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. An Empirical Study of Atmospheric Correction Procedures for Regional Infrasound Amplitudes with Ground Truth.

    NASA Astrophysics Data System (ADS)

    Howard, J. E.

    2014-12-01

    This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.

  3. 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.

  4. 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

  5. Collection and Analysis of Ground Truth Infrasound Data in Kazakhstan and Russia

    DTIC Science & Technology

    2006-05-01

    titled "Ground Truth Data of Large Mining Explosions in Altay -Sayan Region, Southwestern Siberia, Russia." We report on the ground truth data of large...and A. Yemanov for providing us the ground truth information from Kuzbass and Abakan industrial mining area. Staff at Altay -Sayan Experimental and Me...Explosions in Altay -Sayan Region, Southw estern Siberia, R ussia ................................................. 20 3.1 G round Truth D ata

  6. ANTARES explosion as recorded by the US-ARRAY: an unprecedented ground-truth infrasound event

    NASA Astrophysics Data System (ADS)

    Vergoz, Julien; Millet, Christophe; Le Pichon, Alexis

    2016-04-01

    The 28th October 2014 in Wallops Flight Facility, orbital's Antares launch vehicle failed and heavily exploded onto the launch pad area. At that time, the US transportable array of more than 200 operating stations (all equipped with microbarometers), was located on the east coast of the US and surrounded the accident. A large amount and variety of infrasound phases were observed at some stations, highlighting interesting propagation effects. The variety of recorded signals on such a dense network is unprecedented and offers the opportunity to better understand some propagation features, such as (1) the frequency content changes of stratospheric phases; (2) the dispersion of tropospheric phases propagating over thousands of kilometers within a stable and thin waveguide at fast phase speeds (350m/s) with low attenuation; (3) the non-linear effects associated with slow thermospheric phases (180m/s), especially in terms of shape, amplitude and duration. These 3 points will be addressed, and pieces of interpretations will be given thanks to the different propagation techniques: full waveform modelling (Normal Modes, finite element method), parabolic equation and ray tracing technique. Location issues of such an acoustic event based on tens of infrasound arrival times only will also be shown and discussed.

  7. Ground truth events with source geometry in Eurasia and the Middle East

    NASA Astrophysics Data System (ADS)

    Shamsalsadati, S.; O'Donnell, J. P.; Nyblade, A.

    2015-12-01

    Accurate seismic source locations and their geometries are important to improve ground-based system monitoring; however, a few number of Ground Truth (GT) events are available in most regions within Eurasia and Middle East. In this study GT event locations were found for several earthquakes in the Middle East and Africa, including Saudi Arabia and Tanzania, with location errors of less that 5 km. These events were acquired through analyzing several local and near-regional waveforms for hundreds of earthquakes in these areas. A large number of earthquakes occurred beneath the Harrat Lunayyir in northwest Saudi Arabia in 2009. From the 15 Lunayyir GT events recorded on three-component seismographs, 5 with Mw between 3.4 and 5.9 were used for successfully obtaining source parameters. A moment tensor inversion was applied on filtered surface wave data to obtain the best-fitting source mechanism, moment magnitude, and depth. The uncertainty in the derived parameters was investigated by applying the same inversion to selected traces and frequency bands. Focal mechanism for these earthquakes demonstrates normal faulting with a NW-SE trend for all of the events except one, which has a NE-SW trend. The shallow 3 km depth obtained for all the events is consistent with previous studies of dyke intrusion in the area. Spectral analysis of S waves and source parameters for these earthquakes are in progress to find static stress drop, corner frequency and radiated energy.

  8. Transboundary movement of marine litter in an estuarine gradient: Evaluating sources and sinks using hydrodynamic modelling and ground truthing estimates.

    PubMed

    Krelling, Allan Paul; Souza, Mihael Machado; Williams, Allan Thomas; Turra, Alexander

    2017-06-15

    Marine debris' transboundary nature and new strategies to identify sources and sinks in coastal areas were investigated along the Paranaguá estuarine gradient (southern Brazil), through integration of hydrodynamic modelling, ground truthing estimates and regressive vector analysis. The simulated release of virtual particles in different parts of the inner estuary suggests a residence time shorter than 5days before being exported through the estuary mouth (intermediate compartment) to the open ocean. Stranded litter supported this pathway, with beaches in the internal compartment presenting proportionally more items from domestic sources, while fragmented items with unknown sources were proportionally more abundant in the oceanic beaches. Regressive vector analysis reinforced the inner estuarine origin of the stranded litter in both estuarine and oceanic beaches. These results support the applicability of simple hydrodynamic models to address marine debris' transboundary issues in the land-sea transition zone, thus supporting an ecosystem transboundary (and not territorial) management approach. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The European Infrasound Bulletin

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; Vergoz, Julien; Le Pichon, Alexis; Mialle, Pierrick

    2017-04-01

    The European Infrasound Bulletin highlights infrasound activity produced by mostly anthropogenic sources, recorded all over Europe and collected in the course of the ARISE project (Atmospheric dynamics Research InfraStructure in Europe). Data includes high frequency (>0.7 Hz) infrasound detections of 24 European infrasound arrays from 9 different national institutions (BGR, CEA, IRF, NORSAR, KNMI, UNIFI, IAP-Prague, NIEP, SOREQ) complemented with CTBT IMS infrasound stations. Data was acquired during 16 years of operation (from 2000 to 2015), and processed to identify and localize about 48.000 infrasound events within Europe (20°W-40°E, 30°N-72°N). The source location of these events was derived by combining at least two corresponding station detections per event. Comparisons to ground-truth sources, as e.g. Scandinavian mining activity, are provided. Relocation is performed using ray-tracing methods to estimate celerity and back-azimuth corrections based on either HWM-07/MSISE-00 climatologies or actual ECMWF wind and temperature values for each event. This study focuses on repeating infrasound events (e.g. mining blasts and supersonic flights) and on the seasonal, weekly and diurnal variation of the infrasonic activity of sources in Europe. Estimations of the detection and location capability and accuracy will be given in the course of this study to achieve a comprehensive picture of the activity of infrasound sources and capability of infrasound station in Europe.

  10. Ground truth versus no ground truth

    NASA Technical Reports Server (NTRS)

    Torbert, G. B.

    1970-01-01

    The area of study was the southeastern Arizona test site and three areas within the site were studied in detail: Safford, Point of Pines, and Fort Apache-White River. These areas have terrain contrast ranging from flat arid regions to high alpine mountains. Data were obtained from the Apollo 9 photographic missions, high altitude aerial photography, and simulated ERTS-A data from high altitude aircraft. Various monoscopic and steroscopic devices were used to analyze the features, and film density variations were studied. No ground-based data were permitted. Thematic maps were prepared for geology, geomorphology, vegetation, hydrology, and soils. Interpreted boundaries were delineated, with no collaborative data used in the interpretation. Ground-based data were gathered during the overflight of high altitude aerial photography. A further study was made using the ground truth, and the data gathered on the ground were compared with original mapping. 80% to 85% of the interpretations in the areas checked were correct. It was proved that it is possible to monitor gross features of the vigor of crop lands and vegetative cover, to type soils and classify geologic features, and to determine hydrologic conditions.

  11. Ground truth versus no ground truth

    NASA Technical Reports Server (NTRS)

    Torbert, G. B.

    1970-01-01

    The area of study was the southeastern Arizona test site and three areas within the site were studied in detail: Safford, Point of Pines, and Fort Apache-White River. These areas have terrain contrast ranging from flat arid regions to high alpine mountains. Data were obtained from the Apollo 9 photographic missions, high altitude aerial photography, and simulated ERTS-A data from high altitude aircraft. Various monoscopic and steroscopic devices were used to analyze the features, and film density variations were studied. No ground-based data were permitted. Thematic maps were prepared for geology, geomorphology, vegetation, hydrology, and soils. Interpreted boundaries were delineated, with no collaborative data used in the interpretation. Ground-based data were gathered during the overflight of high altitude aerial photography. A further study was made using the ground truth, and the data gathered on the ground were compared with original mapping. 80% to 85% of the interpretations in the areas checked were correct. It was proved that it is possible to monitor gross features of the vigor of crop lands and vegetative cover, to type soils and classify geologic features, and to determine hydrologic conditions.

  12. Use of Numerical Weather Research and Forecasting Specifications in Infrasound Propagation Modeling of Local and Regional Sources - Preliminary Investigations

    NASA Astrophysics Data System (ADS)

    Nava, S.; Masters, S. E.; Norris, D.

    2009-12-01

    High resolution characterization of the lower atmosphere is an important aspect of infrasound propagation modeling of local and regional sources. Rawinsonde weather balloons can be used to obtain such information, but may be impractical or unavailable at the time and location of interest, and do not capture spatial variability that may be important over regional ranges. In this study, we explore the utility of the Weather Research and Forecasting (WRF) Model, a state-of-the-science mesoscale numerical weather prediction system used in operational forecasting and atmospheric research (http://wrf-model.org). A ground truth database of analyst-confirmed mining and military disposal explosions recorded on an infrasound array located near Salt Lake City, Utah (USA), with source-to-receiver distances ranges from 15-200 km, forms the basis of this study. Of primary interest is infrasound propagation within the so-called zone of silence. Cases were identified in which infrasound detections were and were not observed from the same source location. It is assumed that the method of source detonation was similar and the dynamic atmosphere was the only variable affecting the observability. The WRF-model was executed to produce high resolution spatial and temporal wind and temperature fields for input into infrasound propagation models. The WRF simulations extended to 16-20 km altitude, and were configured using nested domains with horizontal spatial resolution of approximately 1.8 km and temporal output resolution of 15 minutes. Each simulation was initialized with the Global Forecast System (GFS) analysis approximately 12-18 hours before the infrasound event of interest and calculations continued for 24 hours. Local observed surface, upper air, radar, and rawinsonde data were used to judge if the WRF model fields were reasonable and matched the actual weather conditions. Ray trace, parabolic equation, and time-domain parabolic equation propagation predictions were computed

  13. Automatic Infrasound Detection and Location of Sources in the western US

    NASA Astrophysics Data System (ADS)

    Park, J.; Arrowsmith, S.; Hayward, C.; Stump, B. W.

    2012-12-01

    Infrasound event catalogs can be used to study the characteristics of events as well as the time varying nature of the atmosphere. Additionally, these catalogs can be used to identify sources that repeat and thus provide ground truth for atmospheric studies. We focus on the production of a western US regional infrasound catalog for the time period of April 2011 to March 2012. Data from the University of Utah Seismograph Stations (UUSS) infrasonic arrays are supplemented with data from three additional infrasound arrays in Nevada. An automated detection procedure was applied to the observations based on an adaptive F-detector (Arrowsmith et al., 2009). The detection results document significant seasonal variations in time and space; detections during the winter tend to produce higher correlations relative to those from the summer, and a seasonal variation in azimuth is observed. These results indicate that the bulletin is seasonally variable. Association of detections and event localization was done utilizing the Bayesian infrasonic source location procedure (BISL, Modrak et al., 2010), accounting for unknown atmospheric propagation effects by adding a random component to the infrasonic group velocity. The resulting infrasonic catalog consists of 963 events for the one-year time period with indication of repeated events from a number of locations. The distribution of infrasound events in this study is well matched with the infrasound hot spots identified by Walker et al. (2011) which were based on a back projection procedure applied to seismic signals from USArray Transportable Array. There are common concentrations of events in both catalogs that include New Bomb in Nevada, Utah Test and Training Range (UTTR), and Dugway Proving Ground in Utah, as well as broader areas in central Nevada and southwest Idaho. The two bulletins document that the vast majority of events occur during work hours, suggesting they are related to human activities.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Sources of Infrasound events listed in IDC Reviewed Event Bulletin

    NASA Astrophysics Data System (ADS)

    Bittner, Paulina; Polich, Paul; Gore, Jane; Ali, Sherif; Medinskaya, Tatiana; Mialle, Pierrick

    2017-04-01

    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, however automatic processing required significant improvements to reduce the number of false events. In the beginning of 2010 the infrasound technology was reintroduced to the IDC operations and has contributed to both automatic and reviewed IDC bulletins. The primary contribution of infrasound technology is to detect atmospheric events. These events may also be observed at seismic stations, which will significantly improve event location. Examples sources of REB events, which were detected by the International Monitoring System (IMS) infrasound 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 (e.g. Zheleznogorsk) and large earthquakes (e.g. Italy 2016) belong to events primarily recorded at seismic stations of the IMS network but often detected at the infrasound stations. In case of earthquakes analysis of infrasound signals may help to estimate the area affected by ground vibration. Infrasound associations to query blast events may help to obtain better source location. The role of IDC analysts is to verify and improve location of events detected by the automatic system and to add events which were missed in the automatic process. Open source materials may help to identify nature of some events. Well recorded examples may be added to the Reference Infrasound Event Database to help in analysis process. This presentation will provide examples of events generated by different sources which were included in the IDC bulletins.

  19. 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

  20. 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

  1. Choroidal thickness maps from spectral domain and swept source optical coherence tomography: algorithmic versus ground truth annotation.

    PubMed

    Philip, Ana-Maria; Gerendas, Bianca S; Zhang, Li; Faatz, Henrik; Podkowinski, Dominika; Bogunovic, Hrvoje; Abramoff, Michael D; Hagmann, Michael; Leitner, Roland; Simader, Christian; Sonka, Milan; Waldstein, Sebastian M; Schmidt-Erfurth, Ursula

    2016-10-01

    The purpose of the study was to create a standardised protocol for choroidal thickness measurements and to determine whether choroidal thickness measurements made on images obtained by spectral domain optical coherence tomography (SD-OCT) and swept source (SS-) OCT from patients with healthy retina are interchangeable when performed manually or with an automatic algorithm. 36 grid cell measurements for choroidal thickness for each volumetric scan were obtained, which were measured for SD-OCT and SS-OCT with two methods on 18 eyes of healthy volunteers. Manual segmentation by experienced retinal graders from the Vienna Reading Center and automated segmentation on >6300 images of the choroid from both devices were statistically compared. Model-based comparison between SD-OCT/SS-OCT showed a systematic difference in choroidal thickness of 16.26±0.725 μm (p<0.001) for manual segmentation and 21.55±0.725 μm (p<0.001) for automated segmentation. Comparison of automated with manual segmentations revealed small differences in thickness of -0.68±0.513 μm (p=0.1833). The correlation coefficients for SD-OCT and SS-OCT measures within eyes were 0.975 for manual segmentation and 0.955 for automatic segmentation. Choroidal thickness measurements of SD-OCT and SS-OCT indicate that these two devices are interchangeable with a trend of choroidal thickness measurements being slightly thicker on SD-OCT with limited clinical relevance. Use of an automated algorithm to segment choroidal thickness was validated in healthy volunteers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  2. Infrasound from the Explosion Sources in the 1-200 km at UTTR

    NASA Astrophysics Data System (ADS)

    Kim, T. S.; Stump, B. W.; Kang, I. B.; Hayward, C.

    2009-04-01

    The propagation of infrasound in the standard atmospheric model is not predicted at the distances less than 250 km, which is called "zone of silence" (Mckenna, 2005). In empirical studies, however, infrasound signals can be recorded in this "shadow zone" (Reed, 1969; Che et al., 2002; Pinsky et al. 2006; Evers et al., 2007) even though the physics of infrasound propagation at this distance range is not well known due to limitations restricted by the quality of ground truth, station distribution and the lack of atmospheric profile. The experiment in Utah performed in August, 2007 had high quality ground truths (G0) from four rocket motors and a dense deployment of infrasound gauges including six arrays and thirteen single stations at distances from 100 meters over 210 kilometers. The atmospheric profile from the surface to about 25 km at the maximum height gave us an opportunity to access the variations of local atmospheric condition and model the infrasound propagation. To understand the characteristics of propagation path effect on the travel time and waveform of infrasound signals, systematic analysis on group and phase velocities, amplitude variation and atmospheric profile was performed. Based on the analysis, the infrasonic arrivals were classified into two groups: The arrivals at the distance less than 100 km (local arrivals) and those between 150 and 210 km (regional arrivals). The estimates of group velocity at local distances are around 350 m/s while those of regional distances vary from 280 to 300 m/s. The mean phase velocity at local distance range is 359 ± 9.8 m/s which is near to the speed of sound at the surface while that of regional distance is 386 ± 7.6 m/s, which can be expected from the turning rays from the stratosphere or thermosphere. The Utah observations also demonstrate that infrasound amplitude does not decay at local distances around 50 km. The PE modeling explains partially that observed acoustic arrivals and focusing of amplitude at

  3. Assessment of Infrasound Detection Capabilities in the Western US Using a Combination of Infrasound Arrays and Single Seismometers

    NASA Astrophysics Data System (ADS)

    Park, J.; Hayward, C.; Stump, B. W.

    2016-12-01

    Ground truth sources can be useful for documenting how infrasound observations are affected by atmospheric conditions as well as testing predictive capabilities of the atmospheric model. To assess these issues, we focus on the infrasound analysis using a hybrid of regional scale seismic stations and infrasound arrays in the western US. The station distributions vary in time when USArray Transportable Array (TA) and local seismic network were installed. A total of 56 ground truth events were collected from static rocket motor burn tests (long duration up to 3 minutes) and rocket body demolitions (impulsive signals) in Utah from 2003 to 2013. In order to review hundreds of stations for individual events, automated infrasound detection and association techniques were developed. The detection procedure is based on STA/LTA trigger in combinations with spectral and amplitude analyses. Detected signals were subsequently associated using the closest three stations with estimates of phase velocity and azimuth used to refine the detections. The automatic detections indicate that infrasound signals from both types of sources are observed to distances of 600 km with some observed beyond 700 km. Infrasound arrival predictions using ground-to-space (G2S) atmospheric specifications compare well with both automatic and analysts infrasound picks including celerity and amplitude documenting seasonal variations in atmospheric conditions. The average detection percentages are 28.8 % and 24.7 % for rocket demolition and burn test datasets, respectively, twice as high as those produced by the analyst. Additional work is needed to quantify the effects of station distribution, atmospheric conditions, source coupling, acoustic to seismic coupling at seismometers, local noise levels and effectiveness of network processing on the proposed automated procedures.

  4. 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

  5. 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.

  6. 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

  7. Imaging volcanic infrasound sources using time reversal mirror algorithm

    NASA Astrophysics Data System (ADS)

    Kim, Keehoon; Lees, Jonathan M.

    2015-09-01

    We investigate the capability of Time Reversal Mirror (TRM) algorithm to image local acoustic sources (<3.5 km) associated with complex, sustained volcanic eruptions. Accurate source localization for volcano infrasound (low-frequency acoustic waves) is often challenging due to pronounced volcanic topography and emergent arrivals of infrasound signals. While the accuracy of the conventional approaches (e.g. triangulation and semblance method) can be severely compromised by the complex volcanic settings, a TRM-based method may have the potential to properly image acoustic sources by the use of full waveform information and numerical modelling of the time-reversed wavefield. We apply the TRM algorithm to a pyroclastic-laden eruption (sustained for ˜60 s) at Santiaguito Volcano, Guatemala, and show that an ordinary TRM operation can undergo significant reduction of its focusing power due to strong topographic propagation effects (e.g. reflection and diffraction). We propose a weighted imaging condition to compensate for complicated transmission loss of the time-reversed wavefield and demonstrate that the presented condition significantly improves the focusing quality of TRM in the presence of complex topography. The consequent TRM source images exhibit remarkable agreement with the visual observation of the eruption implying that the TRM method with a proper imaging condition can be used to localize and track acoustic sources associated with complex volcanic eruptions.

  8. Using Seismic and Infrasonic Data to Identify Persistent Sources

    NASA Astrophysics Data System (ADS)

    Nava, S.; Brogan, R.

    2014-12-01

    Data from seismic and infrasound sensors were combined to aid in the identification of persistent sources such as mining-related explosions. It is of interest to operators of seismic networks to identify these signals in their event catalogs. Acoustic signals below the threshold of human hearing, in the frequency range of ~0.01 to 20 Hz are classified as infrasound. Persistent signal sources are useful as ground truth data for the study of atmospheric infrasound signal propagation, identification of manmade versus naturally occurring seismic sources, and other studies. By using signals emanating from the same location, propagation studies, for example, can be conducted using a variety of atmospheric conditions, leading to improvements to the modeling process for eventual use where the source is not known. We present results from several studies to identify ground truth sources using both seismic and infrasound data.

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

    NASA Astrophysics Data System (ADS)

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

    2009-06-01

    The Wells, Nevada, earthquake of February 21, 2008, generated a complex seismo-acoustic wavefield. Epicentral infrasound was recorded at 5 seismo-acoustic arrays in Nevada, Utah, and Wyoming. In addition to epicentral infrasound, the earthquake triggered a secondary source of infrasound at the BGU array in Utah, which was also triggered 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 (‘Floating Island’) that appears to efficiently generate infrasound through the interaction with seismic surface waves. This hypothesized source location is broadly consistent with crosswind directions extracted from the Ground-to-Space (G2S) atmospheric model (for the appropriate time and source/receiver locations), although modeling the propagation of infrasound predicts this source location to be within the so-called ‘zone-of-silence’. In contrast to epicentral infrasound, secondary infrasound associated with the Wells, Nevada, earthquake sequence appears to be local to each array (i.e., not observed at multiple arrays). Secondary infrasonic arrivals observed at BGU are much higher in amplitude than epicentral arrivals, highlighting the importance of being able to clearly identify and separate epicentral and secondary arrivals for infrasonic event discrimination.

  10. 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.

  11. 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.

  12. 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.

  13. 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://adsabs.harvard.edu/abs/2017GeoJI.209..373N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.209..373N"><span>Seasonal variations of infrasonic arrivals from long-term <span class="hlt">ground</span> <span class="hlt">truth</span> observations in Nevada and implication for event location</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Negraru, Petru; Golden, Paul</p> <p>2017-04-01</p> <p>Long-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, traveltime 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 per cent of the detonations have traveltimes indicative of stratospheric arrivals, while tropospheric waveguides are observed from only 27 per cent 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. Modeling through the Naval Research Laboratory Ground to Space 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 traveltime bias. In the end, we show the possible improvement in location using empirically calibrated traveltime 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 per cent credibility contours by a factor of 2.5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/962383','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/962383"><span>A repeating <span class="hlt">source</span> of <span class="hlt">infrasound</span> from the Wells, Nevada earthquake sequence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arrowsmith, Stephen J.; Whitaker, Rod; Randall, George; Burlacu, Relu</p> <p>2009-01-01</p> <p>The Wells, Nevada earthquake of February 21, 2008, generated a complex seismoacoustic wakefield. In addition to epicentral <span class="hlt">infrasound</span>, the earthquake triggered a secondary <span class="hlt">source</span> of <span class="hlt">infrasound</span>, which was also initiated by subsequent aftershocks. By applying simple constraints on the propagation of seismic and <span class="hlt">infrasound</span> waves, we show that the secondary <span class="hlt">source</span> is an isolated peak that appears to efficiently generate <span class="hlt">infrasound</span> 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 <span class="hlt">infrasound</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2499J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2499J"><span>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>Johnson, J. B.; Fee, D.; Matoza, R. S.</p> <p>2013-12-01</p> <p>Open-vent volcanoes generate prodigious low frequency sound waves that tend to peak in the <span class="hlt">infrasound</span> (<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. <span class="hlt">Infrasound</span> records may be used to remotely monitor eruptions, identify active vents or track gravity-driven flows, and/or characterize <span class="hlt">source</span> 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 <span class="hlt">infrasound</span>. Herein we suggest classification of typical <span class="hlt">infrasound</span> 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 <span class="hlt">infrasound</span> excess pressures are often quantified. We also describe the spectrum of <span class="hlt">source</span> types and radiation patterns, which are typically responsible for recorded <span class="hlt">infrasound</span>. Finally we summarize the variety of propagation paths that are common for volcano <span class="hlt">infrasound</span> 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 <span class="hlt">infrasound</span> studies proliferate and <span class="hlt">infrasound</span> becomes a standard component of volcano monitoring.</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><span class="hlt">Infrasound</span>, Its <span class="hlt">Sources</span> and Its Effects on Man</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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('https://eric.ed.gov/?q=global+AND+temperature+AND+change&pg=3&id=ED396917','ERIC'); return false;" href="https://eric.ed.gov/?q=global+AND+temperature+AND+change&pg=3&id=ED396917"><span><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://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><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://hdl.handle.net/2060/20050192154','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050192154"><span>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> </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/2014AGUFM.V23C4814K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4814K"><span><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> <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>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>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('https://www.osti.gov/scitech/biblio/6187419','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6187419"><span>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>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://adsabs.harvard.edu/abs/2003SPIE.5083..408T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003SPIE.5083..408T"><span><span class="hlt">Ground</span> <span class="hlt">truth</span> and benchmarks for performance evaluation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takeuchi, Ayako; Shneier, Michael; Hong, Tsai Hong; Chang, Tommy; Scrapper, Christopher; Cheok, Geraldine S.</p> <p>2003-09-01</p> <p>Progress in algorithm development and transfer of results to practical applications such as military robotics requires the setup of standard tasks, of standard qualitative and quantitative measurements for performance evaluation and validation. Although the evaluation and validation of algorithms have been discussed for over a decade, the research community still faces a lack of well-defined and standardized methodology. The range of fundamental problems include a lack of quantifiable measures of performance, a lack of data from state-of-the-art sensors in calibrated real-world environments, and a lack of facilities for conducting realistic experiments. In this research, we propose three methods for creating <span class="hlt">ground</span> <span class="hlt">truth</span> databases and benchmarks using multiple sensors. The databases and benchmarks will provide researchers with high quality data from suites of sensors operating in complex environments representing real problems of great relevance to the development of autonomous driving systems. At NIST, we have prototyped a High Mobility Multi-purpose Wheeled Vehicle (HMMWV) system with a suite of sensors including a Riegl ladar, GDRS ladar, stereo CCD, several color cameras, Global Position System (GPS), Inertial Navigation System (INS), pan/tilt encoders, and odometry . All sensors are calibrated with respect to each other in space and time. This allows a database of features and terrain elevation to be built. <span class="hlt">Ground</span> <span class="hlt">truth</span> for each sensor can then be extracted from the database. The main goal of this research is to provide <span class="hlt">ground</span> <span class="hlt">truth</span> databases for researchers and engineers to evaluate algorithms for effectiveness, efficiency, reliability, and robustness, thus advancing the development of algorithms.</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><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>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://www.dtic.mil/docs/citations/ADA130026','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA130026"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Analysis Supporting the High Resolution Flyover.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1983-03-01</p> <p>h -Ai2S 026 <span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> ANALYSIS SUPPORTING THE NIGH RESOLUTIONJ 1/1 FLYOYER(U) NAYAL CORSTAL SYSTEMS CENTER PANAMA CITY FL D F LOTT MAR 83,NCSC-TM...378 83 SB1 AD-F208 051 UNCLR7SIFIED F/G 8/3 N 2. 11111=1.25 klf(RCP ,L- I(N , 011 0 0 0 TECHNICAL MEMORANDUM NCSC TM 370-83 MARCH 1983 <span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> ...provided <span class="hlt">ground</span> <span class="hlt">truth</span> measurements in support of the High Resolution Flyover (NAVAIR Task No. A370370G/076B/lF590550-000). <span class="hlt">Ground</span> <span class="hlt">truthing</span> was provided</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S33E..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S33E..04B"><span>Recent progress in nuclear test detection using <span class="hlt">infrasound</span> technology</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.; Brachet, N.</p> <p>2016-12-01</p> <p>The high performances of the International Monitoring System <span class="hlt">infrasound</span> network were very well demonstrated by the detection and analysis of many <span class="hlt">Ground</span> <span class="hlt">Truth</span> Events in various environmental conditions. This presentation highlights recent progresses based on an improved description of both signal and atmosphere. Firstly, progress concerns observations and data analysis of big data sets. The <span class="hlt">infrasound</span> sensors provide broadband signals in the interest frequency range. However, signals are generally analyzed in several parallel frequency bands. The currently used Progressive Multi-Channel Correlation algorithm (PMCC) is now evolving to process the useful information in a broad standardized frequency range, leading to a more accurate characterization of both <span class="hlt">source</span> and noise which could benefit to operational monitoring purposes. Secondly, progress concerns the development of experimental <span class="hlt">infrasound</span> stations which form a dense <span class="hlt">infrasound</span> network, especially in Europe, enhancing the detectability of <span class="hlt">infrasound</span> events. Thirdly, progress concerns an improved representation of the atmosphere. Systematic processing highlights the necessity to improve propagation modeling in the wave guide between ground and stratosphere-mesosphere-thermosphere system to interpret the observations. The predicted detection periods of volcano eruptions using near field observations and propagation models are shorter than the periods observed in the far field. The lack of representation in the models of large scale atmospheric disturbances such as gravity, planetary waves and sudden stratospheric warming events, is at the origin of these differences. New methods are developed to parameterize these disturbances for further assimilation in atmospheric models, as planned in the framework of the Atmospheric dynamics Research InfraStructure in Europe (ARISE) project. One application is the improvement of the detection capability simulations used for the evaluation of the performances of existing</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><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+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTruth%2BRadicality','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900043101&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTruth%2BRadicality"><span><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('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><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://adsabs.harvard.edu/abs/2016AGUFM.S51A2746P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S51A2746P"><span>Atmospheric Model Effects on <span class="hlt">Infrasound</span> <span class="hlt">Source</span> Inversion from the <span class="hlt">Source</span> Physics Experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Preston, L. A.; Aur, K. A.</p> <p>2016-12-01</p> <p>The <span class="hlt">Source</span> Physics Experiments (SPE) consist of a series of underground explosive shots at the Nevada National Security Site (NNSS) designed to gain an improved understanding of the generation and propagation of physical signals in the near and far field. Characterizing the acoustic and <span class="hlt">infrasound</span> <span class="hlt">source</span> mechanism from underground explosions is of great importance in non-proliferation activities. To this end we perform full waveform <span class="hlt">source</span> inversion of <span class="hlt">infrasound</span> data collected from SPE shots at distances from 300 m to 1 km and frequencies up to 20 Hz. Our method requires estimating the state of the atmosphere at the time of each shot, computing Green's functions through these atmospheric models, and subsequently inverting these signals in the frequency domain to obtain a <span class="hlt">source</span> time function. To estimate the state of the atmosphere at the time of the shot, we utilize two different datasets: North American Regional Reanalysis data, a comprehensive but lower resolution dataset, and locally obtained sonde and surface weather observations. We synthesize Green's functions through these atmospheric models using Sandia's moving media acoustic propagation simulation suite. These models include 3-D variations in topography, temperature, pressure, and wind. We will compare and contrast the atmospheric models derived from the two weather datasets and discuss how these differences affect computed <span class="hlt">source</span> waveforms and contribute to modeling uncertainty. 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('https://ntrs.nasa.gov/search.jsp?R=20070017979&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DTruth%2BRadicality','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070017979&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DTruth%2BRadicality"><span>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('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>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('https://www.ncbi.nlm.nih.gov/pubmed/20033494','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20033494"><span>A comparison of <span class="hlt">ground</span> <span class="hlt">truth</span> estimation methods.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Biancardi, Alberto M; Jirapatnakul, Artit C; Reeves, Anthony P</p> <p>2010-05-01</p> <p>Knowledge of the exact shape of a lesion, or <span class="hlt">ground</span> <span class="hlt">truth</span> (GT), is necessary for the development of diagnostic tools by means of algorithm validation, measurement metric analysis, accurate size estimation. Four methods that estimate GTs from multiple readers' documentations by considering the spatial location of voxels were compared: thresholded Probability-Map at 0.50 (TPM(0.50)) and at 0.75 (TPM(0.75)), simultaneous truth and performance level estimation (STAPLE) and truth estimate from self distances (TESD). A subset of the publicly available Lung Image Database Consortium archive was used, selecting pulmonary nodules documented by all four radiologists. The pair-wise similarities between the estimated GTs were analyzed by computing the respective Jaccard coefficients. Then, with respect to the readers' marking volumes, the estimated volumes were ranked and the sign test of the differences between them was performed. (a) the rank variations among the four methods and the volume differences between STAPLE and TESD are not statistically significant, (b) TPM(0.50) estimates are statistically larger (c) TPM(0.75) estimates are statistically smaller (d) there is some spatial disagreement in the estimates as the one-sided 90% confidence intervals between TPM(0.75) and TPM(0.50), TPM(0.75) and STAPLE, TPM(0.75) and TESD, TPM(0.50) and STAPLE, TPM(0.50) and TESD, STAPLE and TESD, respectively, show: [0.67, 1.00], [0.67, 1.00], [0.77, 1.00], [0.93, 1.00], [0.85, 1.00], [0.85, 1.00]. The method used to estimate the GT is important: the differences highlighted that STAPLE and TESD, notwithstanding a few weaknesses, appear to be equally viable as a GT estimator, while the increased availability of computing power is decreasing the appeal afforded to TPMs. Ultimately, the choice of which GT estimation method, between the two, should be preferred depends on the specific characteristics of the marked data that is used with respect to the two elements that differentiate the</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>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('http://adsabs.harvard.edu/abs/2008AGUFM.S13E..06L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S13E..06L"><span>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://www.dtic.mil/docs/citations/ADA435517','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA435517"><span>Tactical <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2005-05-01</p> <p>appeared on their <span class="hlt">infrasound</span> detector at the Lamont- Doherty observatory on the palisades above the Hudson River was generated by the Tappan Zee bridge ...Impulsive <span class="hlt">sources</span> ..................... 14 3.2.3 Steady <span class="hlt">sources</span>: bridges and structures ......... 15 3.3 Implications for the design of sonic detection...are currently too small (within the US) to produce a healthy and vibrant flow of new ideas, new implementations, and new people. The DoD would derive</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://www.dtic.mil/docs/citations/ADA533902','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA533902"><span>The Temporal Morphology of <span class="hlt">Infrasound</span> Propagation</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-01-01</p> <p>that incorpo- ration of hybrid ground-to-space (G2S) enviromental specifications in numerical calculations of <span class="hlt">infrasound</span> signal travel time and...valuable <span class="hlt">ground-truth</span> information that can be 1 Space Science Division, Naval Research Laboratory, Washington, DC, USA. E-mail: douglas.drob...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Research Laboratory,Space Science Division,4555</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>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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4073649','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4073649"><span>Does function fit structure? A <span class="hlt">ground</span> <span class="hlt">truth</span> for non-invasive neuroimaging</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Stevenson, Claire; Brookes, Matthew; López, José David; Troebinger, Luzia; Mattout, Jeremie; Penny, William; Morris, Peter; Hillebrand, Arjan; Henson, Richard; Barnes, Gareth</p> <p>2014-01-01</p> <p>There are now a number of non-invasive methods to image human brain function in-vivo. However, the accuracy of these images remains unknown and can currently only be estimated through the use of invasive recordings to generate a functional <span class="hlt">ground</span> <span class="hlt">truth</span>. Neuronal activity follows grey matter structure and accurate estimates of neuronal activity will have stronger support from accurate generative models of anatomy. Here we introduce a general framework that, for the first time, enables the spatial distortion of a functional brain image to be estimated empirically. We use a spherical harmonic decomposition to modulate each cortical hemisphere from its original form towards progressively simpler structures, ending in an ellipsoid. Functional estimates that are not supported by the simpler cortical structures have less inherent spatial distortion. This method allows us to compare directly between magnetoencephalography (MEG) <span class="hlt">source</span> reconstructions based upon different assumption sets without recourse to functional <span class="hlt">ground</span> <span class="hlt">truth</span>. PMID:24636880</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24636880','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24636880"><span>Does function fit structure? A <span class="hlt">ground</span> <span class="hlt">truth</span> for non-invasive neuroimaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stevenson, Claire; Brookes, Matthew; López, José David; Troebinger, Luzia; Mattout, Jeremie; Penny, William; Morris, Peter; Hillebrand, Arjan; Henson, Richard; Barnes, Gareth</p> <p>2014-07-01</p> <p>There are now a number of non-invasive methods to image human brain function in-vivo. However, the accuracy of these images remains unknown and can currently only be estimated through the use of invasive recordings to generate a functional <span class="hlt">ground</span> <span class="hlt">truth</span>. Neuronal activity follows grey matter structure and accurate estimates of neuronal activity will have stronger support from accurate generative models of anatomy. Here we introduce a general framework that, for the first time, enables the spatial distortion of a functional brain image to be estimated empirically. We use a spherical harmonic decomposition to modulate each cortical hemisphere from its original form towards progressively simpler structures, ending in an ellipsoid. Functional estimates that are not supported by the simpler cortical structures have less inherent spatial distortion. This method allows us to compare directly between magnetoencephalography (MEG) <span class="hlt">source</span> reconstructions based upon different assumption sets without recourse to functional <span class="hlt">ground</span> <span class="hlt">truth</span>. Copyright © 2014. Published by Elsevier Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1104542','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1104542"><span>Seismic Monitoring System Calibration Using <span class="hlt">Ground</span> <span class="hlt">Truth</span> Database</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chan, Winston; Wagner, Robert</p> <p>2002-12-22</p> <p>Calibration of a seismic monitoring system remains a major issue due to the lack of <span class="hlt">ground</span> <span class="hlt">truth</span> information and uncertainties in the regional geological parameters. Rapid and accurate identification of seismic events is currently not feasible due to the absence of a fundamental framework allowing immediate access to <span class="hlt">ground</span> <span class="hlt">truth</span> information for many parts of the world. Precise location and high-confidence identification of regional seismic events are the primary objectives of monitoring research in seismology. In the Department of Energy Knowledge Base (KB), <span class="hlt">ground</span> <span class="hlt">truth</span> information addresses these objectives and will play a critical role for event relocation and identification using advanced seismic analysis tools. Maintaining the KB with systematic compilation and analysis of comprehensive sets of geophysical data from various parts of the world is vital. The goal of this project is to identify a comprehensive database for China using digital seismic waveform data that are currently unavailable. These data may be analyzed along with <span class="hlt">ground</span> <span class="hlt">truth</span> information that becomes available. To date, arrival times for all regional phases are determined on all events above Mb 4.5 that occurred in China in 2000 and 2001. Travel-time models are constructed to compare with existing models. Seismic attenuation models may be constructed to provide better understanding of regional wave propagation in China with spatial resolution that has not previously been obtained.</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><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="http://www.dtic.mil/">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>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>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><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>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>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>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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2702211','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2702211"><span>On Evaluating Brain Tissue Classifiers without a <span class="hlt">Ground</span> <span class="hlt">Truth</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Martin-Fernandez, Marcos; Ungar, Lida; Nakamura, Motoaki; Koo, Min-Seong; McCarley, Robert W.; Shenton, Martha E.</p> <p>2009-01-01</p> <p>In this paper, we present a set of techniques for the evaluation of brain tissue classifiers on a large data set of MR images of the head. Due to the difficulty of establishing a gold standard for this type of data, we focus our attention on methods which do not require a <span class="hlt">ground</span> <span class="hlt">truth</span>, but instead rely on a common agreement principle. Three different techniques are presented: the Williams’ index, a measure of common agreement; STAPLE, an Expectation Maximization algorithm which simultaneously estimates performance parameters and constructs an estimated reference standard; and Multidimensional Scaling, a visualization technique to explore similarity data. We apply these different evaluation methodologies to a set eleven different segmentation algorithms on forty MR images. We then validate our evaluation pipeline by building a <span class="hlt">ground</span> <span class="hlt">truth</span> based on human expert tracings. The evaluations with and without a <span class="hlt">ground</span> <span class="hlt">truth</span> are compared. Our findings show that comparing classifiers without a gold standard can provide a lot of interesting information. In particular, outliers can be easily detected, strongly consistent or highly variable techniques can be readily discriminated, and the overall similarity between different techniques can be assessed. On the other hand, we also find that some information present in the expert segmentations is not captured by the automatic classifiers, suggesting that common agreement alone may not be sufficient for a precise performance evaluation of brain tissue classifiers. PMID:17532646</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28508065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28508065"><span>The <span class="hlt">ground</span> <span class="hlt">truth</span> about metadata and community detection in networks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peel, Leto; Larremore, Daniel B; Clauset, Aaron</p> <p>2017-05-01</p> <p>Across many scientific domains, there is a common need to automatically extract a simplified view or coarse-graining of how a complex system's components interact. This general task is called community detection in networks and is analogous to searching for clusters in independent vector data. It is common to evaluate the performance of community detection algorithms by their ability to find so-called <span class="hlt">ground</span> <span class="hlt">truth</span> communities. This works well in synthetic networks with planted communities because these networks' links are formed explicitly based on those known communities. However, there are no planted communities in real-world networks. Instead, it is standard practice to treat some observed discrete-valued node attributes, or metadata, as <span class="hlt">ground</span> <span class="hlt">truth</span>. We show that metadata are not the same as <span class="hlt">ground</span> <span class="hlt">truth</span> and that treating them as such induces severe theoretical and practical problems. We prove that no algorithm can uniquely solve community detection, and we prove a general No Free Lunch theorem for community detection, which implies that there can be no algorithm that is optimal for all possible community detection tasks. However, community detection remains a powerful tool and node metadata still have value, so a careful exploration of their relationship with network structure can yield insights of genuine worth. We illustrate this point by introducing two statistical techniques that can quantify the relationship between metadata and community structure for a broad class of models. We demonstrate these techniques using both synthetic and real-world networks, and for multiple types of metadata and community structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMAE31A0273A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMAE31A0273A"><span><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>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/2017JAsGe...6...68E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAsGe...6...68E"><span><span class="hlt">Infrasound</span> detection of meteors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>ElGabry, M. N.; Korrat, I. M.; Hussein, H. M.; Hamama, I. H.</p> <p>2017-06-01</p> <p>Meteorites that penetrate the atmosphere generate <span class="hlt">infrasound</span> waves of very low frequency content. These waves can be detected even at large distances. In this study, we analyzed the <span class="hlt">infrasound</span> waves produced by three meteors. The October 7, 2008 TC3 meteor fell over the north Sudan Nubian Desert, the February 15, 2013 Russian fireball, and the February 6, 2016 Atlantic meteor near to the Brazil coast. The signals of these three meteors were detected by the <span class="hlt">infrasound</span> sensors of the International Monitoring System (IMS) of the Comprehensive Test Ban Treaty Organization (CTBTO). The progressive Multi Channel Technique is applied to the signals in order to locate these <span class="hlt">infrasound</span> <span class="hlt">sources</span>. Correlation of the recorded signals in the collocated elements of each array enables to calculate the delays at the different array element relative to a reference one as a way to estimate the azimuth and velocity of the coming <span class="hlt">infrasound</span> signals. The meteorite <span class="hlt">infrasound</span> signals show a sudden change in pressure with azimuth due to its track variation at different heights in the atmosphere. Due to movement of the <span class="hlt">source</span>, a change in azimuth with time occurs. Our deduced locations correlate well with those obtained from the catalogues of the IDC of the CTBTO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5415338','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5415338"><span>The <span class="hlt">ground</span> <span class="hlt">truth</span> about metadata and community detection in 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>Peel, Leto; Larremore, Daniel B.; Clauset, Aaron</p> <p>2017-01-01</p> <p>Across many scientific domains, there is a common need to automatically extract a simplified view or coarse-graining of how a complex system’s components interact. This general task is called community detection in networks and is analogous to searching for clusters in independent vector data. It is common to evaluate the performance of community detection algorithms by their ability to find so-called <span class="hlt">ground</span> <span class="hlt">truth</span> communities. This works well in synthetic networks with planted communities because these networks’ links are formed explicitly based on those known communities. However, there are no planted communities in real-world networks. Instead, it is standard practice to treat some observed discrete-valued node attributes, or metadata, as <span class="hlt">ground</span> <span class="hlt">truth</span>. We show that metadata are not the same as <span class="hlt">ground</span> <span class="hlt">truth</span> and that treating them as such induces severe theoretical and practical problems. We prove that no algorithm can uniquely solve community detection, and we prove a general No Free Lunch theorem for community detection, which implies that there can be no algorithm that is optimal for all possible community detection tasks. However, community detection remains a powerful tool and node metadata still have value, so a careful exploration of their relationship with network structure can yield insights of genuine worth. We illustrate this point by introducing two statistical techniques that can quantify the relationship between metadata and community structure for a broad class of models. We demonstrate these techniques using both synthetic and real-world networks, and for multiple types of metadata and community structures. PMID:28508065</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>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> </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://adsabs.harvard.edu/abs/2015AGUFMNH32C..03A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH32C..03A"><span><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://adsabs.harvard.edu/abs/2010SPIE.7538E..08M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7538E..08M"><span>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>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.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>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('https://www.ncbi.nlm.nih.gov/pubmed/25729465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25729465"><span>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('http://www.dtic.mil/docs/citations/ADA519124','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA519124"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Locations Using Synergy Between Remote Sensing and Seismic Methods</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2007-09-01</p> <p><span class="hlt">GROUND</span> <span class="hlt">TRUTH</span> LOCATIONS USING SYNERGY BETWEEN REMOTE SENSING AND SEISMIC METHODS Gene A. Ichinose1, Hong Kie Thio2, and Don V. Helmberger3...have relocated a set of 50 <span class="hlt">ground</span> <span class="hlt">truth</span> (GT) earthquakes as determined from regional modeling, to estimate the performance of the station correction...DATES COVERED 00-00-2007 to 00-00-2007 4. TITLE AND SUBTITLE <span class="hlt">Ground</span> <span class="hlt">Truth</span> Locations Using Synergy Between Remote Sensing and Seismic Methods 5a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1713265T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1713265T"><span>Eruption rates in explosive eruptions: <span class="hlt">Ground</span> <span class="hlt">truth</span> and models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tumi Gudmundsson, Magnus; Durig, Tobias; Höskuldsson, Ármann; Thordarson, Thorvaldur; Larsen, Gudrún; Óladóttir, Bergrún A.; Högnadóttir, Thórdís; Oddsson, Björn; Björnsson, Halldór; Gudmundsdóttir, Esther R.</p> <p>2015-04-01</p> <p>Estimations of eruption rates in explosive eruptions are difficult and error margins are invariably high. In small to moderate sized eruptions effects of wind on plume height can be large and in larger eruptions observations are often difficult due to masking of <span class="hlt">source</span> by low cloud, pyroclastic density currents and monitoring system saturation. Several medium-sized explosive eruptions in recent years have been an important in sparking off intense research on e.g. atmosphere-plume interaction and associated effects of wind on plume height. Other methods that do not rely on plume height are e.g. infrared satellite monitoring of atmospheric loading of fine tephra, <span class="hlt">infrasound</span>, analysis of video recordings from vents, and it has been suggested that co-eruptive tilt-meter deformation data can predict eruption intensity. The eruptions of Eyjafjallajökull in 2010 and Grímsvötn in 2011 provided a wealth of data that potentially can be of use in developing constraints of eruption rates in explosive eruptions. A key parameter in all such comparisons between models and data is as detailed knowledge as possible on tephra fallout. For both Eyjafjallajökull and Grímsvötn intensive field efforts took place to map out the deposits during and immediately after the eruptions. The resulting maps cover both individual phases as well as total fallout. Comparison of these data with plume-based and other models of mass discharge rates is presently work in progress. A desirable future aim is near real time estimates of mass eruption rates based several of the parameters mentioned above. This type of work is currently ongoing within the framework of the EU-funded supersite project FUTUREVOLC.</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>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://adsabs.harvard.edu/abs/2015EGUGA..17.8668G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8668G"><span>Seismo-acoustic analysis of the ocean swell <span class="hlt">sources</span> observed with Romanian <span class="hlt">infrasound</span> array and seismic stations</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; Grecu, Bogdan; Popa, Mihaela</p> <p>2015-04-01</p> <p>Romanian Plostina <span class="hlt">infrasound</span> array (IPLOR) is deployed in the central part of the country, in Vrancea region. Presently, IPLOR array configuration includes 6 elements equipped with Chaparral Physics sensors and with aperture of about 2.5 km. For the purpose of assessing the IPLOR performance in observing various types of <span class="hlt">infrasound</span> <span class="hlt">sources</span>, over five years of data (since June 2009 to present) were processed. Signal interactive analysis was performed using WinPMCC software. The detection results show that the station response was gradually improved, as the number of array elements increased from three to six, and wind noise reduction conditions were enhanced. A larger number of detected signals and a better array resolution at lower frequency were noticed as well. Microbaroms - the interaction of ocean swell with the atmosphere - represent a relevant type of infrasonic <span class="hlt">source</span> present in the IPLOR detection plots, for which the signal characterization has been enhanced with the array upgrading process. IPLOR detection capability related to this energetic long-period <span class="hlt">infrasound</span> waves, which propagate over large distances, shows an alternating behavior, being strongly influenced by the upper atmospheric winds, i.e. seasonally dependent stratospheric winds. The ocean swell can be considered as a seismo-acoustic <span class="hlt">source</span>, leaving an imprint on both seismic and infrasonic recordings. The interaction with the atmosphere generates <span class="hlt">infrasound</span> (microbarom), while the interaction with the sea floor emits seismic signal (microseism). Microbaroms have a sinusoidal wave character with a dominant period of 5 s. Due to low damping at this period in stratospheric wave duct, microbaroms are observed over large distance ranges up to a few thousand kilometres. Microseisms occur as an increasing of seismic background noise between 2 and 20 s; in this range, primary and secondary peaks, at 5 and 14 s, are observed. Common broad-band seismic data, recorded with Romanian dense seismic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ISPAr.XL3...59G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ISPAr.XL3...59G"><span>Towards Globally Consistent Scan Matchingwith <span class="hlt">Ground</span> <span class="hlt">Truth</span> Integration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gailis, J.; Nüchter, A.</p> <p>2015-03-01</p> <p>The scan matching based simultaneous localization and mapping method with six dimensional poses is capable of creating a three dimensional point cloud map of the environment, as well as estimating the six dimensional path that the vehicle has travelled. The essence of it is the registering and matching of sequentially acquired 3D laser scans, while moving along a path, in a common coordinate frame in order to provide 6D pose estimations at the respective positions, as well as create a three dimensional map of the environment. An approach that could drastically improve the reliability of acquired data is to integrate available <span class="hlt">ground</span> <span class="hlt">truth</span> information. This paper is about implementing such functionality as a contribution to 6D SLAM (simultaneous localization and mapping with 6 DoF) in the 3DTK - The 3D Toolkit software (Nüchter and Lingemann, 2011), as well as test the functionality of the implementation using real world datasets.</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>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://adsabs.harvard.edu/abs/2014AGUFM.S41B4489L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S41B4489L"><span>Determination and Statistical Analysis of <span class="hlt">Infrasound</span> <span class="hlt">Sources</span> Near Socorro, New Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Larson, T.; Lees, J. M.; Bowman, D. C.; Jones, K. R.</p> <p>2014-12-01</p> <p>Data collected from 2010 to 2014 at a seismo-acoustic array located outside Socorro, New Mexico provides the grounds for investigating atmospheric radiation of acoustic waves in the area. We extracted 698 impulsive signals (less than five seconds duration) as well as numerous longer period signals, likely trains or other vehicular noise in the region. Using arrival time differences, we derived three-dimensional incidence vectors of <span class="hlt">infrasound</span> arrivals by calculating azimuth and inclination angles for a sorted group of 661 well-recorded impulsive signals (179 in 2010, 220 in 2012, 262 in 2013). During this period, impulsive <span class="hlt">sources</span> arrive at the array from an average azimuth angle of 272.4 degrees. Two main clusters of events can be seen each year: the densest cluster spans the azimuth range 250.96-277.18 degrees, while the second cluster spans 294.33-336.35 degrees. Inclinations for both of these clusters are relatively low, as the main cluster spans 16.1-24.68 degrees and the second spans 4.69-18.44 degrees. The main cluster corresponds to the location of The Energetic Materials Research and Testing Center (EMRTC), which detonates regularly scheduled explosions and is located at an azimuth of 266 degrees with respect to the array. The second cluster lies to the north of the EMRTC range, but the <span class="hlt">source</span> of these signals is unknown and requires further investigation. Signals associated with other <span class="hlt">sources</span>, most likely mining explosions, appear each year emanating from south of EMRTC. Additionally, two minor clusters at low azimuth angles and high inclinations are observed, possibly originating from a number of sites including Kirtland Air Force Base, Sandia National Laboratories, and White Sands Missile Range. Waveform cluster analysis suggests distinct waveform similarity associated with specific <span class="hlt">sources</span>.</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>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://adsabs.harvard.edu/abs/2016AGUFM.C23B0753Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C23B0753Y"><span><span class="hlt">Ground-Truthing</span> a Next Generation Snow Radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yan, S.; Brozena, J. M.; Gogineni, P. S.; Abelev, A.; Gardner, J. M.; Ball, D.; Liang, R.; Newman, T.</p> <p>2016-12-01</p> <p>During the early spring of 2016 the Naval Research Laboratory (NRL) performed a test of a next generation airborne snow radar over <span class="hlt">ground</span> <span class="hlt">truth</span> data collected on several areas of fast ice near Barrow, AK. The radar was developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, and includes several improvements compared to their previous snow radar. The new unit combines the earlier Ku-band and snow radars into a single unit with an operating frequency spanning the entire 2-18 GHz, an enormous bandwidth which provides the possibility of snow depth measurements with 1.5 cm range resolution. Additionally, the radar transmits on dual polarizations (H and V), and receives the signal through two orthogonally polarized Vivaldi arrays, each with 128 phase centers. The 8 sets of along-track phase centers are combined in hardware to improve SNR and narrow the beamwidth in the along-track, resulting in 8 cross-track effective phase centers which are separately digitized to allow for beam sharpening and forming in post-processing. Tilting the receive arrays 30 degrees from the horizontal also allows the formation of SAR images and the potential for estimating snow-water equivalent (SWE). <span class="hlt">Ground</span> <span class="hlt">truth</span> data (snow depth, density, salinity and SWE) were collected over several 60 m wide swaths that were subsequently overflown with the snow radar mounted on a Twin Otter. The radar could be operated in nadir (by beam steering the receive antennas to point beneath the aircraft) or side-looking modes. Results from the comparisons will be shown.</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><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://adsabs.harvard.edu/abs/2016AGUFM.H51H1602B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51H1602B"><span>A Comprehensive Laboratory Study to Improve <span class="hlt">Ground</span> <span class="hlt">Truth</span> Calibration of Remotely Sensed Near-Surface Soil Moisture</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Babaeian, E.; Tuller, M.; Sadeghi, M.; Sheng, W.; Jones, S. B.</p> <p>2016-12-01</p> <p>Optical satellite and airborne remote sensing (RS) have been widely applied for characterization of large-scale surface soil moisture distributions. However, despite the excellent spatial resolution of RS data, the electromagnetic radiation within the optical bands (400-2500 nm) penetrates the soil profile only to a depth of a few millimeters; hence obtained moisture estimates are limited to the soil surface region. Furthermore, moisture sensor networks employed for <span class="hlt">ground</span> <span class="hlt">truth</span> calibration of RS observations commonly exhibit very limited spatial resolution, which consequently leads to significant discrepancies between RS and <span class="hlt">ground</span> <span class="hlt">truth</span> observations. To better understand the relationship between surface and near-surface soil moisture, we employed a benchtop hyperspectral line-scan imaging system to generate high resolution surface reflectance maps during evaporation from soil columns filled with <span class="hlt">source</span> soils covering a wide textural range and instrumented with a novel time domain reflectometry (TDR) sensor array that allows monitoring of near surface moisture at 0.5-cm resolution. A recently developed physical model for surface soil moisture predictions from shortwave infrared reflectance was applied to estimate surface soil moisture from surface reflectance and to explore the relationship between surface and near-surface moisture distributions during soil drying. Preliminary results are very promising and their applicability for <span class="hlt">ground</span> <span class="hlt">truth</span> calibration of RS observations will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S51A2766M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S51A2766M"><span>Improvement of <span class="hlt">Ground</span> <span class="hlt">Truth</span> Classification of Soviet Peaceful Nuclear Explosions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mackey, K. G.; Fujita, K.; Bergman, E.</p> <p>2016-12-01</p> <p>From the 1960's through the late 1980's, the Soviet Union conducted 122 Peaceful Nuclear Explosions across its territory. These PNEs are now very important to the seismological community as so-called <span class="hlt">Ground</span> <span class="hlt">Truth</span> (GT) events. The PNE locations are widely distributed, thus GT0-1 locations, meaning that true location is known to within 1 km or better, are used as calibration events for developing seismic velocity models, model validation, seismic discrimination, etc. The nuclear monitoring/verification community generally utilizes published lists of PNE locations as known or verified GT events, though in reality there are errors and some PNEs are poorly located. We have determined or validated GT0-1 locations for 85 of the Soviet PNEs. Some PNEs published as GT1 or better also have larger errors. Our locations were determined using an integrated approach encompassing published open literature, analysis of satellite imagery and regional seismic data. We have visited and verified 10 PNE sites across Kazakhstan and Ukraine, allowing GPS coordinates to be obtained in the field.</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>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/25267257','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25267257"><span><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('http://adsabs.harvard.edu/abs/2016JOSAA..33.1798G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JOSAA..33.1798G"><span>Interactive removal and <span class="hlt">ground</span> <span class="hlt">truth</span> for difficult shadow scenes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gong, Han; Cosker, Darren</p> <p>2016-09-01</p> <p>A user-centric method for fast, interactive, robust and high-quality shadow removal is presented. Our algorithm can perform detection and removal in a range of difficult cases: such as highly textured and colored shadows. To perform detection an on-the-fly learning approach is adopted guided by two rough user inputs for the pixels of the shadow and the lit area. After detection, shadow removal is performed by registering the penumbra to a normalized frame which allows us efficient estimation of non-uniform shadow illumination changes, resulting in accurate and robust removal. Another major contribution of this work is the first validated and multi-scene category <span class="hlt">ground</span> <span class="hlt">truth</span> for shadow removal algorithms. This data set containing 186 images eliminates inconsistencies between shadow and shadow-free images and provides a range of different shadow types such as soft, textured, colored and broken shadow. Using this data, the most thorough comparison of state-of-the-art shadow removal methods to date is performed, showing our proposed new algorithm to outperform the state-of-the-art across several measures and shadow category. To complement our dataset, an online shadow removal benchmark website is also presented to encourage future open comparisons in this challenging field of research.</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://hdl.handle.net/2060/19780004567','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780004567"><span>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('http://www.osti.gov/scitech/servlets/purl/665950','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/665950"><span>Government Applications Task Force <span class="hlt">ground</span> <span class="hlt">truth</span> study of WAG 4</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Evers, T.K.; Smyre, J.L.; King, A.L.</p> <p>1997-06-01</p> <p>This report documents the Government Applications Task Force (GATF) Buried Waste Project. The project was initiated as a field investigation and verification of the 1994 Strategic Environmental Research and Development Program`s (SERDP) Buried Waste Identification Project results. The GATF project team included staff from three US Department of Energy (DOE) Laboratories [Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory (LANL), and the Savannah River Technology Center (SRTC)] and from the National Exploitation Laboratory. Similar studies were conducted at each of the three DOE laboratories to demonstrate the effective use of remote sensing technologies. The three locations were selected to assess differences in buried waste signatures under various environmental conditions (i.e., climate, terrain, precipitation, geology, etc.). After a brief background discussion of the SERDP Project, this report documents the field investigation (<span class="hlt">ground</span> <span class="hlt">truth</span>) results from the 1994--1995 GATF Buried Waste Study at ORNL`s Waste Area Grouping (WAG) 4. Figures for this report are located in Appendix A.</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>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>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><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('https://www.ncbi.nlm.nih.gov/pubmed/28815130','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28815130"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Creation for Complex Clinical NLP Tasks - an Iterative Vetting Approach and Lessons Learned.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liang, Jennifer J; Tsou, Ching-Huei; Devarakonda, Murthy V</p> <p>2017-01-01</p> <p>Natural language processing (NLP) holds the promise of effectively analyzing patient record data to reduce cognitive load on physicians and clinicians in patient care, clinical research, and hospital operations management. A critical need in developing such methods is the "<span class="hlt">ground</span> <span class="hlt">truth</span>" dataset needed for training and testing the algorithms. Beyond localizable, relatively simple tasks, <span class="hlt">ground</span> <span class="hlt">truth</span> creation is a significant challenge because medical experts, just as physicians in patient care, have to assimilate vast amounts of data in EHR systems. To mitigate potential inaccuracies of the cognitive challenges, we present an iterative vetting approach for creating the <span class="hlt">ground</span> <span class="hlt">truth</span> for complex NLP tasks. In this paper, we present the methodology, and report on its use for an automated problem list generation task, its effect on the <span class="hlt">ground</span> <span class="hlt">truth</span> quality and system accuracy, and lessons learned from the effort.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004DPS....36.3805H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004DPS....36.3805H"><span>Reconciling Radar Remote-Sensing with MER <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>Haldemann, A. F. C.; Larsen, K. W.; Jurgens, R. F.; Golombek, M. P.</p> <p>2004-11-01</p> <p>The Goldstone Solar System Radar (GSSR) carried out Earth-based delay-Doppler radar observations of Mars with four receiving stations during the oppositions in 2001 and 2003, supporting Mars Exploration Rover landing site selection. This interferometric technique demonstrated radar mapping of Mars with a 5 km to 10 km spatial resolution. The data for both Gusev Crater and Meridiani Planum indicated smooth terrains, consistent with, but somewhat different from, previous lower spatial resolution Earth-based radar data. Now, with quantitative <span class="hlt">ground-truth</span> roughness measurements by Spirit and Opportunity, along with THEMIS visible camera images, we can begin to reconcile these differing remote-sensing observations. For Gusev crater, older λ =3.5 cm wavelength data did not directly sample the crater but were of nearby terrain of the same map unit as Gusev's floor. The reported Hagfors scattering model parameters were θ rms=4.7±1.6 degrees, and ρ 0=0.04±0.02. These quasi-specular parameters refer to roughness in the range 10 λ to 100 λ . The higher resolution data from 2003, averaged over the whole MER Gusev ellipse were θ rms=1.3+1.0-0.5 degrees and ρ 0=0.02±0.01. The ρ 0 for the 5 km pixel where Spirit landed was like the average, but θ rms=1.6+1.0-0.5. The roughness derived from stereo images from Spirits first 30 sols, available on the PDS, implies near-nadir scattering from 3 m scales is dominant. We examine the spatial coverage of the older data, as well as other radar data to reconcile the differing observations. For Meridiani, GSSR made direct observations at 3.5 cm at both 5 km resolution and at 10×150 km resolution in 2001. We will carry out our comparative analyses once rover navigation data beyond Eagle crater, obtained after Sol 58, are released to the PDS, and expect to have them for presentation at the meeting.</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>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> <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>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><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('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><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('https://www.ncbi.nlm.nih.gov/pubmed/26736941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26736941"><span><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('http://adsabs.harvard.edu/abs/2010AGUFM.S14A..07W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S14A..07W"><span>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('http://adsabs.harvard.edu/abs/2015JGRB..120.8223J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120.8223J"><span><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/28557614','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28557614"><span>The Gold Standard Paradox in Digital Image Analysis: Manual Versus Automated Scoring as <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>Aeffner, Famke; Wilson, Kristin; Martin, Nathan T; Black, Joshua C; Hendriks, Cris L Luengo; Bolon, Brad; Rudmann, Daniel G; Gianani, Roberto; Koegler, Sally R; Krueger, Joseph; Young, G Dave</p> <p>2017-09-01</p> <p>- Novel therapeutics often target complex cellular mechanisms. Increasingly, quantitative methods like digital tissue image analysis (tIA) are required to evaluate correspondingly complex biomarkers to elucidate subtle phenotypes that can inform treatment decisions with these targeted therapies. These tIA systems need a gold standard, or reference method, to establish analytical validity. Conventional, subjective histopathologic scores assigned by an experienced pathologist are the gold standard in anatomic pathology and are an attractive reference method. The pathologist's score can establish the <span class="hlt">ground</span> <span class="hlt">truth</span> to assess a tIA solution's analytical performance. The paradox of this validation strategy, however, is that tIA is often used to assist pathologists to score complex biomarkers because it is more objective and reproducible than manual evaluation alone by overcoming known biases in a human's visual evaluation of tissue, and because it can generate endpoints that cannot be generated by a human observer. - To discuss common visual and cognitive traps known in traditional pathology-based scoring paradigms that may impact characterization of tIA-assisted scoring accuracy, sensitivity, and specificity. - This manuscript reviews the current literature from the past decades available for traditional subjective pathology scoring paradigms and known cognitive and visual traps relevant to these scoring paradigms. - Awareness of the gold standard paradox is necessary when using traditional pathologist scores to analytically validate a tIA tool because image analysis is used specifically to overcome known <span class="hlt">sources</span> of bias in visual assessment of tissue sections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SPIE.7623E..2MC','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7623E..2MC"><span>Reliable fusion of knee bone laser scans to establish <span class="hlt">ground</span> <span class="hlt">truth</span> for cartilage thickness measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Ming-Ching; Trinh, Nhon H.; Fleming, Braden C.; Kimia, Benjamin B.</p> <p>2010-03-01</p> <p>We are interested in establishing <span class="hlt">ground</span> <span class="hlt">truth</span> data for validating morphology measurements of human knee cartilage from MR imaging. One promising approach is to compare the high-accuracy 3D laser scans of dissected cadaver knees before and after the dissolution of their cartilage. This requires an accurate and reliable method to fuse the individual laser scans from multiple views of the cadaver knees. Unfortunately existing methods using Iterative Closest Point (ICP) algorithm from off-the-shell packages often yield unreliable fusion results. We identify two major <span class="hlt">sources</span> of variation: (i) the noise in depth measurements of the laser scans is significantly high and (ii) the use of point-to-point correspondence in ICP is not suitable due to sampling variation in the laser scans. We resolve the first problem by performing adaptive Gaussian smoothing on each individual laser scans prior to the fusion. For the second problem, we construct a surface mesh from the point cloud of each scan and adopt a point-to-mesh ICP scheme for pairwise alignment. The complete surface mesh is constructed by fusing all the scans in the order maximizing mutual overlaps. In experiments on 6 repeated scanning trials of a cadaver knee, our approach reduced the alignment error of point-to-point ICP by 30% and reduced coefficient of variation (CV) of cartilage thickness measurements from 5% down to 1.4%, significantly improving the method's repeatability.</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>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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5543376','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5543376"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Creation for Complex Clinical NLP Tasks – an Iterative Vetting Approach and Lessons Learned</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liang, Jennifer J.; Tsou, Ching-Huei; Devarakonda, Murthy V.</p> <p>2017-01-01</p> <p>Natural language processing (NLP) holds the promise of effectively analyzing patient record data to reduce cognitive load on physicians and clinicians in patient care, clinical research, and hospital operations management. A critical need in developing such methods is the “ground truth” dataset needed for training and testing the algorithms. Beyond localizable, relatively simple tasks, <span class="hlt">ground</span> <span class="hlt">truth</span> creation is a significant challenge because medical experts, just as physicians in patient care, have to assimilate vast amounts of data in EHR systems. To mitigate potential inaccuracies of the cognitive challenges, we present an iterative vetting approach for creating the <span class="hlt">ground</span> <span class="hlt">truth</span> for complex NLP tasks. In this paper, we present the methodology, and report on its use for an automated problem list generation task, its effect on the <span class="hlt">ground</span> <span class="hlt">truth</span> quality and system accuracy, and lessons learned from the effort. PMID:28815130</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>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('http://hdl.handle.net/2060/19720014718','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720014718"><span>Microwave radiometric studies and <span class="hlt">ground</span> <span class="hlt">truth</span> measurements of the NASA/USGS Southern California test site</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Edgerton, A. T.; Trexler, D. T.; Sakamoto, S.; Jenkins, J. E.</p> <p>1969-01-01</p> <p>The field measurement program conducted at the NASA/USGS Southern California Test Site is discussed. <span class="hlt">Ground</span> <span class="hlt">truth</span> data and multifrequency microwave brightness data were acquired by a mobile field laboratory operating in conjunction with airborne instruments. The ground based investigations were performed at a number of locales representing a variety of terrains including open desert, cultivated fields, barren fields, portions of the San Andreas Fault Zone, and the Salton Sea. The measurements acquired <span class="hlt">ground</span> <span class="hlt">truth</span> data and microwave brightness data at wavelengths of 0.8 cm, 2.2 cm, and 21 cm.</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('https://ntrs.nasa.gov/search.jsp?R=20060038023&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTruth%2BRadicality','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060038023&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DTruth%2BRadicality"><span>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.osti.gov/scitech/biblio/973116','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/973116"><span>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>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>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>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>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/2005SPIE.5794.1030P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005SPIE.5794.1030P"><span>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/2060/19790015305','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790015305"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/28829321','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28829321"><span>Designing of <span class="hlt">Ground</span> <span class="hlt">Truth</span> Annotated DBT-TU-JU Breast Thermogram Database towards Early Abnormality Prediction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bhowmik, Mrinal Kanti; Gogoi, Usha Rani; Majumdar, Gautam; Bhattacharjee, Debotosh; Datta, Dhritiman; Ghosh, Anjan Kumar</p> <p>2017-08-17</p> <p>The advancement of research in a specific area of clinical diagnosis crucially depends on the availability and quality of the radiology and other test related databases accompanied by <span class="hlt">ground</span> <span class="hlt">truth</span> and additional necessary medical findings. The paper describes the creation of the Department of Biotechnology-Tripura University-Jadavpur University (DBT-TU-JU) breast thermogram database. The objective of creating the DBT-TU-JU database is to provide a breast thermogram database that is annotated with the <span class="hlt">ground</span> <span class="hlt">truth</span> images of the suspicious regions. Along with the result of breast thermography, the database comprises of the results of other breast imaging methodologies. A standard breast thermogram acquisition protocol suite comprising of several critical factors has been designed for the collection of breast thermograms. Currently, the DBT-TU-JU database contains 1100 breast thermograms of 100 subjects. Due to the necessity of evaluating any breast abnormality detection system, this study emphasizes the generation of the <span class="hlt">ground</span> <span class="hlt">truth</span> images of the hotspot areas, whose presence in a breast thermogram signifies the presence of breast abnormality. With the generated <span class="hlt">ground</span> <span class="hlt">truth</span> images, we compared the results of six state-of-the-art image segmentation methods using five supervised evaluation metrics to identify the proficient segmentation methods for hotspot extraction. Based on the evaluation results, the Fractional-Order Darwinian particle swarm optimization, Region growing, Mean shift and Fuzzy c-means clustering are found to be more efficient in comparison to k-means clustering and Threshold based segmentation methods.</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>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://hdl.handle.net/2060/19740011846','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740011846"><span>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/2016EGUGA..1813473M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813473M"><span><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://adsabs.harvard.edu/abs/2017GeoJI.210.1105C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.210.1105C"><span>Assessing the detection capability of a dense <span class="hlt">infrasound</span> network in the southern Korean Peninsula</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; Le Pichon, Alexis; Kim, Kwangsu; Shin, In-Cheol</p> <p>2017-08-01</p> <p>The Korea <span class="hlt">Infrasound</span> Network (KIN) is a dense seismoacoustic array network consisting of eight small-aperture arrays with an average interarray spacing of ∼100 km. The processing of the KIN historical recordings over 10 yr in the 0.05-5 Hz frequency band shows that the dominant <span class="hlt">sources</span> of signals are microbaroms and human activities. The number of detections correlates well with the seasonal and daily variability of the stratospheric wind dynamics. The quantification of the spatiotemporal variability of the KIN detection performance is simulated using a frequency-dependent semi-empirical propagation modelling technique. The average detection thresholds predicted for the region of interest by using both the KIN arrays and the International Monitoring System (IMS) <span class="hlt">infrasound</span> station network at a given frequency of 1.6 Hz are estimated to be 5.6 and 10.0 Pa for two- and three-station coverage, respectively, which was about three times lower than the thresholds predicted by using only the IMS stations. The network performance is significantly enhanced from May to August, with detection thresholds being one order of magnitude lower than the rest of the year due to prevailing steady stratospheric winds. To validate the simulations, the amplitudes of <span class="hlt">ground-truth</span> repeated surface mining explosions at an open-pit limestone mine were measured over a 19-month period. Focusing on the spatiotemporal variability of the stratospheric winds which control to first order where <span class="hlt">infrasound</span> signals are expected to be detected, the predicted detectable signal amplitude at the mine and the detection capability at one KIN array located at a distance of 175 km are found to be in good agreement with the observations from the measurement campaign. The detection threshold in summer is ∼2 Pa and increases up to ∼300 Pa in winter. Compared with the low and stable thresholds in summer, the high temporal variability of the KIN performance is well predicted throughout the year. Simulations</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>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><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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B11J..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B11J..02D"><span>High-Resolution Precipitation Mapping in a Mountainous Watershed: <span class="hlt">Ground</span> <span class="hlt">Truth</span> for Evaluating Uncertainty in a National Precipitation Dataset</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daly, C.; Slater, M. E.; Roberti, J. A.; Laseter, S. H.; Swift, L. W.</p> <p>2016-12-01</p> <p>A 69-station, densely-spaced rain gauge network was maintained over the period 1951-1958 in the Coweeta Hydrologic Laboratory, located in the southern Appalachians in western North Carolina, USA. This unique dataset was used to develop the first digital seasonal and annual precipitation maps for the Coweeta basin, using elevation regression functions and residual interpolation. It was found that a 10-m elevation grid filtered to an approximately 7-km effective wavelength explained the most variance in precipitation (R2 = 0.82-0.95). A "dump zone" of locally high precipitation a short distance downwind from the mountain crest marking the southern border of the basin was the main feature that was not explained well by the precipitation-elevation relationship. These data and maps provided a rare "<span class="hlt">ground-truth</span>" for estimating uncertainty in the national-scale Parameter-elevation Relationships on Independent Slopes Model (PRISM) precipitation grids for this location and time period. Differences between PRISM and <span class="hlt">ground-truth</span> were compared to uncertainty estimates produced by the PRISM model and cross-validation errors. Potential <span class="hlt">sources</span> of uncertainty in the national PRISM grids were evaluated, including the effects of coarse grid resolution, limited station data, and imprecise station locations. The PRISM national grids matched closely (within five percent) with the Coweeta dataset. The PRISM regression prediction interval, which includes the influence of stations in an area of tens of km around a given location, overestimated the local error at Coweeta (12-20 percent). Offsetting biases and generally low error rates made it difficult to isolate major <span class="hlt">sources</span> of uncertainty in the PRISM grids. However, station density and selection, and mis-location of stations were identified as likely <span class="hlt">sources</span> of error. The methods used in this study can be repeated in other areas where high-density data exist to gain a more comprehensive picture of the uncertainties in national</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>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>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://www.dtic.mil/docs/citations/ADA569455','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569455"><span>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="http://www.dtic.mil/">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('http://www.dtic.mil/docs/citations/ADA505417','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA505417"><span>Multiple-Array Detection, Association and Location of <span class="hlt">Infrasound</span> and Seismo-Acoustic Events - Utilization of <span class="hlt">Ground-Truth</span> Information</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2009-09-30</p> <p>2009 Monitoring Research Review 23 September 2009, Tucson, AZ, Volume VI pp 706 - 713. Ground-Based Nuclear Explosion Monitoring Technologies , 21 14...Prescribed by ANSI Std. 239.18 o o 2009 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies MULTIPLE-ARRAY DETECTION...Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies OBJECTIVES There are two primary objectives to our effort on the</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://adsabs.harvard.edu/abs/2011AGUFM.A31A0033M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0033M"><span>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('https://ntrs.nasa.gov/search.jsp?R=19980201635&hterms=sampling+methods&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsampling%2Bmethods','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19980201635&hterms=sampling+methods&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsampling%2Bmethods"><span>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://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>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('http://adsabs.harvard.edu/abs/2006AIPC..852...51P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AIPC..852...51P"><span>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('http://www.osti.gov/scitech/servlets/purl/805806','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/805806"><span>Comparison of MTI Water Temperatures with <span class="hlt">Ground</span> <span class="hlt">Truth</span> Measurements at Crater Lake, OR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kurzeja, R.J.</p> <p>2002-12-09</p> <p>Water surface temperatures calculated with the Los Alamos National Laboratory Robust algorithm were compared with <span class="hlt">ground</span> <span class="hlt">truth</span> water temperature measurements near the Oregon State University buoy in Crater Lake, OR. Bulk water measurements at the OSU buoy were corrected for the skin temperature depression and temperature gradient in the top 10 cm of the water to find the water surface temperature for 18 MTI images for June 2000 to Feb 2002. The MTI robust temperatures were found to be biased by 0.1C, with an RMS error of 1.9C compared with the <span class="hlt">ground</span> <span class="hlt">truth</span> water surface temperatures. When corrected for the errors in the buoy temperatures the RMS was reduced to 1.3C. This RMS difference is greater than the 1C found at the Pacific Island of Nauru because of the greater variability in the lake temperature and the atmosphere at Crater Lake and the much smaller target area used in the comparison.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/28350382','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28350382"><span>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>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/2017NatSD...470034C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatSD...470034C"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Canessa, Andrea; Gibaldi, Agostino; Chessa, Manuela; Fato, Marco; Solari, Fabio; Sabatini, Silvio P.</p> <p>2017-03-01</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.</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>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>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/2016JVGR..327..585J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..327..585J"><span><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><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=Geographic+information+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGeographic%2Binformation%2Bsystems','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930020045&hterms=Geographic+information+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGeographic%2Binformation%2Bsystems"><span>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('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>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://www.osti.gov/scitech/servlets/purl/656739','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/656739"><span>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, R.P.; McDonald, T.S.</p> <p>1998-08-01</p> <p>Sandia is evaluating the performance of various <span class="hlt">infrasound</span> sensors that could be used as part of the International Monitoring Systems (IMS). Specifications for <span class="hlt">infrasound</span> stations are outlined in CTBT/PC/II/1/Add.2. This document specifies minimum requirements for sensor, digitizer and system. The <span class="hlt">infrasound</span> sensors evaluation task has the following objectives: provide an overview of the sensors presently in use; evaluate these sensors with respect to the requirements of the IMS.</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>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>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/2010EGUGA..12.8465L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8465L"><span>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('http://adsabs.harvard.edu/abs/2016EGUGA..1813340P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813340P"><span>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> </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('https://www.ncbi.nlm.nih.gov/pubmed/28436849','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28436849"><span>Reverse Classification Accuracy: Predicting Segmentation Performance 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>Valindria, Vanya V; Lavdas, Ioannis; Bai, Wenjia; Kamnitsas, Konstantinos; Aboagye, Eric O; Rockall, Andrea G; Rueckert, Daniel; Glocker, Ben</p> <p>2017-08-01</p> <p>When integrating computational tools, such as automatic segmentation, into clinical practice, it is of utmost importance to be able to assess the level of accuracy on new data and, in particular, to detect when an automatic method fails. However, this is difficult to achieve due to the absence of <span class="hlt">ground</span> <span class="hlt">truth</span>. Segmentation accuracy on clinical data might be different from what is found through cross validation, because validation data are often used during incremental method development, which can lead to overfitting and unrealistic performance expectations. Before deployment, performance is quantified using different metrics, for which the predicted segmentation is compared with a reference segmentation, often obtained manually by an expert. But little is known about the real performance after deployment when a reference is unavailable. In this paper, we introduce the concept of reverse classification accuracy (RCA) as a framework for predicting the performance of a segmentation method on new data. In RCA, we take the predicted segmentation from a new image to train a reverse classifier, which is evaluated on a set of reference images with available <span class="hlt">ground</span> <span class="hlt">truth</span>. The hypothesis is that if the predicted segmentation is of good quality, then the reverse classifier will perform well on at least some of the reference images. We validate our approach on multi-organ segmentation with different classifiers and segmentation methods. Our results indicate that it is indeed possible to predict the quality of individual segmentations, in the absence of <span class="hlt">ground</span> <span class="hlt">truth</span>. Thus, RCA is ideal for integration into automatic processing pipelines in clinical routine and as a part of large-scale image analysis studies.</p> </li> <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><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>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('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>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> <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>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>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('http://hdl.handle.net/2060/19760021545','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760021545"><span>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=19890045478&hterms=bureau+meteorology+rainfall&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbureau%2Bmeteorology%2Brainfall','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890045478&hterms=bureau+meteorology+rainfall&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbureau%2Bmeteorology%2Brainfall"><span>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://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>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://ntrs.nasa.gov/search.jsp?R=19920073185&hterms=Environmental+science&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEnvironmental%2Bscience','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920073185&hterms=Environmental+science&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DEnvironmental%2Bscience"><span><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('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><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('https://www.ncbi.nlm.nih.gov/pubmed/26988710','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26988710"><span>Modified <span class="hlt">ground-truthing</span>: an accurate and cost-effective food environment validation method for town and rural areas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Caspi, Caitlin Eicher; Friebur, Robin</p> <p>2016-03-17</p> <p>A major concern in food environment research is the lack of accuracy in commercial business listings of food stores, which are convenient and commonly used. Accuracy concerns may be particularly pronounced in rural areas. <span class="hlt">Ground-truthing</span> or on-site verification has been deemed the necessary standard to validate business listings, but researchers perceive this process to be costly and time-consuming. This study calculated the accuracy and cost of <span class="hlt">ground-truthing</span> three town/rural areas in Minnesota, USA (an area of 564 miles, or 908 km), and simulated a modified validation process to increase efficiency without comprising accuracy. For traditional <span class="hlt">ground-truthing</span>, all streets in the study area were driven, while the route and geographic coordinates of food stores were recorded. The process required 1510 miles (2430 km) of driving and 114 staff hours. The <span class="hlt">ground-truthed</span> list of stores was compared with commercial business listings, which had an average positive predictive value (PPV) of 0.57 and sensitivity of 0.62 across the three sites. Using observations from the field, a modified process was proposed in which only the streets located within central commercial clusters (the 1/8 mile or 200 m buffer around any cluster of 2 stores) would be validated. Modified <span class="hlt">ground-truthing</span> would have yielded an estimated PPV of 1.00 and sensitivity of 0.95, and would have resulted in a reduction in approximately 88 % of the mileage costs. We conclude that <span class="hlt">ground-truthing</span> is necessary in town/rural settings. The modified <span class="hlt">ground-truthing</span> process, with excellent accuracy at a fraction of the costs, suggests a new standard and warrants further evaluation.</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>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/2016AGUFM.S11C2469M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S11C2469M"><span>Reanalysis of large <span class="hlt">infrasound</span> datasets with FLOWS</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.; Millet, C.; Bertin, M.; Vergoz, J.</p> <p>2016-12-01</p> <p>While long-range <span class="hlt">infrasound</span> propagation modeling is a useful tool in geophysics and nuclear treaty verification, the inherent unpredictability of subgrid-scale atmosphere dynamics results in a poorly constrained propagation medium and a large number of length scales. When faced with such a situation it is natural to treat incomplete knowledge within a probabilistic framework and to seek a numerical approach that describes long-range propagation at the lowest numerical cost and complexity. Such a task is rendered complex by the fact that each plausible atmospheric state produces large deviations from the operational numerical weather predictions. In this work, we pursue a new approach, in which propagation modeling is based on reduced-order models provided by the numerical platform FLOWS (Fast Low-Order Wave Simulation). The reduced models are obtained by retaining a few propagating modes, with the aim of simplifying the acoustic model to the point that the predicted statistics/sensitivities of signals are correct. In the atmosphere, these modes are confined within waveguides causing the sound to propagate through multiple paths to the receiver. FLOWS performance is demonstrated using several <span class="hlt">ground</span> <span class="hlt">truth</span> events registered by the International Monitoring System (IMS). By examining how the uncertainty manifests statistically within the waveforms, we will show how we can update the numerically obtained signals from a sequence of reduced models and how we can decide from modeling whether a recorded signal is plausible or not. In time, the use of FLOWS in combination with a bayesian approach should help the global <span class="hlt">infrasound</span> association process.</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><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('https://www.ncbi.nlm.nih.gov/pubmed/28950802','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28950802"><span>We get the algorithms of our <span class="hlt">ground</span> <span class="hlt">truths</span>: Designing referential databases in digital image processing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaton, Florian</p> <p>2017-09-01</p> <p>This article documents the practical efforts of a group of scientists designing an image-processing algorithm for saliency detection. By following the actors of this computer science project, the article shows that the problems often considered to be the starting points of computational models are in fact provisional results of time-consuming, collective and highly material processes that engage habits, desires, skills and values. In the project being studied, problematization processes lead to the constitution of referential databases called '<span class="hlt">ground</span> <span class="hlt">truths</span>' that enable both the effective shaping of algorithms and the evaluation of their performances. Working as important common touchstones for research communities in image processing, the <span class="hlt">ground</span> <span class="hlt">truths</span> are inherited from prior problematization processes and may be imparted to subsequent ones. The ethnographic results of this study suggest two complementary analytical perspectives on algorithms: (1) an 'axiomatic' perspective that understands algorithms as sets of instructions designed to solve given problems computationally in the best possible way, and (2) a 'problem-oriented' perspective that understands algorithms as sets of instructions designed to computationally retrieve outputs designed and designated during specific problematization processes. If the axiomatic perspective on algorithms puts the emphasis on the numerical transformations of inputs into outputs, the problem-oriented perspective puts the emphasis on the definition of both inputs and outputs.</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>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://www.osti.gov/scitech/servlets/purl/805807','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/805807"><span>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/2016SPIE.9786E..22S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9786E..22S"><span>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/2012AGUFM.A52A..04Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A52A..04Q"><span><span class="hlt">Infrasound</span> characterization of some Yellowstone geysers' eruptions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quezada-Reyes, A.; Johnson, J.</p> <p>2012-12-01</p> <p>Geysers are springs that intermittently erupt hot water and steam. As with volcanoes, infrasonic airwaves produced by different geysers provide information about the processes that occur near the nozzle, such as the amount of fluid released during eruptive episodes. The aim of this study was to investigate acoustic <span class="hlt">sources</span> from different geyser behaviors observed at Lone Star, Sawmill and Great Fountain geysers, Yellowstone National Park, Wyoming. Acoustic signal were measured by arrays of microphones deployed around Lone Star and Great Fountain geysers between August 9th to 14th, 2011, and during one hour on August 16th, 2011 at Sawmill Geyser. <span class="hlt">Infrasound</span> was analyzed with coincident video recordings to quantify and compare the pressure fields generated during explosive phases at the three geysers. We propose that the periodic <span class="hlt">infrasound</span> recorded at Sawmill, and dominated by energy at 1 to 40 Hz, is generated by: 1) steam-filled bubble oscillations, and 2) subsequent bursting at the free surface resulting in a violent steam and water discharge. At Lone Star geyser, where ~18 m/s eruption jets endure for about 30 minutes, sound is dominated by higher frequency <span class="hlt">infrasound</span> and audio-band signal evolving from 20 - 60 Hz to 40 - 85 Hz. We suggest that the <span class="hlt">infrasound</span> tremor amplitudes are related to the transition of the erupted two-phase mixture from mostly water (low acoustic radiation) to steam (high acoustic radiation). At Great Fountain we observed three explosive bursts of water and steam during the last stage on the August 11 eruption with bi-modal <span class="hlt">infrasound</span> pulses of up to 0.7 Pa-m. We model these pulses as volumetric sound <span class="hlt">sources</span> and infer up to 32 m3 of fluid ejection. The variety of recordings reflect the variety of eruption mechanisms at the different geyser systems. Better understanding of the mechanisms of geyser <span class="hlt">infrasound</span> radiation may help us to understand <span class="hlt">infrasound</span> analogues at erupting silicic volcanoes, which are considerably more difficult 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_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('http://adsabs.harvard.edu/abs/2013JGRE..118..369I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRE..118..369I"><span>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('http://adsabs.harvard.edu/abs/2014AGUFM.S41B4490W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S41B4490W"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/27830168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27830168"><span>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/2015PApGe.172.1397Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PApGe.172.1397Z"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Location of Earthquakes by Use of Ambient Seismic Noise From a Sparse Seismic Network: A Case Study in Western Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeng, Xiangfang; Xie, Jun; Ni, Sidao</p> <p>2015-06-01</p> <p>The estimated Green's function (EGF) extracted from the ambient seismic noise cross-correlation function (NCF) enables valuable calibration of surface wave propagation along the path connecting seismic stations. Such calibration is adopted in a new method for <span class="hlt">ground</span> <span class="hlt">truth</span> location of earthquakes, achieved from the location relative to a seismic station. The surface wave group travel times were obtained from the NCFs between a station near the earthquake and remote stations. The differential travel times from the NCFs and the surface wave of the earthquake were used in a relative location procedure. When this method was applied to earthquake location with only six seismic stations in western Australia, the location of the Mw 4.1 Kalannie (September 21, 2005) earthquake was found to be accurate to within 2 km compared with the <span class="hlt">ground</span> <span class="hlt">truth</span> location with InSAR for which azimuth coverage of seismic stations is preferable. Synthetic tests suggest that the group travel time is slightly affected by focal mechanism and focal depth, thus unknown earthquake <span class="hlt">source</span> parameters did not introduce substantial bias to earthquake location with the group travel time method.</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>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/2017CSR...138...65B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CSR...138...65B"><span>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/2012PhDT.......217A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT.......217A"><span><span class="hlt">Infrasound</span> as upper atmospheric monitor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Assink, Jelle D.</p> <p></p> <p>Understanding and specification of the higher altitudes of the atmosphere with global coverage over all local times is hampered by the challenges of obtaining direct measurements in the upper atmosphere. Methods to measure the properties of the atmosphere above the stratopause is an active area of scientific research. In this thesis, we revisit the use of <span class="hlt">infrasound</span> as a passive remote sensing technique for the upper atmosphere. Signals from the Tungurahua volcano in Ecuador are used to investigate the behavior of the upper atmosphere. Depending on the atmospheric conditions, stratospheric, mesospheric and thermospheric arrivals are observed during intervals of explosive volcanic activity. It is found that the travel times and dominant frequencies of the thermospheric arrivals exhibit a coherent variability with periods equal to those of the tidal harmonics. Theoretical predictions using atmospheric specifications show that the stratospheric arrivals are predicted within 1% of the observed value. For thermospheric arrivals, this error can be as high as 10%. The error in thermospheric celerities is found to be in accord with the typical uncertainty in upper atmospheric winds. Given the observed response of the <span class="hlt">infrasound</span> celerities to upper atmospheric tidal variability, it is suggested that <span class="hlt">infrasound</span> observations may be used as an additional <span class="hlt">source</span> of information to constrain the atmospheric specifications in the upper atmosphere. We present corrected wind profiles that have been obtained by minimizing misfits in traveltime and <span class="hlt">source</span> location using a Bayesian statistics grid search algorithm. Also, a Levenberg-Marquardt search algorithm is developed. Additionally, a new numerical method has been developed to solve the problem of <span class="hlt">infrasound</span> propagation in a stratified medium with (high Mach number) background flow, based on a modal expansion. The underlying mathematics is by no means new and has been earlier described. This solution goes beyond the effective sound</p> </li> <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>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('http://hdl.handle.net/2060/20160008877','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160008877"><span>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=19900043102&hterms=rain+Gauge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drain%2BGauge','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900043102&hterms=rain+Gauge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drain%2BGauge"><span>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('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>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('https://www.ncbi.nlm.nih.gov/pubmed/26930629','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26930629"><span>Validation of neural spike sorting algorithms without <span class="hlt">ground-truth</span> information.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barnett, Alex H; Magland, Jeremy F; Greengard, Leslie F</p> <p>2016-05-01</p> <p>The throughput of electrophysiological recording is growing rapidly, allowing thousands of simultaneous channels, and there is a growing variety of spike sorting algorithms designed to extract neural firing events from such data. This creates an urgent need for standardized, automatic evaluation of the quality of neural units output by such algorithms. We introduce a suite of validation metrics that assess the credibility of a given automatic spike sorting algorithm applied to a given dataset. By rerunning the spike sorter two or more times, the metrics measure stability under various perturbations consistent with variations in the data itself, making no assumptions about the internal workings of the algorithm, and minimal assumptions about the noise. We illustrate the new metrics on standard sorting algorithms applied to both in vivo and ex vivo recordings, including a time series with overlapping spikes. We compare the metrics to existing quality measures, and to <span class="hlt">ground-truth</span> accuracy in simulated time series. We provide a software implementation. Metrics have until now relied on <span class="hlt">ground-truth</span>, simulated data, internal algorithm variables (e.g. cluster separation), or refractory violations. By contrast, by standardizing the interface, our metrics assess the reliability of any automatic algorithm without reference to internal variables (e.g. feature space) or physiological criteria. Stability is a prerequisite for reproducibility of results. Such metrics could reduce the significant human labor currently spent on validation, and should form an essential part of large-scale automated spike sorting and systematic benchmarking of algorithms. Copyright © 2016 Elsevier B.V. All rights reserved.</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>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('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><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://ntrs.nasa.gov/search.jsp?R=19950002611&hterms=wieneke&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwieneke','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950002611&hterms=wieneke&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dwieneke"><span><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('http://adsabs.harvard.edu/abs/2013EGUGA..15.4411L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4411L"><span><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/2003AGUFM.U32B..03E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.U32B..03E"><span>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><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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S11C2475D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S11C2475D"><span>Improving <span class="hlt">Infrasound</span> Signal Detection and Event Location in the Western US Using Atmospheric Modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dannemann, F. K.; Park, J.; Marcillo, O. E.; Blom, P. S.; Stump, B. W.; Hayward, C.</p> <p>2016-12-01</p> <p>Data from five <span class="hlt">infrasound</span> arrays in the western US jointly operated by University of Utah Seismograph Station and Southern Methodist University are used to test a database-centric processing pipeline, InfraPy, for automated event detection, association and location. Infrasonic array data from a one-year time period (January 1 2012 to December 31 2012) are used. This study focuses on the identification and location of 53 <span class="hlt">ground-truth</span> verified events produced from near surface military explosions at the Utah Test and Training Range (UTTR). Signals are detected using an adaptive F-detector, which accounts for correlated and uncorrelated time-varying noise in order to reduce false detections due to the presence of coherent noise. Variations in detection azimuth and correlation are found to be consistent with seasonal changes in atmospheric winds. The Bayesian infrasonic <span class="hlt">source</span> location (BISL) method is used to produce <span class="hlt">source</span> location and time credibility contours based on posterior probability density functions. Updates to the previous BISL methodology include the application of celerity range and azimuth deviation distributions in order to accurately account for the spatial and temporal variability of <span class="hlt">infrasound</span> propagation through the atmosphere. These priors are estimated by ray tracing through Ground-to-Space (G2S) atmospheric models as a function of season and time of day using historic atmospheric characterizations from 2007 to 2013. Out of the 53 events, 31 are successfully located using the InfraPy pipeline. Confidence contour areas for maximum a posteriori event locations produce error estimates which are reduced a maximum of 98% and an average of 25% from location estimates utilizing a simple time independent uniform atmosphere. We compare real-time ray tracing results with the statistical atmospheric priors used in this study to examine large time differences between known origin times and estimated origin times that might be due to the misidentification of</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>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> </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://adsabs.harvard.edu/abs/2012EGUGA..1411204M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411204M"><span>Engineering and development projects for the sustainment and enhancement 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>Marty, J.; Martysevich, P.; Kramer, A.; Haralabus, G.</p> <p>2012-04-01</p> <p>The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has a continuous interest in enhancing its capability in <span class="hlt">infrasound</span> <span class="hlt">source</span> localization and characterization. This capability is based on the processing of data recorded by the <span class="hlt">infrasound</span> network of the International Monitoring System (IMS). This <span class="hlt">infrasound</span> network consists of sixty stations, among which forty-five are already certified and continuously transmit data to the International Data Center (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. It is the responsibility of the Engineering and Development Section of the IMS Division to ensure the highest quality for IMS <span class="hlt">infrasound</span> data. This includes the design of robust and reliable <span class="hlt">infrasound</span> stations, the use of accurate and calibrated <span class="hlt">infrasound</span> measuring chains, the installation of efficient wind noise reduction systems and the implementation of quality-control tools. The purpose of this paper is to present ongoing PTS <span class="hlt">infrasound</span> engineering and development projects related to the testing and validation of wind noise reduction system models, the implementation of <span class="hlt">infrasound</span> data QC tools, the definition of guidelines for the design of IMS power supply systems and the development of a portable <span class="hlt">infrasound</span> calibrator and of field kits for site survey and certification.</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>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://adsabs.harvard.edu/abs/2007PhDT........44G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT........44G"><span><span class="hlt">Infrasound</span> studies and seismic station development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Golden, Paul W.</p> <p></p> <p>A large-scale set of experiments involving measurement of <span class="hlt">infrasound</span> (long period acoustic signals) from high altitude explosions on rockets launched at White Sands Missile Range (WSMR) was conducted during 2005 and 2006. Studies of the <span class="hlt">infrasound</span> signals from the explosions determined that propagation patterns were predictable from climatology data but that the predictions of explosive yield using established period/yield relationships underestimated known yields by about one order of magnitude. In addition, yield estimates did not scale at <span class="hlt">source</span> heights greater than about 40 km indicating some physical change in the atmosphere above these heights that was not included in the scaling relations. A subsequent study to the WSMR experiments motivated by the apparent discrepancies in yield estimation and studies of <span class="hlt">infrasound</span> propagation to distances less than about 250 km was completed. This distance range is traditionally known as the zone of silence where it was believed that no energy would return to the ground surface based on classical ray theory using average atmospheric models. This study supports similar observations by others that documents the presence of signals at these distances and relates them to empirically determined atmospheric models which predict complex and multiple energy returns to the surface. In addition to quantification of these propagation path effects the explosive <span class="hlt">source</span> strength is calibrated using a period-yield scaling relationship originally developed for nuclear explosions on the surface. Significant work conducted by the Geophysics Laboratory at Southern Methodist University since about 1993 focusing on the design, construction, installation and utilization of high performance seismic and <span class="hlt">infrasound</span> regional arrays is documented. These designs have made significant international contributions to the field of regional seismic and <span class="hlt">infrasound</span> monitoring for purposes of characterizing man made activities and in particular, 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>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/2003APS..MAR.H3002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..MAR.H3002B"><span>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>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/2012AGUFM.V33E..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V33E..05K"><span>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/2016AGUOSPC51A..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC51A..02S"><span><span class="hlt">Ground-truthing</span> the Foraminifera-bound Nitrogen Isotope Paleo-proxy in the Modern Sargasso Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smart, S.; Ren, H. A.; Fawcett, S. E.; Conte, M. H.; Rafter, P. A.; Ellis, K. K.; Weigand, M. A.; Sigman, D. M.</p> <p>2016-02-01</p> <p>We present the nitrogen isotope ratios (δ15N) of planktonic foraminifera, a type of calcifying zooplankton, collected from surface ocean net tows, moored sediment traps and core-top sediments at the Bermuda Atlantic Time-series Study site in the Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually averaged δ15N of organic matter bound within the shells of euphotic zone-dwelling foraminifera approximates that of thermocline nitrate, the dominant <span class="hlt">source</span> of new nitrogen to Sargasso Sea surface waters. Based on net tow collections in the upper 200 m of the water column, we observe no systematic difference between the biomass δ15N and shell-bound δ15N of a given foraminifera species. For multiple species, the δ15N of net tow-collected upper ocean shells is lower than shells from sediment traps (by 0.5-2.1‰) and lower than shells from seafloor sediments (by 0.5-1.4‰). We are currently investigating whether these differences reflect actual processes affecting shell-bound δ15N or instead relate to the different time periods over which the three sample types integrate. The foraminiferal biomass δ15N time-series from the surface Sargasso Sea exhibits significant seasonal variations, with the lowest values in fall and the highest values in spring. The roles of hydrography, biogeochemistry, and ecosystem dynamics in driving these seasonal variations will be discussed. These data from the modern subtropical ocean form part of a greater effort to <span class="hlt">ground-truth</span> the use of foram-bound δ15N to reconstruct past nutrient conditions, not only as a recorder of the isotopic composition of nitrogen supply in oligotrophic environments but also as a recorder of the degree of nitrate consumption in high-latitude regions such as the Southern Ocean.</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><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><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/2017P%26SS..143..169G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017P%26SS..143..169G"><span>Refinement of bolide characteristics from <span class="hlt">infrasound</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>Gi, Nayeob; Brown, Peter</p> <p>2017-09-01</p> <p>We have detected and performed signal measurements on 78 individual bolide events as recorded at 179 <span class="hlt">infrasound</span> stations between 2006 and 2015. We compared period-yield relations with AFTAC nuclear period-yield data, finding these to be similar with a slight offset. Scatter in period measurements for individual bolide is found to be caused in part by station noise levels and by attenuation effects with range. No correlation was found between the <span class="hlt">infrasound</span> signal period and any of bolide height at peak brightness, entry speed or impact angle. We examined in detail three well constrained bolides having energy deposition curves, known trajectories and <span class="hlt">infrasound</span> detections finding some evidence at shorter ranges that a component of station period scatter is due to varying <span class="hlt">source</span> heights sampled by different stations. However, for longer-range stations in these three case studies, we were not able to assign unique <span class="hlt">source</span> heights using raytracing due to large uncertainties in atmospheric conditions. Our results suggest that while <span class="hlt">source</span> height contributes to the observed variance in <span class="hlt">infrasound</span> signal periods from a given bolide, range and station noise play a larger role.</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><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/2011SPIE.8018E..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SPIE.8018E..05K"><span><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/752199','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/752199"><span><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://hdl.handle.net/2060/19740021574','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740021574"><span>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('https://ntrs.nasa.gov/search.jsp?R=19950039070&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950039070&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041"><span>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://hdl.handle.net/2060/20160008889','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160008889"><span>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://adsabs.harvard.edu/abs/2015AGUFM.S41B2712F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S41B2712F"><span>Accuracy of Absolute Earthquake Location with Ambient Seismic Noise via <span class="hlt">Ground</span> <span class="hlt">Truth</span> Event Experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, B.</p> <p>2015-12-01</p> <p>The absolute earthquake location with high precision is the key to determine the seismogenic fault. Nonetheless, it is very challenging to achieve high accuracy location in the sparse seismic network. Recently ambient seismic noise has been demonstrated to be able to achieve 2km or better accuracy of earthquake location, using the noise cross-correlation function (NCF) between the stations near the epicenter and distant stations, where similar path between the epicenter and the corresponding station helps to reduce the location error caused by the velocity structure variation. This method is not systematically investigated yet, hence we have installed a portable seismic station around Suining earthquake, a <span class="hlt">ground</span> <span class="hlt">truth</span> event observed by InSAR, and applied the bootstraping method to investigate effects upon location accuracy due to number of stations, epicentral distance of station, azimuthal gap as well as seasonality of observation. Studies have indicated that ambient seismic noise location method can increase positioning accuracy with sparse network, and it is also helpful to study the historical earthquake.</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>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://hdl.handle.net/2060/20060024664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060024664"><span>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> </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://www.osti.gov/scitech/servlets/purl/806536','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/806536"><span>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> <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>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://adsabs.harvard.edu/abs/2016EGUGA..18.2948P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2948P"><span>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://www.dtic.mil/docs/citations/ADA111957','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA111957"><span>Antarctic Atmospheric <span class="hlt">Infrasound</span>.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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('https://www.ncbi.nlm.nih.gov/pubmed/28113570','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28113570"><span>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><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/2013AGUFM.S14A..02D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S14A..02D"><span><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/22894187','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22894187"><span>Nonlinear synthesis of <span class="hlt">infrasound</span> propagation through an inhomogeneous, 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 D</p> <p>2012-08-01</p> <p>An accurate and efficient method to predict <span class="hlt">infrasound</span> amplitudes from large explosions in the atmosphere is required for diverse <span class="hlt">source</span> types, including bolides, volcanic eruptions, and nuclear and chemical explosions. A finite-difference, time-domain approach is developed to solve a set of nonlinear fluid dynamic equations for total pressure, temperature, and density fields rather than acoustic perturbations. Three key features for the purpose of synthesizing nonlinear <span class="hlt">infrasound</span> propagation in realistic media are that it includes gravitational terms, it allows for acoustic absorption, including molecular vibration losses at frequencies well below the molecular vibration frequencies, and the environmental models are constrained to have axial symmetry, allowing a three-dimensional simulation to be reduced to two dimensions. Numerical experiments are performed to assess the algorithm's accuracy and the effect of <span class="hlt">source</span> amplitudes and atmospheric variability on <span class="hlt">infrasound</span> waveforms and shock formation. Results show that <span class="hlt">infrasound</span> waveforms steepen and their associated spectra are shifted to higher frequencies for nonlinear <span class="hlt">sources</span>, leading to enhanced <span class="hlt">infrasound</span> attenuation. Results also indicate that nonlinear <span class="hlt">infrasound</span> amplitudes depend strongly on atmospheric temperature and pressure variations. The solution for total field variables and insertion of gravitational terms also allows for the computation of other disturbances generated by explosions, including gravity waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1022761','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1022761"><span><span class="hlt">Ground</span> <span class="hlt">Truth</span> Events with <span class="hlt">Source</span> Geometry in Eurasia and the Middle East</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-06-02</p> <p>J . M. Kendall, M. A. Kahn, C. M. R . Fowler , S. L. Klemperer, G. R . Keller, S. Harder, T . Furman, K. Mickus, L. Asfaw, A. Ayele, and...Arabian Events 6 Approved for public release; distribution is unlimited. 8 16 24 32 D e p t h ( k m ) 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 1 . 0 0 F it Z R T1...0 T i m e ( s e c ) KBRS Z R T1 . 9 0 x 1 0 - 0 7 0 . 2 553% LNY03 9 . 3 4 x 1 0 - 0 8 - 0 . 5 0 40% LNY01 9 . 7 7 x 1 0 - 0 8 0 . 2 5 81% 7 . 1 6</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.P51D1231B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.P51D1231B"><span>Subsurface Organics in Aseptic Cores From the MARTE Robotic Drilling Experiment: <span class="hlt">Ground</span> <span class="hlt">truth</span> and Contamination Issues</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonaccorsi, R.; Stoker, C. R.</p> <p>2006-12-01</p> <p>The subsurface is the key environment for searching for life on planets lacking surface life. This includes the search for past/present life on Mars where possible subsurface life could exist [1]. The Mars-Analog-Rio-Tinto-Experiment (MARTE) performed a simulation of a Mars robotic drilling at the RT Borehole#7 Site ~6.07m, atop a massive-pyrite deposit from the Iberian Pyritic Belt. The RT site is considered an important analog of Sinus Meridiani on Mars, an ideal model analog for a subsurface Martian setting [2], and a relevant example of deep subsurface microbial community including aerobic and anaerobic chemoautotrophs [4-5]. Searching for microbes or bulk organics of biological origin in a subsurface sample from a planet is a key scientific objective of Robotic drilling missions. During the 2005 Field experiment 28 minicores were robotically handled and subsampled for life detection experiments under anti-contamination protocols. <span class="hlt">Ground</span> <span class="hlt">truth</span> included visual observation of cores and lab based Elemental and Isotope Ratios Mass Spectrometry analysis (EA-IRMS) of bulk organics in Hematite and Gohetite-rich gossanized tuffs, gossan and clay layers within 0-6m-depth. C-org and N-tot vary up to four orders of magnitude among the litter (~11Wt%, 0-1cm) and the mineralized (~3Wt%, 1-3cm) layers, and the first 6 m-depth (C-org=0.02-0.38Wt%). Overall, the distribution/ preservation of plant and soil-derived organics (d13C-org = 26 per mil to 24 per mil) is ten times higher (C-org=0.33Wt%) that in hematite-poor clays, or where rootlets are present, than in hematite- rich samples (C-org=<0.01Wt%). This is consistent with ATP assay (Lightning-MVP, Biocontrol) for total biomass in subsurface (Borehole#7 ~6.07m, ~avg. 153RLU) vs. surface soil samples (~1,500-81,449RLU) [5]. However, the in-situ ATP assay failed in detecting presence of roots during the in-situ life detection experiment. Furthermore, cm-sized roots were overlooked during remote observations. Finally, ATP</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>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('http://adsabs.harvard.edu/abs/2015P%26SS..119..194O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..119..194O"><span>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>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/2015HydJ...23..335C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015HydJ...23..335C"><span><span class="hlt">Ground</span> <span class="hlt">truthing</span> groundwater-recharge estimates derived from remotely sensed evapotranspiration: a case in South Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crosbie, Russell S.; Davies, Phil; Harrington, Nikki; Lamontagne, Sebastien</p> <p>2015-03-01</p> <p>Using a water balance to estimate groundwater recharge through the use of remotely sensed evapotranspiration offers a spatial and temporal density of data that other techniques cannot match. However, the estimates are uncertain and therefore <span class="hlt">ground</span> <span class="hlt">truthing</span> of the recharge estimates is necessary. This study, conducted in the south-east of South Australia, demonstrated that the raw water-balance estimates of recharge had a negative bias of 45 mm/yr when compared to 190 recharge estimates using the water-table fluctuation method over a 10-year period (2001-2010). As this bias was not related to the magnitude of the recharge estimated using the water-table fluctuation method, a simple offset was used to bias-correct the water-balance recharge estimates. The bias-corrected recharge estimates had a mean residual that was not significantly different from an independent set of 99 historical recharge estimates but did have a large mean absolute residual indicating a lack of precision. The value in this technique is the density of the data (250-m grid over 29,000 km2). The relationship between the water-table depth and net recharge under different vegetation types was investigated. Under pastures, there was no relationship with water-table depth, as the shallow roots do not intercept groundwater. However, under plantation forestry, there was a relationship between net recharge and water-table depth. Net recharge under plantation forestry growing on sandy soils was independent of the water table at around 6 m depth but, under heavier textured soils, the trees were using groundwater from depths of more than 20 m.</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><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/2016JGRD..121...95S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121...95S"><span>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://adsabs.harvard.edu/abs/2015EGUGA..1714122A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714122A"><span><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/2006GeoRL..33.5611G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..33.5611G"><span><span class="hlt">Infrasound</span> from large surf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garcés, M.; Aucan, J.; Fee, D.; Caron, P.; Merrifield, M.; Gibson, R.; Bhattacharyya, J.; Shah, S.</p> <p>2006-03-01</p> <p>Simultaneous infrasonic, visual, and ocean-bottom pressure sensor observations of large swells on the island of Kauai and small to medium-sized surf on the island of Hawaii yielded a clear relationship between breaking wave height and low-frequency atmospheric sound amplitudes in the 1-20 Hz frequency range. These experiments confirmed that <span class="hlt">infrasound</span> can be generated by barreling waves as well as by waves crashing against rocky shorelines and exposed ledges. As will be demonstrated in a companion paper, breaking wave period may also be extracted from <span class="hlt">infrasound</span> data. The results of these experiments demonstrate that low-frequency sound may be used for real-time estimates of the amplitude, period, and spatial distribution of surf in the littoral zone, with a potential application to the identification of breaking wave types.</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>Antarctic Atmospheric <span class="hlt">Infrasound</span>.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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://www.osti.gov/scitech/servlets/purl/296585','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/296585"><span>BBN technical memorandum W1291 <span class="hlt">infrasound</span> model feasibility study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Farrell, T., BBN Systems and Technologies</p> <p>1998-05-01</p> <p>The purpose of this study is to determine the need and level of effort required to add existing atmospheric databases and <span class="hlt">infrasound</span> propagation models to the DOE`s Hydroacoustic Coverage Assessment Model (HydroCAM) [1,2]. The rationale for the study is that the performance of the <span class="hlt">infrasound</span> monitoring network will be an important factor for both the International Monitoring System (IMS) and US national monitoring capability. Many of the technical issues affecting the design and performance of the <span class="hlt">infrasound</span> network are directly related to the variability of the atmosphere and the corresponding uncertainties in <span class="hlt">infrasound</span> propagation. It is clear that the study of these issues will be enhanced by the availability of software tools for easy manipulation and interfacing of various atmospheric databases and <span class="hlt">infrasound</span> propagation models. In addition, since there are many similarities between propagation in the oceans and in the atmosphere, it is anticipated that much of the software infrastructure developed for hydroacoustic database manipulation and propagation modeling in HydroCAM will be directly extendible to an <span class="hlt">infrasound</span> capability. The study approach was to talk to the acknowledged domain experts in the <span class="hlt">infrasound</span> monitoring area to determine: 1. The major technical issues affecting <span class="hlt">infrasound</span> monitoring network performance. 2. The need for an atmospheric database/<span class="hlt">infrasound</span> propagation modeling capability similar to HydroCAM. 3. The state of existing <span class="hlt">infrasound</span> propagation codes and atmospheric databases. 4. A recommended approach for developing the required capabilities. A list of the people who contributed information to this study is provided in Table 1. We also relied on our knowledge of oceanographic and meteorological data <span class="hlt">sources</span> to determine the availability of atmospheric databases and the feasibility of incorporating this information into the existing HydroCAM geographic database software. This report presents a summary of the need for an integrated</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/2012EGUGA..14.7161C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7161C"><span><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://adsabs.harvard.edu/abs/2012AGUFM.P42A..04G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.P42A..04G"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greenhagen, B. T.; Lucey, P. G.; Song, E.; Thomas, I. R.; Bowles, N. E.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.; Allen, C.</p> <p>2012-12-01</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 μm 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. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.U31A0012J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.U31A0012J"><span>LRO Camera Imaging of the Moon: Apollo 17 and other Sites for <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>Jolliff, B. L.; Wiseman, S. M.; Robinson, M. S.; Lawrence, S.; Denevi, B. W.; Bell, J. F.</p> <p>2009-12-01</p> <p>One of the fundamental goals of the Lunar Reconnaissance Orbiter (LRO) is the determination of mineralogic and compositional distributions and their relation to geologic features on the Moon’s surface. Through a combination of imaging with the LRO narrow-angle cameras and wide-angle camera (NAC, WAC), very fine-scale geologic features are resolved with better than meter-per-pixel resolution (NAC) and correlated to spectral variations mapped with the lower resolution, 7-band WAC (400-m/pix, ultraviolet bands centered at 321 and 360 nm; 100-m/pix, visible bands centered at 415, 566, 604, 643, and 689 nm). Keys to understanding spectral variations in terms of composition, and relationships between compositional variations and surface geology, are <span class="hlt">ground-truth</span> sites where surface compositions and mineralogy, as well as geology and geologic history, are well known. The Apollo 17 site is especially useful because the site geology includes a range of features from high-Ti mare basalts to Serenitatis-Basin-related massifs containing basin impact-melt breccia and feldspathic highlands materials, and a regional black and orange pyroclastic deposit. Moreover, relative and absolute ages of these features are known. In addition to rock samples, astronauts collected well-documented soil samples at 22 different sample locations across this diverse area. Many of these sample sites can be located in the multispectral data using the co-registered NAC images. Digital elevation data are used to normalize illumination geometry and thus fully exploit the multispectral data and compare derived compositional parameters for different geologic units. Regolith characteristics that are known in detail from the Apollo 17 samples, such as maturity and petrography of mineral, glass, and lithic components, contribute to spectral variations and are considered in the assessment of spectral variability at the landing site. In this work, we focus on variations associated with the ilmenite content</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>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/2009AGUFM.S34C..04F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S34C..04F"><span><span class="hlt">Infrasound</span> from lightning: characteristics and impact on an <span class="hlt">infrasound</span> station</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farges, T.; Blanc, E.</p> <p>2009-12-01</p> <p>More than two third of the <span class="hlt">infrasound</span> stations of the International Monitoring System (IMS) of the CTBTO are now certified and measure routinely signals due particularly to natural activity (swell, volcano, severe weather including lightning, …). It is well established that more than 2,000 thunderstorms are continuously active all around the world and that about 45 lightning flashes are produced per second over the globe. During the Eurosprite 2005 campaign, we took the opportunity to measure, in France during summer, <span class="hlt">infrasound</span> from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure <span class="hlt">infrasound</span> from lightning when thunderstorms are close or far from the <span class="hlt">infrasound</span> station. Main results concern detection range of <span class="hlt">infrasound</span> from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that <span class="hlt">infrasound</span> from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, <span class="hlt">infrasound</span> from lightning can be detected when thunderstorms are located more than 200 km from the station. No signal is recorded from lightning flashes occurring between 75 and 200 km away from the station, defining then a silence zone. When the thunderstorm is close to the station, the <span class="hlt">infrasound</span> signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. <span class="hlt">Infrasound</span> propagate upward where the highest frequencies are dissipated and can produce a significant heating of the upper mesosphere. Some of these results have been confirmed by case studies with data from the IMS Ivory Coast station. The coverage of the IMS stations is very good to study the thunderstorm activity and its disparity which is a good proxy of the global warming. Progress in data processing for <span class="hlt">infrasound</span> data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.8273F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.8273F"><span><span class="hlt">Infrasound</span> from lightning: characteristics and impact on an <span class="hlt">infrasound</span> station</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; Blanc, Elisabeth</p> <p>2010-05-01</p> <p>More than two third of the <span class="hlt">infrasound</span> stations of the International Monitoring System (IMS) of the CTBTO are now certified and measure routinely signals due particularly to natural activity (swell, volcano, severe weather including lightning, …). It is well established that more than 2,000 thunderstorms are continuously active all around the world and that about 45 lightning flashes are produced per second over the globe. During the Eurosprite 2005 campaign, we took the opportunity to measure, in France during summer, <span class="hlt">infrasound</span> from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure <span class="hlt">infrasound</span> from lightning when thunderstorms are close or far from the <span class="hlt">infrasound</span> station. Main results concern detection range of <span class="hlt">infrasound</span> from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that <span class="hlt">infrasound</span> from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, <span class="hlt">infrasound</span> from lightning can be detected when thunderstorms are located more than 200 km from the station. No signal is recorded from lightning flashes occurring between 75 and 200 km away from the station, defining then a silence zone. When the thunderstorm is close to the station, the <span class="hlt">infrasound</span> signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. <span class="hlt">Infrasound</span> propagate upward where the highest frequencies are dissipated and can produce a significant heating of the upper mesosphere. Some of these results have been confirmed by case studies with data from the IMS Ivory Coast station. The coverage of the IMS stations is very good to study the thunderstorm activity and its disparity which is a good proxy of the global warming. Progress in data processing for <span class="hlt">infrasound</span> data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning</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>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://adsabs.harvard.edu/abs/2006SPIE.6360E..0DH','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SPIE.6360E..0DH"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/28587563','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28587563"><span>How Precise Are Preinterventional Measurements Using Centerline Analysis Applications? Objective <span class="hlt">Ground</span> <span class="hlt">Truth</span> Evaluation Reveals Software-Specific Centerline Characteristics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoegen, Philipp; Wörz, Stefan; Müller-Eschner, Matthias; Geisbüsch, Philipp; Liao, Wei; Rohr, Karl; Schmitt, Matthias; Rengier, Fabian; Kauczor, Hans-Ulrich; von Tengg-Kobligk, Hendrik</p> <p>2017-08-01</p> <p>To evaluate different centerline analysis applications using objective <span class="hlt">ground</span> <span class="hlt">truth</span> from realistic aortic aneurysm phantoms with precisely defined geometry and centerlines to overcome the lack of unknown true dimensions in previously published in vivo validation studies. Three aortic phantoms were created using computer-aided design (CAD) software and a 3-dimensional (3D) printer. Computed tomography angiograms (CTAs) of phantoms and 3 patients were analyzed with 3 clinically approved and 1 research software application. The 3D centerline coordinates, intraluminal diameters, and lengths were validated against CAD <span class="hlt">ground</span> <span class="hlt">truth</span> using a dedicated evaluation software platform. The 3D centerline position mean error ranged from 0.7±0.8 to 2.9±2.5 mm between tested applications. All applications calculated centerlines significantly different from <span class="hlt">ground</span> <span class="hlt">truth</span>. Diameter mean errors varied from 0.5±1.2 to 1.1±1.0 mm among 3 applications, but exceeded 8.0±11.0 mm with one application due to an unsteady distortion of luminal dimensions along the centerline. All tested commercially available software tools systematically underestimated centerline total lengths by -4.6±0.9 mm to -10.4±4.3 mm (maximum error -14.6 mm). Applications with the highest 3D centerline accuracy yielded the most precise diameter and length measurements. One clinically approved application did not provide reproducible centerline-based analysis results, while another approved application showed length errors that might influence stent-graft choice and procedure success. The variety and specific characteristics of endovascular aneurysm repair planning software tools require scientific evaluation and user awareness.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8089D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8089D"><span>Nonlinear Propagation of <span class="hlt">Infrasound</span> from Large Explosions</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, Catherine</p> <p>2015-04-01</p> <p>Atmospheric explosions release immense quantities of <span class="hlt">infrasound</span> energy that can be detected at receivers located from hundreds to thousands of kilometers from the origin. This has led to the deployment of a global 60-station network of micro-barometer arrays to aid in nuclear explosion monitoring. Current methods of estimating the radiated <span class="hlt">source</span> energy from remote recordings of <span class="hlt">infrasound</span> signals use simplified empirical <span class="hlt">source</span>-yield relations that account for stratospheric winds along the <span class="hlt">source</span>-receiver path. These formulations apply only to direct and stratospherically ducted arrivals. More recently, considerable progress has been made in applying numerical modeling techniques to develop more accurate <span class="hlt">source</span>-yield formulations for realistic sound and wind speed profiles. However, these methods assume linear <span class="hlt">infrasound</span> propagation along the travel path even though nonlinear effects - which arise when the amplitude of the acoustic pressure perturbation is a finite fraction of the ambient atmospheric pressure - are known to significantly alter <span class="hlt">infrasound</span> frequencies, velocities and amplitudes, and thus can affect derived <span class="hlt">source</span> yield estimates. For realistic atmospheric profiles, nonlinearity can be significant both in the vicinity of a large explosive <span class="hlt">source</span> as well as at much greater distances. Within the stratosphere, nonlinearity may arise at caustics created by ducting; in the thermosphere, nonlinearity may arise due to very low ambient pressures at high altitudes. In this study, the effects of nonlinearity on <span class="hlt">infrasound</span> signal amplitudes and frequencies are simulated using a nonlinear finite difference, time-domain (FDTD) method. The key features that allow for accurate and efficient nonlinear synthesis of <span class="hlt">infrasound</span> propagation through realistic media are that 1) it includes for atmospheric viscosity, and 2) the environmental models are constrained to have axial symmetry, yielding solutions relevant to a point <span class="hlt">source</span> in a fully 3D model with rotational</p> </li> <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>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/2015AGUFM.B41D0464C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B41D0464C"><span>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>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://adsabs.harvard.edu/abs/2017EGUGA..19.1516K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1516K"><span>Results from a student built balloon-borne <span class="hlt">infrasound</span> sensing instrument</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klein, Viliam; Young, Eliot; Bowman, Daniel; Abernathy, Robert</p> <p>2017-04-01</p> <p>Balloon-borne <span class="hlt">infrasound</span> sensors should have two advantages over ground based counterparts: lack of wind noise, and the potential for <span class="hlt">infrasound</span> concentration in stratospheric ducts. In this paper we present the design and results from a student-built payload for sensing <span class="hlt">infrasound</span> waves (between 0.1Hz to 20Hz) from a NASA stratospheric balloon that reached altitudes of 37km on September 28th of 2016. The SISE (Student <span class="hlt">Infrasound</span> Experiment) uses a unique arrangement of COTS differential pressure sensors and student designed signal conditioning to eliminate noise and sense <span class="hlt">infrasound</span> waves below 20Hz. To calibrate the sensitivity of ground based and balloon-borne sensors, we contracted EMRTC to set off three large explosions from Socorro NM during flight, roughly 200-400 km west of the balloon position at the time of the explosions. The goal of this experiment was to detect the artificially generated <span class="hlt">infrasound</span> waves at altitude despite the lower expected amplitudes. This presentation contains discussions of the overall design for the instrument, laboratory and in flight performance characteristics, as well as in flight observations of <span class="hlt">infrasound</span> generated from the artificial <span class="hlt">sources</span>. The instrument successfully detected <span class="hlt">infrasound</span> waves of about 0.03 Pa at an altitude of 37 kilometers and a distance of 350km from the <span class="hlt">source</span>.</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><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://www.osti.gov/scitech/servlets/purl/10165578','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10165578"><span>Ground motions and the <span class="hlt">infrasound</span> signal: A new model and the discovery of a significant cavity rebound signal. Los Alamos <span class="hlt">Source</span> Region Program</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jones, E.M.; App, F.N.; Whitaker, R.W.</p> <p>1993-03-01</p> <p>A model is presented that relates <span class="hlt">infrasound</span> signals from underground nuclear tests to the peak vertical velocity at surface-ground-zero. For the most part, agreement between the model and observations is good, the exceptions being events conducted in shallow tuff layers in Yucca Flat. These events all have low values of the peak surface velocity. The authors have determined that the lack of agreement for these events is due to an unusual, second spall event. A stress-wave calculation is presented that reproduces the second-spall phenomenon and indicates that it is due to interference of cavity-rebound-associated signal with the initial ballistic motion of the surface layers. The effect of the rebound signal is to increase the amplitude of the <span class="hlt">infrasound</span> signal and thus make low velocity events more detectable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S51D2709I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2709I"><span>Constraining the Spatial and Temporal Variability of Atmospheric Conditions to Explore the <span class="hlt">Infrasound</span> Detection of Volcanic Eruptions in Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iezzi, A. M.; Schwaiger, H. F.; Fee, D.; Haney, M. M.</p> <p>2015-12-01</p> <p>Alaska's over 50 historically active volcanoes span 2,500 kilometers, and their eruptions pose great threats to the aviation industry. This makes both prompt observations of explosion onsets and changes in intensity a necessity. Due to their expansive range and remoteness, these volcanoes are predominantly monitored by local seismic networks, remote observations including satellite imagery and <span class="hlt">infrasound</span> sensors. <span class="hlt">Infrasound</span> is an especially crucial tool in this area because <span class="hlt">infrasound</span> data collection is not obstructed by frequent cloud cover (as in satellite imagery) and <span class="hlt">infrasound</span> waves can travel hundreds to thousands of kilometers. However, <span class="hlt">infrasound</span> station coverage is relatively sparse and strong wind and temperature gradients in the atmosphere create multiple waveguides and shadow zones where the propagation of <span class="hlt">infrasound</span> is enhanced and diminished, respectively. To accurately constrain volcanic <span class="hlt">source</span> information and the long-range propagation of <span class="hlt">infrasound</span> waves, a detailed characterization of the spatial and temporal variability of the atmosphere is vital. These properties can be constrained using a ground-to-space model similar to that of Drob et al. (2003) based upon varied meteorological observations and applied to <span class="hlt">infrasound</span> waves to model the propagation of <span class="hlt">infrasound</span>. Here we present the first results of a re-analysis system constructed by the Alaska Volcano Observatory to accurately characterize and model long-range <span class="hlt">infrasound</span> propagation from volcanic eruptions. We select a number of case studies to examine <span class="hlt">infrasound</span> detections (or lack thereof) from recent eruptions of Alaskan volcanoes, including the November 2014 eruption of Pavlof Volcano and July 2015 eruption of Cleveland Volcano. Detailed examination of the acoustic propagation conditions will provide additional insight into detection capability and eruption dynamics with future work aiming to implement real-time long-range <span class="hlt">infrasound</span> propagation modeling.Drob, Douglas P., J. M. Picone</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><span class="hlt">Infrasound</span> Sensor Calibration and Response</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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>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> </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://hdl.handle.net/2060/19780007606','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780007606"><span>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/2015AGUFM.S51C2690R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51C2690R"><span>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/2060/19790013470','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790013470"><span>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://hdl.handle.net/2060/19800019173','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800019173"><span>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>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://adsabs.harvard.edu/abs/2014AGUFM.V23C4809R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4809R"><span><span class="hlt">Infrasound</span> from Rock Fall at Santiaguito 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>Ronan, T.; Terbush, B.; Miller, A. J. C.; Anderson, J.; Johnson, J. B.</p> <p>2014-12-01</p> <p>Volcanoes generate <span class="hlt">infrasound</span> from incidental rock fall and from rock fall directly associated with eruptions. This study demonstrates that arrays of <span class="hlt">infrasound</span> microphones are capable of surveillance and quantification of rock fall events, including their size, location, velocity and frequency of occurrence. The study performed at Volcan Santiaguito (Guatemala) in January 2014 made use of a three element <span class="hlt">infrasound</span> array with 30 m aperture deployed ~500 m from the active vent and ~300 m from the slide path where numerous rock falls descend. Rock fall events were detected on average 5 to 10 times per hour and were easily distinguishable from vent activity (e.g., explosions) by their dynamic back azimuth projection. As blocks tumbled down the southwest flanks of Santiaguito, <span class="hlt">sources</span> were tracked across an azimuthal range of nearly 30 degrees, consistent with the dome's slope. Back azimuths, determined with a [progressive] multichannel cross correlation technique, are projected to the volcano's steep flanks and are used to precisely locate the <span class="hlt">source</span> of <span class="hlt">infrasound</span> (i.e., rocks impacting on the volcano slopes) and their velocity (10-30 m/s). Typical signals last about one minute and are characterized by cigar-shaped tremor envelopes with a predominance of energy above ~5 Hz this spectral content contrasts with Santiaguito eruption <span class="hlt">infrasound</span>, which is peaked at ~1 Hz. Synchronous video records of the responsible rock fall confirm position and velocity and illustrate that even the smallest rock falls (estimated block size of ~1 m) are capable of producing a traceable signal. This study is a testament to the capabilities of <span class="hlt">infrasound</span> array remote sensing for detecting volcanic unrest in the form of rock fall, which is common at most active silicic domes.</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>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://adsabs.harvard.edu/abs/2016PhDT........67B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT........67B"><span><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.ars.usda.gov/research/publications/publication/?seqNo115=299746','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=299746"><span>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="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</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://www.osti.gov/scitech/servlets/purl/1221711','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1221711"><span>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://adsabs.harvard.edu/abs/2012AGUFM.A53B0147M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A53B0147M"><span>Urban <span class="hlt">Infrasound</span> Observations - Examples from July 4th 2012</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McComas, S.; Hayward, C.; Golden, P.; McKenna, M.; Simpson, C.</p> <p>2012-12-01</p> <p>Historical observations indicate that urban environments are rich in <span class="hlt">infrasound</span> signals and thus provide the opportunity to characterize <span class="hlt">sources</span>, monitor propagation path effects, and document diurnal and seasonal variability in the urban acoustical noise environment. If <span class="hlt">infrasound</span> is to be used as viable signal for monitoring the urban environment and for identifying human and natural activities, the following key scientific issues must be examined: (1) What are the typical infrastructural <span class="hlt">sources</span> of <span class="hlt">infrasound</span> and their levels? (2) How saturated is the urban environment with infrasonic signals, i.e., do many signals propagate over long distances to reach a given sensor, or can individual <span class="hlt">sources</span> be well differentiated? (3) Does <span class="hlt">infrasound</span> provide new information to characterize rapidly evolving physical, cultural, economic, and military actions of interest? Each of these issues will be addressed with the acquisition and analysis of data from this observational study, including an analysis of the seasonal variation in <span class="hlt">infrasound</span> noise and propagation effects. Such studies differ from typical <span class="hlt">infrasound</span> work in that the propagation paths are short, i.e. ~1- 100 km, and signal frequencies can extend from the <span class="hlt">infrasound</span> band to the low frequency acoustic band (100 Hz). We have begun a study to address some of the unique <span class="hlt">infrasound</span> research questions and <span class="hlt">sources</span> found in an urban environment. Our initial investigation of the data and a description of the identified noise and <span class="hlt">source</span> signals are reported here. 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. The first rooftop array, the Moody Coliseum, includes four elements at the corners of a 38m square and one element in the center. A seismometer is included at the central element. The second Multi-rooftop Array is spread across multiple building rooftops and has a 140m aperture. The third array</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>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/2015AGUFM.S51F..04A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51F..04A"><span>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/2013AGUFM.S23B2490P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2490P"><span>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('http://adsabs.harvard.edu/abs/2015JGRE..120..413S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRE..120..413S"><span>Optical observations of meteors generating <span class="hlt">infrasound</span>: Weak shock theory and validation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Silber, Elizabeth A.; Brown, Peter G.; Krzeminski, Zbigniew</p> <p>2015-03-01</p> <p>We have recorded a data set of 24 cm sized meteoroids detected simultaneously by video and <span class="hlt">infrasound</span> to critically examine the ReVelle (1974) weak shock meteor <span class="hlt">infrasound</span> model. We find that the effect of gravity wave perturbations to the wind field and updated absorption coefficients in the linear regime on the initial value of the blast radius (R0), which is the strongly nonlinear zone of shock propagation near the body and corresponds to energy deposition per path length, is relatively small (<10%). Using optical photometry for <span class="hlt">ground</span> <span class="hlt">truth</span> for energy deposition, we find that the ReVelle model accurately predicts blast radii from <span class="hlt">infrasound</span> periods (τ) but systematically underpredicts R0 using pressure amplitude. If the weak shock to linear propagation distortion distance is adjusted as part of the modeling process, we are able to self-consistently fit a single blast radius value for amplitude and period. In this case, the distortion distance is always much less (usually just a few percent) than the value of 10% assumed in the ReVelle model. Our study shows that fragmentation is an important process even for centimeter-sized meteoroids, implying that R0, while a good measure of energy deposition by the meteoroid, is not a reliable means of obtaining the meteoroid mass. We derived an empirical period-blast radius relation of the form R0 = 15.4τ - 0.5 (τ ≤ 0.7 s) and R0 = 29.1τ - 11.6 (τ > 0.7 s) appropriate to centimeter-sized meteoroids. Our observations suggest that meteors having blast radii as small as 1 m are detectable infrasonically at the ground, an order of magnitude smaller than previously considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.7325G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.7325G"><span>Recent development of <span class="hlt">infrasound</span> monitoring network in Romania</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; Ionescu, Constantin</p> <p>2017-04-01</p> <p>The second half of 2016 was marked at National Institute for Earth Physics (NIEP) by a significant development of <span class="hlt">infrasound</span> monitoring infrastructure in Romania. In addition to IPLOR, the 6-element acoustic array installed at Plostina, in the central part of Romania, since 2009, two other four-element arrays were deployed. The first one, BURARI <span class="hlt">infrasound</span> research array, was deployed in late July 2016, under a joint effort of AFTAC, USA and NIEP, in the northern part of Romania, in Bucovina region. The sites, placed in vicinity of the central elements of BURAR seismic array (over 1.2 km aperture), are equipped with Chaparral Physics Model 21 microbarometers and Reftek RT 130 data loggers. The data, used mainly for research purposes within the scientific collaboration project between NIEP and AFTAC, are available to scientific community. The second one is a PTS portable <span class="hlt">infrasound</span> array (I67RO) deployed for one year, starting with the end of September 2016, within a collaboration project between NIEP and PTS of the Preparatory Commission for CTBTO. This array is located in the western part of Romania, at Marisel, Cluj County, covering a 0.9 km aperture and being equipped with CEA/DAM MB2005 microbarometers and Reftek RT 130 data loggers. This joint experiment aims to contribute both to advanced understanding of <span class="hlt">infrasound</span> <span class="hlt">sources</span> in Central-Europe and to ARISE design study project, as an expansion of the spatial coverage of the European <span class="hlt">infrasound</span> network. The data recorded by the three <span class="hlt">infrasound</span> arrays deployed in Romania, during a same time interval (October - December 2016) were processed into detection arrival bulletins applying CEA/DASE PMCC algorithm embedded in DTK-GPMCC (extended CTBTO NDC-in-a-box) and WinPMCC software applications. The results were plotted and analyzed using DTK-DIVA software (extended CTBTO NDC-in-a-box), in order to assess detectability of each station, as well as the capacity of fusing detections into support of <span class="hlt">infrasound</span> monitoring</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S23B2500K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2500K"><span>Three-Dimensional, Finite-Difference, Time-Domain Modeling of Local Volcano <span class="hlt">Infrasound</span> Radiation Using GPU</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.; Lees, J. M.</p> <p>2013-12-01</p> <p>Since volcano <span class="hlt">infrasound</span> is a direct measure of atmospheric pressure fluctuation near open-vent activity, it can provide important constraints on eruption <span class="hlt">source</span> parameters including the volume of gas released and eruption velocity. Local <span class="hlt">infrasound</span> data (<15 Km) have been used to quantify and characterize acoustic <span class="hlt">sources</span> of volcanic eruptions since they are relatively less affected by atmospheric velocity structures in the near field. The interaction of volcano <span class="hlt">infrasound</span> <span class="hlt">sources</span> and complex topography near the volcanic edifice, however, has not been fully explored. <span class="hlt">Infrasound</span> observations from world-wide volcanoes and two-dimensional numerical modeling of <span class="hlt">infrasound</span> radiation in the vicinity of the crater suggest a strong distortion of the wavefield by local topography [Kim and Lees, GRL, 2011]. To get a complete picture of these effects, however, full three-dimensional modeling is required. We have developed a new, accelerated, 3D finite-difference time-domain program using GPU (Grpahic Processing Units) to simulate local <span class="hlt">infrasound</span> propagation near volcanoes, while taking into account complex topography, local wind distortion, and atmospheric sound velocity structures. While CPU-based 3D FDTD method requires a prohibitive amount of computational resources, GPU-based algorithms significantly reduce the computational time of <span class="hlt">infrasound</span> modeling, making parallel processing practical even on a desktop computer. In these simulations we provide a comprehensive solution of volcano <span class="hlt">infrasound</span> radiation assuming different acoustic <span class="hlt">sources</span> and real volcano topography. We illustrate the interaction of local vent topography and difference acoustic <span class="hlt">sources</span> and how they combine to affect the <span class="hlt">infrasound</span> wavefield. By removing topographic effects from local <span class="hlt">infrasound</span> observation we can begin to quantitatively model acoustic <span class="hlt">sources</span> and finally establish the partitioning of energy, at the vent, between the acoustic and seismic wavefields.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/19105754','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19105754"><span>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('https://ntrs.nasa.gov/search.jsp?R=19930016609&hterms=Geographic+information+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGeographic%2Binformation%2Bsystems','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930016609&hterms=Geographic+information+systems&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DGeographic%2Binformation%2Bsystems"><span>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_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('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>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> <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><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>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/2013GeoRL..40.3517L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.3517L"><span>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.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>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>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('https://www.ncbi.nlm.nih.gov/pubmed/19268708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19268708"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/25870463','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25870463"><span>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="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vajda, Szilárd; Rangoni, Yves; Cecotti, Hubert</p> <p>2015-06-01</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.</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>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://www.osti.gov/scitech/servlets/purl/15001980','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15001980"><span>LLNL Calibration Program: Data Collection, <span class="hlt">Ground</span> <span class="hlt">Truth</span> Validation, and Regional Coda Magnitude</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Myers, S C; Mayeda, K; Walter, C; Schultz, C; O'Boyle, J; Hofstetter, A; Rodgers, A; Ruppert, S</p> <p>2001-08-28</p> <p>Lawrence Livermore National Laboratory (LLNL) integrates and collects data for use in calibration of seismic detection, location, and identification. Calibration data is collected by (1) numerous seismic field efforts, many conducted under NNSA (ROA) and DTRA (PRDA) contracts, and (2) permanent seismic stations that are operated by national and international organizations. Local-network operators and international organizations (e.g. International Seismic Center) provide location and other <span class="hlt">source</span> characterization (collectively referred to as <span class="hlt">source</span> parameters) to LLNL, or LLNL determines these parameters from raw data. For each seismic event, LLNL rigorously characterizes the uncertainty of <span class="hlt">source</span> parameters. This validation process is used to identify events whose <span class="hlt">source</span> parameters are accurate enough for use in calibration. LLNL has developed criteria for determining the accuracy of seismic locations and methods to characterize the covariance of calibration datasets. Although the most desirable calibration events are chemical and nuclear explosions with highly accurate locations and origin times, catalogues of naturally occurring earthquakes offer needed geographic coverage that is not provided by man made <span class="hlt">sources</span>. The issue in using seismically determined locations for calibration is validating the location accuracy. Sweeney (1998) presented a 50/90 teleseismic, network-coverage criterion (50 defining phases and 90{sup o} maximum azimuthal gap) that generally results in 15-km maximum epicenter error. We have also conducted tests of recently proposed local/regional criteria and found that 10-km accuracy can be achieved by applying a 20/90 criteria. We continue to conduct tests that may validate less stringent criteria (which will produce more calibration events) while maintaining desirable location accuracy. Lastly, we examine methods of characterizing the covariance structure of calibration datasets. Each dataset is likely to be effected by distinct error</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>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('http://adsabs.harvard.edu/abs/2013EP%26S...65..109C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EP%26S...65..109C"><span><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>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('https://www.ncbi.nlm.nih.gov/pubmed/22818588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22818588"><span>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/2017GeoRL..44..143Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44..143Y"><span>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://adsabs.harvard.edu/abs/2013AGUFM.S23B2489H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S23B2489H"><span><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/15005407','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15005407"><span>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('http://www.osti.gov/scitech/servlets/purl/1213302','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1213302"><span>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/2010EGUGA..12.4661G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4661G"><span>Databases for Studies of <span class="hlt">Infrasound</span> Propagation in the European Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gibbons, Steven J.; Ringdal, Frode</p> <p>2010-05-01</p> <p>Industrial and military <span class="hlt">sources</span> in northern Fennoscandia and NW Russia generate both seismic and <span class="hlt">infrasound</span> signals observed at regional distances. Similar seismic signals constrain origin times and explosion yield and, using correlation detectors at the ARCES array, have enabled us to detect and classify hundreds of events from a small number of sites. This has in turn provided superb datasets for <span class="hlt">infrasound</span> propagation studies. The multi-channel waveform correlation procedure has even had considerable success in detecting closely spaced events when the signals from subsequent events show considerable differences. A post-processing system which examines the alignment of the single-channel cross-correlation traces allows for very low detection thresholds with low false alarm rates. Near-surface explosions at Hukkakero in northern Finland generate <span class="hlt">infrasound</span> signals on the seismic sensors at ARCES, 175 km to the North, near to the edge of the classical "Zone of Silence". Many tropospheric phase observations can be predicted using ray-tracing given favourable winds at low altitudes. However, the vast majority of the observed <span class="hlt">infrasound</span> signals - probably refracted from stratospheric heights - are not predicted by ray-tracing, warranting a re-evaluation of propagation models for these distances. In 2008, a mini-array of microbarographs, co-located with ARCES seismometers, also observed later signals probably refracted from thermospheric heights. These signals are more impulsive and of smaller amplitude than the more typically observed signals. A second site near the northern coast of the Kola Peninsula is approximately 250 km from ARCES to the West and Apatity to the South. Despite poor waveform similarity between events, multichannel correlation detectors assign confidently over 350 events over an 8 year period to this site. <span class="hlt">Infrasound</span> is observed at ARCES for almost all events in the summer and almost no events in the winter, and is observed at Apatity for almost</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>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> </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/2015AGUFM.S51D2705W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S51D2705W"><span>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://adsabs.harvard.edu/abs/2013EGUGA..15.4572A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4572A"><span><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/2017EGUGA..1916909G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916909G"><span>Towards improved characterization of northern wetlands (or other landscapes) by remote sensing - a rapid approach to collect <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>Gålfalk, Magnus; Karlson, Martin; Crill, Patrick; Bastviken, David</p> <p>2017-04-01</p> <p>The calibration and validation of remote sensing land cover products is highly dependent on accurate <span class="hlt">ground</span> <span class="hlt">truth</span> data, which are costly and practically challenging to collect. This study evaluates a novel and efficient alternative to field surveys and UAV imaging commonly applied for this task. The method consists of i) a light weight, water proof, remote controlled RGB-camera mounted on an extendable monopod used for acquiring wide-field images of the ground from a height of 4.5 meters, and ii) a script for semi-automatic image classification. In the post-processing, the wide-field images are corrected for optical distortion and geometrically rectified so that the spatial resolution is the same over the surface area used for classification. The script distinguishes land surface components by color, brightness and spatial variability. The method was evaluated in wetland areas located around Abisko, northern Sweden. Proportional estimates of the six main surface components in the wetlands (wet and dry Sphagnum, shrub, grass, water, rock) were derived for 200 images, equivalent to 10 × 10 m field plots. These photo plots were then used as calibration data for a regional scale satellite based classification which separates the six wetland surface components using a Sentinel-1 time series. The method presented in this study is accurate, rapid, robust and cost efficient in comparison to field surveys (time consuming) and drone mapping (which require low wind speeds and no rain, suffer from battery limited flight times, have potential GPS/compass errors far north, and in some areas are prohibited by law).</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><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> <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>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.dtic.mil/docs/citations/ADA528730','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA528730"><span><span class="hlt">Infrasound</span> Detection of Rocket Launches</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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/2012AGUFM.V33E..08F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V33E..08F"><span>Combining <span class="hlt">Infrasound</span> and Imaging Techniques to Characterize and Quantify Eruptive Activity 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>Fee, D.; Lopez, T. M.; Rowell, C.; Matoza, R. S.; Szuberla, C.; Prata, F.; Firstov, P.; Makhmudov, E.</p> <p>2012-12-01</p> <p>Changes in atmospheric pressure at volcanic vents caused by the rapid release and expansion of volcanic material (e.g., gas, ash, lava) produce low frequency sound waves known as <span class="hlt">infrasound</span>. Because of the direct link between the <span class="hlt">infrasound</span> <span class="hlt">source</span> and the eruption and emission of volcanic material, complementary direct and remote observations of gas, ash, and other eruptive phenomena can be combined with <span class="hlt">infrasound</span> measurements to characterize and quantify volcanic activity. Here we present coincident measurements collected over two 10-day periods at Karymsky Volcano in August 2011 and July 2012 of <span class="hlt">infrasound</span>, SO2, thermal radiation, ash (2011 only), and visual imagery. <span class="hlt">Infrasound</span> and audible (up to 250 Hz) acoustic data were recorded using arrays of portable digital microphones. SO2 emissions were measured using both a scanning FLYSPEC ultraviolet spectrometer system as well as a CyClops infrared camera equipped with broadband, 8.6, 10, and 11 micron filters permitting detection and quantification of both SO2 and ash. A FLIR infrared camera was utilized to record high temporal resolution thermal observations of the volcanic emissions and hot eruption deposits. Lastly, visual imagery was taken with an HD camcorder. Correlations between this multiparameter dataset allow a better understanding of both the <span class="hlt">infrasound</span> data and eruptive activity. Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, Russia, with activity during our experiments consisting of vigorous degassing, frequent ash explosions, apparent vent sealing, and intermittent explosive magmatic eruptions. This varied activity produced diverse acoustic and emissions signals. Large explosive eruptions in 2011 are preceded by vent sealing and produce high-amplitude <span class="hlt">infrasound</span> with occasional visible shock waves. Vigorous gas jetting is also observed and accompanied by elevated SO2 emissions and low <span class="hlt">infrasound</span> levels. The gas jetting produced clear audible sound (~20-100 Hz) that</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>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://www.osti.gov/scitech/servlets/purl/761837','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/761837"><span><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/2015EGUGA..17.6684J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6684J"><span>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://adsabs.harvard.edu/abs/2005AGUFMPP43C..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFMPP43C..02H"><span>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://pubs.er.usgs.gov/publication/70023012','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023012"><span><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/2012AGUFM.A53B0150B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A53B0150B"><span><span class="hlt">Infrasound</span> product resources at the IRIS DMC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bahavar, M.; Trabant, C.; Hutko, A. R.; Karstens, R.</p> <p>2012-12-01</p> <p>In 2011 <span class="hlt">infrasound</span> sensors were installed at some existing USArray Transportable Array (TA) sites and became a standard component of all new sites. Currently there are over 400 sites with <span class="hlt">infrasound</span> sensors with an average spacing of 70 kilometers. To promote and facilitate the use of these data the IRIS Data Management Center has developed two new data products: an <span class="hlt">infrasound</span> reference event database and an <span class="hlt">infrasound</span> signal detector. The TA <span class="hlt">Infrasound</span> Reference Event Database (TAIRED) is a user-supported database that contains information on events of interest for which there are associated USArray microbarograph recordings. This database is initially populated with a few events from observations on the USArray <span class="hlt">infrasound</span> data, event bulletins, news on explosions, meteorological events and rocket launches. As a user-supported resource, we ask users to submit events of interest to be included in the database or submit their alternate solutions to the existing events. The second data product is an <span class="hlt">infrasound</span> signal detector that regularly scans the USArray broadband <span class="hlt">infrasound</span> data (BDF channel sampled at 40 Hz) and produces detections that highlight time intervals containing potential signals of interest. The detection product includes two components, standard signal-to-noise ratio based detections and spectral power based detections. No attempt is made to categorize detections or associate them to events. These data products join the growing collection of products produced and managed at the IRIS DMC, for the complete list please visit http://www.iris.edu/dms/products/.</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>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><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/2011AGUFM.A31A0042S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0042S"><span>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>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/2015EGUGA..1711518T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711518T"><span>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/2016APS..DFD.H4004T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.H4004T"><span>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/2004ASAJ..115..253S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..115..253S"><span>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> </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/2010JGRD..115.0L10F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRD..115.0L10F"><span>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><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><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('http://adsabs.harvard.edu/abs/2010BGD.....7.3227K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010BGD.....7.3227K"><span>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914867D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914867D"><span>Curiosity's traverse through the upper Murray formation (Gale crater): <span class="hlt">ground</span> <span class="hlt">truth</span> for orbital detections of Martian clay minerals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dehouck, Erwin; Carter, John; Gasnault, Olivier; Pinet, Patrick; Daydou, Yves; Gondet, Brigitte; Mangold, Nicolas; Johnson, Jeffrey; Arvidson, Raymond; Maurice, Sylvestre; Wiens, Roger</p> <p>2017-04-01</p> <p>Orbital observations from visible/near-infrared (VNIR) spectrometers have shown that hydrated clay minerals are widespread on the surface of Mars (e.g., Carter et al., JGR, 2013), but implications in terms of past environmental conditions are debated. In this context, in situ missions can play a crucial role by providing "<span class="hlt">ground</span> <span class="hlt">truth</span>" and detailed geological setting for orbital signatures. Since its landing in 2012, the Mars Science Laboratory rover Curiosity has found evidence for clay minerals in several sedimentary formations within Gale crater. The first clays were encountered at Yellowknife Bay, where results from the CheMin X-ray diffractometer (XRD) showed the presence of 20 wt% tri-octahedral, Fe/Mg-bearing smectites (Vaniman et al., Science, 2014). However, due to dust cover, this location lacks any signature of clay minerals in orbital VNIR observations. Smaller amounts of clay minerals were found later in the rover's traverse, but again at locations with no specific signature from orbit. More recently, Curiosity reached the upper Murray formation, a sedimentary layer consisting primarily of mudstones and belonging to the basal part of Aeolis Mons (or Mt Sharp), the central mound of Gale crater. There, for the first time, orbital signatures of clay minerals can be compared to laterally-equivalent samples that were analyzed by Curiosity's payload. Orbital VNIR spectra suggest the prevalence of di-octahedral, Al/Fe-bearing smectites, clearly distinct from the tri-octahedral, Fe/Mg-bearing species of Yellowknife Bay (Carter et al., LPSC, 2016). Preliminary results from XRD and EGA analyses performed by the CheMin and SAM instruments at Marimba, Quela and Sebina drill sites are broadly consistent with such interpretation. However, and perhaps unsurprisingly, in situ data show more complexity than orbital observations. In particular, in situ data suggest the possible presence of an illitic component as well as the possible co-existence of both di</p> </li> <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>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://adsabs.harvard.edu/abs/2014EGUGA..1612591S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1612591S"><span><span class="hlt">Infrasound</span> propagation modelling using 4d atmospheric backgrounds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Streicher, Florian; Wuest, Sabine; Bittner, Michael</p> <p>2014-05-01</p> <p><span class="hlt">Infrasound</span> is very low frequency sound. Because of its low attenuation in the atmosphere, it is able to travel up to thousands of kilometers around the globe. A sound wave may cover a distance of about 1.000km within an hour. Sensors monitoring <span class="hlt">infrasound</span> however can be some thousands of kilometers away from a specific <span class="hlt">source</span>. For determining an infrasonic event, e.g. by the use of propagation modelling, with growing distance it is increasingly important to consider changes of the atmosphere in space and time. Most important and always accounted for in propagation modelling are changes of the atmosphere in vertical direction. Changes in horizontal direction generally are much smaller and sometimes are left away, e.g. for short distance calculations. Finally, changes in time hardly are considered. Effect and potential benefit of the use of 4d atmospheric specifications in <span class="hlt">infrasound</span> propagation modelling are compared to 1d and 3d backgrounds, also taking into account selected atmospheric conditions and weather events. Differences in propagation on short and long distances are discussed. The results are based on HARPA/DLR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914300M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914300M"><span>Progresses with Net-VISA on Global <span class="hlt">Infrasound</span> Association</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mialle, Pierrick; Arora, Nimar</p> <p>2017-04-01</p> <p>Global <span class="hlt">Infrasound</span> Association algorithms are an important area of active development at the International Data Centre (IDC). These algorithms play an important part of the automatic processing system for verification technologies. A key focus at the IDC is to enhance association and signal characterization methods by incorporating the identification of signals of interest and the optimization of the network detection threshold. The overall objective 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 (REB), and hence reduce IDC analyst workload. Despite good accuracy by the IDC categorization, a number of signal detections due to clutter <span class="hlt">sources</span> such as microbaroms or surf are built into events. In this work we aim to optimize the association criteria based on knowledge acquired by IDC in the last 6 years, and focus on the specificity of seismo-acoustic events. The resulting work has been incorporated into NETVISA [1], a Bayesian approach to network processing. The model that we propose is a fusion of seismic, hydroacoustic and <span class="hlt">infrasound</span> processing built on a unified probabilistic framework. References: [1] 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('https://www.ncbi.nlm.nih.gov/pubmed/24437743','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24437743"><span>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>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('https://www.ncbi.nlm.nih.gov/pubmed/28066888','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28066888"><span>Technical Note: A new zeolite PET phantom to test segmentation algorithms on heterogeneous activity distributions featured with <span class="hlt">ground-truth</span> contours.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Soffientini, Chiara D; De Bernardi, Elisabetta; Casati, Rosangela; Baselli, Giuseppe; Zito, Felicia</p> <p>2017-01-01</p> <p>Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour <span class="hlt">ground</span> <span class="hlt">truth</span>. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different (18) F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions. Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in (18) F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% and 443% of a uniform radioactive solution. Assembled phantom included eight lesions with volumes ranging from 1.86 to 7.24 ml and lesion to background contrasts ranging from 4.8:1 to 21.7:1. A novel phantom for the evaluation of PET-AS algorithms was developed. It is provided with both reference contours and activity <span class="hlt">ground</span> <span class="hlt">truth</span>, and it covers a wide range of volumes and lesion to background contrasts. The dataset is open to the community of PET-AS developers and utilizers. © 2016 American Association of Physicists in Medicine.</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>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/2011AGUFMAE12A..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMAE12A..02F"><span><span class="hlt">Infrasound</span> from lightning measured in Ivory Coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farges, T.; Matoza, R. S.</p> <p>2011-12-01</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. More than two thirds (42) 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 worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but 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. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning <span class="hlt">infrasound</span> from thunderstorms within a range of distances from the <span class="hlt">infrasound</span> station. <span class="hlt">Infrasound</span> from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS <span class="hlt">infrasound</span> station has been installed in Ivory Coast for 8 years. The optical space-based instrument OTD measured a rate of 10-20 flashes/km^2/year in that country and showed strong seasonal variations (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 3 years of data (2005-2008).</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>The Effects of High Level <span class="hlt">Infrasound</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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/2017JGRB..122.2946M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRB..122.2946M"><span>Automated detection and cataloging of global explosive volcanism using the International Monitoring System <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>Matoza, Robin S.; Green, David N.; Le Pichon, Alexis; Shearer, Peter M.; Fee, David; Mialle, Pierrick; Ceranna, Lars</p> <p>2017-04-01</p> <p>We experiment with a new method to search systematically through multiyear data from the International Monitoring System (IMS) <span class="hlt">infrasound</span> network to identify explosive volcanic eruption signals originating anywhere on Earth. Detecting, quantifying, and cataloging the global occurrence of explosive volcanism helps toward several goals in Earth sciences and has direct applications in volcanic hazard mitigation. We combine <span class="hlt">infrasound</span> signal association across multiple stations with <span class="hlt">source</span> location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent unwanted <span class="hlt">infrasound</span> signals (clutter) in a global grid, without needing to screen array processing detection lists from individual stations prior to association. We develop the algorithm using case studies of explosive eruptions: 2008 Kasatochi, Alaska; 2009 Sarychev Peak, Kurile Islands; and 2010 Eyjafjallajökull, Iceland. We apply the method to global IMS <span class="hlt">infrasound</span> data from 2005-2010 to construct a preliminary acoustic catalog that emphasizes sustained explosive volcanic activity (long-duration signals or sequences of impulsive transients lasting hours to days). This work represents a step toward the goal of integrating IMS <span class="hlt">infrasound</span> data products into global volcanic eruption early warning and notification systems. Additionally, a better understanding of volcanic signal detection and location with the IMS helps improve operational event detection, discrimination, and association capabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S53B1984N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S53B1984N"><span><span class="hlt">Infrasound</span> Sensor Coverage at Regional Ranges as driven by the Atmospheric State</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norris, D.</p> <p>2010-12-01</p> <p><span class="hlt">Infrasound</span> is an attractive regional sensor modality in explosion monitoring applications due to its non line-of-sight, long-range detection capability. Anthropomorphic activity, including impulsive events such as explosions and continuous events such as vehicle operation, can be routinely detected over tens of kilometer ranges and beyond. This study addresses the issues associated with effectively leveraging <span class="hlt">infrasound</span> for regional monitoring applications. A key challenge in applying <span class="hlt">infrasound</span> at these ranges is adequately understanding the propagation. Spatial and temporal features of the atmospheric state create evolving regions of acoustic focusing and shadowing at the surface. Understanding this acoustic "footprint" and having the capability to predict it over time is necessary for two reasons. It drives the planning process of where to deploy a given permanent or temporary suite of <span class="hlt">infrasound</span> sensors. In addition, knowing the observability of a stationary or mobile <span class="hlt">source</span> supports the interpretation of operational data. This research includes a sample study on characterization of atmospheric effects on regionally deployed <span class="hlt">infrasound</span> networks. Predictions are made from real atmospheric states to illustrate the range of observability conditions that may occur. It was found that the observability can have significant frequency dependence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S11C2470D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S11C2470D"><span>Detection of the Combined Seismic and <span class="hlt">Infrasound</span> Fields at the USArray Transportable Array</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.; Hedlin, M. A. H.</p> <p>2016-12-01</p> <p>Many geophysical events, of natural or anthropogenic origin, are significant <span class="hlt">sources</span> of both seismic and <span class="hlt">infrasound</span> signals. Routine detection and accurate location of <span class="hlt">sources</span> that generate both signal types is a significant processing challenge. We have recently developed a novel `big data' method to detect and locate geophysical events using a dense sensor network. In this method, the stations are divided into a mesh of "triad" arrays, which each comprise three adjacent stations. Standard array processing methods are used at each triad to detect signals that are consistent with plane wave propagation. When a coherent signal is detected, its phase velocity and direction of propagation is computed using tau-p. Results from all triads with signal detections that are consistent with a common <span class="hlt">source</span> are collectively used to automatically and rapidly provide an accurate estimate of the <span class="hlt">source</span>'s origin time and location. This method has proven highly effective at detecting weak <span class="hlt">sources</span> of <span class="hlt">infrasound</span> and seismic signals that were located within or near the 400-station USArray Transportable Array. Examination of contemporaneous seismic and <span class="hlt">infrasound</span> event catalogs reveals a number of <span class="hlt">sources</span> that generate both <span class="hlt">infrasound</span> and seismic signals. Most of these are identified as anthropogenic, as they occur during regular working hours each week, however a few of the <span class="hlt">sources</span> appear to have a natural origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S13D..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S13D..05S"><span>Seismic and <span class="hlt">Infrasound</span> Characteristics of North Korean Nuclear Explosions Utilizing Regional Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stump, B. W.; Park, J.; Che, I. Y.; Hayward, C.</p> <p>2016-12-01</p> <p>This work analyzes seismic and <span class="hlt">infrasound</span> signals from four underground nuclear tests by North Korea in 2006, 2009, 2013, and 2016. Regional data from eight seismo-acoustic arrays, operated by Southern Methodist University (SMU) and Korea Institute of Geosciences and Mineral Resources (KIGAM) located in the Korean peninsula, a seismic station in China (MDJ), and two nearby International Monitoring System (IMS) <span class="hlt">infrasound</span> arrays in Russia (IS45) and Japan (IS30) are used. <span class="hlt">Infrasound</span> signals at the arrays are detected using the progressive multi-channel correlation (PMCC; Cansi, 1995) followed by analyst review and compared to model predictions based on the method of Blom and Waxler (2012) using Ground-to-Space (G2S) specifications (Drob et al., 2003). This comparison documents that <span class="hlt">infrasound</span> detection and event locations are dependent on the atmospheric conditions and local noise levels at the time of each explosion. Based on empirical yield-scaling relation of Whitaker et al. (2003), <span class="hlt">infrasound</span> <span class="hlt">source</span> energies are estimated at the closest array (KSGAR) to be 0.6, 23.5, and 8.2 tons of TNT for 2009, 2013, and 2016, respectively (no clear observations from 2006). The relative seismic <span class="hlt">source</span> scaling of the four explosions is assessed using Mueller and Murphy <span class="hlt">source</span> model (1971) based upon regional seismic station spectral ratios of Pn, Pg, Sn, and Lg. Using a grid search method, we explore the range of acceptable <span class="hlt">source</span> models in terms of depth of burial and yields for 2009/2006, 2013/2006, 2016/2006, 2013/2009, 2016/2009, and 2013/2016. Using this methodology the 2013/2016-yield ratio is from 1.05-1.30 with an estimated depth range from 0.71-1.15. The small <span class="hlt">infrasound</span> yield is a reflection of the fact that the <span class="hlt">infrasound</span> signal is a result of coupling from strong ground motion directly above the explosion and the atmosphere. Differences in relative yield ratios for seismic and <span class="hlt">infrasound</span> provide constraints on <span class="hlt">source</span> depth as well as free surface interactions.</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>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>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> </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/2015AGUFM.T53C..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T53C..03M"><span>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/19206769','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19206769"><span><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/2017EGUGA..1914636T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914636T"><span><span class="hlt">Infrasound</span>'s capability to detect and characterise volcanic events, from local to regional scale.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taisne, Benoit; Perttu, Anna</p> <p>2017-04-01</p> <p>Local <span class="hlt">infrasound</span> and seismic networks have been successfully used for identification and quantification of explosions at single volcanoes. However the February, 2014 eruption of Kelud volcano, Indonesia, destroyed most of the local monitoring network. The use of remote seismic and <span class="hlt">infrasound</span> sensors proved to be essential in the reconstruction of the eruptive sequence. The first recorded explosive event, with relatively weak seismic and infrasonic signature, was followed by a 2 hour sustained signal detected as far away as 11,000 km by <span class="hlt">infrasound</span> sensors and up to 2,300 km away by seismometers. The volcanic intensity derived from these observations places the 2014 Kelud eruption between the intensity of the 1980 Mount St. Helens and the 1991 Pinatubo eruptions. The use of remote seismic stations and <span class="hlt">infrasound</span> arrays in deriving valuable information about the onset, evolution, and intensity of volcanic eruptions is clear from the Kelud example. After this eruption the Singapore <span class="hlt">Infrasound</span> Array became operational. This array, along with the other regional <span class="hlt">infrasound</span> arrays which are part of the International Monitoring System, have recorded events from fireballs and regional volcanoes. The detection capability of this network for any specific volcanic event is not only dependent on the amplitude of the <span class="hlt">source</span>, but also the propagation effects, noise level at each station, and characteristics of the regional persistent noise <span class="hlt">sources</span> (like the microbarum). Combining the spatial and seasonal characteristics of this noise, within the same frequency band as significant eruptive events, with the probability of such events to occur, gives us a comprehensive understanding of detection capability for any of the 750 active or potentially active volcanoes in Southeast Asia.</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><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('https://www.ncbi.nlm.nih.gov/pubmed/24347142','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24347142"><span>The Truth, the Whole Truth, and Nothing but the <span class="hlt">Ground-Truth</span>: Methods to Advance Environmental Justice and Researcher-Community Partnerships.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sadd, James; Morello-Frosch, Rachel; Pastor, Manuel; Matsuoka, Martha; Prichard, Michele; Carter, Vanessa</p> <p>2014-06-01</p> <p>Environmental justice advocates often argue that environmental hazards and their health effects vary by neighborhood, income, and race. To assess these patterns and advance preventive policy, their colleagues in the research world often use complex and methodologically sophisticated statistical and geospatial techniques. One way to bridge the gap between the technical work and the expert knowledge of local residents is through community-based participatory research strategies. We document how an environmental justice screening method was coupled with "<span class="hlt">ground-truthing</span>"-a project in which community members worked with researchers to collect data across six Los Angeles neighborhoods-which demonstrated the clustering of potentially hazardous facilities, high levels of air pollution, and elevated health risks. We discuss recommendations and implications for future research and collaborations between researchers and community-based organizations. © 2013 Society for Public Health Education.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002ASAJ..111.2335P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ASAJ..111.2335P"><span><span class="hlt">Infrasounds</span> and biorhythms of the human brain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panuszka, Ryszard; Damijan, Zbigniew; Kasprzak, Cezary; McGlothlin, James</p> <p>2002-05-01</p> <p>Low Frequency Noise (LFN) and <span class="hlt">infrasound</span> has begun a new public health hazard. Evaluations of annoyance of (LFN) on human occupational health were based on standards where reactions of human auditory system and vibrations of parts of human body were small. Significant sensitivity has been observed on the central nervous system from infrasonic waves especially below 10 Hz. Observed follow-up effects in the brain gives incentive to study the relationship between parameters of waves and reactions obtained of biorhythms (EEG) and heart action (EKG). New results show the impact of LFN on the electrical potentials of the brain are dependent on the pressure waves on the human body. Electrical activity of circulatory system was also affected. Signals recorded in industrial workplaces were duplicated by loudspeakers and used to record data from a typical LFN spectra with 5 and 7 Hz in a laboratory chamber. External noise, electromagnetic fields, temperature, dust, and other elements were controlled. Results show not only a follow-up effect in the brain but also a result similar to arrhythmia in the heart. Relaxations effects were observed of people impacted by waves generated from natural <span class="hlt">sources</span> such as streams and waterfalls.</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>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/2014AGUFM.A41G3144M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A41G3144M"><span>Field Spectroradiometer Characterization of Solar-Induced Fluorescence to Monitor Plant Health, Estimate Carbon Flux, and Application as <span class="hlt">Ground-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>Merrick, T.; Bennartz, R.; Rausch, J.</p> <p>2014-12-01</p> <p>Solar-Induced Fluorescence (SIF) has been demonstrated to be an indicator of plant photosynthetic functioning and is proportional carbon uptake. Other indices, such as the Normalized Difference Vegetation Index (NDVI) and the Photochemical Reflectance Index (PRI) are also commonly used to monitor plant activity using remote sensing techniques. Determining the best indices for plant health, calculating carbon fixation efficiently and economically, and developing reliable <span class="hlt">ground</span> <span class="hlt">truthing</span> methods for satellite data will allow monitoring and comparison of regional scale carbon fluxes. In this study, spectral measurements made with a passive field spectroradiometer were used to record spectral radiances from a selection of plants in the laboratory and field. SIF is less complicated to extract under limited wavelength illumination in the laboratory. These were used to validate the Fraunhofer Line Depth Method (FLD) applied to field measurements under solar illumination. SIF, NDVI, and PRI were calculated from the spectral measurements to determine functioning of the plants and to estimate carbon fixation under both normal and water stress conditions. Previous literature and preliminary findings suggest SIF is an earlier indicator of stress and clearer estimator of carbon uptake than NDVI or PRI. Therefore, SIF is a potential monitoring index for photosynthetic activity and its retrieval with this instrument and process is desirable. We will report on the comparison of laboratory and field estimates of SIF, the evaluation of plant health indices, and the changes in SIF with stress. Given strong evidence that obtaining accurate carbon flux information via this remote sensing process is possible, this retrieval method could be reliably utilized as <span class="hlt">ground</span> <span class="hlt">truth</span> data for OCO2 and OCO3. In the near future, ground spectral data such as these can be combined with OCO2 data for regional monitoring and comparisons of carbon fixation, advancing carbon flux calculations and carbon</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>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('http://adsabs.harvard.edu/abs/2008AGUFM.S11B1734N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S11B1734N"><span>Dispersed <span class="hlt">Infrasound</span> Signals in the "Zone of Silence"</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.; Golden, P.; Herrin, E.</p> <p>2008-12-01</p> <p>During the last few years the use of seismo-acoustic recordings have become increasingly important; however, <span class="hlt">infrasound</span> analysis methods lag behind seismic methods. The current paper discusses infrasonic signals in the so called 'Zone of Silence', at a distance up to 300 km from the <span class="hlt">source</span>. During controlled <span class="hlt">source</span> experiments in 2006 and 2007, tropospheric, stratospheric and thermospheric signals were recorded at a suite of temporary <span class="hlt">infrasound</span> arrays; some of the tropospheric arrivals exhibit dispersion. The most common types of infrasonic signals observed during our studies beyond 76 km are stratospheric. These signals are not predicted by atmospheric modeling (raytracing and PE calculations) using the Naval Research Laboratory Ground to Space (G2S) model. The G2S model does not explain the observed tropospheric arrivals. Meteorological data from balloon launched rawinsondes obtained in the path of the propagating signals are able to predict the tropospheric propagation if the data closest to the detonation time is used. In a previous research study in the China Sea, a suite of dispersed <span class="hlt">infrasound</span> signals were successfully interpreted as propagating in a low velocity waveguide. We also observed dispersed signals from an explosion at White Sands Missile Range recorded at TXIAR at a distance of 546 km. The signals exhibit dispersion between 0.2-1 Hz, and can be successfully modeled as propagating in a low velocity layer 1.2 km thick. However, dispersed signals recorded in Nevada suggest propagation in a waveguide consisting of a single low velocity layer is too simplistic. Effects due to lateral changes in effective sound speed, topography, turbulence and multiple layering can significantly affect the dispersion.</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>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/2004ASAJ..115.2594P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ASAJ..115.2594P"><span>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/2012EGUGA..14.1285F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.1285F"><span><span class="hlt">Infrasound</span> from lightning measured in Ivory Coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farges, T.; Millet, C.; Matoza, R. S.</p> <p>2012-04-01</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. More than two thirds (42) 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 worldwide lightning detection networks (e.g. WWLLN) have a weak detection capability but 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. For example, Farges and Blanc (2010) show clearly that it is possible to measure lightning <span class="hlt">infrasound</span> from thunderstorms within a range of distances from the <span class="hlt">infrasound</span> station. <span class="hlt">Infrasound</span> from lightning can be detected when the thunderstorm is within about 75 km from the station. The motion of the squall zone is very well measured inside this zone. Up to 25% of lightning flashes can be detected with this technique, giving better results locally than worldwide lightning detection networks. An IMS <span class="hlt">infrasound</span> station has been installed in Ivory Coast for 9 years. 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 4 years of data (2005-2009). For short lightning distances (less than 20 km), up to 60 % of lightning detected by WWLLN has been one-to-one correlated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23477573','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23477573"><span>Can expectations produce symptoms from <span class="hlt">infrasound</span> associated with 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>Crichton, Fiona; Dodd, George; Schmid, Gian; Gamble, Greg; Petrie, Keith J</p> <p>2014-04-01</p> <p>The development of new wind farms in many parts of the world has been thwarted by public concern that subaudible sound (<span class="hlt">infrasound</span>) generated by wind turbines causes adverse health effects. Although the scientific evidence does not support a direct pathophysiological link between <span class="hlt">infrasound</span> and health complaints, there is a body of lay information suggesting a link between <span class="hlt">infrasound</span> exposure and health effects. This study tested the potential for such information to create symptom expectations, thereby providing a possible pathway for symptom reporting. A sham-controlled double-blind provocation study, in which participants were exposed to 10 min of <span class="hlt">infrasound</span> and 10 min of sham <span class="hlt">infrasound</span>, was conducted. Fifty-four participants were randomized to high- or low-expectancy groups and presented audiovisual information, integrating material from the Internet, designed to invoke either high or low expectations that exposure to <span class="hlt">infrasound</span> causes specified symptoms. High-expectancy participants reported significant increases, from preexposure assessment, in the number and intensity of symptoms experienced during exposure to both <span class="hlt">infrasound</span> and sham <span class="hlt">infrasound</span>. There were no symptomatic changes in the low-expectancy group. Healthy volunteers, when given information about the expected physiological effect of <span class="hlt">infrasound</span>, reported symptoms that aligned with that information, during exposure to both <span class="hlt">infrasound</span> and sham <span class="hlt">infrasound</span>. Symptom expectations were created by viewing information readily available on the Internet, indicating the potential for symptom expectations to be created outside of the laboratory, in real world settings. Results suggest psychological expectations could explain the link between wind turbine exposure and health complaints.</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>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('https://www.osti.gov/scitech/biblio/7077711','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7077711"><span>The effects of high level <span class="hlt">infrasound</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Johnson, D.L.</p> <p>1980-02-01</p> <p>This paper will attempt to survey the current knowledge on the effects of relative high levels of <span class="hlt">infrasound</span> on humans. While this conference is concerned mainly about hearing, some discussion of other physiological effects is appropriate. Such discussion also serves to highlight a basic question, 'Is hearing the main concern of <span class="hlt">infrasound</span> and low frequency exposure, or is there a more sensitive mechanism'. It would be comforting to know that the focal point of this conference is indeed the most important concern. Therefore, besides hearing loss and auditory threshold of infrasonic and low frequency exposure, four other effects will be provided. These are performance, respiration, annoyance, and vibration.</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><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/2009EGUGA..11.7845Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.7845Z"><span>Using the UFL-8 UV fluorescent LIDAR to collect <span class="hlt">ground</span> <span class="hlt">truth</span> data for calibrating MODIS based CDOM, chlorophyll and suspended sediment measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zlinszky, A.; Pelevin, V.; Goncharenko, I.; Soloviev, D.; Molnár, G.</p> <p>2009-04-01</p> <p>Satellite remote sensing of water quality parameters is becoming a routine method in oceanological applications around the world. One of the main difficulties of calibrating satellite images to map water quality parameters is the large number and high spatial coverage of <span class="hlt">ground</span> <span class="hlt">truth</span> data needed. The UFL-8 fluorescent LIDAR developed by the Shirshov Oceanological Institute of the Russian Academy of Sciences measures CDOM, chlorophyll and suspended sediment near-surface concentrations optically in situ, on a travelling boat, and so is capable of a large number of widespread measurements very quickly. The registration of the measured values is connected to a GPS, so all measurements are geo-tagged and can be used for interpolating maps of the measured parameters. Since this instrument also has to be calibrated, some water samples have to be collected, but the optical measurements usually show very strong correlation to the water sample data. This approach was tested on Lake Balaton, Hungary in September 2008. Lake Balaton is characterized by its large area (597 km2), elongated shape and relatively shallow water depth (avg 3,2 m). The lake has a strong trophic gradient from the SW to the NE, the main tributary river carries large amounts of CDOM and suspended sediment concentrations can be very high because the lake is shallow and the sediment is fine grained. We measured in diverse weather conditions, and in an enclosed bay, a narrow strait and a large area of open water. 28 water samples were collected during the LIDAR measurement and the CDOM, chlorophyll and suspended sediment concentrations were measured in the laboratory using classic hydrological methods. These results were used to calibrate the LIDAR measurements with R2 values between 0,90 and 0,95. The relative values measured by the LIDAR were converted to absolute values using this regression, and the point-by-point results were interpolated into a raster with a cell size equal to the spatial resolution of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912257K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912257K"><span><span class="hlt">Infrasound</span> signals from events at the DPRK test site: observations and modeling results</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; Pilger, Christoph</p> <p>2017-04-01</p> <p>Over the last ten years North Korea announced underground nuclear test explosions at its Punggyi-ri test site in October 2006, May 2009, February 2013 as well as in January and September 2016. For the test in February 2013 <span class="hlt">infrasound</span> arrivals are clearly seen in recordings at IMS station IS45 in Russia. These have been associated to the event in the Reviewed Event Bulletin (REB) along with an arrival for IMS station IS30, which appears hidden in the background noise of the waveforms. Even before these <span class="hlt">infrasound</span> arrivals were detected, there have been reports from <span class="hlt">infrasound</span> signals observed at a network of national <span class="hlt">infrasound</span> stations in South Korea for the May 2009 events. These stations subsequently were also reported to have detected the 2013 event acoustically. More recently it was found for IS45 that it may have detections from the January 2016 underground nuclear explosion. Based on these reports we undertook a comprehensive study and searched for <span class="hlt">infrasound</span> arrivals in the data of two IMS stations, IS30 and IS45, that could have originated from near-<span class="hlt">source</span> conversion near the primary nuclear explosion <span class="hlt">source</span>. For all events analyzed using the frequency-wavenumber (F-K) technique, we find <span class="hlt">infrasound</span> signals, except for the events in 2009 and September 2016, that can be attributed to the <span class="hlt">source</span> at the test site, in terms of appropriate arrival directions and apparent velocities. For the 2009 event we find a late acoustic arrival at IS45 corresponding to a previously observed arrival arriving early at South Korean stations, which are located in the opposite direction of IS45. We apply propagation modeling using ray tracing and parabolic equation calculations in order to verify all observed <span class="hlt">infrasound</span> detections at the IMS stations as well as reported arrivals from a station in South Korea. Finally we also examined the case of the 12 May 2010 event, for which we find weak or spurious detections, but which we can model sufficiently well, so that we can not rule</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSIS51A..01R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSIS51A..01R"><span>pCO2 time series <span class="hlt">ground</span> <span class="hlt">truthing</span> and internal consistency at the Gray's Reef mooring (NDBC-41008) in the South Atlantic Bight</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reimer, J.; Cai, W. J.; Noakes, S.; Hu, X.; Chen, B.; Wang, A. Z.; Jiang, L.; Salisbury, J.; Wanninkhof, R. H.; Barbero, L.; Feely, R. A.; Sutton, A.; Mathis, J. T.; Sabine, C. L.</p> <p>2016-02-01</p> <p>Periodic cruises allow us to <span class="hlt">ground</span> <span class="hlt">truth</span> autonomous moored time series of pCO2 via underway system measurements and discrete bottle samples for carbonate parameters (DIC, TA, pH). These time series are essential for monitoring ocean acidification (OA), yet their performance with respect to internal consistency is not yet widely documented. During cruises we focus extra effort at the Gray's Reef (GR) mooring to <span class="hlt">ground</span> <span class="hlt">truth</span> and perform inter-consistency checks on our instrumentation by collecting water samples for carbonate parameters as well as underway pCO2. We remain as close to the GR mooring as possible for an extended period, up to several hours. Cruises include seasonal 2005-2015 and the three major east coast efforts: GOMECC I (Aug. 2007), GOMECC II (Aug. 2012), and ECOA (July 2015). We compare mooring and underway observations, which for the three major cruises agreed within ±8 µatm, with differences likely due to spatial heterogeneity and known system uncertainty. With bottle data we also calculate pCO2 from the DIC-TA pair, for which we have the most observations, which agrees with the mooring within ±17 µatm, approximately ¼ of the mean daily variability of the GR mooring time series (2006-2014). One of the goals of autonomous moored time series is to use continuous salinity to estimate TA (using known regional linear models), then use TA and pCO2 to calculate the other parameters. An internal consistency check for the three major cruises between the various discrete measured parameters and calculated mooring parameters all result in Ωar values, the OA biological measure, within the best-practices uncertainty range of ±0.2 units. These preliminary results GOMECC's I and II and ECOA show that the mooring time series can be used to calculate DIC, TA, pH, Ωar, however ongoing work seeks to incorporate smaller scale regional cruises. Finally, this work may be a guide in other regional intercomparisons across platforms.</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://adsabs.harvard.edu/abs/2013AGUFM.S14A..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S14A..07M"><span>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://www.dtic.mil/docs/citations/AD1006592','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1006592"><span>Measurement of <span class="hlt">Infrasound</span> from the Marine Environment</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-09-01</p> <p>heave, as measured by the sea surface spectrum, is shown to occupy a significant portion of the <span class="hlt">infrasound</span> receive frequency band. Measurements were...taken with a microbarometer fielded on board a ship during an at- sea experiment. The collected sound pressure data shows the interference effects of...6 WIND AND OCEAN SURFACE ROUGHNESS .............................................................. 6 SEA SURFACE SPECTRUM</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>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><span class="hlt">Infrasound</span> Signal Characteristics from Small Earthquakes</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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><span class="hlt">Infrasound</span> Signal Characteristics from Small Earthquakes</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">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://www.dtic.mil/docs/citations/ADA516178','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA516178"><span><span class="hlt">Infrasound</span> Signals from Ground-Motion <span class="hlt">Sources</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2008-09-01</p> <p>piston. Let the piston displacement be given by z = Asin(2π ft) , (11) where A is the amplitude of the motion, f is frequency, and t is time...13) can be rewritten as (for the maximum value) p(h) = ρcAa2y = 2π 2Aρ f 2R2 h . (17) Evaluation then requires only the displacement...nuclear explosion, Amparo Corporation report (unpublished). 2008 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies 920</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>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('https://www.osti.gov/scitech/biblio/15001667','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/15001667"><span>Evaluation of <span class="hlt">Infrasound</span> and Strobe Lights for Eliciting 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>2001-12-01</p> <p>Laboratory tests were conducted using juvenile chinook salmon Oncorhynchus tshawytscha, 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. The objective of these tests was to determine if juvenile salmonids could be deterred from entrainment at water diversion structures. 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 and by observing startle and habituation responses. Wild chinook salmon (40-45 mm TL) and hatchery reared chinook salmon (45-50 mm TL) exhibited avoidance responses when initially exposed to a 10-Hz volume displacement <span class="hlt">source</span> of <span class="hlt">infrasound</span>. Rainbow and eastern brook trout (25-100 mm TL) did not respond with avoidance or other behaviors to <span class="hlt">infrasound</span>. Evidence of 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 consistent movement in wild chinook salmon (60% of the tests), hatchery reared chinook salmon (50%), and rainbow trout (80%). No measurable responses were observed for brook trout. Results indicate that consistent, repeatable responses can be elicited from some fish using high-intensity strobe lights under a controlled laboratory testing. The species 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.</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>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/2016JGRD..12114651Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..12114651Z"><span>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/2017EGUGA..19.9197P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9197P"><span>LIF LiDAR high resolution <span class="hlt">ground</span> <span class="hlt">truth</span> data, suitable to validate medium-resolution bands of MODIS/Terra radiometer in case of inner waterbody ecological monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelevin, Vadim; Zavialov, Peter; Zlinszky, Andras; Khimchenko, Elizaveta; Toth, Viktor; Kremenetskiy, Vyacheslav</p> <p>2017-04-01</p> <p>The report is based on field measurements on the lake Balaton (Hungary) in September 2008 as obtained by Light Induced Fluorescence (LIF) portable LiDAR UFL-8. It was tested in natural lake waters and validated by contact conventional measurements. We had opportunity to compare our results with the MODIS/Terra spectroradiometer satellite images received at the satellite monitoring station of the Eötvös Loránd University (Budapest, Hungary) to make an attempt of lidar calibration of satellite medium-resolution bands data. Water quality parameters were surveyed with the help of UFL-8 in a time interval very close to the satellite overpass. High resolution maps of the chlorophyll-a, chromophoric dissolved organic matter and total suspended sediments spatial distributions were obtained. Our results show that the resolution provided by laboratory measurements on a few water samples does not resemble actual conditions in the lake, and it would be more efficient to measure these parameters less accurately but in a better spatial distribution with the LiDAR. The UFL instrument has a great potential for being used for collecting <span class="hlt">ground</span> <span class="hlt">truth</span> data for satellite remote sensing of these parameters. Its measurement accuracy is comparable to classic water sample measurements, the measurement speed is high and large areas can be surveyed in a time interval very close to the satellite overpass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3225128','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3225128"><span>Gebiss: an ImageJ plugin for the specification of <span class="hlt">ground</span> <span class="hlt">truth</span> and the performance evaluation of 3D segmentation algorithms</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2011-01-01</p> <p>Background Image segmentation is a crucial step in quantitative microscopy that helps to define regions of tissues, cells or subcellular compartments. Depending on the degree of user interactions, segmentation methods can be divided into manual, automated or semi-automated approaches. 3D image stacks usually require automated methods due to their large number of optical sections. However, certain applications benefit from manual or semi-automated approaches. Scenarios include the quantification of 3D images with poor signal-to-noise ratios or the generation of so-called <span class="hlt">ground</span> <span class="hlt">truth</span> segmentations that are used to evaluate the accuracy of automated segmentation methods. Results We have developed Gebiss; an ImageJ plugin for the interactive segmentation, visualisation and quantification of 3D microscopic image stacks. We integrated a variety of existing plugins for threshold-based segmentation and volume visualisation. Conclusions We demonstrate the application of Gebiss to the segmentation of nuclei in live Drosophila embryos and the quantification of neurodegeneration in Drosophila larval brains. Gebiss was developed as a cross-platform ImageJ plugin and is freely available on the web at http://imaging.bii.a-star.edu.sg/projects/gebiss/. PMID:21668958</p> </li> <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><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/2017EGUGA..1913671H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913671H"><span>Using the IMS <span class="hlt">infrasound</span> network for the identification of mountain-associated waves and gravity waves hotspots</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hupe, Patrick; Ceranna, Lars; Pilger, Christoph; Le Pichon, Alexis</p> <p>2017-04-01</p> <p>The <span class="hlt">infrasound</span> network of the International Monitoring System (IMS) has been established for monitoring the atmosphere to detect violations of the Comprehensive nuclear-Test-Ban Treaty (CTBT). The IMS comprises 49 certified <span class="hlt">infrasound</span> stations which are globally distributed. Each station provides data for up to 16 years. Due to the uniform distribution of the stations, the IMS <span class="hlt">infrasound</span> network can be used to derive global information on atmospheric dynamics' features. This study focuses on mountain-associated waves (MAWs), i.e. acoustic waves in the frequency range between approximately 0.01 Hz and 0.05 Hz. MAWs can be detected in <span class="hlt">infrasound</span> data by applying the Progressive Multi-Channel Correlation (PMCC) algorithm. As a result of triangulation, global hotspots of MAWs can be identified. Previous studies on gravity waves indicate that global hotspots of gravity waves are similar to those found for MAWs by using the PMCC algorithm. The objective of our study is an enhanced understanding of the excitation <span class="hlt">sources</span> and of possible interactions between MAWs and gravity waves. Therefore, spatial and temporal correlation analyses will be performed. As a preceding step, we will present (seasonal) hotspots of MAWs as well as hotspots of gravity waves derived by the IMS <span class="hlt">infrasound</span> network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.1122G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.1122G"><span>Methane emission estimates from rice fields using <span class="hlt">ground</span> <span class="hlt">truths</span> and GIS/ RS approach for Karnal in Haryana-India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gupta, Prabhat; Gupta, Vandana; Chandna, Parvesh; Kumar, Krishan; Ladha, J. K.</p> <p></p> <p>Methane (CH4 ) is an important atmospheric greenhouse gas and has been estimated to account for 15-20 % of current radiative forcing. Rice cultivation has been identified as one of the important anthropogenic <span class="hlt">sources</span> of CH4 and the type of water regime has been a major <span class="hlt">source</span> of uncertainty in CH4 emission estimates and has direct bearing on its emissions. The present study aims to fill the gaps in uncertainty by adopting RS/ GIS based approach for the rice acreage estimation under different water regimes, so as to obtain CH4 emission estimates at the block level for Karnal district in Haryana state of India, using water regime specific methane emission factors (EF) generated from earlier emission data without any organic amendments and for low soil organic carbon. Total rice area was estimated using IRS LISS III - P6 satellite data of kharif season 2006. A survey was done from the rice-growing farmers across the village clusters of 3 blocks (Indri, Karnal and Nilokheri) of Karnal district, to capture the spatial variability of water regimes and its corresponding layer has been generated in GIS using inverse distance weightage (IDW) interpolation. The resulting spatial variability of water regimes was 42, 44 and 14% for MA, SA and CF, respectively. The overlay and intersection of thematic layer of rice crop with the water regime and administrative block boundary layers was done using GIS tools to arrive at the rice area under different water regimes at block level for Karnal. The annual CH4 emission from paddy fields of 3 blocks of Karnal district was estimated, using IPCC-1997 methodology, as the product of the rice area under each water regime of paddy growing ecosystem with the corresponding CH4 emission factors, at block level. The total budget, which is the sum of emissions, from each water regime at block level, was estimated to be 5.14 + 1.7 Gg y-1 .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRD..120.9855M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRD..120.9855M"><span>On <span class="hlt">infrasound</span> generated by wind farms and its propagation in low-altitude tropospheric waveguides</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; Blom, Philip; Jones, Kyle</p> <p>2015-10-01</p> <p><span class="hlt">Infrasound</span> from a 60-turbine wind farm was found to propagate to distances up to 90 km under nighttime atmospheric conditions. Four <span class="hlt">infrasound</span> sensor arrays were deployed in central New Mexico in February 2014; three of these arrays captured <span class="hlt">infrasound</span> from a large wind farm. The arrays were in a linear configuration oriented southeast with 13, 54, 90, and 126 km radial distances and azimuths of 166°, 119°, 113°, and 111° from the 60 1.6 MW turbine Red Mesa Wind Farm, Laguna Pueblo, New Mexico, USA. Peaks at a fundamental frequency slightly below 0.9 Hz and its harmonics characterize the spectrum of the detected <span class="hlt">infrasound</span>. The generation of this signal is linked to the interaction of the blades, flow gradients, and the supporting tower. The production of wind-farm sound, its propagation, and detection at long distances can be related to the characteristics of the atmospheric boundary layer. First, under stable conditions, mostly occurring at night, winds are highly stratified, which enhances the production of thickness sound and the modulation of other higher-frequency wind turbine sounds. Second, nocturnal atmospheric conditions can create low-altitude waveguides (with altitudes on the order of hundreds of meters) allowing long-distance propagation. Third, night and early morning hours are characterized by reduced background atmospheric noise that enhances signal detectability. This work describes the characteristics of the <span class="hlt">infrasound</span> from a quasi-continuous <span class="hlt">source</span> with the potential for long-range propagation that could be used to monitor the lower part of the atmospheric boundary layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeoRL..29.1886L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeoRL..29.1886L"><span>Ground-coupled air waves and diffracted <span class="hlt">infrasound</span> from the Arequipa earthquake of June 23, 2001</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.; Guilbert, J.; Vega, A.; Garcés, M.; Brachet, N.</p> <p>2002-09-01</p> <p>On June 23, 2001, a strong earthquake measuring Mw 8.4 occurred along the coast of south-central Peru. Coherent infrasonic waves were detected over a period of one hour by the IS08 <span class="hlt">infrasound</span> station in Bolivia. Analysis of the ground-coupled air waves shows that the rupture propagated from the northwestern to the southeastern part of the fault with a rupture velocity of 3.3 km/s. The azimuth variation of the infrasonic waves is attributed to a distribution of secondary <span class="hlt">sources</span> along the highest mountain ranges, which excite infrasonic waves that are diffracted to the ground. The predominant <span class="hlt">source</span> of <span class="hlt">infrasound</span> is likely distributed along the Andean Cordillera. Using the azimuth and arrival time determination, the horizontal scale size of the distant <span class="hlt">source</span> regions of infrasonic waves is reconstructed over distances greater than 400 km.</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>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://www.osti.gov/scitech/servlets/purl/957399','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/957399"><span>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/2001AGUSM...S32A01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM...S32A01S"><span>The Characterization of Seismic and <span class="hlt">Infrasound</span> Signals from Mining Explosions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stump, B. W.</p> <p>2001-05-01</p> <p>Implementation of the Comprehensive Test Ban Treaty introduces complexities to nuclear test monitoring that will be addressed by wide access to data from an international monitoring system that includes seismic, hydroacoustic, infrasonic and radionuclide sensors. These sensors will detect a myriad of natural and man-made events and be used by Treaty signatories to identify events that have explosive characteristics and might be clandestine nuclear tests. Detection and identification of seismic events at a lower magnitude threshold (mb = 3.5 and lower) increases the number of events that must be scrutinized. <span class="hlt">Source</span> identification at small magnitude will not be limited to the separation of single-fired nuclear explosions from earthquakes but will include explosions designed for construction and mining. It is important that the signals from construction and mining explosions are properly identified to avoid possible false alarms of the monitoring system. This paper will review current work in discriminating mining explosions from earthquakes and single-fired explosions using seismic observations. Numerous <span class="hlt">source</span> models for mining explosions exist and provide some basis for understanding the resulting seismic signatures. The role of mining explosions as <span class="hlt">ground</span> <span class="hlt">truth</span> for the monitoring system will also be explored. The inclusion of infrasonic data as part of the IMS introduces a potential for the combined use of seismic and infrasonic data for the identification of near-surface explosions. The generation and, to a lessor extent, the propagation of mining explosion infrasonic signals is not well understood but empirical data attests to its future utility. Problematic mining events that include the simultaneous detonation of explosives will also be discussed.</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/2003AGUFMPP22C..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMPP22C..03P"><span>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('http://adsabs.harvard.edu/abs/2011AGUFM.A31A0049L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31A0049L"><span>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://adsabs.harvard.edu/abs/2017EGUGA..19.2989W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2989W"><span>Addressing the social dimensions of citizen observatories: The <span class="hlt">Ground</span> <span class="hlt">Truth</span> 2.0 socio-technical approach for sustainable implementation of citizen observatories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wehn, Uta; Joshi, Somya; Pfeiffer, Ellen; Anema, Kim; Gharesifard, Mohammad; Momani, Abeer</p> <p>2017-04-01</p> <p>Owing to ICT-enabled citizen observatories, citizens can take on new roles in environmental monitoring, decision making and co-operative planning, and environmental stewardship. And yet implementing advanced citizen observatories for data collection, knowledge exchange and interactions to support policy objectives is neither always easy nor successful, given the required commitment, trust, and data reliability concerns. Many efforts are facing problems with the uptake and sustained engagement by citizens, limited scalability, unclear long-term sustainability and limited actual impact on governance processes. Similarly, to sustain the engagement of decision makers in citizen observatories, mechanisms are required from the start of the initiative in order to have them invest in and, hence, commit to and own the entire process. In order to implement sustainable citizen observatories, these social dimensions therefore need to be soundly managed. We provide empirical evidence of how the social dimensions of citizen observatories are being addressed in the <span class="hlt">Ground</span> <span class="hlt">Truth</span> 2.0 project, drawing on a range of relevant social science approaches. This project combines the social dimensions of citizen observatories with enabling technologies - via a socio-technical approach - so that their customisation and deployment is tailored to the envisaged societal and economic impacts of the observatories. The projects consists of the demonstration and validation of six scaled up citizen observatories in real operational conditions both in the EU and in Africa, with a specific focus on flora and fauna as well as water availability and water quality for land and natural resources management. The demonstration cases (4 EU and 2 African) cover the full 'spectrum' of citizen-sensed data usage and citizen engagement, and therefore allow testing and validation of the socio-technical concept for citizen observatories under a range of conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18287376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18287376"><span>Neighborhood socioeconomic deprivation and minority composition are associated with better potential spatial access to the <span class="hlt">ground-truthed</span> food environment in a large rural area.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sharkey, Joseph R; Horel, Scott</p> <p>2008-03-01</p> <p>Little is known about spatial inequalities and potential access to the food environment in rural areas. In this study, we assessed the food environment in a 6-county rural region of Texas (11,567 km2) through <span class="hlt">ground-truthed</span> methods that included direct observation and on-site Global Positioning System technology to examine the relationship between neighborhood inequalities (e.g., socioeconomic deprivation and minority composition) and network distance from all 101 rural neighborhoods to the nearest food store (FS). Neighborhood deprivation was determined from socioeconomic characteristics using 2000 census block group (CBG) data. Network distances were calculated from the population-weighted center of each CBG to the nearest supermarket, grocery, convenience, and discount store. Multiple regression models examined associations among deprivation, minority composition, population density, and network distance to the nearest FS. The median distance to the nearest supermarket was 14.9 km one way (range 0.12 to 54.0 km). The distance decreased with increasing deprivation, minority composition, and population density. The worst deprived neighborhoods with the greatest minority composition had better potential spatial access to the nearest FS. For >20% of all rural residents, their neighborhoods were at least 17.7 km from the nearest supermarket or full-line grocery or 7.6 km from the nearest convenience store. This makes food shopping a challenge, especially in rural areas that lack public transportation and where many have no vehicular access. Knowledge of potential access to the food environment is essential for combining environmental approaches and health interventions so that families, especially those in rural areas, can make healthier food choices.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/27782589','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27782589"><span>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('https://ntrs.nasa.gov/search.jsp?R=19830017020&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTruth%2BRadicality','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830017020&hterms=Truth+Radicality&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTruth%2BRadicality"><span><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('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><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/2012JASTP..80..208E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JASTP..80..208E"><span><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://www.osti.gov/scitech/servlets/purl/629378','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/629378"><span><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/2009AGUFM.V23D2122M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V23D2122M"><span>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>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/2011JVGR..199....1J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JVGR..199....1J"><span>Characterizing complex eruptive activity at Santiaguito, Guatemala using <span class="hlt">infrasound</span> semblance in networked arrays</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.; Lees, J.; Varley, N.</p> <p>2011-01-01</p> <p>We implement an <span class="hlt">infrasound</span> semblance technique to identify acoustic <span class="hlt">sources</span> originating from volcanic vents and apply the technique to the generally low-amplitude <span class="hlt">infrasound</span> (< 3 Pa at 1 km) signals produced by Santiaguito dome in Guatemala. Semblance detection is demonstrated with data collected from two-element miniature arrays with ~ 30 m spacing between elements. The semblance technique is effective at identifying a range of eruptive phenomena, including pyroclastic-laden eruptions, vigorous degassing events, and rockfalls, even during periods of high wind contamination Many of the detected events are low in amplitude (tens of mPa) such that they are observed only by select arrays positioned with proximity and line-of-sight to the <span class="hlt">source</span>. Larger events, such as the pyroclastic-laden eruptions, which occurred bi-hourly in 2009, were detected by all five arrays and produced an infrasonic signal that was correlated across the network. Network correlated events can be roughly located and map to the summit of the Caliente Vent where pyroclastic-laden eruptions originate. In general, the degree of Santiaguito <span class="hlt">infrasound</span> event correlation is poor across the network, suggesting that complex <span class="hlt">source</span> geometry contributes to asymmetric sound radiation.</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>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('http://adsabs.harvard.edu/abs/2015EGUGA..17.4688P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4688P"><span>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>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://adsabs.harvard.edu/abs/2016AGUFMNH53D..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMNH53D..07L"><span>Balloon Borne <span class="hlt">Infrasound</span> Platforms for Remote 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>Lees, J. M.; Bowman, D. C.</p> <p>2016-12-01</p> <p>In the last three years several NASA supported balloon launches were instrumented with <span class="hlt">infrasound</span> sensors to monitor acoustic wavefields in the stratosphere. Such high altitude platforms may detect geoacoustic phenomena at much greater ranges than equivalent ground stations, and perhaps record sound waves that rarely reach the Earth's surface. Since acoustic waves are a key diagnostic for several natural hazards (volcanic eruptions, severe storms, and tsunamis, for example), the increased range and spatial coverage of balloon borne arrays promise greater quantification and perhaps early warning of such events. Before this can be accomplished, the performance of stratospheric arrays must be compared to tthat of those on the ground. Here, we show evidence for 0.2 Hz <span class="hlt">infrasound</span> associated with oceanic oscillations recorded during night time hours of the flights, consistent with concurrent ground recordings on the east and west coasts of North America. We also report numerous narrow band acoustic signals (5-30 Hz) that resemble recordings made in in the 1960's, the last time microphones were lofted into the stratosphere. Theoretical and ground based observational data from Rind(1977) indicate loss of acoustic energy in the thermosphere, where heating of the upper atmosphere is predicted to be on the order of 30-40 degrees Kelvin per day. We propose testing these ideas by using extensive ground arrays recently deployed in North America in conjunction with airborne platforms installed in the mid-stratosphere. New experiments scheduled for 2016 include circumnavigation of Antarctica (collected in June) as well as two proposed flights in New Mexico in September. The flights are designed to both capture known acoustic <span class="hlt">sources</span> as well as events of opportunity.</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>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://adsabs.harvard.edu/abs/2016EGUGA..1814909G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814909G"><span><span class="hlt">Infrasound</span> of basaltic effusive activity at Piton de la Fournaise Volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Genco, Riccardo; Valade, Sebastien; Villeneuve, Nicolas; Peltier, Aline; Ferrazzini, Valérie; Di Muro, Andrea; Ripepe, Maurizio</p> <p>2016-04-01</p> <p>On August 24th 2015, a 67 days long eruptive activity started at Piton de la Fournaise Volcano. During the last phases of the eruption we deployed a portable, small aperture, infrasonic array which allowed us to record unprecedented data from effusive volcanic activity. The array consisted on four, few tens of meters spaced, <span class="hlt">infrasound</span> pressure sensors and was installed on the outer rim of the Enclos Foqué, roughly 2.5 km far from the active vent, sited on the southern flank of the central cone. The system was almost continuously operating from October, 15th to December, 7th 2015, thus recording the end of the first eruptive phase (Autust 24th - October 17th) as well as the two short-living following phases (from 22 to 24 and from 29 to 31 October, 2015). The <span class="hlt">infrasound</span> records have been coupled with discrete high-rate (30 Hz) thermal and visible imagery acquisitions located at a short distance from the vent (100-200 m) providing detailed information on the eruptive <span class="hlt">source</span> dynamics. The comparison with seismic and ground tilt data recorded by the permanent network operated by the Observatoire Volcanologique du Piton de la Fournaise (OVPF), shows that <span class="hlt">infrasound</span> can be succesfully used to locate the <span class="hlt">source</span>, detect the onset, and the end, of the effusive phases as well as accurately track the time evolution of the effusive process. We present results which allows a detailed analysis of the shallow magma dynamics during the effusive activity at Piton de la Fournaise Volcano. As far as we know these are amongst the few rare <span class="hlt">infrasound</span> dataset reported for this style of basaltic volcanic activity.</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>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_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://www.osti.gov/scitech/servlets/purl/961863','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/961863"><span>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://www.dtic.mil/docs/citations/ADA569478','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA569478"><span><span class="hlt">Infrasound</span> as a Depth Discriminant</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-09-01</p> <p>Technologies 659 Data Analysis An overall comparison of the detectability of shallow and deep earthquakes is given in Figure 3 (noting that this...acquisition of a high-quality dataset comprising both regional (Western US) and global components. An analysis of detectability highlights the fact that...identification through analysis of the variability of the repeating <span class="hlt">source</span>. We discuss steps that are being taken to better constrain <span class="hlt">source</span>, path, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S31A2696S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S31A2696S"><span>IMS Seismic and <span class="hlt">Infrasound</span> Stations Instrumental Challenges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Starovoit, Y. O.; Dricker, I. G.; Marty, J.</p> <p>2016-12-01</p> <p>The IMS seismic network is a set of monitoring facilities including 50 primary stations and 120 auxiliary stations. Besides the difference in the mode of data transmission to the IDC, technical specifications for seismographic equipment to be installed at both types of stations are essentially the same. The IMS <span class="hlt">infrasound</span> network comprises 60 facilities with the requirement of continuous data transmission to IDC. The objective of this presentation is to report instrumental challenges associated with both seismic and <span class="hlt">infrasound</span> technologies. In context of specifications for IMS seismic stations it was stressed that verification seismology is concerned with searching of reliable methods of signal detections at high frequencies. In the meantime MS/mb screening criteria between earthquakes and explosions relies on reliable detection of surface waves. The IMS seismic requirements for instrumental noise and operational range of data logger are defined as certain dB level below minimum background within the required frequency band from 0.02 to 16Hz. The type of sensors response is requested to be flat either in velocity or acceleration. The compliance with IMS specifications may thus introduce a challenging task when low-noise conditions have been recorded at the site. It means that as a station noise PSD approaches the NLNM it requires a high sensitive sensor to be connected to a quiet digitizer which may cause a quick system clip and waste of the available dynamic range. The experience has shown that hybrid frequency response of seismic sensors where combination of flat to velocity and flat to acceleration portions of the sensor frequency response may provide an optimal solution for utilization of the dynamic range and low digitizer noise floor. Vast efforts are also being undertaken and results achieved in the <span class="hlt">infrasound</span> technology to standardize and optimize the response of the Wind-Noise Reduction System within the IMS <span class="hlt">infrasound</span> passband from 0.02-4Hz and to deploy</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>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('http://adsabs.harvard.edu/abs/2016EGUGA..18.8524B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8524B"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/24116535','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24116535"><span>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>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>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><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>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>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/2012EGUGA..1412986R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412986R"><span>Seismic and <span class="hlt">infrasound</span> monitoring at Cotopaxi volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruiz, M.; Yepes, H.; Palacios, P.; Troncoso, L.; Mothes, P.; Kumagai, H.</p> <p>2012-04-01</p> <p>Cotopaxi is an active ice-capped volcano (5967m) located 60 km SE from Quito and is one of the largest and more hazardous volcanoes in the Northern Andes. Monitoring of Cotopaxi, using seismic and <span class="hlt">infrasound</span> techniques has improving significantly since 1976, when three short-period stations were deployed temporarily in response to an increase of fumarolic activity. Later in May 1977, a short-period vertical seismometer was installed on the NW flank at 7 km from the crater. Since 1986 a short-period seismic station is working at the northern flank of Cotopaxi and transmitting analog data to the Instituto Geofisico. In 1993 a network of 4 short-period seismic stations were installed on all flanks of the volcano. Between March 1996 and June 1997 a temporal network of 16 stations were deployed for several months in order to study local seismicity and internal structure (Metaxian et al., 1999). Since 2006, a network of five broad band stations (0.02-60 s) and low-frequency <span class="hlt">infrasound</span> sensors (0.01-10 s) were installed through a JICA Cooperation Project (Kumagai et al., 2007). Data is transmitted to the Instituto Geofisico via a digital radio system. Through this network, LP and VLP events have been recorded and analyzed (Molina et al., 2008). VLP events were located beneath the north and north-eastern flank using waveform inversion and amplitude distribution methods (Kumagai et al., 2010).</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>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>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/2017EGUGA..1919140K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919140K"><span>Volcanic <span class="hlt">Infrasound</span> - A technical topic communicated in an entertaining way</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kerlow, Isaac</p> <p>2017-04-01</p> <p>Volcanic <span class="hlt">Infrasound</span> is a 9-minute film about using <span class="hlt">infrasound</span> waves to detect and measure volcanic eruptions as they unfold. The film was made by an interdisciplinary team of filmmakers and scientists for a general audience. The movie explains the basic facts of using <span class="hlt">infrasound</span> to detect volcanic activity, and it also shows volcano researchers as they install <span class="hlt">infrasound</span> sensors in a natural reserve in the middle of the city. This is the first in a series of films that seek to address natural hazards of relevance to Singapore, a country shielded from violent hazards. This presentation reviews the science communication techniques and assumptions used to develop and produce this entertaining scientific documentary short. Trailer: https://vimeo.com/192206460</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>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/2016DPS....4832704Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4832704Y"><span>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>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>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/2012EGUGA..14.7532P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.7532P"><span>Effects of fine-scale orography 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>Pilger, C.; Streicher, F.; Wüst, S.; Bittner, M.</p> <p>2012-04-01</p> <p>The sensitivity of <span class="hlt">infrasound</span> propagation to reflections by a non-flat surface is investigated within this study. <span class="hlt">Infrasound</span> propagation modelling is performed at the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) using improved 3d ray-tracing methods (HARPA/DLR). Terrain information is newly included in the modelling using a high-resolution digital surface model. The SRTM30-PLUS digital surface model incorporates the DLR "Shuttle Radar Topography Mission" and complementary surface information to generate a global, equidistant and complete data set for surface orography. The maximum horizontal resolution is 30 arc seconds (about 1km), the maximum vertical resolution is 1m. The resolution of the model can be adapted to the wavelength of the considered <span class="hlt">infrasound</span> signal. The orography is implemented as background data using bicubic spline interpolation and thus provides smooth surface layer information for <span class="hlt">infrasound</span> propagation modelling. First modelling cases containing the European Alps region show that orography has a significant influence on <span class="hlt">infrasound</span> propagation. Ducts and propagation patterns can be veritably changed according to reflection by non-flat fine-scale orography. First results on the sensitivity of <span class="hlt">infrasound</span> propagation to surface orography will be presented.</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://adsabs.harvard.edu/abs/2014AGUFM.V23C4812M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V23C4812M"><span>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>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/2017EGUGA..1914065P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914065P"><span><span class="hlt">Infrasound</span> detections of polar lows during the last three winters from the Norwegian <span class="hlt">infrasound</span> station #IS18.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pol, Katy; Claud, Chantal; Rojo, Maxence; Le Pichon, Alexis; Hauchecorne, Alain; Blanc, Elisabeth</p> <p>2017-04-01</p> <p>Polar lows are intense and very short (1 or 2 days) high latitude maritime cyclones of small horizontal (few hundred kilometers) and vertical scales (up to 5 km), that develop when very cold air is advected over relatively warmer water. Associated with severe meteorological conditions (large ocean waves, heavy precipitations, thunders and low visibility), they represent a real hazard for maritime and coastal activities but remain difficult to forecast, because of their rarity and the scarcity of observations in polar regions where they develop. With the signature of the Comprehensive Nuclear-Test-Ban Treaty (CTBT - http://www.ctbto.org) in 1996, a global <span class="hlt">infrasound</span> monitoring network (named International Monitoring System - IMS) has been developed and provides a potential new technology to detect polar lows. According to Orbaek and Naustvik (1995), polar lows are indeed assumed to generate strong <span class="hlt">infrasound</span> signals in the frequency range of 0.2-13 Hz, which are detectable over distances of up to 1000km. However, until recently and the exploratory study of Claud et al. (submitted), no similar study was available to generalize the possibility to use <span class="hlt">infrasound</span>, as an alternative technology to detect and monitor polar lows. By analysing the <span class="hlt">infrasound</span> measurements of the Norwegian <span class="hlt">infrasound</span> station #IS18, we here try to detect the <span class="hlt">infrasound</span> signatures of dated polar lows in the Barents and Norwegian Seas, during the 2013-2014, 2014-2015 and 2015-2016 winters.</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>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>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/2014EGUGA..16.6407K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6407K"><span>Joint interpretation of <span class="hlt">infrasound</span>, acoustic, and seismic waves from meteorites: Chelyabinsk bolide and other events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitov, Ivan; Rozhkov, Mikhail; Bobrov, Dmitry; Ovtchinnikov, Vladimir</p> <p>2014-05-01</p> <p>Meteorites are always the events that testing the capability of the International Monitoring System to measure and the International Data Centre to analyze <span class="hlt">sources</span> similar to nuclear explosions. Monitoring of the Comprehensive Nuclear-Test-Ban Treaty suggests the possibility to detect <span class="hlt">infrasound</span> (acoustic) and seismic signals from atmospheric and underground events and to locate their <span class="hlt">sources</span>. Chelyabinsk meteor was one of the best exemplar in a row of other atmospheric events exposing the ability of IDC and IMS to handle the atmospheric explosions. The uniqueness of this event is that the generated seismic, acousto-seismic and <span class="hlt">infrasound</span> wave fields were recorded by considerable number of IMS stations of different technologies at wide distance range. The shock waves from the Chelyabinsk meteor generated an I-phase recorded by IMS <span class="hlt">infrasound</span> stations and a series of seismic phases. The Pn-waves were observed by five near-regional seismic stations together with Sn- and Lg-waves. They are most likely associated with the impact of the meteor debris and the location associated with their <span class="hlt">source</span> differs by tens of kilometers from that obtained by Rayleigh and Love waves. The latter were generated by acoustic (low-amplitude shock) waves hitting the ground beneath the trajectory of the meteor. Surprisingly, these surface waves associated with the meteor and observed at least at distances of 45º were not associated with the event in the Reviewed Event Bulletin. This implies a conceptual gap in the IDC processing and fusion of acoustic and seismic waves. The trajectory of the meteorite built with the epicenters of seismic, acousto-seismic and <span class="hlt">infrasound</span> events is in good compliance with the trajectories built by different scientific institutions including NASA. We present an approximate distribution of energy release along the trajectory and thus the amplitude of the generated shock wave. It allows interpreting the period and amplitude dependence of the LR and LQ waves on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.209.1913G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.209.1913G"><span>A re-analysis of Carancas meteorite seismic and <span class="hlt">infrasound</span> data based on sonic boom hypothesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gainville, O.; Henneton, M.; Coulouvrat, F.</p> <p>2017-06-01</p> <p>Meteoroids entering the Earth atmosphere at high hypersonic velocities are a <span class="hlt">source</span> of sonic boom that is recorded as <span class="hlt">infrasound</span> signal at the ground level. The Carancas meteorite (Peru, 2007) is re-examined in this way as a reference case with ground crater and nearby seismic and infrasonic recordings. A new trajectory is proposed for this meteorite by minimizing the difference between computed and observed times of arrivals for geometrical arrivals. A scenario based on diffraction is proposed to explain non-geometrical arrivals. Model frequency spectra show a reasonable agreement with data, which allows estimation of the meteorite diameter in a narrow range compatible with crater observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1412617P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1412617P"><span>Design and Operation of <span class="hlt">Infrasound</span> Stations for Hazardous Weather Detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pepyne, D.</p> <p>2012-04-01</p> <p>Each year tornadoes cause property damage and death, some of which could be avoided with increased warning lead time. The year 2011 was particularly severe, with more than 1600 tornadoes causing in excess of 500 deaths in the U.S. It is known that tornadoes and their precursors generate <span class="hlt">infrasound</span> in the 0.5Hz to 10Hz frequency band, with precursors occurring some 30-60 minutes prior to tornado touch down, which is some 15-45 minutes earlier than the average tornado warning lead time in the U.S. Given the potential of <span class="hlt">infrasound</span> to improve tornado early warning and emergency response, the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), in conjunction with its research on small, boundary-layer observing X-band weather radars, has begun a research project whose goal is to combine the passive detection of tornado <span class="hlt">infrasound</span> with active tracking of the parent storms that carry the tornadoes with its weather radars. In the spring of 2011 CASA conducted an <span class="hlt">infrasound</span> field-test in Oklahoma, in the heart of the so-called "tornado-alley" where statistically the majority of springtime tornadoes in the U.S. occur. This being CASA's first <span class="hlt">infrasound</span> experiment, the goal of the field-test was to gain an understanding of the issues involved in the design and operation of <span class="hlt">infrasound</span> stations for severe weather monitoring and early warning. In this application, it is not so much the ability of <span class="hlt">infrasound</span> to travel long distances that is of importance, but rather the fact that there can be precursor signals that unlike radar do not require line-of-sight to detect. In fact, for early warning, detection distance would generally need to be less than 100 km, since a propagation delay of much more than 5 minutes would be too late. Challenges encountered included persistent <span class="hlt">infrasound</span> "clutter" from a nearby large windfarm, accurate bearing detection over a wide bandwidth with a fixed four sensor aperture, and the need to operate in the the high winds that surround</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S11C2462K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S11C2462K"><span>Is there evidence for an acoustic signal at IMS <span class="hlt">infrasound</span> stations from the North Korean event of 12 May 2010?</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.; Pilger, C.</p> <p>2016-12-01</p> <p>Over the last two years more and more evidence has been presented that a small seismic event had occurred in North Korea on 12 May 2010. Most recent work has concluded that the event shows earthquake-like features when applying event identification methods based on regional phase amplitude ratios. These findings are in contrast to previous hypotheses and identification studies which claimed that low-yield nuclear testing had been carried out. Some of these studies were based solely on radionuclide and noble gas detections found at International Monitoring System (IMS) stations as well as at national facilities. Turning to another technology, it has been shown in several studies that underground nuclear tests carried out at the Punggye-ri test site in North Korea have produced <span class="hlt">infrasound</span> signatures at the closest IMS stations I45RU and I30JP and at national <span class="hlt">infrasound</span> stations in South Korea. In particular this holds for the tests carried out in 2009, 2013 and 2016. For the 2013 test <span class="hlt">infrasound</span> arrivals have been included in the Reviewed Event Bulletin (REB) issued by the International Data Center of CTBTO. Based on this experience an effort was undertaken to analyze <span class="hlt">infrasound</span> data from these IMS stations and to search for signals that may be associated to the 12 May 2010 event. While it is not expected to obtain such a signal for an earthquake <span class="hlt">source</span> at depth, as would not be expected as well for a buried explosion <span class="hlt">source</span> of rather small magnitude, the analysis of I45RU and I30JP data suggests a very weak arrival as obtained from frequency-wavenumber analysis showing parameters similar to those obtained for the announced tests. If the features found are indeed not artifacts then one could speculate that (1) the event of concern may not be an earthquake, even though it exhibits seismic signal characteristics causing it to be classified as an earthquake, or (2) the detections may be related to incidental blasting activity in nearby quarries. Propagation modeling of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914522M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914522M"><span><span class="hlt">Infrasound</span> and seismic array analysis of snow avalanches: results from the 2015-2017 experiment in Dischma valley above Davos, Switzerland</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; van Herwijnen, Alec; Ripepe, Maurizio</p> <p>2017-04-01</p> <p>While flowing downhill a snow avalanche radiates seismic and infrasonic waves being coupled both with the ground and the atmosphere. <span class="hlt">Infrasound</span> waves are mostly generated by the powder cloud of the avalanche, while seismic waves are mostly generated by the dense flowing snow mass on the ground, resulting in different energy partitioning between seismic and <span class="hlt">infrasound</span> for different kinds of avalanches. This results into a general uncertainty on the efficiency of seismic and <span class="hlt">infrasound</span> monitoring, in terms of the size and <span class="hlt">source</span>-to-receiver distance of detectable events. Nevertheless, both seismic and <span class="hlt">infrasound</span> have been used as monitoring systems for the remote detection of snow avalanches, being the reliable detection of snow avalanches of crucial importance to better understand triggering mechanisms, identify possible precursors, or improve avalanche forecasting. We present infrasonic and seismic array data collected during the winters of 2015- 2016 and 2016-2017 in the Dischma valley above Davos, Switzerland, where a five element <span class="hlt">infrasound</span> array and a 7 element seismic array had been deployed at short distance from each other and with several avalanche paths nearby. Avalanche observation in the area is performed through automatic cameras providing additional information on the location, type (dry or wet), size and occurrence time of the avalanches released. The use of arrays instead of single sensors allows increasing the signal-to-noise ratio and identifying events in terms of back-azimuth and apparent velocity of the wave-field, thus providing indication on the <span class="hlt">source</span> position of the recorded signal. For selected snow avalanches captured with automatic cameras, we therefore perform seismic and <span class="hlt">infrasound</span> array processing to constrain the avalanche path and dynamics and investigate the partitioning of seismic and <span class="hlt">infrasound</span> energy for the different portions of the avalanche path. Moreover we compare results of seismic and <span class="hlt">infrasound</span> array processing for the</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>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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPA51A2250P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPA51A2250P"><span>Visualizing the deep end of sound: plotting multi-parameter results from <span class="hlt">infrasound</span> data analysis</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.; Taisne, B.</p> <p>2016-12-01</p> <p><span class="hlt">Infrasound</span> is sound below the threshold of human hearing: approximately 20 Hz. The field of <span class="hlt">infrasound</span> research, like other waveform based fields relies on several standard processing methods and data visualizations, including waveform plots and spectrograms. The installation of the International Monitoring System (IMS) global network of <span class="hlt">infrasound</span> arrays, contributed to the resurgence of <span class="hlt">infrasound</span> research. Array processing is an important method used in <span class="hlt">infrasound</span> research, however, this method produces data sets with a large number of parameters, and requires innovative plotting techniques. The goal in designing new figures is to be able to present easily comprehendible, and information-rich plots by careful selection of data density and plotting methods.</p> </li> <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>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>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('http://adsabs.harvard.edu/abs/2016EGUGA..1811672W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811672W"><span>Steps toward quantitative <span class="hlt">infrasound</span> propagation modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Waxler, Roger; Assink, Jelle; Lalande, Jean-Marie; Velea, Doru</p> <p>2016-04-01</p> <p>Realistic propagation modeling requires propagation models capable of incorporating the relevant physical phenomena as well as sufficiently accurate atmospheric specifications. The wind speed and temperature gradients in the atmosphere provide multiple ducts in which low frequency sound, <span class="hlt">infrasound</span>, can propagate efficiently. The winds in the atmosphere are quite variable, both temporally and spatially, causing the sound ducts to fluctuate. For ground to ground propagation the ducts can be borderline in that small perturbations can create or destroy a duct. In such cases the signal propagation is very sensitive to fluctuations in the wind, often producing highly dispersed signals. The accuracy of atmospheric specifications is constantly improving as sounding technology develops. There is, however, a disconnect between sound propagation and atmospheric specification in that atmospheric specifications are necessarily statistical in nature while sound propagates through a particular atmospheric state. In addition infrasonic signals can travel to great altitudes, on the order of 120 km, before refracting back to earth. At such altitudes the atmosphere becomes quite rare causing sound propagation to become highly non-linear and attenuating. Approaches to these problems will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912272Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912272Y"><span>Prospects for <span class="hlt">infrasound</span> bolide detections from balloon-borne platforms</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; Bowman, Daniel; Arrowsmith, Stephen; Boslough, Marc; Klein, Viliam; Ballard, Courtney; Lees, Jonathan</p> <p>2017-04-01</p> <p>We report on an experiment to assess whether balloon-borne instruments can improve sensitivities to bolides exploding in the Earth's atmosphere (essentially using the atmosphere as a witness plate to characterize the small end of the NEO (Near Earth Object) population). The CTBTO's <span class="hlt">infrasound</span> network regularly detects <span class="hlt">infrasound</span> disturbances caused by bolides, including the 15-FEB-2013 Chelybinsk impact. Balloon-borne <span class="hlt">infrasound</span> sensors should have two important advantages over ground-based <span class="hlt">infrasound</span> stations: there should be virtually no wind noise on a free-floating platform, and a sensor in the stratosphere should benefit from its location within the stratospheric duct. Balloon-borne sensors also have the disadvantage that the amplitude of <span class="hlt">infrasound</span> waves will decrease as they ascend with altitude. To test the performance of balloon-borne sensors, we conducted an experiment on a NASA high altitude (35 km) balloon launched from Ft Sumner, NM on 28-SEP-2016. We were able to put two independent <span class="hlt">infrasound</span> payloads on this flight. We arranged for three 3000-lb ANFO explosions to be detonated from Socorro, NM at 12:00, 14:00 and 16:29:59 MST. The first two explosions were detected from the NASA balloon, with the first explosion showing three separate waveforms arriving within a 25-s span. The peak-to-peak amplitude of the waveforms was about 0.06 Pa, and the cleanest microphone channel detected this waveform with an SNR greater than 20. A second balloon at 15 km altitude also detected the second explosion. We have signals from a dozen ground stations at various positions from Socorro to Ft Sumner. We will report on wave propagation models and how they compare with observations from the two balloons and the various ground-stations.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/20649183','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20649183"><span>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/2013AGUFMNH21D..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMNH21D..06P"><span>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> </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://adsabs.harvard.edu/abs/2017GeoJI.208..437T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.208..437T"><span>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/2016GeoJI.tmp..412T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.tmp..412T"><span>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/2002ASAJ..112.2380S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002ASAJ..112.2380S"><span>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/2017EGUGA..19.6097R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.6097R"><span>On modeling internal gravity wave dynamics from <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>Ribstein, Bruno; Millet, Christophe; Lott, Francois</p> <p>2017-04-01</p> <p>Low frequency acoustic waves (<span class="hlt">infrasounds</span>) are generally used to remotely detect strong explosions, using their possibility of long-distance and coherent propagation. Numerical prediction of <span class="hlt">infrasounds</span> is a complex issue due to constantly changing atmospheric conditions and to the random nature of small-scale flows. Although it is well-known that part of the upward propagating wave is refracted at stratospheric levels, where gravity waves significantly affect both the temperature and the wind, yet the process by which the gravity wave field changes some <span class="hlt">infrasound</span> arrivals remains not well understood. In the present work, we use a stochastic parameterization to model the subgrid scale gravity wave field from atmospheric states provided by ECMWF. Numerical evidence are presented showing that regardless of whether the superimposed gravity wave field possesses relatively small or large features the sensitivity of ground-based <span class="hlt">infrasound</span> signals can be significantly different. A version of the gravity wave parameterization previously tuned by co-authors for climate modeling purpose is shown to not retrieve the duration of recorded acoustic signals. A new version of the wave-parameterization is here proposed which more accurately predict the small scale content of gravity wave fields, especially in the middle atmosphere. Compare to other semi-empirical approaches one value of this new parameterization is that the gravity wave drag obtained is in agreement with observations.</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>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/2016AGUFM.V53C3099M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V53C3099M"><span>Multidirectional seismo-acoustic wavefield of strombolian explosions at Yasur, Vanuatu using a broadband seismo-acoustic network, <span class="hlt">infrasound</span> arrays, and infrasonic sensors on tethered balloons</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.; Jolly, A. D.; Fee, D.; Johnson, R.; Kilgour, G.; Christenson, B. W.; Garaebiti, E.; Iezzi, A. M.; Austin, A.; Kennedy, B.; Fitzgerald, R.; Key, N.</p> <p>2016-12-01</p> <p>Seismo-acoustic wavefields at volcanoes contain rich information on shallow magma transport and subaerial eruption processes. Acoustic wavefields from eruptions are predicted to be directional, but sampling this wavefield directivity is challenging because <span class="hlt">infrasound</span> sensors are usually deployed on the ground surface. We attempt to overcome this observational limitation using a novel deployment of <span class="hlt">infrasound</span> sensors on tethered balloons in tandem with a suite of dense ground-based seismo-acoustic, geochemical, and eruption imaging instrumentation. We present preliminary results from a field experiment at Yasur Volcano, Vanuatu from July 26th to August 4th 2016. Our observations include data from a temporary network of 11 broadband seismometers, 6 single infrasonic microphones, 7 small-aperture 3-element <span class="hlt">infrasound</span> arrays, 2 <span class="hlt">infrasound</span> sensor packages on tethered balloons, an FTIR, a FLIR, 2 scanning Flyspecs, and various visual imaging data. An introduction to the dataset and preliminary analysis of the 3D seismo-acoustic wavefield and <span class="hlt">source</span> process will be presented. This unprecedented dataset should provide a unique window into processes operating in the shallow magma plumbing system and their relation to subaerial eruption dynamics.</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>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>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="