evaluation of reconstruction methods for quantitative SPECT imaging in the absence of <span class="hlt">ground</span> <span class="hlt">truth</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jha, Abhinav K; Song, Na; Caffo, Brian; Frey, Eric C</p> <p>2015-04-13</p> <p>Quantitative single-photon emission computed tomography (SPECT) imaging is emerging as an important tool in clinical studies and biomedical research. There is thus a need for optimization and evaluation of systems and algorithms that are being developed for quantitative SPECT imaging. An appropriate objective method to evaluate these systems is by comparing their performance in the end task that is required in quantitative SPECT imaging, such as estimating the mean activity concentration in a volume of interest (VOI) in a patient image. This objective evaluation can be performed if the true value of the estimated parameter is known, i.e. we have a gold standard. However, very rarely is this gold standard known in human studies. Thus, no-gold-standard techniques to optimize and evaluate systems and algorithms in the absence of gold standard are required. In this work, we developed a no-gold-standard technique to objectively evaluate reconstruction methods used in quantitative SPECT when the parameter to be estimated is the mean activity concentration in a VOI. We studied the performance of the technique with realistic simulated image data generated from an object database consisting of five phantom anatomies with all possible combinations of five sets of organ uptakes, where each anatomy consisted of eight different organ VOIs. Results indicate that the method provided accurate ranking of the reconstruction methods. We also demonstrated the application of consistency checks to test the no-gold-standard output.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750021458','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750021458"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> data for test sites (SL-3). [solar radiation and thermal radiation brightness temperature measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1974-01-01</p> <p>Field measurements performed simultaneously with Skylab overpasses in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. The solar radiation region from 400 to 1300 nanometers and the thermal radiation region from 8 to 14 micrometer region were investigated. The measurements of direct solar radiation were analyzed for atmospheric optical depth; the total and reflected solar radiation were analyzed for target reflectivity. These analyses were used in conjunction with a radiative transfer computer program in order to calculate the amount and spectral distribution of solar radiation at the apertures of the EREP sensors. The instrumentation and techniques employed, calibrations and analyses performed, and results obtained are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750022555','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750022555"><span id="translatedtitle">Skylab program earth resources experiment package: <span class="hlt">Ground</span> <span class="hlt">truth</span> data for test sites (SL-2)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1975-01-01</p> <p>Field measurements were performed at selected ground sites in order to provide comparative calibration measurements of sensors for the Earth Resources Experiment Package. Specifically, the solar radiation (400 to 1300 namometers) and thermal radiation (8-14 micrometers) were measured. Sites employed for the thermal measurements consisted of warm and cold water lakes. The thermal brightness temperature of the lake water, the temperature and humidity profile above the lake, and near surface meteorology (wind speed, pressure, etc.) were measured near the time of overpass. Sites employed for the solar radiation measurements were two desert type sites. Ground measurements consisted of: (1) direct solar radiation - optical depth; (2) diffuse solar radiation; (3) total solar radiation, (4) target directional (normal) reflectance; (5) target hemispherical reflectance; and (6) near surface meteorology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750021459','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750021459"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">truth</span> data for test sites (SL-4). [thermal radiation brightness temperature and solar radiation measurments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1974-01-01</p> <p>Field measurements performed simultaneous with Skylab overpass in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. Wavelength region covered include: solar radiation (400 to 1300 nanometer), and thermal radiation (8 to 14 micrometer). Measurements consisted of general conditions and near surface meteorology, atmospheric temperature and humidity vs altitude, the thermal brightness temperature, total and diffuse solar radiation, direct solar radiation (subsequently analyzed for optical depth/transmittance), and target reflectivity/radiance. The particular instruments used are discussed along with analyses performed. Detailed instrument operation, calibrations, techniques, and errors are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA108342','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA108342"><span id="translatedtitle"><span class="hlt">Ground-Truth</span> Observations of Ice-Covered North Slope Lakes Imaged by Radar</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1981-10-01</p> <p>published by the American Society for Testing and Materi- als, 1916 Race St., Philadelphia, Pa. 19103. Cover: Radar image of the north coast of Alaska...truth observations of ice-covered North Slope lakes imaged by radar W.F. Weeks, A.J. Cow and R.J. Schertler J October 1981 ’AA Prepared for OCEAN...PROCESSES BRANCH NATIONAL AERONAUTICS AND SPACE ADMINISTRATION By UNITED STATES ARMY CORPS OF ENGINEERS COLD REGIONS RESEARCH AND ENGINEERING LABORATORY</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1510959P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1510959P"><span id="translatedtitle">Experimental impact cratering provides <span class="hlt">ground</span> <span class="hlt">truth</span> data for understanding planetary-scale collision processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poelchau, Michael H.; Deutsch, Alex; Kenkmann, Thomas</p> <p>2013-04-01</p> <p>Impact cratering is generally accepted as one of the primary processes that shape planetary surfaces in the solar system. While post-impact analysis of craters by remote sensing or field work gives many insights into this process, impact cratering experiments have several advantages for impact research: 1) excavation and ejection processes can be directly observed, 2) physical parameters of the experiment are defined and can be varied, and 3) cratered target material can be analyzed post-impact in an unaltered, uneroded state. The main goal of the MEMIN project is to comprehensively quantify impact processes by conducting a stringently controlled experimental impact cratering campaign on the meso-scale with a multidisciplinary analytical approach. As a unique feature we use two-stage light gas guns capable of producing impact craters in the decimeter size-range in solid rocks that, in turn, allow detailed spatial analysis of petrophysical, structural, and geochemical changes in target rocks and ejecta. In total, we have carried out 24 experiments at the facilities of the Fraunhofer EMI, Freiburg - Germany. Steel, aluminum, and iron meteorite projectiles ranging in diameter from 2.5 to 12 mm were accelerated to velocities ranging from 2.5 to 7.8 km/s. Targets were solid rocks, namely sandstone, quartzite and tuff that were either dry or saturated with water. In the experimental setup, high speed framing cameras monitored the impact process, ultrasound sensors were attached to the target to record the passage of the shock wave, and special particle catchers were positioned opposite of the target surface to capture the ejected target and projectile material. In addition to the cratering experiments, planar shock recovery experiments were performed on the target material, and numerical models of the cratering process were developed. The experiments resulted in craters with diameters up to 40 cm, which is unique in laboratory cratering research. Target porosity exponentially reduces crater volumes and cratering efficiency relative to non-porous rocks, and also yields less steep ejecta angles. Microstructural analysis of the subsurface shows a zone of pervasive grain crushing and pore space reduction. This is in good agreement with new mesoscale numerical models, which are able to quantify localized shock pressure behavior in the target's pore space. Planar shock recovery experiments confirm these local pressure excursions, based on microanalysis of shock metamorphic features in quartz. Saturation of porous target rocks with water counteracts many of the effects of porosity. Post-impact analysis of projectile remnants shows that during mixing of projectile and target melts, the Fe of the projectile is preferentially partitioned into target melt to a greater degree than Ni and Co. We plan to continue evaluating the experimental results in combination with numerical models. These models help to quantify and evaluate cratering processes, while experimental data serve as benchmarks to validate the improved numerical models, thus helping to "bridge the gap" between experiments and nature. The results confirm and expand current crater scaling laws, and make an application to craters on planetary surfaces possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMNH31D..04K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMNH31D..04K"><span id="translatedtitle">Eltanin: <span class="hlt">Ground</span> <span class="hlt">Truth</span> for Kilometer-Sized Deep-Ocean Impacts (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kyte, F. T.; Gersonde, R.; Kuhn, G.</p> <p>2009-12-01</p> <p>Deposits of the late Pliocene (2.5 Ma) Eltanin impact are unique in the known geological record. The only known example of a km-sized asteroid to impact a deep-ocean (5 km) basin, is the most meterorite-rich locality known on Earth. This was discovered as an Ir anomaly in sediments from three cores collected in the SE Pacific in 1965 by the USNS Eltanin. Subsequently, two expeditions of the R/V Polarstern in 1995 and 2001 have conducted geological and geophysical investigations in the impact region. An area of ~80,000 km2 has been mapped in some detail, and deposits from the impact are found in 23 cores spanning a region extending 660 (E-W) by 250 km (N-S). We find a central region 50 to 100 km across, near the Freeden Seamounts (57.3S, 90.5W), where sediments as old as Eocene have been ripped up (perhaps to basement) and redeposited by the impact into a chaotic mix of pebble to boulder-sized fragments. This is overlain by a fining upward sequence of sediments with laminations and some cross-bedding consistent with deposition in a high-energy flow regime. Near the top of this impact deposit, sub mm- to cm-sized meteoritic ejecta is mixed into the disturbed sediment. This ejecta is composed of 90% shock-melted asteroid and 10% unmelted meteorite fragments from the lo-metal mesosiderite asteroid. The amount of meteoritic ejecta in 13 cores from the central region record deposition of 3 to 50 kg of asteroid material per square meter. Km-sized impacts are fairly common on geological timescales, occurring a few times per m.y., so one or two other similar-sized, and several smaller projectiles likely hit the Pacific basin since the Late Pliocene. Undoubtedly, this is not the only such impact collected in deep-sea cores; it is unique only in that it has been recognized. Eltanin thus serves as type section for identifying ocean-impact deposits at other localities. Projectiles of this size cannot penetrate to the ocean floor and indeed there is no chemical evidence in the ejecta of mixing between asteroidal and terrestrial silicates. However, severe disturbance of of seafloor sediments over a wide region attest to the energy of this event. We have found no evidence of a physical “crater,” but it is conceivable that the water cavity formed by the impact extended to the bottom and could have even briefly exposed large areas of the seafloor. If deep-ocean impacts represent a significant hazard due to climate change or wave propagation, Eltanin could be a good test case if it’s effects can just be discerned outside the immediate impact region. The late Pliocene was a time of rapid climate change, but we have been unsuccessful at detecting Eltanin ejecta in high-resolution cores from the S. Atlantic. Unfortunately, the poor time-resolution in the Polarstern piston cores is insufficient to tie the impact to the O-isotope-based climate record. Perhaps the best chance would be to search for tsunami deposits. Models projecting the propagation of Eltanin-sized impact waves would be useful in evaluating the effects of this impact across the Pacific and other ocean basins.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/350952','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/350952"><span id="translatedtitle">Operation of an array of field-change detectors to provide <span class="hlt">ground</span> <span class="hlt">truth</span> for FORTE data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Massey, R.S.; Eack, K.B.; Eberle, M.H.; Shao, X.M.; Smith, D.A.; Wiens, K.C.</p> <p>1999-06-01</p> <p>The authors have deployed an array of fast electric-field-change sensors around the state of New Mexico to help identify the lightning processes responsible for the VHF RF signals detected by the FORTE satellite`s wide-band transient radio emission receivers. The array provides them with locations and electric-field waveforms for events within New Mexico and into surrounding states, and operates continuously. They are particularly interested in events for which there are coincident FORTE observations. For these events, they can correct both the array and FORTE waveforms for time of flight, and can plot the two waveforms on a common time axis. Most of the coincident events are from cloud-go-ground discharges, but the most powerful are from a little-studied class of events variously called narrow bipolar events and compact intra-cloud discharges. They have therefore focused their attention on these events whether or not FORTE was in position to observe them.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=220563','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=220563"><span id="translatedtitle">Airborne multi-spectral remote sensing with <span class="hlt">ground</span> <span class="hlt">truth</span> for areawide pest management</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Scientists and researchers have been developing, integrating, and evaluating multiple strategies and technologies into a systems approach for management of field crop insect pests. Remote sensing along with Global Positioning Systems, Geographic Information Systems, and variable rate technology are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=classification+AND+algorithm&pg=2&id=ED554172','ERIC'); return false;" href="http://eric.ed.gov/?q=classification+AND+algorithm&pg=2&id=ED554172"><span id="translatedtitle">Liberal or Conservative: Evaluation and Classification with Distribution as <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Zhou, Daniel Xiaodan</p> <p>2013-01-01</p> <p>The ability to classify the political leaning of a large number of articles and items is valuable to both academic research and practical applications. The challenge, though, is not only about developing innovative classification algorithms, which constitutes a "classifier" theme in this thesis, but also about how to define the…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..117R2408H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..117R2408H"><span id="translatedtitle"><span class="hlt">Ground-truthing</span> evoked potential measurements against behavioral conditioning in the goldfish, Carassius auratus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, Randy J.; Mann, David A.</p> <p>2005-04-01</p> <p>Auditory evoked potentials (AEPs) have become commonly used to measure hearing thresholds in fish. However, it is uncertain how well AEP thresholds match behavioral hearing thresholds and what effect variability in electrode placement has on AEPs. In the first experiment, the effect of electrode placement on AEPs was determined by simultaneously recording AEPs from four locations on each of 12 goldfish, Carassius auratus. In the second experiment, the hearing sensitivity of 12 goldfish was measured using both classical conditioning and AEP's in the same setup. For behavioral conditioning, the fish were trained to reduce their respiration rate in response to a 5 s sound presentation paired with a brief shock. A modified staircase method was used in which 20 reversals were completed for each frequency, and threshold levels were determined by averaging the last 12 reversals. Once the behavioral audiogram was completed, the AEP measurements were made without moving the fish. The recording electrode was located subdermally over the medulla, and was inserted prior to classical conditioning to minimize handling of animal. The same sound stimuli (pulsed tones) were presented and the resultant evoked potentials were recorded for 1000-6000 averages. AEP input-output functions were then compared to the behavioral audiogram to compare techniques for estimating behavioral thresholds from AEP data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA487579','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA487579"><span id="translatedtitle">Crustal Structure of the Iran Region from In-Country and <span class="hlt">Ground-Truth</span> Data</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2008-09-30</p> <p>region. Recent studies report crustal thickness in the Arabian shield ranging from 32-37 km, thickening to 43-45 km in the foredeep basin of the Zagros ...the foredeep, folding and faulting in the Zagros Mountains is exposed at the surface and surface elevation steadily increases. However, crustal...thickness remains relatively constant from the foredeep to the main Zagros thrust fault (Paul et al., 2006). From the main Zagros thrust to -50-90 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9416E..1KJ','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9416E..1KJ"><span id="translatedtitle">Objective evaluation of reconstruction methods for quantitative SPECT imaging in the absence of <span class="hlt">ground</span> <span class="hlt">truth</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jha, Abhinav K.; Song, Na; Caffo, Brian; Frey, Eric C.</p> <p>2015-03-01</p> <p>Quantitative single-photon emission computed tomography (SPECT) imaging is emerging as an important tool in clinical studies and biomedical research. There is thus a need for optimization and evaluation of systems and algorithms that are being developed for quantitative SPECT imaging. An appropriate objective method to evaluate these systems is by comparing their performance in the end task that is required in quantitative SPECT imaging, such as estimating the mean activity concentration in a volume of interest (VOI) in a patient image. This objective evaluation can be performed if the true value of the estimated parameter is known, i.e. we have a gold standard. However, very rarely is this gold standard known in human studies. Thus, no-gold-standard techniques to optimize and evaluate systems and algorithms in the absence of gold standard are required. In this work, we developed a no-gold-standard technique to objectively evaluate reconstruction methods used in quantitative SPECT when the parameter to be estimated is the mean activity concentration in a VOI. We studied the performance of the technique with realistic simulated image data generated from an object database consisting of five phantom anatomies with all possible combinations of five sets of organ uptakes, where each anatomy consisted of eight different organ VOIs. Results indicate that the method pro- vided accurate ranking of the reconstruction methods. We also demonstrated the application of consistency checks to test the no-gold-standard output.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/840064','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/840064"><span id="translatedtitle">Grid-Search Location Methods for <span class="hlt">Ground-Truth</span> Collection From Local and Regional Seismic Networks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>William Rodi; Craig A. Schultz; Gardar Johannesson; Stephen C. Myers</p> <p>2005-05-13</p> <p>This project investigated new techniques for improving seismic event locations derived from regional and local networks. The technqiues include a new approach to empirical travel-time calibration that simultaneously fits data from multiple stations and events, using a generalization of the kriging method, and predicts travel-time corrections for arbitrary event-station paths. We combined this calibration approach with grid-search event location to produce a prototype new multiple-event location method that allows the use of spatially well-distributed events and takes into account correlations between the travel-time corrections from proximate event-station paths. Preliminary tests with a high quality data set from Nevada Test Site explosions indicated that our new calibration/location method offers improvement over the conventional multiple-event location methods now in common use, and is applicable to more general event-station geometries than the conventional methods. The tests were limited, however, and further research is needed to fully evaluate, and improve, the approach. Our project also demonstrated the importance of using a realistic model for observational errors in an event location procedure. We took the initial steps in developing a new error model based on mixture-of-Gaussians probability distributions, which possess the properties necessary to characterize the complex arrival time error processes that can occur when picking low signal-to-noise arrivals. We investigated various inference methods for fitting these distributions to observed travel-time residuals, including a Markov Chain Monte Carlo technique for computing Bayesian estimates of the distribution parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUSM.A11B..02G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUSM.A11B..02G"><span id="translatedtitle">Anomalous Transmission of <span class="hlt">Infrasound</span> Through Air-Water and Air-Ground Interfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Godin, O. A.</p> <p>2009-05-01</p> <p>Speed of compressional waves in air is smaller than in water and in the ground, while mass density of air is much smaller than mass densities of water and the ground. This results in a very strong acoustic impedance contrast at air-water and air-ground interfaces. Sound transmission through a boundary with a strong impedance contrast is normally very weak. This paper reports theoretical studies of the power output of localized sound <span class="hlt">sources</span> and acoustic power fluxes through plane gas-liquid and gas-solid interfaces in a layered medium. It is found that the transparency of the interfaces increases dramatically at low frequencies. For low-frequency sound, a phenomenon of anomalous transparency can occur where most of the acoustic power generated by a <span class="hlt">source</span> in water is radiated into the atmosphere. Contrary to the conventional wisdom based on ray-theoretical predictions and observations at higher frequencies, infrasonic energy from localized waterborne <span class="hlt">sources</span> can be effectively transmitted into air. The main physical mechanism responsible for the anomalous transparency of air-water interface is found to be an acoustic power transfer by inhomogeneous (evanescent) waves in the plane-wave decomposition of the acoustic field in water. The effects of ocean and atmosphere stratification and of guided sound propagation in water or in air on the anomalous transparency of the air-water interface are considered. In the case of air-ground interface, the increase of the acoustic power flux into atmosphere, when a compact <span class="hlt">source</span> approaches the interface from below, proves to be even larger than for an underwater <span class="hlt">source</span>. The physics behind the increase of the power flux into the atmosphere, when the <span class="hlt">source</span> depth decreases, is shown to be rather different for the air-ground and air-water interfaces. Depending on attenuation of compressional and shear waves in the ground, a leaky interface wave supported by the air-ground interface can be responsible for the bulk of acoustic power</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.2683M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.2683M"><span id="translatedtitle">Ionosonde tracking of <span class="hlt">infrasound</span> wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel</p> <p>2016-03-01</p> <p>Ionospheric disturbances associated with the M8.8 Chile earthquake (35.91°S, 72.73°W) on 27 February 2010 were observed at Kazan, Russia (55.85°N, 48.81°E). Rapid-run ionograms at 1 min intervals exhibited multiple-cusp signatures (MCSs) for more than 30 min, which have been observed several times after large earthquakes. The ionospheric disturbances were caused by <span class="hlt">infrasound</span> propagating upward in the atmosphere, which modified the electron density distribution through ion-neutral collisions. The anomaly of the vertical electron density distribution responsible for the MCSs was analyzed by converting the ionogram traces into real height profiles. The density profiles at 1 min intervals allowed the tracking of the vertical propagation of <span class="hlt">infrasound</span> and provided information on parameters of acoustic waves, which was not possible from the previous measurements such as standard ionograms at 5-15 min intervals, HF Doppler soundings, and total electron content using satellite beacon signals. The speed of acoustic waves in the thermosphere was evaluated from the consecutive ionograms with MCSs, and it was found that the thermospheric temperature was slightly higher than that calculated using the Mass Spectrometer and Incoherent Scatter Radar empirical model (NRLMSISE-00).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1175842','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1175842"><span id="translatedtitle">Methods and systems for low frequency seismic and <span class="hlt">infrasound</span> detection of geo-pressure transition zones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Shook, G. Michael; LeRoy, Samuel D.; Benzing, William M.</p> <p>2006-07-18</p> <p>Methods for determining the existence and characteristics of a gradational pressurized zone within a subterranean formation are disclosed. One embodiment involves employing an attenuation relationship between a seismic response signal and increasing wavelet wavelength, which relationship may be used to detect a gradational pressurized zone and/or determine characteristics thereof. In another embodiment, a method for analyzing data contained within a response signal for signal characteristics that may change in relation to the distance between an input signal <span class="hlt">source</span> and the gradational pressurized zone is disclosed. In a further embodiment, the relationship between response signal wavelet frequency and comparative amplitude may be used to estimate an optimal wavelet wavelength or range of wavelengths used for data processing or input signal selection. Systems for seismic exploration and data analysis for practicing the above-mentioned method embodiments are also disclosed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/918544','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/918544"><span id="translatedtitle">Systems for low frequency seismic and <span class="hlt">infrasound</span> detection of geo-pressure transition zones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Shook, G. Michael; LeRoy, Samuel D.; Benzing, William M.</p> <p>2007-10-16</p> <p>Methods for determining the existence and characteristics of a gradational pressurized zone within a subterranean formation are disclosed. One embodiment involves employing an attenuation relationship between a seismic response signal and increasing wavelet wavelength, which relationship may be used to detect a gradational pressurized zone and/or determine characteristics thereof. In another embodiment, a method for analyzing data contained within a response signal for signal characteristics that may change in relation to the distance between an input signal <span class="hlt">source</span> and the gradational pressurized zone is disclosed. In a further embodiment, the relationship between response signal wavelet frequency and comparative amplitude may be used to estimate an optimal wavelet wavelength or range of wavelengths used for data processing or input signal selection. Systems for seismic exploration and data analysis for practicing the above-mentioned method embodiments are also disclosed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ERL.....6c5103B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ERL.....6c5103B"><span id="translatedtitle"><span class="hlt">Infrasound</span> and low frequency noise from wind turbines: exposure and health effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bolin, Karl; Bluhm, Gösta; Eriksson, Gabriella; Nilsson, Mats E.</p> <p>2011-07-01</p> <p>Wind turbines emit low frequency noise (LFN) and large turbines generally generate more LFN than small turbines. The dominant <span class="hlt">source</span> of LFN is the interaction between incoming turbulence and the blades. Measurements suggest that indoor levels of LFN in dwellings typically are within recommended guideline values, provided that the outdoor level does not exceed corresponding guidelines for facade exposure. Three cross-sectional questionnaire studies show that annoyance from wind turbine noise is related to the immission level, but several explanations other than low frequency noise are probable. A statistically significant association between noise levels and self-reported sleep disturbance was found in two of the three studies. It has been suggested that LFN from wind turbines causes other, and more serious, health problems, but empirical support for these claims is lacking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1258366','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1258366"><span id="translatedtitle">InfraPy: Python-Based Signal Analysis Tools for <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Blom, Philip Stephen; Marcillo, Omar Eduardo; Euler, Garrett Gene</p> <p>2016-05-31</p> <p>InfraPy is a Python-based analysis toolkit being development at LANL. The algorithms are intended for ground-based nuclear detonation detection applications to detect, locate, and characterize explosive <span class="hlt">sources</span> using infrasonic observations. The implementation is usable as a stand-alone Python library or as a command line driven tool operating directly on a database. With multiple scientists working on the project, we've begun using a LANL git repository for collaborative development and version control. Current and planned work on InfraPy focuses on the development of new algorithms and propagation models. Collaboration with Southern Methodist University (SMU) has helped identify bugs and limitations of the algorithms. The current focus of usage development is focused on library imports and CLI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeoRL..3622802C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeoRL..3622802C"><span id="translatedtitle"><span class="hlt">Infrasound</span> observation of the apparent North Korean nuclear test of 25 May 2009</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, Il-Young; Kim, Tae Sung; Jeon, Jeong-Soo; Lee, Hee-Il</p> <p>2009-11-01</p> <p>On 25 May 2009, a seismic event (mb 4.6) was recorded from a <span class="hlt">source</span> in northeastern North Korea, close to the location of a previous seismic event on 9 October 2006. Both events have been declared to be nuclear tests by North Korea. For the more recent test, five seismo-acoustic arrays in South Korea recorded epicentral infrasonic signals. The signals are characterized by amplitudes from 0.16 to 0.35 microbar and dominant frequencies between 0.8 and 4.3 Hz. Celerities determined for the arrivals suggest that most of the infrasonic energy travelled as a stratospheric phase. Based on observed stratospheric amplitudes, the epicentral infrasonic energy was estimated to be equivalent to that expected from 3.0 tons of high explosives detonated on the surface. We conclude that this small energy estimate is due to the atmospheric coupling from the strong surface ground motion rather than the direct transfer of explosion energy to the air. This relatively small infrasonic to seismic energy ratio could be used to distinguish the event from a common surface explosion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..177..673J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..177..673J"><span id="translatedtitle">Acoustic <span class="hlt">source</span> characterization of impulsive Strombolian eruptions from the Mount Erebus lava lake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, Jeffrey; Aster, Richard; Jones, Kyle R.; Kyle, Philip; McIntosh, Bill</p> <p>2008-11-01</p> <p>We invert for acoustic <span class="hlt">source</span> volume outflux and momentum imparted to the atmosphere using an infrasonic network distributed about the erupting lava lake at Mount Erebus, Ross Island, Antarctica. By modeling these relatively simple eruptions as monopole point <span class="hlt">sources</span> we estimate explosively ejected gas volumes that range from 1,000 m 3 to 24,000 m 3 for 312 lava lake eruptions recorded between January 6 and April 13, 2006. Though these volumes are compatible with bubble volumes at rupture (as estimated from explosion video records), departures from isotropic radiation are evident in the recorded acoustic wavefield for many eruptions. A point-<span class="hlt">source</span> acoustic dipole component with arbitrary axis orientation and strength provides precise fit to the recorded <span class="hlt">infrasound</span>. This dipole <span class="hlt">source</span> axis, corresponding to the axis of inferred short-duration material jetting, varies significantly between events. Physical interpretation of dipole orientation as being indicative of eruptive directivity is corroborated by directional emissions of ejecta observed in Erebus eruption video footage. Although three azimuthally distributed stations are insufficient to fully characterize the eruptive acoustic <span class="hlt">source</span> we speculate that a monopole with a minor amount of oriented dipole radiation may reasonably model the primary features of the recorded <span class="hlt">infrasound</span> for these eruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S11B1741P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S11B1741P"><span id="translatedtitle">Tomographic Inversion for Regional Phase Attenuation and <span class="hlt">Source</span> Parameters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, W. S.; Mayeda, K. M.; Malagnini, L.</p> <p>2008-12-01</p> <p>Our ability to monitor seismic events that are too small to be observed at teleseismic distances depends critically on the accurate characterization of the effects of <span class="hlt">source</span>, path and site on regional phases. Magnitude, yield and event identification procedures rely on path and site corrections, while identification schemes such as MDAC (magnitude and distance amplitude correction) additionally rely on <span class="hlt">source</span> correction via a regionally appropriate scaling model. Independently determined Mw can drive the <span class="hlt">source</span> correction. Here, we focus on the use of Lg amplitudes to obtain a laterally varying attenuation model with power law frequency dependence, site amplification terms, and <span class="hlt">source</span> scaling parameters such as apparent stress, using data from the USArray deployment. We collected amplitudes from broadband vertical channels of 605 USArray stations for 986 western US PDE events through June 2008. The IRIS DMC provided waveform data and instrument response information. We measured RMS amplitudes in eleven overlapping octave width bands between 0.25 and 16 Hz, for windows defined by group velocities 3.6 to 3.0 km/s. Over 320,000 amplitudes passed a pre-phase signal-to-noise threshold of 2. Berkeley moments were used to set absolute levels. We found 1-Hz attenuation (Qo) to be high in stable regions and across batholiths, and low in areas of recent volcanism. The power law exponent (eta) varied from 0.4 to 0.9 and was generally lower in the high Q regions. We explore methods that break the tradeoff between attenuation and stress by damping mean Qo and eta to values determined by inverting for frequency dependent <span class="hlt">source</span> terms, and by applying <span class="hlt">ground</span> <span class="hlt">truth</span> scaling information from relative coda studies for particular events. Tests that evaluate regionalization of apparent stress are underway, although we acknowledge that the limited bandwidth and deployment period are not ideal for this purpose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22676714','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22676714"><span id="translatedtitle">The modulating impact of illumination and background radiation on 8 Hz-induced <span class="hlt">infrasound</span> effect on physicochemical properties of physiolagical solution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baghdasaryan, Naira; Mikayelyan, Yerazik; Barseghyan, Sedrak; Dadasyan, Erna; Ayrapetyan, Sinerik</p> <p>2012-12-01</p> <p>At present, when the level of background ionizing radiation is increasing in a number of world locations, the problem of the study of biological effect of high background radiation becomes one of the extremely important global problems in modern life sciences. The modern research in biophysics proved that water is a most essential target, through which the biological effects of ionizing and non-ionizing radiations are realized. Therefore, there is no doubt about the strong dependency of non-ionizing radiation-induced effect on the level of background radiation. Findings have shown that illumination and background radiation have a strong modulation effect on <span class="hlt">infrasound</span>-induced impacts on water physicochemical properties, which could also have appropriate effect on living organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B51B0368H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B51B0368H"><span id="translatedtitle">Atmospheric Rawinsonde and Pigeon Release Data Implicate <span class="hlt">Infrasound</span> as the Long- Range Map Cue in Avian Navigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hagstrum, J. T.</p> <p>2007-12-01</p> <p>Pigeons ( Columba livia) and other birds released from distant familiar and unfamiliar sites generally head in the homeward (loft) direction, but often vanish from view or radio contact consistently off the exact homeward bearing. At some sites the deviation can be a significant and stable amount, while at other sites birds can appear to become completely lost and depart in random directions. These deviations or biases can change from hour to hour, day to day, and year to year, but have not, over the last ~50 years of intensive research, been related to any atmospheric factor. They are, however, still considered to reflect significant irregularities in the pigeons' "map" function. Celestial and geomagnetic "compasses" have been shown to orient avian flight, but how pigeons determine their location in order to select the correct homeward bearing remains controversial. At present the debate is primarily between workers advocating an olfactory "map" and those advocating variations in the direction and intensity of the geomagnetic field as map functions. Alternatively, infrasonic cues can travel 1000s of km in the atmosphere with little attenuation, and can be detected in the laboratory by pigeons at frequencies down to 0.05 Hz. Although <span class="hlt">infrasound</span> has been considered as a navigational tool for homing and migratory birds, little supporting evidence of its use has been found. Infrasonic ray paths in the atmosphere are controlled primarily by temperature and secondarily by wind. Assuming birds use infrasonic cues, atmospheric conditions could cause the perplexing changes (both geographic and temporal) observed in the mean vanishing bearings (MVBs) of pigeons released from experimental sites. To test for correlations between MVBs and tropospheric conditions, release data collected by the late W.T. Keeton between 1968 and 1980 from around the Cornell University lofts in upstate NY are compared to rawinsonde data from stations near Buffalo and Albany. For example, birds</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21373993','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21373993"><span id="translatedtitle">An open <span class="hlt">source</span> multivariate framework for n-tissue segmentation with evaluation on public data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Avants, Brian B; Tustison, Nicholas J; Wu, Jue; Cook, Philip A; Gee, James C</p> <p>2011-12-01</p> <p>We introduce Atropos, an ITK-based multivariate n-class open <span class="hlt">source</span> segmentation algorithm distributed with ANTs ( http://www.picsl.upenn.edu/ANTs). The Bayesian formulation of the segmentation problem is solved using the Expectation Maximization (EM) algorithm with the modeling of the class intensities based on either parametric or non-parametric finite mixtures. Atropos is capable of incorporating spatial prior probability maps (sparse), prior label maps and/or Markov Random Field (MRF) modeling. Atropos has also been efficiently implemented to handle large quantities of possible labelings (in the experimental section, we use up to 69 classes) with a minimal memory footprint. This work describes the technical and implementation aspects of Atropos and evaluates its performance on two different <span class="hlt">ground-truth</span> datasets. First, we use the BrainWeb dataset from Montreal Neurological Institute to evaluate three-tissue segmentation performance via (1) K-means segmentation without use of template data; (2) MRF segmentation with initialization by prior probability maps derived from a group template; (3) Prior-based segmentation with use of spatial prior probability maps derived from a group template. We also evaluate Atropos performance by using spatial priors to drive a 69-class EM segmentation problem derived from the Hammers atlas from University College London. These evaluation studies, combined with illustrative examples that exercise Atropos options, demonstrate both performance and wide applicability of this new platform-independent open <span class="hlt">source</span> segmentation tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ISPArXL15..249G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ISPArXL15..249G"><span id="translatedtitle">Improvement of dem Generation from Aster Images Using Satellite Jitter Estimation and Open <span class="hlt">Source</span> Implementation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Girod, L.; Nuth, C.; Kääb, A.</p> <p>2015-12-01</p> <p>The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) system embarked on the Terra (EOS AM-1) satellite has been a <span class="hlt">source</span> of stereoscopic images covering the whole globe at a 15m resolution at a consistent quality for over 15 years. The potential of this data in terms of geomorphological analysis and change detection in three dimensions is unrivaled and needs to be exploited. However, the quality of the DEMs and ortho-images currently delivered by NASA (ASTER DMO products) is often of insufficient quality for a number of applications such as mountain glacier mass balance. For this study, the use of Ground Control Points (GCPs) or of other <span class="hlt">ground</span> <span class="hlt">truth</span> was rejected due to the global "big data" type of processing that we hope to perform on the ASTER archive. We have therefore developed a tool to compute Rational Polynomial Coefficient (RPC) models from the ASTER metadata and a method improving the quality of the matching by identifying and correcting jitter induced cross-track parallax errors. Our method outputs more accurate DEMs with less unmatched areas and reduced overall noise. The algorithms were implemented in the open <span class="hlt">source</span> photogrammetric library and software suite MicMac.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3297199','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3297199"><span id="translatedtitle">An Open <span class="hlt">Source</span> Multivariate Framework for n-Tissue Segmentation with Evaluation on Public Data</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tustison, Nicholas J.; Wu, Jue; Cook, Philip A.; Gee, James C.</p> <p>2012-01-01</p> <p>We introduce Atropos, an ITK-based multivariate n-class open <span class="hlt">source</span> segmentation algorithm distributed with ANTs (http://www.picsl.upenn.edu/ANTs). The Bayesian formulation of the segmentation problem is solved using the Expectation Maximization (EM) algorithm with the modeling of the class intensities based on either parametric or non-parametric finite mixtures. Atropos is capable of incorporating spatial prior probability maps (sparse), prior label maps and/or Markov Random Field (MRF) modeling. Atropos has also been efficiently implemented to handle large quantities of possible labelings (in the experimental section, we use up to 69 classes) with a minimal memory footprint. This work describes the technical and implementation aspects of Atropos and evaluates its performance on two different <span class="hlt">ground-truth</span> datasets. First, we use the BrainWeb dataset from Montreal Neurological Institute to evaluate three-tissue segmentation performance via (1) K-means segmentation without use of template data; (2) MRF segmentation with initialization by prior probability maps derived from a group template; (3) Prior-based segmentation with use of spatial prior probability maps derived from a group template. We also evaluate Atropos performance by using spatial priors to drive a 69-class EM segmentation problem derived from the Hammers atlas from University College London. These evaluation studies, combined with illustrative examples that exercise Atropos options, demonstrate both performance and wide applicability of this new platform-independent open <span class="hlt">source</span> segmentation tool. PMID:21373993</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9170R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9170R"><span id="translatedtitle"><span class="hlt">Sources</span> of Uncertainty in Rainfall Maps from Cellular Communication Networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rios Gaona, Manuel Felipe; Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko</p> <p>2015-04-01</p> <p>Accurate measurements of rainfall are important in many hydrological applications, for instance, flash-flood early-warning systems, hydraulic structures design, agriculture, weather forecasting, and climate modelling. Rainfall intensities can be retrieved from (commercial) microwave link networks. Whenever possible, link networks measure and store the decrease in power of the electromagnetic signal at regular intervals. The decrease in power is largely due to the attenuation by raindrops along the link paths. Such an alternative technique fulfills the continuous strive for measurements of rainfall in time and space at higher resolutions, especially in places where traditional rain gauge networks are scarce or poorly maintained. Rainfall maps from microwave link networks have recently been introduced at country-wide scales. Despite their potential in rainfall estimation at high spatiotemporal resolutions, the uncertainties present in rainfall maps from link networks are not yet fully comprehended. The aim of this work is to identify and quantify the <span class="hlt">sources</span> of uncertainty present in interpolated rainfall maps from link rainfall depths. In order to disentangle these <span class="hlt">sources</span> of uncertainty, we classified them into two categories: (1) those associated with the individual microwave link measurements, i.e., the physics involved in the measurements such as wet antenna attenuation, sampling interval of measurements, wet/dry period classification, drop size distribution (DSD), and multi-path propagation; (2) those associated with mapping, i.e., the combined effect of the interpolation methodology, the spatial density of the network, and the availability of link measurements. We computed ~ 3500 rainfall maps from real and simulated link rainfall depths for 12 days for the land surface of The Netherlands. These rainfall maps were compared against quality-controlled gauge-adjusted radar rainfall fields (assumed to be the <span class="hlt">ground</span> <span class="hlt">truth</span>). Thus, we were able to not only identify</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1614108K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1614108K"><span id="translatedtitle">Seismo-acoustic signals of the 2013 Russian meteor recorded across Central and Northern Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koch, Karl</p> <p>2014-05-01</p> <p>The meteor over Russia entering the Earth's atmosphere on 15 February 2013 around 03:20UT near the city of Chelyabinsk was the largest since the 1908 Tunguska fireball. As such the shock waves generated by this event were observed at infrasonic stations globally, in particular the network of some 45 of the planned 60 <span class="hlt">infrasound</span> systems of the International Monitoring System (IMS) being deployed for the verification of the Comprehensive Nuclear Test-Ban Treaty (CTBT). Furthermore the shock waves coupling into the ground near the <span class="hlt">source</span> location were observed as Rayleigh waves at seismic stations to distances of more than 4000 km. Beyond the acoustic observations that were made at <span class="hlt">infrasound</span> sensors we report here on additional observations of the acoustic waves which have coupled into the Earth at the receiver. The corresponding observations were made in Central Europe, in particular at the Gräfenberg broad-band array, as well as in Northern Europe (NORSAR in Scandinavia and on Spitsbergen), where also broad-band seismic array stations are located. That indeed the acoustic arrival from the bolide was recorded can be confirmed by frequency-wavenumber analyses giving compatible velocities and back-azimuths for the <span class="hlt">ground-truth</span> <span class="hlt">source</span> location over Russia. Theses observations are compatible with IMS station observations and also with shock wave arrivals on seismic stations on the Eurasian platform.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3727301','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3727301"><span id="translatedtitle">Inverse Electrocardiographic <span class="hlt">Source</span> Localization of Ischemia: An Optimization Framework and Finite Element Solution</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Dafang; Kirby, Robert M.; MacLeod, Rob S.; Johnson, Chris R.</p> <p>2013-01-01</p> <p>With the goal of non-invasively localizing cardiac ischemic disease using body-surface potential recordings, we attempted to reconstruct the transmembrane potential (TMP) throughout the myocardium with the bidomain heart model. The task is an inverse <span class="hlt">source</span> problem governed by partial differential equations (PDE). Our main contribution is solving the inverse problem within a PDE-constrained optimization framework that enables various physically-based constraints in both equality and inequality forms. We formulated the optimality conditions rigorously in the continuum before deriving finite element discretization, thereby making the optimization independent of discretization choice. Such a formulation was derived for the L2-norm Tikhonov regularization and the total variation minimization. The subsequent numerical optimization was fulfilled by a primal-dual interior-point method tailored to our problem’s specific structure. Our simulations used realistic, fiber-included heart models consisting of up to 18,000 nodes, much finer than any inverse models previously reported. With synthetic ischemia data we localized ischemic regions with roughly a 10% false-negative rate or a 20% false-positive rate under conditions up to 5% input noise. With ischemia data measured from animal experiments, we reconstructed TMPs with roughly 0.9 correlation with the <span class="hlt">ground</span> <span class="hlt">truth</span>. While precisely estimating the TMP in general cases remains an open problem, our study shows the feasibility of reconstructing TMP during the ST interval as a means of ischemia localization. PMID:23913980</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27723609','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27723609"><span id="translatedtitle">Illumination Variation-Resistant Video-Based Heart Rate Measurement Using Joint Blind <span class="hlt">Source</span> Separation and Ensemble Empirical Mode Decomposition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Juan; Chen, Xun; Xu, Lingxi; Wang, Z Jane</p> <p>2016-10-06</p> <p>Recent studies have demonstrated that heart rate (HR) could be estimated using video data (e.g., exploring human facial regions of interest (ROIs)) under well controlled conditions. However, in practice, the pulse signals may be contaminated by motions and illumination variations. In this paper, tackling the illumination variation challenge, we propose an illuminationrobust framework using joint blind <span class="hlt">source</span> separation (JBSS) and ensemble empirical mode decomposition (EEMD) to effectively evaluate HR from webcam videos. The framework takes the hypotheses that both facial ROI and background ROI have similar illumination variations. The background ROI is then considered as a noise reference sensor to denoise the facial signals by using the JBSS technique to extract the underlying illumination variation <span class="hlt">sources</span>. Further, the reconstructed illumination-resisted green channel of the facial ROI is detrended and decomposed into a number of intrinsic mode functions (IMFs) using EEMD to estimate the HR. Experimental results demonstrated that the proposed framework could estimate HR more accurately than the state-of-the-art methods. The Bland-Altman plots showed that it led to better agreement with HR <span class="hlt">ground</span> <span class="hlt">truth</span> with the mean bias 1.15 beat per minute (bpm), with 95 % limits from -15.43 bpm to 17.73 bpm, and the correlation coefficient 0.53. This study provides a promising solution for realistic non-contact and robust HR measurement applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=293978','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=293978"><span id="translatedtitle">Evaluation of several calibration procedures for a portable soil moisture sensor</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>The calibration and validation of remotely sensed soil moisture products relies upon an accurate <span class="hlt">source</span> of <span class="hlt">ground</span> <span class="hlt">truth</span> data. The primary method of providing this <span class="hlt">ground</span> <span class="hlt">truth</span> is to conduct intensive field campaigns with manual surface soil moisture sampling measurements, which utilize gravimetric s...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.V33A2608M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.V33A2608M"><span id="translatedtitle">Volcanic jet noise: infrasonic <span class="hlt">source</span> processes and atmospheric propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matoza, R. S.; Fee, D.; Ogden, D. E.</p> <p>2011-12-01</p> <p>Volcanic eruption columns are complex flows consisting of (possibly supersonic) injections of ash-gas mixtures into the atmosphere. A volcanic eruption column can be modeled as a lower momentum-driven jet (the gas-thrust region), which transitions with altitude into a thermally buoyant plume. Matoza et al. [2009] proposed that broadband infrasonic signals recorded during this type of volcanic activity represent a low-frequency form of jet noise. Jet noise is produced at higher acoustic frequencies by smaller-scale man-made jet flows (e.g., turbulent jet flow from jet engines and rockets). Jet noise generation processes could operate at larger spatial scales and produce infrasonic frequencies in the lower gas-thrust portion of the eruption column. Jet-noise-like infrasonic signals have been observed at ranges of tens to thousands of kilometers from sustained volcanic explosions at Mount St. Helens, WA; Tungurahua, Ecuador; Redoubt, AK; and Sarychev Peak, Kuril Islands. Over such distances, the atmosphere cannot be considered homogeneous. Long-range <span class="hlt">infrasound</span> propagation takes place primarily in waveguides formed by vertical gradients in temperature and horizontal winds, and exhibits strong spatiotemporal variability. The timing and location of volcanic explosions can be estimated from remote infrasonic data and could be used with ash cloud dispersion forecasts for hazard mitigation. <span class="hlt">Source</span> studies of infrasonic volcanic jet noise, coupled with <span class="hlt">infrasound</span> propagation modeling, hold promise for being able to constrain more detailed eruption jet parameters with remote, ground-based geophysical data. Here we present recent work on the generation and propagation of volcanic jet noise. Matoza, R. S., D. Fee, M. A. Garcés, J. M. Seiner, P. A. Ramón, and M. A. H. Hedlin (2009), Infrasonic jet noise from volcanic eruptions, Geophys. Res. Lett., 36, L08303, doi:10.1029/2008GL036486.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ISPAr.XL5b.647T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ISPAr.XL5b.647T"><span id="translatedtitle">Validation Tests of Open-<span class="hlt">Source</span> Procedures for Digital Camera Calibration and 3d Image-Based Modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toschi, I.; Rivola, R.; Bertacchini, E.; Castagnetti, C.; Dubbini, M.; Capra, A.</p> <p>2013-07-01</p> <p>Among the many open-<span class="hlt">source</span> software solutions recently developed for the extraction of point clouds from a set of un-oriented images, the photogrammetric tools Apero and MicMac (IGN, Institut Géographique National) aim to distinguish themselves by focusing on the accuracy and the metric content of the final result. This paper firstly aims at assessing the accuracy of the simplified and automated calibration procedure offered by the IGN tools. Results obtained with this procedure were compared with those achieved with a test-range calibration approach using a pre-surveyed laboratory test-field. Both direct and a-posteriori validation tests turned out successfully showing the stability and the metric accuracy of the process, even when low textured or reflective surfaces are present in the 3D scene. Afterwards, the possibility of achieving accurate 3D models from the subsequently extracted dense point clouds is also evaluated. Three different types of sculptural elements were chosen as test-objects and "<span class="hlt">ground-truth</span>" data were acquired with triangulation laser scanners. 3D models derived from point clouds oriented with a simplified relative procedure show a suitable metric accuracy: all comparisons delivered a standard deviation of millimeter-level. The use of Ground Control Points in the orientation phase did not improve significantly the accuracy of the final 3D model, when a small figure-like corbel was used as test-object.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA564064','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA564064"><span id="translatedtitle">Performance Assessment of Multi-Array Processing with <span class="hlt">Ground</span> <span class="hlt">Truth</span> for Infrasonic, Seismic and Seismo-Acoustic Events</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2012-07-03</p> <p>INTRODUCTION AND SUMMARY OF RESEARCH ............................................................1 2. MULTIPLE-ARRAY DETECTION ASESSMENT AND...RELATIONSHIP TO ENVIRONMENTAL CONDITIONS .............................................................................................2 2.1 Abstract...followed by the systematic application of the procedures to seismo-acoustic data in Korea and the western US during the final phase. The optimization of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810020956','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810020956"><span id="translatedtitle">Evaluation of gravimetric <span class="hlt">ground</span> <span class="hlt">truth</span> soil moisture data collected for the agricultural soil moisture experiment, 1978 Colby, Kansas, aircraft mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arya, L. M.; Phinney, D. E. (Principal Investigator)</p> <p>1980-01-01</p> <p>Soil moisture data acquired to support the development of algorithms for estimating surface soil moisture from remotely sensed backscattering of microwaves from ground surfaces are presented. Aspects of field uniformity and variability of gravimetric soil moisture measurements are discussed. Moisture distribution patterns are illustrated by frequency distributions and contour plots. Standard deviations and coefficients of variation relative to degree of wetness and agronomic features of the fields are examined. Influence of sampling depth on observed moisture content an variability are indicated. For the various sets of measurements, soil moisture values that appear as outliers are flagged. The distribution and legal descriptions of the test fields are included along with examinations of soil types, agronomic features, and sampling plan. Bulk density data for experimental fields are appended, should analyses involving volumetric moisture content be of interest to the users of data in this report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=251966','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=251966"><span id="translatedtitle">Spatio-Temporal Analysis of Surface Soil Moisture in Evaluating <span class="hlt">Ground</span> <span class="hlt">Truth</span> Monitoring Sites for Remotely Sensed Observations</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Soil moisture is an intrinsic state variable that varies considerably in space and time. Although soil moisture is highly variable, repeated measurements of soil moisture at the field or small watershed scale can often reveal certain locations as being temporally stable and representative of the are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890067471&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890067471&hterms=truth&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtruth"><span id="translatedtitle">Using radar <span class="hlt">ground-truth</span> to validate and improve the location accuracy of a lightning direction-finding network</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goodman, Steven J.</p> <p>1989-01-01</p> <p>A technique is described in which isolated radar echoes associated with clusters of lightning strikes are used to validate and improve the location accuracy of a lightning-direction-finding network. Using this technique, site errors of a magnetic direction-finding network for locating lightning strikes to ground were accurately determined. The technique offers advantages over existing techniques in that large sample sizes are readily attainable over a broad area on a regular basis; the technique can also provide additional constraints to redundant data methods such as that described by Orville (1987). Since most lightning strike networks have either partial or full weather radar coverage, the technique is practical for all but a few users.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290429','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4290429"><span id="translatedtitle">The Sampled Red List Index for Plants, phase II: <span class="hlt">ground-truthing</span> specimen-based conservation assessments</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Brummitt, Neil; Bachman, Steven P.; Aletrari, Elina; Chadburn, Helen; Griffiths-Lee, Janine; Lutz, Maiko; Moat, Justin; Rivers, Malin C.; Syfert, Mindy M.; Nic Lughadha, Eimear M.</p> <p>2015-01-01</p> <p>The IUCN Sampled Red List Index (SRLI) is a policy response by biodiversity scientists to the need to estimate trends in extinction risk of the world's diminishing biological diversity. Assessments of plant species for the SRLI project rely predominantly on herbarium specimen data from natural history collections, in the overwhelming absence of accurate population data or detailed distribution maps for the vast majority of plant species. This creates difficulties in re-assessing these species so as to measure genuine changes in conservation status, which must be observed under the same Red List criteria in order to be distinguished from an increase in the knowledge available for that species, and thus re-calculate the SRLI. However, the same specimen data identify precise localities where threatened species have previously been collected and can be used to model species ranges and to target fieldwork in order to test specimen-based range estimates and collect population data for SRLI plant species. Here, we outline a strategy for prioritizing fieldwork efforts in order to apply a wider range of IUCN Red List criteria to assessments of plant species, or any taxa with detailed locality or natural history specimen data, to produce a more robust estimation of the SRLI. PMID:25561676</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25561676','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25561676"><span id="translatedtitle">The sampled Red List Index for plants, phase II: <span class="hlt">ground-truthing</span> specimen-based conservation assessments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brummitt, Neil; Bachman, Steven P; Aletrari, Elina; Chadburn, Helen; Griffiths-Lee, Janine; Lutz, Maiko; Moat, Justin; Rivers, Malin C; Syfert, Mindy M; Nic Lughadha, Eimear M</p> <p>2015-02-19</p> <p>The IUCN Sampled Red List Index (SRLI) is a policy response by biodiversity scientists to the need to estimate trends in extinction risk of the world's diminishing biological diversity. Assessments of plant species for the SRLI project rely predominantly on herbarium specimen data from natural history collections, in the overwhelming absence of accurate population data or detailed distribution maps for the vast majority of plant species. This creates difficulties in re-assessing these species so as to measure genuine changes in conservation status, which must be observed under the same Red List criteria in order to be distinguished from an increase in the knowledge available for that species, and thus re-calculate the SRLI. However, the same specimen data identify precise localities where threatened species have previously been collected and can be used to model species ranges and to target fieldwork in order to test specimen-based range estimates and collect population data for SRLI plant species. Here, we outline a strategy for prioritizing fieldwork efforts in order to apply a wider range of IUCN Red List criteria to assessments of plant species, or any taxa with detailed locality or natural history specimen data, to produce a more robust estimation of the SRLI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA519779','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA519779"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span>, Magnitude Calibration and Regional Phase Propagation and Detection in the Middle East and Horn of Africa</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2007-09-01</p> <p>seismic stations in the Arabian Peninsula used in this study. KACST stations belong to the Saudi Arabia Digital National Seismic network. The...waveforms. In addition to the KACST and Program for the Array Siesmic Studies of the continental Lithosphere (PASSCAL) stations, data recorded at...from stations in Arabia. We augmented the KACST data with delay times measured from permanent stations in the region (RAYN, EIL and MRNI) and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27475147','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27475147"><span id="translatedtitle">Passive acoustic monitoring of coastally associated Hawaiian spinner dolphins, Stenella longirostris, <span class="hlt">ground-truthed</span> through visual surveys.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heenehan, Heather L; Tyne, Julian A; Bejder, Lars; Van Parijs, Sofie M; Johnston, David W</p> <p>2016-07-01</p> <p>Effective decision making to protect coastally associated dolphins relies on monitoring the presence of animals in areas that are critical to their survival. Hawaiian spinner dolphins forage at night and rest during the day in shallow bays. Due to their predictable presence, they are targeted by dolphin-tourism. In this study, comparisons of presence were made between passive acoustic monitoring (PAM) and vessel-based visual surveys in Hawaiian spinner dolphin resting bays. DSG-Ocean passive acoustic recording devices were deployed in four bays along the Kona Coast of Hawai'i Island between January 8, 2011 and August 30, 2012. The devices sampled at 80 kHz, making 30-s recordings every four minutes. Overall, dolphins were acoustically detected on 37.1% to 89.6% of recording days depending on the bay. Vessel-based visual surveys overlapped with the PAM surveys on 202 days across the four bays. No significant differences were found between visual and acoustic detections suggesting acoustic surveys can be used as a proxy for visual surveys. Given the need to monitor dolphin presence across sites, PAM is the most suitable and efficient tool for monitoring long-term presence/absence. Concomitant photo-identification surveys are necessary to address changes in abundance over time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=309337&keyword=scale+AND+cope&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78691665&CFTOKEN=20963531','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=309337&keyword=scale+AND+cope&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78691665&CFTOKEN=20963531"><span id="translatedtitle"><span class="hlt">Ground-Truthing</span> Validation to Assess the Effect of Facility Locational Error on Cumulative Impacts Screening Tools</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Over the past three decades, a number of researchers in the fields of environmental justice (EJ) and environmental public health have highlighted the existence of regional and local scale differences in exposure to air pollution, as well as calculated health risk and impacts of a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P51E1770H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P51E1770H"><span id="translatedtitle">Modeling the Impact Ejected Dust Contribution to the Lunar Exosphere: Results from Experiments and <span class="hlt">Ground</span> <span class="hlt">Truth</span> from LADEE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hermalyn, B.; Colaprete, A.</p> <p>2013-12-01</p> <p>A considerable body of evidence indicates the presence of lofted regolith dust above the lunar surface. These observations range from multiple in-situ and orbital horizon glow detections to direct measurement of dust motion on the surface, as by the Apollo 17 Lunar Ejecta and Meteorites (LEAM) experiment. Despite this evidence, the specific mechanisms responsible for the lofting of regolith are still actively debated. These include impact ejection, electrostatic lofting, effects of high energy radiation, UV/X- rays, and interplay with solar wind plasma. These processes are highly relevant to one of the two main scientific objectives of the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission (due to launch September, 2013): to directly measure the lunar exospheric dust environment and its spatial and temporal variability towards the goal of better understanding the dust flux. Of all the proposed mechanisms taking place on the lunar surface, the only unequivocal ongoing process is impact cratering. Hypervelocity impact events, which mobilize and redistribute regolith across planetary surfaces, are arguably the most pervasive geologic process on rocky bodies. While many studies of dust lofting state that the impact flux rate is orders of magnitude too low to account for the lunar horizon glow phenomenon and discount its contribution, it is imperative to re-examine these assumptions in light of new data on impact ejecta, particularly from the contributions from mesoscale (impactor size on the order of grain size) and macroscale (impactor > grain size) cratering. This is in large part due to a previous lack of data, for while past studies have established a canonical ejecta model for main-stage ejection of sand targets from vertical impacts, only recent studies have been able to begin quantitatively probing the intricacies of the ejection process outside this main-stage, vertical regime. In particular, it is the high-speed early-time ejecta that will reach significant altitude above the surface and remain aloft ballistically for hours. In addition, ejecta dynamics in the transition regime between microcratering and macro scale events is not yet well understood. As such, there is no currently accepted encompassing model of impact ejecta delivery to the lunar exosphere. It is important to note that the work described here is not to duplicate or exclude other lofting mechanisms -- in reality, the lofting of dust is almost definitely a complex combination of processes -- but instead to provide essential constraints on the impact contribution. This study attempts to constrain the expected contributions from cratering to the lunar exosphere by assessing the ejecta 'background' signal lofted above the surface and the effects of transient focused events (meteor showers) which can produce significant increases in ejecta. In particular, this work couples scaling of previous ejecta studies with Monte-Carlo and ballistics models and will present LADEE data analysis (particularly from the UVS and LDEX instruments) and interpretation in context of constraining the ejected mass distribution. These results are relevant to both our understanding of exospheric dust and for constraint of hazards for future human habitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADP023091','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADP023091"><span id="translatedtitle">Tracker Analysis and <span class="hlt">Ground</span> <span class="hlt">Truth</span> Tool Description for the Proceedings of the 2002 Ground Target Modeling and Validation Conference</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2002-08-01</p> <p>Mark A. Chamblis.. Judson R. Griffin III, Daniel Konkle. Paul D. Lavallee, Dr. Jay Lightfoot Dynetics . Inc. Huntsville, AL 35814 USA ABSTRACT The...displays contact information for Dynetics , Inc, and gives acknowledgement to AMCOM (Aviation and Missile Command) for their sponsorship of the...create avi movies, and adding a tool to remove bad frames from a sequence. ACKNOWLEDGEMENTS This paper was based on work that Dynetics performed for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA555945','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA555945"><span id="translatedtitle">Establishing and Validating Empirically-Based <span class="hlt">Ground</span> <span class="hlt">Truth</span> Criteria for Seismic Events Recorded on Regional Networks (Postprint)</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-12-30</p> <p>against the existing global criteria for a range of tectonic settings (i.e., stable craton, plateau within a collisional zone, and an active rift). We...the global 2004 and 2009 criteria. Now that the EBGT criteria appropriate for each tectonic setting has been established, in the second part of this...Plateau resulted from a continent-continent collision between the Indian and Eurasian plates , creating an uplifted region (5km of topography in places</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B43C1454B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B43C1454B"><span id="translatedtitle">Estimation of Leaf Area Index (LAI) Through the Acquisition of <span class="hlt">Ground</span> <span class="hlt">Truth</span> Data in Yosemite National Park</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Basson, G.; Hawk, A.; Lue, E.; Ottman, D.; Schiffman, B.; Ghosh, M.; Melton, F.; Schmidt, C.; Skiles, J.</p> <p>2007-12-01</p> <p>Leaf area index (LAI) is an important indicator of ecosystem health. Remote sensing offers the only feasible method of estimating LAI at global and regional scales. Land managers can efficiently monitor changes in vegetation by using NASA data products such as the MODIS LAI 1km product. To increase confidence in use of the MODIS LAI product in Yosemite National Park, we investigated the accuracy of remotely sensed LAI data and created LAI maps using three optical in-situ instruments: the LAI-2000 instrument, digital hemispheric photography (DHP), and the Tracing Radiation and Architecture of Canopies (TRAC) instrument. We compared our in-situ data with three spectral vegetation indices derived from Landsat Thematic Mapper imagery: Reduced Simple Ratio (RSR), Simple Ratio (SR), and Normalized Difference Vegetation Index (NDVI) to produce models which created LAI maps at 30m and 1km resolution. The strongest correlations occurred between DHP LAI values and RSR. Pixel values from the 1km LAI map were then compared to pixel values from a MODIS LAI map. A strong correlation exists between our in-situ data and MODIS LAI values which confirms its accuracy for use by the National Park Service as a decision support tool in Yosemite. The MODIS LAI product is particularly useful because of its high temporal resolution of 1-2 days and can be used to monitor current and future vegetation changes. The model created using the in-situ data can also be applied to Landsat data to provide thirty years of historical LAI values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA418214','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA418214"><span id="translatedtitle">Polarimetric Interferometric Experiment Trials for Years 2001 and 2002: Experiment Design <span class="hlt">Ground</span> <span class="hlt">Truthing</span> Data Quality and Analysis</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2003-09-01</p> <p>analyse documentaire et sur l’utilit6 que ce domaine reprnsente pour le MDN. Ce projet est financ6 dans le cadre du Fonds d’investissement technologique...apprentissages realises sont egalement detailles. Ce document technique accompagne un autre rapport de RDDC portant sur une analyse de documents qui...which is beneficial for these types of studies. Ideally, a single pass Pol InSAR system would have been easier to analyse and assess. However, during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA516241','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA516241"><span id="translatedtitle"><span class="hlt">Ground</span> <span class="hlt">Truth</span>, Magnitude Calibration, and Regional Phase Propagation and Detection in the Middle East and the Horn of Africa</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2008-09-01</p> <p>Iranian Plateau, Zagros Mountains, Arabian Peninsula, Turkish Plateau, Gulf of Aqaba, Dead Sea Rift) and the Horn of Africa (including the northern part...the Arabian Peninsula. In the first part of this project, seismograms from earthquakes in the Zagros Mountains recorded at regional distances have...algorithm and forward modeling of teleseismic depth phases. Early studies of the distribution of seismicity in the Zagros region found evidence for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820049374&hterms=sampling+distribution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsampling%2Bdistribution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820049374&hterms=sampling+distribution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsampling%2Bdistribution"><span id="translatedtitle">Field size, length, and width distributions based on LACIE <span class="hlt">ground</span> <span class="hlt">truth</span> data. [large area crop inventory experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pitts, D. E.; Badhwar, G.</p> <p>1980-01-01</p> <p>The development of agricultural remote sensing systems requires knowledge of agricultural field size distributions so that the sensors, sampling frames, image interpretation schemes, registration systems, and classification systems can be properly designed. Malila et al. (1976) studied the field size distribution for wheat and all other crops in two Kansas LACIE (Large Area Crop Inventory Experiment) intensive test sites using ground observations of the crops and measurements of their field areas based on current year rectified aerial photomaps. The field area and size distributions reported in the present investigation are derived from a representative subset of a stratified random sample of LACIE sample segments. In contrast to previous work, the obtained results indicate that most field-size distributions are not log-normally distributed. The most common field size observed in this study was 10 acres for most crops studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011epsc.conf..416K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011epsc.conf..416K"><span id="translatedtitle">Shape reconstruction of irregular bodies with multiple complementary data <span class="hlt">sources</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaasalainen, M.; Viikinkoski, M.; Carry, B.; Durech, J.; Lamy, P.; Jorda, L.; Marchis, F.; Hestroffer, D.</p> <p>2011-10-01</p> <p>. We have applied our procedure to several asteroids, and the <span class="hlt">ground</span> <span class="hlt">truth</span> from the Rosetta/Lutetia flyby confirmed the ability of the approach to recover shape details [1] (see also Carry et al., this meeting). We have created a general flyby-version of the procedure to construct full models of planetary targets for which probe images are only available of a part of the surface (a typical setup for many planetary missions). We have successfully combined flyby images with photometry (Steins [4]) and adaptive optics images (Lutetia); the portion of the surface accurately determined by the flyby constrains the shape solution of the "dark side" efficiently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25115932','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25115932"><span id="translatedtitle">EEG <span class="hlt">source</span> connectivity analysis: from dense array recordings to brain networks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hassan, Mahmoud; Dufor, Olivier; Merlet, Isabelle; Berrou, Claude; Wendling, Fabrice</p> <p>2014-01-01</p> <p>The recent past years have seen a noticeable increase of interest for electroencephalography (EEG) to analyze functional connectivity through brain <span class="hlt">sources</span> reconstructed from scalp signals. Although considerable advances have been done both on the recording and analysis of EEG signals, a number of methodological questions are still open regarding the optimal way to process the data in order to identify brain networks. In this paper, we analyze the impact of three factors that intervene in this processing: i) the number of scalp electrodes, ii) the combination between the algorithm used to solve the EEG inverse problem and the algorithm used to measure the functional connectivity and iii) the frequency bands retained to estimate the functional connectivity among neocortical <span class="hlt">sources</span>. Using High-Resolution (hr) EEG recordings in healthy volunteers, we evaluated these factors on evoked responses during picture recognition and naming task. The main reason for selection this task is that a solid literature background is available about involved brain networks (<span class="hlt">ground</span> <span class="hlt">truth</span>). From this a priori information, we propose a performance criterion based on the number of connections identified in the regions of interest (ROI) that belong to potentially activated networks. Our results show that the three studied factors have a dramatic impact on the final result (the identified network in the <span class="hlt">source</span> space) as strong discrepancies were evidenced depending on the methods used. They also suggest that the combination of weighted Minimum Norm Estimator (wMNE) and the Phase Synchronization (PS) methods applied on High-Resolution EEG in beta/gamma bands provides the best performance in term of topological distance between the identified network and the expected network in the above-mentioned cognitive task.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4130623','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4130623"><span id="translatedtitle">EEG <span class="hlt">Source</span> Connectivity Analysis: From Dense Array Recordings to Brain Networks</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hassan, Mahmoud; Dufor, Olivier; Merlet, Isabelle; Berrou, Claude; Wendling, Fabrice</p> <p>2014-01-01</p> <p>The recent past years have seen a noticeable increase of interest for electroencephalography (EEG) to analyze functional connectivity through brain <span class="hlt">sources</span> reconstructed from scalp signals. Although considerable advances have been done both on the recording and analysis of EEG signals, a number of methodological questions are still open regarding the optimal way to process the data in order to identify brain networks. In this paper, we analyze the impact of three factors that intervene in this processing: i) the number of scalp electrodes, ii) the combination between the algorithm used to solve the EEG inverse problem and the algorithm used to measure the functional connectivity and iii) the frequency bands retained to estimate the functional connectivity among neocortical <span class="hlt">sources</span>. Using High-Resolution (hr) EEG recordings in healthy volunteers, we evaluated these factors on evoked responses during picture recognition and naming task. The main reason for selection this task is that a solid literature background is available about involved brain networks (<span class="hlt">ground</span> <span class="hlt">truth</span>). From this a priori information, we propose a performance criterion based on the number of connections identified in the regions of interest (ROI) that belong to potentially activated networks. Our results show that the three studied factors have a dramatic impact on the final result (the identified network in the <span class="hlt">source</span> space) as strong discrepancies were evidenced depending on the methods used. They also suggest that the combination of weighted Minimum Norm Estimator (wMNE) and the Phase Synchronization (PS) methods applied on High-Resolution EEG in beta/gamma bands provides the best performance in term of topological distance between the identified network and the expected network in the above-mentioned cognitive task. PMID:25115932</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/379097','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/379097"><span id="translatedtitle">Detection of the large meteoroid/NEO flux using <span class="hlt">infrasound</span>: Recent detection of the November 21, 1995 Colorado fireball</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>ReVelle, D.O.; Whitaker, R.W.</p> <p>1996-08-01</p> <p>During the early morning of November 21, 1995, a fireball as bright as the full moon entered the atmosphere over southeastern Colorado and subsequently produced audible sonic boom reports from Texas to Wyoming. The event was detected locally by a security video camera which showed the reflection of the fireball event on the hood of a truck. The camera also recorded tree shadows cast by the light of the fireball. This recording includes the audio signal of a strong double boom as well. Subsequent investigation of the array near Los Alamos, New Mexico operated by the Los Alamos National Laboratory as part of its commitment to the Comprehensive Test Ban Treaty negotiations, showed the presence of an infrasonic signal from the proper direction at about the correct time for this fireball. The Los Alamos array is a four-element infrasonic array in near-continuous operation on the Laboratory property. The preliminary characteristics of the signal include the signal onset arrival time of 0939:20 UT (0239:20 MST), with a maximum timing uncertainty of {+-} 2 minutes, the signal onset time delay from the appearance of the fireball of 19 minutes, 20 seconds, the total signal duration of 2 minutes 10 seconds, the <span class="hlt">source</span> location toward 31 degrees from true north, the horizontal trace velocity of 429 m/sec, the signal velocity of 0.30 {+-} 0.03 km/sec, assuming a 400 km horizontal range to the fireball, the dominant signal frequency content of 0.25 to 0.84 Hz (analyzed in the frequency interval from 0.2 to 2.0 Hz), the maximum signal cross-correlation of 0.97 and the maximum signal amplitude of 2.0 {+-} 0.1 microbars. Also, on the basis of the signal period at maximum amplitude, we estimate a <span class="hlt">source</span> energy for this event of between 10 to 100 tons of TNT (53.0 tons nominal).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/793868','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/793868"><span id="translatedtitle">Use of Imploding Spheres: An Alternative to Explosives as Acoustic <span class="hlt">Sources</span> at Mid-Latitude SOFAR Channel Depths</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harben, P.E.; Boro, C.; Dorman, L.; Pulli, J.</p> <p>2000-05-12</p> <p>The hydroacoustic nuclear explosion monitoring regime, like it's counterpart in seismic monitoring, requires <span class="hlt">ground</span> <span class="hlt">truth</span> calibration. Model predictions of traveltimes, blockages, reflections, diffractions, and waveform envelopes need to be verified with <span class="hlt">ground</span> <span class="hlt">truth</span> experiments, particularly in the high latitudes where models often fail. Although pressure detonated explosives are a simple, reliable, and flexible method to generate an impulsive hydroacoustic calibration <span class="hlt">source</span> at a desired depth; safety procedures, specialized training, and local regulations often preclude their use. This leaves few alternatives since airgun and other seismic marine <span class="hlt">sources</span> are designed for use only at shallow depths and hence do not effectively couple into the SOFAR channel, a necessary requirement for long range propagation. Imploding spheres could be an effective <span class="hlt">source</span> at mid-ocean depths and below but development of a method to reliably break such spheres has been elusive. We designed and tested a prototype system to initiate catastrophic glass sphere failure at a prescribed depth. The system firmly holds a glass sphere in contact with a piston-ram assembly. The end cap on the cylinder confining the piston and opposing the ram has a rupture disk sealed to it. The rupture disk is calibrated to fail within 5% of the calibrated failure pressure, 1000 psi in our tests. Failure of the rupture disk results in a sudden inrush of high pressure water into the air-filled piston chamber, driving the piston--and attached ram--towards the glass sphere. The spherecracker was first tested on Benthos Corp. flotation spheres. The spherecracker mechanism successfully punched a hole in the Benthos sphere at the nominal pressure of 1000 psi or at about 700 meters depth in each of four tests. Despite the violent inrush of high pressure water the spheres did not otherwise fail. We concluded that the Benthos spheres were too thick-walled to be used as an imploding <span class="hlt">source</span> at nominal SOFAR channel</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S23C2745B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S23C2745B"><span id="translatedtitle">VLP <span class="hlt">Source</span> Inversion and Evaluation of Error Analysis Techniques at Fuego Volcano, Guatemala</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p