Science.gov

Sample records for ground-truth infrasound source

  1. Comparing infrasound measurements of a ground truth source at regional distances with modeling results

    NASA Astrophysics Data System (ADS)

    Streicher, Florian; Wüst, Sabine; Bittner, Michael; Pilger, Christoph; Koch, Karl

    2013-04-01

    The infrasound stations of the International Monitoring System (IMS) have a relatively coarse geographical coverage. Even when taking national infrasound stations which are not part of the IMS into account, the inter-station spacing is still in the range of several hundreds of kilometers. For tasks involving the recovery of dynamic properties of the source and hence the understanding of the atmospheric propagation conditions of the infrasonic waves, it is important to validate the methods applied in infrasound modeling, in particular for shorter distances. The shadow zone that exists for paths between the tropospheric and stratospheric ducts thereby poses the most significant difficulty. A field study has been performed utilizing six single infrasound sensors along the great circle path between a known source (DLR engine test facility, Lampoldshausen) and a nearby receiver (BGR infrasound array I26, Bavarian Forest) covering a distance of about 320km in total. The recordings gathered give new possibilities in studying the evolution of the infrasonic wave-field to regional distances and, in particular, through the shadow zone by comparing measured signals with modeling results. In this study we thus aim at testing and improving our infrasound modeling, especially the prediction of shadow zones in ray-tracing. For numerical modeling the ray-tracer HARPA/DLR is used. Compared to its original version HARPA/DLR was improved by the integration of adequate atmospheric temperature and wind fields (ECMWF weather forecast data for altitudes up to 80km, statistical values given by the MSISE00 (temperature) and HWM07 (horizontal wind) climatologies for greater heights). The modeling shows shadow zones which extend from about 20-40km to some 130-170km for the months from December 2011 to March 2012, in good agreement with the observations. However, the modeling effort for April and May 2012 shows a much broader shadow zone, which is less conforming to the observations. Our

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Ground Truth Studies. Teacher Handbook. Second Edition.

    ERIC Educational Resources Information Center

    Boyce, Jesse; And Others

    Ground Truth 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…

  14. NASA Ground-Truthing Capabilities Demonstrated

    NASA Technical Reports Server (NTRS)

    Lopez, Isaac; Seibert, Marc A.

    2004-01-01

    NASA Research and Education Network (NREN) ground truthing is a method of verifying the scientific validity of satellite images and clarifying irregularities in the imagery. Ground-truthed imagery can be used to locate geological compositions of interest for a given area. On Mars, astronaut scientists could ground truth satellite imagery from the planet surface and then pinpoint optimum areas to explore. These astronauts would be able to ground truth 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 ground-truthing 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.

  15. 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

  16. Fiber-optic ground-truth thermometer

    SciTech Connect

    Ekdahl, C.A. Jr.; Forman, P.; Veeser, L.

    1993-07-01

    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 ground truth calibration for a satellite imaging system.

  17. GEOS-3 phase B ground truth summary

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.; Goodman, L. R.

    1975-01-01

    Ground truth 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.

  18. A Ground Truth Database of Seismo-Acoustic Events in Northern Europe

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Kværna, Tormod

    2013-04-01

    The international network of infrasound sensors records a continuous datastream containing signals from events of both known and unknown origin. For events of known origin, i.e. with the location and time well-determined, we are able to validate and improve upon our characterization of the wind and temperature structure of the atmosphere, since we can compare directly infrasonic observations with model predictions. For events of unknown origin, such as unannounced or accidental explosions or extreme natural phenomena, infrasound should ideally be exploited to locate the event(s) in time and space and to characterize the source(s). The ability to do this will clearly improve with an improved atmospheric specification and modeling capability. "Ground Truth", or GT, denotes events for which the origin time and source location are known. Calibration experiments (explosions of specified yield, time and location) have been performed in order to validate atmospheric specifications and propagation models and to investigate the detectability of infrasound over networks. However, such explosions are extremely expensive to execute and so can only sample the evolving atmosphere on a very limited number of occasions. Fortunately, many other types of explosions occur regularly. These include detonations of expired ordnance by militaries and routine quarry blasting. There are many such sources in northern Europe which generate infrasound signals detected at distances from many hundreds to several thousands of kilometers, but which also generate seismic signals which have been recorded by stations in Fennoscandia for over 25 years. The seismic signals generated by events at a given location, recorded on any given seismometer, are like a fingerprint for that source region and pattern recognition methods (e.g. waveform correlation and Empirical Matched Field Processing or EMFP) can attribute a signal to a particular source given sufficient calibration information. The seismic

  19. Improved Bayesian Infrasonic Source Localization for regional infrasound

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The mathematical framework used in 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. 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. 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.

  20. 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.

  1. Improved Bayesian Infrasonic Source Localization for regional infrasound

    DOE PAGESBeta

    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

  2. Ground Truth Sampling and LANDSAT Accuracy Assessment

    NASA Technical Reports Server (NTRS)

    Robinson, J. W.; Gunther, F. J.; Campbell, W. J.

    1982-01-01

    It is noted that the key factor in any accuracy assessment of remote sensing data is the method used for determining the ground truth, 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.

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

    SciTech Connect

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

    2009-01-01

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

  4. Ground truth data requirements for altimeter performance verification

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.

    1972-01-01

    The amount and type of ground truth required for an altimeter experiment is a function of the uncertainty in the satellite orbit, the altimeter error budget and the type of operation being performed. Ground truth requirements will be discussed with reference to three areas of operation: the global mode, the high intensity mode and calibration.

  5. Source Inversions of Volcano Infrasound: Mass Outflux and Force System for Transient Explosive Eruptions

    NASA Astrophysics Data System (ADS)

    Kim, K.; Fee, D.; Lees, J. M.; Yokoo, A.; Ruiz, M. C.

    2014-12-01

    Sources of volcano infrasound 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 source region during eruptions. Therefore, appropriate acoustic source inversions of volcano infrasound data can provide estimates of eruption parameters which are critical to understanding eruption dynamics. Reliability of the source parameters is dominantly controlled by the accuracy of the acoustic Green's functions between the source and receiver positions. Conventional source inversions of volcano infrasound, 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 source parameters, especially when the infrasound 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 infrasound 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 infrasound 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 source directivity or topographic barriers/reflections. Here the role of topography in controlling the infrasound radiation is investigated through numerical modeling, and then the observed

  6. Ground Truth Accuracy Tests of GPS Seismology

    NASA Astrophysics Data System (ADS)

    Elosegui, P.; Oberlander, D. J.; Davis, J. L.; Baena, R.; Ekstrom, G.

    2005-12-01

    As the precision of GPS determinations of site position continues to improve the detection of smaller and faster geophysical signals becomes possible. However, lack of independent measurements of these signals often precludes an assessment of the accuracy of such GPS position determinations. This may be particularly true for high-rate GPS applications. We have built an apparatus to assess the accuracy of GPS position determinations for high-rate applications, in particular the application known as "GPS seismology." The apparatus consists of a bidirectional, single-axis positioning table coupled to a digitally controlled stepping motor. The motor, in turn, is connected to a Field Programmable Gate Array (FPGA) chip that synchronously sequences through real historical earthquake profiles stored in Erasable Programmable Read Only Memory's (EPROM). A GPS antenna attached to this positioning table undergoes the simulated seismic motions of the Earth's surface while collecting high-rate GPS data. Analysis of the time-dependent position estimates can then be compared to the "ground truth," and the resultant GPS error spectrum can be measured. We have made extensive measurements with this system while inducing simulated seismic motions either in the horizontal plane or the vertical axis. A second stationary GPS antenna at a distance of several meters was simultaneously collecting high-rate (5 Hz) GPS data. We will present the calibration of this system, describe the GPS observations and data analysis, and assess the accuracy of GPS for high-rate geophysical applications and natural hazards mitigation.

  7. Fluid Impact as a Source Mechanism for Surf Infrasound

    NASA Astrophysics Data System (ADS)

    Fee, D.; Garces, M.; McNamara, S.; Aucan, J.; Merrifield, M.

    2006-12-01

    The ability to provide infrasonic estimates of breaking ocean wave height and period in shallow reefs, steep rocky coastlines, and sand beaches has been demonstrated in previous work. Yet defining the source process and isolating the source pressure function remained elusive because of ambiguity introduced by complex coastlines and multiple breaker zones. Due to the steep bathymetry and its proximity to land, the Temae reef in the northeast coast of Moorea island, French Polynesia, provided a well constrained experimental environment where individual breaking waves could be identified and recorded. Synchronous wave height, infrasonic, seismic, and visual recordings of individual waves breaking against the shallow reef ledge were made and correlated. We characterize a possible fluid impact source mechanism for surf infrasound, demonstrate the capability to acoustically track alongshore traveling (peeling) plunging waves, and confirm a relationship between ocean wave height and infrasonic amplitude. Depending on the swell and coastal conditions, estimates of ocean wave period are also possible. We also present preliminary results on near-real-time remote infrasonic monitoring of the surf zone on the North Shore of Oahu, Hawaii, during the 2006-07 Winter high surf season.

  8. Remote and Ground Truth Spectral Measurement Comparisons

    NASA Technical Reports Server (NTRS)

    Abercromby, Kira Jorgensen; Hamada, Kris; Guyote, Michael; Okada, Jennifer; Barker, Edwin

    2007-01-01

    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. Ground truth 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

  9. Ground Truth Collections for Explosions in Northern Fennoscandia and Russia

    SciTech Connect

    Harris, D B; Ringdal, F; Kremenetskaya, E; Mykkeltveit, S; Schweitzer, J.; Hauk, T; Asming, V; Rock, D; Lewis, P

    2003-07-28

    This project is providing ground-truth information on explosions conducted at the principal mines within 500 kilometers of the ARCES station, and is assembling a seismic waveform database for these events from local and regional stations. The principal mines of interest are in northwest Russia (Khibiny Massif, Olenogorsk, Zapolyamy, and Kovdor groups) and Sweden (Malmberget, Kiruna). These mines form a natural laboratory for examining the variation of mining explosion observations with source type, since they include colocated surface and underground mines and mines conducting a variety of different shot types. In September 2002 we deployed two lines of temporary stations from the Khibiny Massif through and to the north of the ARCES station. This deployment is producing data that will allow researchers to examine the variation of discriminants caused by varying source-receiver distance and the diversity of explosion types. To date, we have collected ground-truth information on 1,118 explosions in the Kola Peninsula, and have assembled waveform data for approximately 700 of these. The database includes waveforms from instruments temporarily deployed in the Khibiny Massif mines, from the Apatity network just outside of the Massif, from LVZ, KEV and ARCES, and from the stations deployed along the two lines into northern Norway. In this paper we present representative waveforms for several types of shots recorded at various regional distances. We have conducted a preliminary study of the variation of phase ratios as a function of source type. This study shows significant differences in Pd/Sn and Pd/Lg ratios for two types of mining explosions: surface ripple-fired explosions and compact underground explosions. Compact explosions are, typically, underground explosions of a few tons with only one or two short delays, and are the closest approximation to single, well-tamped explosions available in the Khibiny mines. The surface shots typically are much larger (ranging up

  10. Infrasound Interferometry for Active and Passive Sources: A Synthetic Example for Waves Refracted in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Fricke, J.; Ruigrok, E. N.; Evers, L. G.; El Allouche, N.; Simons, D.; Wapenaar, C. A.

    2012-12-01

    The travel time of infrasound through the stratosphere depends on the temperature profile and the wind speed. These atmospheric conditions can be estimated by determining the travel times between different receivers (microbarometers). Therefore the determination of the travel time of infrasound between different receivers becomes more and more important. An approach to determine the travel time is infrasound interferometry. In this work, the infrasound interferometry is applied to synthetic data of active and passive sources refracted by the stratosphere is tested. The synthetic data were generated with a raytracing model. The inputs of the raytracing model are the atmospheric conditions and a source wavelet. As source wavelet we used blast waves and microbaroms. With the atmospheric conditions and the source wavelet the raytracing model calculates the raypath and the travel time of the infrasound. In order to simulate the measurement of a receiver the rays which reach the receiver need to be found. The rays which propagate from a source to the receiver are called eigen rays. The simulation of the receiver measurements takes into account the travel time along the eigen rays, the attenuation of the different atmospheric layers, the spreading of the rays and the influence of caustics. The simulated measurements of the different receivers are combined to synthetic barograms. Two synthetic experiments were performed with the described model. In the first experiment the interferometry was applied to barograms of active sources like blast waves. The second experiment with microbaroms tests the applicability of interferometry to barograms of passive sources. In the next step infrasound interferometry will be applied to measured barograms. These barograms are measured with the 'Large Aperture Infrasound Array' (LAIA). LAIA is being installed by the Royal Netherlands Meteorological Institute (KNMI) in the framework of the radio-astronomical 'Low Frequency Array' (LOFAR

  11. Monitoring the Earth's Atmosphere with the Global IMS Infrasound Network

    NASA Astrophysics Data System (ADS)

    Brachet, Nicolas; Brown, David; Mialle, Pierrick; Le Bras, Ronan; Coyne, John; Given, Jeffrey

    2010-05-01

    , 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 infrasound 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 infrasound network, the recent developments of the IDC infrasound software, and the progress accomplished during the last decade in the domain of real-time atmospheric modelling have allowed better understanding of infrasound signals and identification of a growing data set of ground-truth sources. These infragenic sources originate from natural or man-made sources. Some of the detected signals are emitted by local or regional phenomena recorded by a single IMS infrasound 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 infrasound 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.

  12. Snowpack ground truth Donner Pass site, Soda Springs, California

    NASA Technical Reports Server (NTRS)

    Jones, E. B.

    1977-01-01

    Ground truth data taken near Soda Springs, California, on January 18, 1977, in support of the NASA Airborne Instrumentation Research Program are presented. Ground truth 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.

  13. Does function fit structure? A ground truth for non-invasive neuroimaging

    PubMed Central

    Stevenson, Claire; Brookes, Matthew; López, José David; Troebinger, Luzia; Mattout, Jeremie; Penny, William; Morris, Peter; Hillebrand, Arjan; Henson, Richard; Barnes, Gareth

    2014-01-01

    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 ground truth. 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) source reconstructions based upon different assumption sets without recourse to functional ground truth. PMID:24636880

  14. Time reversal for localization of sources of infrasound signals in a windy stratified atmosphere.

    PubMed

    Lonzaga, Joel B

    2016-06-01

    Time reversal is used for localizing sources of recorded infrasound signals propagating in a windy, stratified atmosphere. Due to the convective effect of the background flow, the back-azimuths of the recorded signals can be substantially different from the source back-azimuth, posing a significant difficulty in source localization. The back-propagated signals are characterized by negative group velocities from which the source back-azimuth and source-to-receiver (STR) distance can be estimated using the apparent back-azimuths and trace velocities of the signals. The method is applied to several distinct infrasound arrivals recorded by two arrays in the Netherlands. The infrasound signals were generated by the Buncefield oil depot explosion in the U.K. in December 2005. Analyses show that the method can be used to substantially enhance estimates of the source back-azimuth and the STR distance. In one of the arrays, for instance, the deviations between the measured back-azimuths of the signals and the known source back-azimuth are quite large (-1° to -7°), whereas the deviations between the predicted and known source back-azimuths are small with an absolute mean value of <1°. Furthermore, the predicted STR distance is off only by <5% of the known STR distance. PMID:27369127

  15. Interactive degraded document enhancement and ground truth generation

    NASA Astrophysics Data System (ADS)

    Bal, G.; Agam, G.; Frieder, O.; Frieder, G.

    2008-01-01

    Degraded documents are frequently obtained in various situations. Examples of degraded document collections include historical document depositories, document obtained in legal and security investigations, and legal and medical archives. Degraded document images are hard to to read and are hard to analyze using computerized techniques. There is hence a need for systems that are capable of enhancing such images. We describe a language-independent semi-automated system for enhancing degraded document images that is capable of exploiting inter- and intra-document coherence. The system is capable of processing document images with high levels of degradations and can be used for ground truthing of degraded document images. Ground truthing of degraded document images is extremely important in several aspects: it enables quantitative performance measurements of enhancement systems and facilitates model estimation that can be used to improve performance. Performance evaluation is provided using the historical Frieder diaries collection.1

  16. Aeolian dunes as ground truth for atmospheric modeling on Mars

    USGS Publications Warehouse

    Hayward, R.K.; Titus, T.N.; Michaels, T.I.; Fenton, L.K.; Colaprete, A.; Christensen, P.R.

    2009-01-01

    Martian aeolian dunes preserve a record of atmosphere/surface interaction on a variety of scales, serving as ground truth 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 ground truth for GCMs, 2) DCA may be useful as ground truth for both GCM and mesoscale models, and 3) SF may be useful as ground truth for mesoscale models. Copyright 2009 by the American Geophysical Union.

  17. Synthetic ground truth for validation of brain tumor MRI segmentation.

    PubMed

    Prastawa, Marcel; Bullitt, Elizabeth; Gerig, Guido

    2005-01-01

    Validation and method of comparison for segmentation of magnetic resonance images (MRI) presenting pathology is a challenging task due to the lack of reliable ground truth. We propose a new method for generating synthetic multi-modal 3D brain MRI with tumor and edema, along with the ground truth. Tumor mass effect is modeled using a biomechanical model, while tumor and edema infiltration is modeled as a reaction-diffusion process that is guided by a modified diffusion tensor MRI. We propose the use of warping and geodesic interpolation on the diffusion tensors to simulate the displacement and the destruction of the white matter fibers. We also model the process where the contrast agent tends to accumulate in cortical csf regions and active tumor regions to obtain contrast enhanced T1w MR image that appear realistic. The result is simulated multi-modal MRI with ground truth available as sets of probability maps. The system will be able to generate large sets of simulation images with tumors of varying size, shape and location, and will additionally generate infiltrated and deformed healthy tissue probabilities. PMID:16685825

  18. Network-based evaluation of infrasound source location at Sakurajima Volcano, Japan

    NASA Astrophysics Data System (ADS)

    McKee, K. F.; Fee, D.; Rowell, C. R.; Johnson, J. B.; Yokoo, A.; Matoza, R. S.

    2013-12-01

    An important step in advancing the science and application of volcano infrasound is improved source location and characterization. Here we evaluate different network-based infrasonic source location methods, primarily srcLoc and semblance, using data collected at Sakurajima Volcano, Japan in July 2013. We investigate these methods in 2- and 3-dimensions to assess the necessity of considering 3-D sensor and vent locations. In addition, we compare source locations found using array back azimuth projection from dual arrays. The effect of significant local topography on source location will also be evaluated. Preliminary analysis indicates periods of high- and low-level activity, suggesting different processes occurring in the upper conduit and vent. Network processing will be applied to determine signal versus noise, a technique which illuminates when the volcano is producing infrasound, to further investigate these processes. We combine this with other methods to identify the number and style of eruptions. By bringing together source location, timing of activity level, type of activity (such as tremor, explosions, etc.), and number of events, we aim to improve understanding of the activity and associated infrasound signals at Sakurajima Volcano.

  19. Magnetic infrasound sensor

    DOEpatents

    Mueller, Fred M.; Bronisz, Lawrence; Grube, Holger; Nelson, David C.; Mace, Jonathan L.

    2006-11-14

    A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source 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.

  20. Overview of the 2009 and 2011 Sayarim Infrasound Calibration Experiments

    NASA Astrophysics Data System (ADS)

    Fee, D.; Waxler, R.; Drob, D.; Gitterman, Y.; Given, J.

    2012-04-01

    out to 6500 km, in addition to multiple tropospheric, stratospheric, and thermospheric arrivals at arrays deployed to the east. These experiments represented a considerable, successful collaboration between the CTBTO and numerous other groups and will provide a rich ground-truth dataset for detailed infrasound studies in the future.

  1. Misty Picture: A Unique Experiment for the Interpretation of the Infrasound Propagation from Large Explosive Sources

    NASA Astrophysics Data System (ADS)

    Gainville, O.; Blanc, E.; Blanc-Benon, P.; Roche, R.; Millet, C.; Le Piver, F.; Piserchia, P.

    2008-12-01

    In the framework of the Comprehensive Nuclear-Test-Ban Treaty, the International Monitoring System develops a 60 micro-barometric stations network. These stations, which records infrasound, detect various powerful natural and artificial sources like long range explosions, oceanic swell, and volcano eruptions. The Misty Picture experiment is a high explosive event (4685 Tons of ANFO) realized in 1987 in New Mexico (US). Infrasound waves were recorded by an amount of 22 sensors installed by the Sandia National Laboratories (J.W. Reed et al., 1977, SAND--87-2978C), the Los Alamos National Laboratories (R.W. Whitaker et al. 1990, 4th LRSP) and the CEA (E. Blanc, 1998, CEA). Multi-reflected tropospheric, stratospheric and thermospheric phases are detected until a distance of 1000 km in a quiet background noise condition. Signals recorded near the source (1 km away) and observed in the geometrical shadow zone (between 150 km and 250 km) are of particular interest. This reference experiment is used to improve our understanding of the atmospheric propagation of infrasound as well as to evaluate our models. Using various methods such as ray tracing and parabolic equation, we investigate effects of the wind, atmospheric absorption, nonlinearity, refraction and scattering by small atmospheric scales on observed phase kinds, their travel time and their waveform.

  2. Compositional Ground Truth of Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

    Greenhagen, B. T.; Thomas, I. R.; Bowles, N. E.; Allen, C. C.; Donaldson Hanna, K. L.; Foote, E. J.; Paige, D. A.

    2012-01-01

    The Moon affords us a unique opportunity to "ground truth" 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).

  3. Fish Farms at Sea: The Ground Truth from Google Earth

    PubMed Central

    Trujillo, Pablo; Piroddi, Chiara; Jacquet, Jennifer

    2012-01-01

    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 ground truth 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 ground truth data. PMID:22347383

  4. Generating high precision ionospheric ground-truth measurements

    NASA Technical Reports Server (NTRS)

    Komjathy, Attila (Inventor); Sparks, Lawrence (Inventor); Mannucci, Anthony J. (Inventor)

    2007-01-01

    A method, apparatus and article of manufacture provide ionospheric ground-truth 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.

  5. AMS Ground Truth Measurements: Calibration and Test Lines

    SciTech Connect

    Wasiolek, P.

    2013-11-01

    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 ground truth 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 ground truth measurements, is described in this document.

  6. Infrasound Calibration Experiment at Sayarim, Israel: preliminary tests

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Hofstetter, A.; Garces, M.; Bowman, J. R.; Fee, D.; Israelsson, H.

    2009-12-01

    We are establishing a Ground Truth (GT0) infrasound 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 source 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 infrasound 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-source and local distances. We compared energy generation for different explosives, including cratering conditions, and investigated the influence of wind direction on infrasound

  7. Ground Truth Collection for Mining Explosions in Northern Fennoscandia and Northwestern Russia

    SciTech Connect

    Harris, D B; Ringdal, R; Kremenetskaya, E; Mykkeltveit, S; Rock, D W; Maercklin, N; Schweitzer, J; Hauk, T F; Lewis, J P

    2005-07-13

    We concluded comprehensive ground truth 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 ground truth 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 source 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 source. We have an update on the P/S ratio analysis contrasting different source 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

  8. Empirical Relationships from Regional Infrasound Signals

    NASA Astrophysics Data System (ADS)

    Negraru, P. T.; Golden, P.

    2011-12-01

    Two yearlong infrasound observations were collected at two arrays located within the so called "Zone of Silence" or "Shadow Zone" from well controlled explosive sources 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 infrasound arrivals can be used to improve ground truth 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.

  9. IDC Infrasound technology development

    NASA Astrophysics Data System (ADS)

    Mialle, P.; Brown, D. J.; Le Bras, R.; Charbit, M. J. C.; Given, J. W.

    2014-12-01

    The first atmospheric event built only from infrasound 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 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The infrasound component of the IMS daily registers infragenic signals originating from various sources such as volcanic eruptions, earthquakes, microbaroms, meteorites entering the atmosphere and accidental explosions. The IDC routinely and automatically processes infrasound 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 infrasound 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 infrasound 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 infrasound signal detector DFX-PMCC (Detection and Feature eXtraction - Progressive Multi-Channel Correlation) and by evaluating the performances of detection software. - separating infrasound 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. Infrasound rules in Global Association (GA) are revisited to pursue a lower ratio of false alarms. - determining station noise for IMS infrasound, seismic and

  10. Object Segmentation and Ground Truth in 3D Embryonic Imaging

    PubMed Central

    Rajasekaran, Bhavna; Uriu, Koichiro; Valentin, Guillaume; Tinevez, Jean-Yves; Oates, Andrew C.

    2016-01-01

    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 ground truth 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

  11. Government Applications Task Force ground truth study of WAG 4

    SciTech Connect

    Evers, T.K.; Smyre, J.L.; King, A.L.

    1997-06-01

    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 (ground truth) 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.

  12. Interactive removal and ground truth for difficult shadow scenes.

    PubMed

    Gong, Han; Cosker, Darren

    2016-09-01

    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 nonuniform shadow illumination changes, resulting in accurate and robust removal. Another major contribution of this work is the first validated and multiscene category ground truth 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 algorithm to outperform the state of the art across several measures and shadow categories. To complement our data set, an online shadow removal benchmark website is also presented to encourage future open comparisons in this challenging field of research. PMID:27607503

  13. Infrasound Propagation Modeling for Explosive Yield Estimation

    NASA Astrophysics Data System (ADS)

    Howard, J. E.; Golden, P.; Negraru, P.

    2013-12-01

    This study focuses on developing methods of estimating the size or yield of HE surface explosions from local and regional infrasound measurements in the southwestern United States. A munitions disposal facility near Mina, Nevada provides a repeating ground-truth source for this study, with charge weights ranging from 870 - 3800 lbs. Detonation logs and GPS synchronized videos were obtained for a sample of shots representing the full range of weights. These are used to calibrate a relationship between charge weight and spectral level from seismic waveforms recorded at the Nevada Seismic Array (NVAR) at a distance of 36 km. Origin times and yields for the remaining shots are inferred from the seismic recordings at NVAR. Infrasound arrivals from the detonations have been continuously recorded on three four-element, small aperture infrasound arrays since late 2009. NVIAR is collocated with NVAR at a range of approximately 36 km to the northeast. FALN and DNIAR are located at ranges of 154 km to the north, and 293 km to the southeast respectively. Travel times and amplitudes for stratospheric arrivals at DNIAR show strong seasonal variability with the largest amplitudes and celerities occurring during the winter months when the stratospheric winds are favorable. Stratospheric celerities for FNIAR to the north are more consistent as they are not strongly affected by the predominantly meridional stratospheric winds. Tropospheric arrivals at all three arrays show considerable variability that does not appear to be a seasonal effect. Naval Research Laboratory Ground to Space (NRL-G2S) Mesoscale models are used to specify the atmosphere along the propagation path for each detonation. Ray-tracing is performed for each source/receiver pair to identify events for which the models closely match the travel-time observations. This subset of events is used to establish preliminary wind correction formulas using wind values from the G2S profile for the entire propagation path. These

  14. Automated infrasound signal detection algorithms implemented in MatSeis - Infra Tool.

    SciTech Connect

    Hart, Darren

    2004-07-01

    MatSeis's infrasound 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 infrasound signal detection. Our goal was to automate the process of infrasound signal detection. The critical aspect of infrasound 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 infrasound signal was detected. A format for an infrasound 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 ground truth event was processed using the four-element DLIAR infrasound 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 source 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

  15. Ground truth crop proportion summaries for US segments, 1976-1979

    NASA Technical Reports Server (NTRS)

    Horvath, R. (Principal Investigator); Rice, D.; Wessling, T.

    1981-01-01

    The original ground truth data was collected, digitized, and registered to LANDSAT data for use in the LACIE and AgRISTARS projects. The numerous ground truth 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 ground truth 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.

  16. Infrasound Monitoring of Natural Hazards

    NASA Astrophysics Data System (ADS)

    Arrowsmith, S.

    2015-12-01

    Infrasound 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 infrasound is low, it can propagate long distances through atmospheric waveguides, making it a valuable tool for remote monitoring of hazards. Advances in using infrasound 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 source and propagation physics. This presentation provides an overview of recent advances in infrasound monitoring of natural hazards, focusing on selected hazards in the earth (earthquakes and volcanoes), ocean (tsunamis), and atmosphere (meteoroids).

  17. Ground Truth Collection for Mining Explosions in Northern Fennoscandia and Russia

    SciTech Connect

    Harris, D; Ringdal, F; Kremenetskaya, E; Mykkeltveit, S; Rock, D E; Schweitzer, J; Hauk, T; Lewis, J

    2004-07-15

    Analysis of data from our deployments and ground truth 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 source. 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 ground truth collection at the Khibiny

  18. Ground truth management system to support multispectral scanner /MSS/ digital analysis

    NASA Technical Reports Server (NTRS)

    Coiner, J. C.; Ungar, S. G.

    1977-01-01

    A computerized geographic information system for management of ground truth has been designed and implemented to relate MSS classification results to in situ observations. The ground truth 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 ground truth array allows direct pixel by pixel comparison between classification results of MSS data and ground truth. 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 ground truth 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.

  19. Seismo-acoustic analysis of the ocean swell sources observed with Romanian infrasound array and seismic stations

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Grecu, Bogdan; Popa, Mihaela

    2015-04-01

    Romanian Plostina infrasound 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 infrasound sources, 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 source 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 infrasound 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 source, leaving an imprint on both seismic and infrasonic recordings. The interaction with the atmosphere generates infrasound (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

  20. Determination and Statistical Analysis of Infrasound Sources Near Socorro, New Mexico

    NASA Astrophysics Data System (ADS)

    Larson, T.; Lees, J. M.; Bowman, D. C.; Jones, K. R.

    2014-12-01

    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 infrasound 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 sources 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 source of these signals is unknown and requires further investigation. Signals associated with other sources, 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 sources.

  1. Reliable fusion of knee bone laser scans to establish ground truth for cartilage thickness measurement

    NASA Astrophysics Data System (ADS)

    Chang, Ming-Ching; Trinh, Nhon H.; Fleming, Braden C.; Kimia, Benjamin B.

    2010-03-01

    We are interested in establishing ground truth 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 sources 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.

  2. Retina Lesion and Microaneurysm Segmentation using Morphological Reconstruction Methods with Ground-Truth Data

    SciTech Connect

    Karnowski, Thomas Paul; Govindaswamy, Priya; Tobin Jr, Kenneth William; Chaum, Edward; Abramoff, M.D.

    2008-01-01

    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 ground-truth data. Since the method tends to over-segment imagery, ground-truth 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.

  3. Infrasound Rocket Signatures

    NASA Astrophysics Data System (ADS)

    Olson, J.

    2012-09-01

    This presentation reviews the work performed by our research group at the Geophysical Institute as we have applied the tools of infrasound research to rocket studies. This report represents one aspect of the effort associated with work done for the National Consortium for MASINT Research (NCMR) program operated by the National MASINT Office (NMO) of the Defense Intelligence Agency (DIA). Infrasound, the study of acoustic signals and their propagation in a frequency band below 15 Hz, enables an investigator to collect and diagnose acoustic signals from distant sources. Absorption of acoustic energy in the atmosphere decreases as the frequency is reduced. In the infrasound band signals can propagate hundreds and thousands of kilometers with little degradation. We will present an overview of signatures from rockets ranging from small sounding rockets such as the Black Brandt and Orion series to larger rockets such as Delta 2,4 and Atlas V. Analysis of the ignition transients provides information that can uniquely identify the motor type. After the rocket ascends infrasound signals can be used to characterize the rocket and identify the various events that take place along a trajectory such as staging and maneuvering. We have also collected information on atmospheric shocks and sonic booms from the passage of supersonic vehicles such as the shuttle. This review is intended to show the richness of the unique signal set that occurs in the low-frequency infrasound band.

  4. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures

    PubMed Central

    Blecha, Kevin A.; Alldredge, Mat W.

    2015-01-01

    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 ground-truthing component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for sources of ground-truthing false-absences can bias the number of predicted feeding events to be low. Thus we account for some ground-truthing error sources 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 ground-truthing 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

  5. Semi-automated based ground-truthing GUI for airborne imagery

    NASA Astrophysics Data System (ADS)

    Phan, Chung; Lydic, Rich; Moore, Tim; Trang, Anh; Agarwal, Sanjeev; Tiwari, Spandan

    2005-06-01

    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 ground-truthing 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 ground-truthing imagery. The semi-automated ground-truthing 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 ground-truthing 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.

  6. Detailed analysis of CAMS procedures for phase 3 using ground truth inventories

    NASA Technical Reports Server (NTRS)

    Carnes, J. G.

    1979-01-01

    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 ground-truth inventories. The proportion estimation accuracy, dot labeling accuracy, and clustering effectiveness are discussed.

  7. Application of remote sensing in agriculture and forestry and ground truth documentation in resource planning

    NASA Technical Reports Server (NTRS)

    1974-01-01

    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. Ground truth acquisition for forest identification using multispectral aerial photographs is reviewed.

  8. Soil moisture ground truth: Steamboat Springs, Colorado, site and Walden, Colorado, site

    NASA Technical Reports Server (NTRS)

    Jones, E. B.

    1976-01-01

    Ground-truth 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.

  9. Ground truth and CT image model simulation for pathophysiological human airway system

    NASA Astrophysics Data System (ADS)

    Ortner, Margarete; Fetita, Catalin; Brillet, Pierre-Yves; Pr"teux, Françoise; Grenier, Philippe

    2010-02-01

    Recurrent problem in medical image segmentation and analysis, establishing a ground truth 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 ground truth for analysis. This paper focuses on the case of human pulmonary airways and develops a method 1) to simulate the ground truth 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 ground truth. 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 ground truth. 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.

  10. Evaluation of Event-Based Algorithms for Optical Flow with Ground-Truth from Inertial Measurement Sensor

    PubMed Central

    Rueckauer, Bodo; Delbruck, Tobi

    2016-01-01

    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-source 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 source for the ground truth: 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 ground-truth to which we can compare algorithms that measure optical flow by means of motion cues. An analysis of error sources 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

  11. A Ground Truthing Method for AVIRIS Overflights Using Canopy Absorption Spectra

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Serrano, Lydia; Roberts, Dar A.; Ustin, Susan L.

    1996-01-01

    Remote sensing for ecological field studies requires ground truthing 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 "ground truthing" that could be related both to AVIRIS imagery and to conventional ground sampling (e.g., plot harvests and pigment assays).

  12. Comparison of MTI Water Temperatures with Ground Truth Measurements at Crater Lake, OR

    SciTech Connect

    Kurzeja, R.J.

    2002-12-09

    Water surface temperatures calculated with the Los Alamos National Laboratory Robust algorithm were compared with ground truth 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 ground truth 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.

  13. ERTS-1 DCS technical support provided by Wallops Station. [ground truth stations and DCP repair depot

    NASA Technical Reports Server (NTRS)

    Smith, R.

    1975-01-01

    Wallops Station accepted the tasks of providing ground truth to several ERTS investigators, operating a DCP repair depot, designing and building an airborne DCP Data Acquisition System, and providing aircraft underflight support for several other investigators. Additionally, the data bank is generally available for use by ERTS and other investigators that have a scientific interest in data pertaining to the Chesapeake Bay area. Working with DCS has provided a means of evaluating the system as a data collection device possibly applicable to ongoing Earth Resources Program activities in the Chesapeake Bay area as well as providing useful data and services to other ERTS investigators. The two areas of technical support provided by Wallops, ground truth stations and repair for DCPs, are briefly discussed.

  14. Success Stories: Data Collection And Ground Truth For The Portuguese Case Study (Caia Irrigation District)

    NASA Astrophysics Data System (ADS)

    Perdigão, A.; Oliveira, P.; Chinita, A.; Chinita, S.; Maia, J.; Nunes, J.

    2006-08-01

    A Field Campaign has been carried on the Caia Irrigation District area pilot zone, in order to obtain ground truth 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 ground truth 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

  15. SuReSim: simulating localization microscopy experiments from ground truth models.

    PubMed

    Venkataramani, Varun; Herrmannsdörfer, Frank; Heilemann, Mike; Kuner, Thomas

    2016-04-01

    Super-resolution fluorescence microscopy has become a widely used tool in many areas of research. However, designing and validating super-resolution experiments to address a research question in a technically feasible and scientifically rigorous manner remains a fundamental challenge. We developed SuReSim, a software tool that simulates localization data of arbitrary three-dimensional structures represented by ground truth models, allowing users to systematically explore how changing experimental parameters can affect potential imaging outcomes. PMID:26928761

  16. Acoustic seafloor discrimination with echo shape parameters: A comparison with the ground truth

    NASA Astrophysics Data System (ADS)

    van Walree, Paul A.; Tęgowski, Jaroslaw; Laban, Cees; Simons, Dick G.

    2005-11-01

    Features extracted from echosounder bottom returns are compared with the ground truth in a North Sea survey area. The ground truth consists of 50 grab samples for which the grain size distribution, and the gravel and shell contents were determined. Echo envelopes are analysed for two single-beam echosounders, operated at frequencies of 66 and 150 kHz. It is shown that a set of six energetic, statistical, spectral and fractal parameters carries useful information that can be exploited for seafloor characterization and classification purposes. A quantitative comparison of the individual features with the grab sample mean grain size reveals significant correlations. The echo features are also subjected to a principal component analysis in tandem with a cluster analysis. Four sediment classes with different geo-acoustic properties are examined and compared with the grab samples and existing geological information. A subtle difference between the two sounder frequencies is observed in the rendition of an isolated trench with a soft infill of clay and Holocene channel deposits. The acoustic transition from the valley to neighbouring sand and gravel fields occurs more rapidly at the lower of the two examined frequencies. A direct comparison of the acoustic sediment classes with the ground truth reveals that the main sediment types mud, sand, and gravel are more clearly separated at 150 kHz. The acoustic bottom classification scheme also appears particularly sensitive to the presence of gravel at this sounder frequency.

  17. VERIFICATION & VALIDATION OF A SEMANTIC IMAGE TAGGING FRAMEWORK VIA GENERATION OF GEOSPATIAL IMAGERY GROUND TRUTH

    SciTech Connect

    Gleason, Shaun Scott; Ferrell, Regina Kay; Cheriyadat, Anil M; Vatsavai, Raju; Sari-Sarraf, Hamed; Dema, Mesfin A

    2011-01-01

    As a result of increasing geospatial image libraries, many algorithms are being developed to automatically extract and classify regions of interest from these images. However, limited work has been done to compare, validate and verify these algorithms due to the lack of datasets with high accuracy ground truth annotations. In this paper, we present an approach to generate a large number of synthetic images accompanied by perfect ground truth annotation via learning scene statistics from few training images through Maximum Entropy (ME) modeling. The ME model [1,2] embeds a Stochastic Context Free Grammar (SCFG) to model object attribute variations with Markov Random Fields (MRF) with the final goal of modeling contextual relations between objects. Using this model, 3D scenes are generated by configuring a 3D object model to obey the learned scene statistics. Finally, these plausible 3D scenes are captured by ray tracing software to produce synthetic images with the corresponding ground truth annotations that are useful for evaluating the performance of a variety of image analysis algorithms.

  18. Ground truth and mapping capability of urban areas in large scale using GE images

    NASA Astrophysics Data System (ADS)

    Ramzi, Ahmed I.

    2015-10-01

    Monitoring and mapping complex urban features (e.g. roads and buildings) from remotely sensed data multispectral and hyperspectral has gained enormous research interest. Accurate ground truth allows for high quality assessment of classified images and to verify the produced map. Ground truth 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. Ground truth 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 ground truth 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

  19. Local and remote infrasound from explosive volcanism

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Fee, D.; LE Pichon, A.

    2014-12-01

    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. Infrasound (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 sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. Advances in infrasound technology and the efficient propagation of infrasound in the atmosphere therefore greatly enhance our ability to monitor volcanoes in remote regions such as the North Pacific Ocean. Infrasound 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 infrasound networks (2008 Kasatochi, Alaska, USA; 2008 Okmok, Alaska, USA; 2009 Sarychev Peak, Kuriles, Russian Federation; 2010 Eyjafjallajökull, Icleand) and show how infrasound is currently used in volcano monitoring. We also present progress towards characterizing and modeling the variability in source mechanisms of infrasound from explosive eruptions using dedicated local infrasound field deployments at volcanoes Karymsky, Russian Federation and Sakurajima, Japan.

  20. Geographic information system for fusion and analysis of high-resolution remote sensing and ground truth data

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony; Dubois, Pascale; Leberl, Franz; Norikane, L.; Way, Jobea

    1991-01-01

    Viewgraphs on Geographic Information System for fusion and analysis of high-resolution remote sensing and ground truth data are presented. Topics covered include: scientific objectives; schedule; and Geographic Information System.

  1. Ground truth seismic events and location capability at Degelen mountain, Kazakhstan

    USGS Publications Warehouse

    Trabant, C.; Thurber, C.; Leith, W.

    2002-01-01

    We utilized nuclear explosions from the Degelen Mountain sub-region of the Semipalatinsk Test Site (STS), Kazakhstan, to assess seismic location capability directly. Excellent ground truth 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 ground truth 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 ground truth 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.

  2. Infrasound from volcanic rockfalls

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Ronan, Timothy J.

    2015-12-01

    Proximal infrasound 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 sources, 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. Infrasound rockfall signal character is readily distinguishable from explosion infrasound, which is manifested by a relatively fixed location source 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.

  3. IDC Infrasound Pipeline initiative for technology development

    NASA Astrophysics Data System (ADS)

    Mialle, Pierrick; Le Bras, Ronan; Sudakov, Alexander; Fernando, Chaminda; Tomuta, Elena

    2015-04-01

    The first atmospheric event built exclusively from infrasound 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 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The infrasound component of the IMS daily registers infragenic signals originating from various natural sources such as volcanic eruptions, earthquakes, microbaroms, meteorites entering the atmosphere and anthropogenic sources such as mining and accidental explosions. The IDC routinely processes infrasound data and creates automatic bulletins which are then reviewed interactively.. The IDC advances its methods and continuously improves its automatic systems, including the infrasound 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. The current operational system handles seismic, hydroacoustic, and infrasound technologies within the same instance of the Global Association (GA) automatic association algorithm. The Infrasound Pipeline initiative consists in separating the infrasound technology at the stage of automatic association. An objective of this study is to reduce the number of automatically associated infrasound arrivals that are rejected by the analysts. This study also prepares the way for the implementation of the next generation of automatic waveform association algorithms. Infrasound processing in Global Association (GA) is revisited to pursue a lower ratio of false alarms. Tests are performed using historical events from IDC bulletins and the Infrasound Reference Event Data Base (IRED).

  4. Ground Truth Studies - A hands-on environmental science program for students, grades K-12

    NASA Technical Reports Server (NTRS)

    Katzenberger, John; Chappell, Charles R.

    1992-01-01

    The paper discusses the background and the objectives of the Ground Truth 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.

  5. Methods for improving accuracy and extending results beyond periods covered by traditional ground-truth in remote sensing classification of a complex landscape

    NASA Astrophysics Data System (ADS)

    Mueller-Warrant, George W.; Whittaker, Gerald W.; Banowetz, Gary M.; Griffith, Stephen M.; Barnhart, Bradley L.

    2015-06-01

    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 ground truth 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 ground-truth, elaborating on previously published work and traditional sources 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 ground-truth data to classify prior year landuse, an

  6. Field Ground Truthing Data Collector - a Mobile Toolkit for Image Analysis and Processing

    NASA Astrophysics Data System (ADS)

    Meng, X.

    2012-07-01

    Field Ground Truthing Data Collector is one of the four key components of the NASA funded ICCaRS project, being developed in Southeast Michigan. The ICCaRS ground truthing 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.

  7. Phantom-based ground-truth generation for cerebral vessel segmentation and pulsatile deformation analysis

    NASA Astrophysics Data System (ADS)

    Schetelig, Daniel; Säring, Dennis; Illies, Till; Sedlacik, Jan; Kording, Fabian; Werner, René

    2016-03-01

    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 ground-truth images for evaluation of appropriate segmentation and motion analysis algorithms is developed. The acquired ground-truth 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.

  8. Ground truthing for methane hotspots at Railroad Valley, NV - application to Mars

    NASA Astrophysics Data System (ADS)

    Detweiler, A. M.; Kelley, C. A.; Bebout, B.; McKay, C. P.; DeMarines, J.; Yates, E. L.; Iraci, L. T.

    2011-12-01

    .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 ground truthing 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.

  9. Overview of the 2009 and 2011 Sayarim Infrasound Calibration Experiments

    NASA Astrophysics Data System (ADS)

    Fee, David; Waxler, Roger; Assink, Jelle; Gitterman, Yefim; Given, Jeffrey; Coyne, John; Mialle, Pierrick; Garces, Milton; Drob, Douglas; Kleinert, Dan; Hofstetter, Rami; Grenard, Patrick

    2013-06-01

    Three large-scale infrasound calibration experiments were conducted in 2009 and 2011 to test the International Monitoring System (IMS) infrasound network and provide ground truth data for infrasound propagation studies. Here we provide an overview of the deployment, detonation, atmospheric specifications, infrasound 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 infrasound arrays in the region to supplement the IMS network and increase station density. Infrasound 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 infrasound 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 infrasound 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

  10. Infrasound research of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Ripepe, Maurizio

    2016-04-01

    Volcanic eruptions are efficient sources of infrasound produced by the rapid perturbation of the atmosphere by the explosive source. Being able to propagate up to large distances from the source, 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 source dynamics, to eventually play a primary role in volcano research. Nowadays, infrasound 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 infrasound and has been used to infer complex eruptive source mechanisms for the different kinds of events. Improved processing capability and sensors has allowed unprecedented precise locations of the explosive source and is progressively increasing the possibility to monitor volcanoes from distant records. Very broadband infrasound 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.

  11. The ground truth analysis of rain gauge data for the TRMM project. [Tropical Rainfall Measuring Mission

    NASA Technical Reports Server (NTRS)

    Kowalewsky, Karen J.; Thiele, Otto

    1989-01-01

    As a part of the Tropical Rainfall Measuring Missioin (TRMM) ground truth 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.

  12. Design of the primary pre-TRMM and TRMM ground truth site

    NASA Technical Reports Server (NTRS)

    Garstang, Michael

    1988-01-01

    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 ground truth 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.

  13. Comparing Eyewitness-Derived Trajectories of Bright Meteors to Ground Truth Data

    NASA Technical Reports Server (NTRS)

    Moser, D. E.

    2016-01-01

    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 ground truth data observed by the NASA All Sky Fireball Network are presented.

  14. A network of scintillometers for ground-truthing of surface fluxes in New Mexico

    NASA Astrophysics Data System (ADS)

    Kleissl, J.; Hong, S.; Gomez, J. D.; Hendrickx, J. M.

    2007-05-01

    A network of seven scintillometer transects was established in New Mexico in 2006 covering different soils, vegetation types, and altitudes. Scintillometers measure spatially-averaged sensible heat fluxes over transects of 0.5 - 4 kms, i.e., over footprints comparable in size to several pixels of a satellite image. The Surface Energy Balance for Land (SEBAL) algorithm is applied to radiances from Landsat and MODIS to obtain net radiation Rnet, soil heat flux G, and sensible heat flux H. The latent heat flux is obtained from the energy balance equation as LE = Rnet - G - H. The scintillometer measurements are used to validate and calibrate the SEBAL sensible heat flux product. Results from this ground-truthing experiment and plans for automated and calibrated daily evapotranspiration maps will be presented.

  15. Towards a repository for standardized medical image and signal case data annotated with ground truth.

    PubMed

    Deserno, Thomas M; Welter, Petra; Horsch, Alexander

    2012-04-01

    Validation of medical signal and image processing systems requires quality-assured, representative and generally acknowledged databases accompanied by appropriate reference (ground truth) 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 ground truth 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. PMID:22075810

  16. Ground truth and detection threshold from WWII naval clean-up in Denmark

    NASA Astrophysics Data System (ADS)

    Larsen, Tine B.; Dahl-Jensen, Trine; Voss, Peter

    2013-04-01

    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 ground truth 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 ground truth. 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.

  17. Searching for Organics During the Robotic Mars Analog Rio Tinto Drilling Experiment: Ground Truth and Contamination Issues

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; Stoker, C. R.; Marte Project Science Team

    2007-03-01

    The Mars Analog Rio Tinto Experiment (MARTE) performed a simulation of a Mars drilling experiment at the Rio Tinto (Spain). Ground-truth and contamination issues during the distribution of bulk organics and their CN isotopic composition in hematite and go

  18. A 868MHz-based wireless sensor network for ground truthing of soil moisture for a hyperspectral remote sensing campaign - design and preliminary results

    NASA Astrophysics Data System (ADS)

    Näthe, Paul; Becker, Rolf

    2014-05-01

    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-source 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-source 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-source 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-source based wireless sensor network is developed and specified for the application of ground truthing. 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

  19. Ground Truth Observations of the Interior of a Rockglacier as Validation for Geophysical Monitoring Data Sets

    NASA Astrophysics Data System (ADS)

    Hilbich, C.; Roer, I.; Hauck, C.

    2007-12-01

    Monitoring the permafrost evolution in mountain regions is currently one of the important tasks in cryospheric studies as little data on past and present changes of the ground thermal regime and its material properties are available. In addition to recently established borehole temperature monitoring networks, techniques to determine and monitor the ground ice content have to be developed. A reliable quantification of ground ice is especially important for modelling the thermal evolution of frozen ground and for assessing the hazard potential due to thawing permafrost induced slope instability. Near surface geophysical methods are increasingly applied to detect and monitor ground ice occurrences in permafrost areas. Commonly, characteristic values of electrical resistivity and seismic velocity are used as indicators for the presence of frozen material. However, validation of the correct interpretation of the geophysical parameters can only be obtained through boreholes, and only regarding vertical temperature profiles. Ground truth of the internal structure and the ice content is usually not available. In this contribution we will present a unique data set from a recently excavated rockglacier near Zermatt/Valais in the Swiss Alps, where an approximately 5 m deep trench was cut across the rockglacier body for the construction of a ski track. Longitudinal electrical resistivity tomography (ERT) and refraction seismic tomography profiles were conducted prior to the excavation, yielding data sets for cross validation of commonly applied geophysical interpretation approaches in the context of ground ice detection. A recently developed 4-phase model was applied to calculate ice-, air- and unfrozen water contents from the geophysical data sets, which were compared to the ground truth data from the excavated trench. The obtained data sets will be discussed in the context of currently established geophysical monitoring networks in permafrost areas. In addition to the

  20. Recent Advances in Infrasound Science for National Security Applications

    NASA Astrophysics Data System (ADS)

    Arrowsmith, S.; Blom, P. S.; Marcillo, O. E.; Whitaker, R. W.

    2014-12-01

    Infrasound is sound below the frequency-threshold of human hearing, covering the frequency range from 0.01 - 20 Hz. Infrasound science studies the generation, propagation, measurement, and analysis of infrasound. Sources of infrasound 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 infrasound are the spatial and temporal variations in temperature, wind speed, and wind direction. In recent years, Infrasound Science has experienced a renaissance due to the installation of an international monitoring system of 60 infrasound arrays for monitoring the Comprehensive Nuclear Test Ban Treaty, and to the demonstrated value of regional infrasound networks for both scientific and applied purposes. Furthermore, in the past decade, significant advances have been made on using measurements of infrasound 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 infrasound science as relevant to National Security applications.

  1. Detecting geyser activity with infrasound

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Anderson, J. F.; Anthony, R. E.; Sciotto, M.

    2013-04-01

    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 sources. During a week in August 2011 we located repeating infrasound 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 infrasound from nearby Botryoidal and persistent sound from Firehole Spring. Although activity from nearby cone-type geysers was not detected in the infrasound 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 infrasound 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.

  2. Ground Truth, Magnitude Calibration and Regional Phase Propagation and Detection in the Middle East and Horn of Africa

    SciTech Connect

    Nyblade, A; Brazier, R; Adams, A; Park, Y; Rodgers, A; Al-Amri, A

    2007-07-08

    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 source 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 ground truth at GT5 (local) and GT20 (regional) levels for seismic events with M > 2.5, including source geometry information and source 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 source depths of the earthquakes via waveform matching. The source 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 source 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 source 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

  3. GROUND TRUTH, MAGNITUDE CALIBRATION AND REGIONAL PHASE PROPAGATION AND DETECTION IN THE MIDDLE EAST AND HORN OF AFRICA

    SciTech Connect

    Nyblade, A; Adams, A; Brazier, R; Park, Y; Rodgers, A

    2006-07-10

    In this project, we are exploiting unique and open source 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 source 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 ground truth at GT5 (local) and GT20 (regional) levels for seismic events with M > 2.5, including source geometry information and source 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 source 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 source depths are generally much shallower, lying mainly within the upper crust. Nine events with magnitudes between 5 and 6 have been studied so far. Source depths for six of the events are within the upper crust, and three are located within the lower crust. The uncertainty in the source 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

  4. Ground truth measurements plan for the Multispectral Thermal Imager (MTI) satellite

    SciTech Connect

    Garrett, A.J.

    2000-01-03

    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 ground truth 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.

  5. The ground-truth problem for satellite estimates of rain rate

    NASA Technical Reports Server (NTRS)

    North, Gerald R.; Valdes, Juan B.; Eunho, HA; Shen, Samuel S. P.

    1994-01-01

    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 ground-truth 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.

  6. MTI Ground Truth Collection Ivanpah Dry Lake Bed, California, May, July, and August 2002

    SciTech Connect

    David L. Hawley

    2002-10-01

    A multi-agency collaboration successfully completed a series of ground truth 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.

  7. Monitoring the pollution of river Ganga by tanneries using the multiband ground truth radiometer

    NASA Astrophysics Data System (ADS)

    Tripathi, Nitin Kumar; Venkobachar, C.; Singh, Ramesh Kumar; Singh, Shiv Pal

    The feasibility of utilising the multiband ground truth radiometer (MGTR) for monitoring the pollution of the river Ganga by tanneries at Kanpur, India is explored. Parameters targeted in the study were Secchi depth (a measure of turbidity), turbidity, tannin concentration and chemical oxygen demand (COD). MGTR offers reflectance in 11 bands within the spectral range of 0.45 to 0.90 μm. The reflectance data has been utilised to develop empirical relationships with Secchi depth, turbidity and tannin concentration. The spectral reflectance data does not directly indicate the measure of the COD. However, an empirical relationship between tannin concentration and COD has been established which allows an indirect measurement of the COD. The conventional environmental engineering laboratory approach for determination of the above parameters is time consuming, expensive and slow. This results in serious constraints in monitoring pollution parameters at frequent intervals for a large number of sampling points. The outcome of the study shows the viability of MGTR as a means of quick, repetitive and handy remote sensing for monitoring pollution caused by tanneries in narrow surface streams.

  8. Comparing Eyewitness-Derived Trajectories of Bright Meteors to Ground Truth Data

    NASA Technical Reports Server (NTRS)

    Moser, D. E.

    2016-01-01

    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 ground truth data observed by the NASA All Sky Fireball Network will be presented.

  9. Ground truth methods for optical cross-section modeling of biological aerosols

    NASA Astrophysics Data System (ADS)

    Kalter, J.; Thrush, E.; Santarpia, J.; Chaudhry, Z.; Gilberry, J.; Brown, D. M.; Brown, A.; Carter, C. C.

    2011-05-01

    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 ground truth 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.

  10. Comparisons of Ground Truth and Remote Spectral Measurements of the FORMOSAT and ANDE Spacecrafts

    NASA Technical Reports Server (NTRS)

    JorgensenAbercromby, Kira; Hamada, Kris; Okada, Jennifer; Guyote, Michael; Barker, Edwin

    2006-01-01

    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 ground-truth 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.

  11. The source of infrasound associated with long-period events at mount St. Helens

    USGS Publications Warehouse

    Matoza, R.S.; Garces, M.A.; Chouet, B.A.; D'Auria, L.; Hedlin, M.A.H.; De Groot-Hedlin, C.; Waite, G.P.

    2009-01-01

    During the early stages of the 2004-2008 Mount St. Helens eruption, the source 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 source configuration are considered. The simulations show that a shallow source 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 source 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 source. The observations therefore require a more complex source 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

  12. Ground-truthing electrical resistivity methods in support of submarine groundwater discharge studies: Examples from Hawaii, Washington, and California

    USGS Publications Warehouse

    Johnson, Cordell; Swarzenski, Peter W.; Richardson, Christina M.; Smith, Christopher G.; Kroeger, Kevin D.; Ganguli, Priya M.

    2015-01-01

    Rigorous ground-truthing 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.

  13. IDC Infrasound Pipeline development

    NASA Astrophysics Data System (ADS)

    Mialle, P.; Bittner, P.; Brown, D.; Given, J.

    2012-04-01

    The first atmospheric event built only from infrasound 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, 44 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The growing amount of infrasound data and detections produced by the automatic system challenged the station and network processing at the IDC, which require the Organization to improve the infrasound data processing. For nearly 2 years, the IDC resumed automatic processing of infrasound data reviewed by interactive analysis; the detected and located events are being systematically included in the Late Event Bulletin (LEB) and REB. Approximately 16% of SEL3 (Selected Event List 3, produced 6 hours after real-time) events with an infrasound component make it to the IDC bulletins and 41% of SEL3 events rejected after review are built including only 2 associated infrasound phases (and potentially seismic and hydroacoustic detections). Therefore, the process whereby infrasound and seismic detections are associated into an event needed to be investigated further. The IDC works on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold. Thus the IDC investigates ways to refine the signal characterization methodology and the association criteria. The objective of this study is to reduce the number of associated infrasound arrivals that are rejected from the SEL3 pipeline when generating the LEB and REB bulletins. The study is performed in the virtual Data Exploitation Center (vDEC) from the CTBTO in order to separate the automatic processing into two streams: seismic and hydroacoustic (SH) pipeline on one side, and infrasound (I) pipeline on the other side. The "fusion" of the two parallel event-forming streams will have to be

  14. Subsurface Organics in Aseptic Cores From the MARTE Robotic Drilling Experiment: Ground truth and Contamination Issues

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; Stoker, C. R.

    2006-12-01

    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. Ground truth 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

  15. Station characteristics of the Singapore Infrasound Array

    NASA Astrophysics Data System (ADS)

    Perttu, Anna; Taisne, Benoit; Caudron, Corentin; Garces, Milton; Avila Encillo, Jeffrey; Ildefonso, Sorvigenaleon

    2016-04-01

    Singapore, located in Southeast Asia, presents an ideal location for an additional regional infrasound array, with diverse persistent natural and anthropogenic regional infrasound sources, 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 infrasound 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 infrasound array to the existing International Monitoring System (IMS) infrasound stations in the region has increased regional infrasound 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.

  16. Ten Years of Infrasound Observation in Korea

    NASA Astrophysics Data System (ADS)

    Lee, Hee-Il; Che, Il-Young; Kim, Tae Sung

    2010-05-01

    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 infrasound with an infrasound array network, named KIN (Korean Infrasound 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 infrasound signals associated with different kind of anthropogenic source 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 infrasound database. This database is used to study characteristics of seasonally dependent propagation of the infrasound 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.

  17. Ground Truth for Geological and Geophysical Mapping of New York Harbor

    NASA Astrophysics Data System (ADS)

    Murphy, W.; Ward, W. B.; Boyd, B.; Fleming, G.; Nolen-Hoeksema, R.; Murphy, W.

    2005-05-01

    As part of the project to deepen the harbors of the Ports of New York, Newark, and Elizabeth to 50 feet, we are mapping the geology of New York and New Jersey harbor, particularly the eastern edge of the Newark Basin, with geophysical measurements and core borings. The results are geological cross-sections, stratigraphic columns, and geological maps with resolutions approaching 1 foot. Sonar images map the surface of the bottom. Multichannel and single-channel, reflection seismic methods penetrate the sediment and rock to 100 feet below mean low water (MLW). The subsurface materials include black silt, gray silt, gray sands, Pleistocene till, Pleistocene varves, Jurassic diabase, Triassic sands and shales, Ordovician serpentinite, Cambro-Ordovician schist. We measure formation properties including lateral extent, thickness, strike and dip, contamination, fracture density, and diggability. The range of compressional velocity among these materials is a factor of six. Fundamental axioms of mapping, causality, equipresence, and frame indifference require sampling by core borings. Sampling is straightforward yet rarely required. We calibrate the water column for bathymetric studies and the subsurface for geotechnical studies. We measure Blow counts (or drill rate) Recovery efficiency Lithological description Digital photographs Rock quality designation (RQD) Fractures per foot Ultrasonic compressional wave velocity Unconfined compressive strength The measurements provide Ground truth Stratigraphic calibration Velocity modeling for time-to-depth conversion Material for correlation and experimentation The acoustic properties of the materials involved vary as a function of season. A sensitive issue is stability of the sediments in the channel slope. We place the hundreds of core borings into a single reference frame with the geophysical measurements. The geological maps and cross-sections follow from the interpretation of the processed geophysical results.

  18. Ground-truthing 6. 5-kHz side scan sonographs: What are we really imaging

    SciTech Connect

    Gardner, J.V.; Field, M.E.; Lee, H.; Edwards, B.E. ); Masson, D.G.; Kenyon, N. ); Kidd, R.B. )

    1991-04-10

    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 ground truth 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.

  19. Sunrise-driven movements of dust on the Moon: Apollo 12 Ground-truth measurements

    NASA Astrophysics Data System (ADS)

    O'Brien, Brian J.; Hollick, Monique

    2015-12-01

    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 Ground truth 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.

  20. A systematic review of automated melanoma detection in dermatoscopic images and its ground truth data

    NASA Astrophysics Data System (ADS)

    Ali, Abder-Rahman A.; Deserno, Thomas M.

    2012-02-01

    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 (ground truth) 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

  1. A global ground truth view of the lunar air pressure tide L2

    NASA Astrophysics Data System (ADS)

    Schindelegger, Michael; Dobslaw, Henryk

    2016-01-01

    A comprehensive model of the lunar air pressure tide L2 is developed on the basis of 2315 ground truth 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.

  2. Topographic effects on infrasound propagation.

    PubMed

    McKenna, Mihan H; Gibson, Robert G; Walker, Bob E; McKenna, Jason; Winslow, Nathan W; Kofford, Aaron S

    2012-01-01

    Infrasound data were collected using portable arrays in a region of variable terrain elevation to quantify the effects of topography on observed signal amplitude and waveform features at distances less than 25 km from partially contained explosive sources during the Frozen Rock Experiment (FRE) in 2006. Observed infrasound signals varied in amplitude and waveform complexity, indicating propagation effects that are due in part to repeated local maxima and minima in the topography on the scale of the dominant wavelengths of the observed data. Numerical simulations using an empirically derived pressure source function combining published FRE accelerometer data and historical data from Project ESSEX, a time-domain parabolic equation model that accounted for local terrain elevation through terrain-masking, and local meteorological atmospheric profiles were able to explain some but not all of the observed signal features. Specifically, the simulations matched the timing of the observed infrasound signals but underestimated the waveform amplitude observed behind terrain features, suggesting complex scattering and absorption of energy associated with variable topography influences infrasonic energy more than previously observed. PMID:22280569

  3. Infrasound characterization of some Yellowstone geysers' eruptions

    NASA Astrophysics Data System (ADS)

    Quezada-Reyes, A.; Johnson, J.

    2012-12-01

    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 sources 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. Infrasound 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 infrasound 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 infrasound and audio-band signal evolving from 20 - 60 Hz to 40 - 85 Hz. We suggest that the infrasound 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 infrasound pulses of up to 0.7 Pa-m. We model these pulses as volumetric sound sources 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 infrasound radiation may help us to understand infrasound analogues at erupting silicic volcanoes, which are considerably more difficult to

  4. LRO Camera Imaging of the Moon: Apollo 17 and other Sites for Ground Truth

    NASA Astrophysics Data System (ADS)

    Jolliff, B. L.; Wiseman, S. M.; Robinson, M. S.; Lawrence, S.; Denevi, B. W.; Bell, J. F.

    2009-12-01

    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 ground-truth 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

  5. Using Apollo Sites and Soils to Compositionally Ground Truth Diviner Lunar Radiometer Observations

    NASA Technical Reports Server (NTRS)

    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.

    2012-01-01

    Apollo landing sites and returned soils afford us a unique opportunity to "ground truth" 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

  6. Implementation of a ground truth process for development of a submerged aquatic vegetation (SAV) mapping protocol using hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Hall, Carlton R.; Bostater, Charles R., Jr.; Virnstein, Robert W.

    2006-09-01

    Protocol development for science based mapping of submerged aquatic vegetation (SAV) requires comprehensive ground truth 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 ground truth 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 ground truth grid cells without significant concern for rectification and registration error.

  7. Mid-Pacific Ground-Truth Data For Validation of the CrIMSS Sensor Suite Aboard Suomi-NPP

    NASA Astrophysics Data System (ADS)

    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.

    2013-12-01

    The Aerospace Transportable Lidar System 2 (ATLS-2) provides ground truth humidity and temperature data for the testing and evaluation of instruments aboard environmental satellites. The Aerospace ground-truth 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 ground truth 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 ground truth 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

  8. Groundwater storage change in the Ngadda Catchment of the Lake Chad Basin using GRACE and ground truth data

    NASA Astrophysics Data System (ADS)

    Skaskevych, A.; Lee, J.

    2013-12-01

    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 ground truth groundwater depth data collected in 2005 and 2009. The challenge of the present study is sparseness of the ground truth 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.

  9. UAS-Borne Photogrammetry for Surface Topographic Characterization: A Ground-Truth Baseline for Future Change Detection and Refinement of Scaled Remotely-Sensed Datasets

    NASA Astrophysics Data System (ADS)

    Coppersmith, R.; Schultz-Fellenz, E. S.; Sussman, A. J.; Vigil, S.; Dzur, R.; Norskog, K.; Kelley, R.; Miller, L.

    2015-12-01

    While long-term objectives of monitoring and verification regimes include remote characterization and discrimination of surficial geologic and topographic features at sites of interest, ground truth 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 Source Physics Experiment's (Snelson et al., 2013) second phase. Ground-truth 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

  10. Studies of infrasound propagation using the USArray seismic network (Invited)

    NASA Astrophysics Data System (ADS)

    Hedlin, M. A.; Degroot-Hedlin, C. D.; Walker, K. T.

    2010-12-01

    Although there are currently ~ 100 infrasound arrays worldwide, more than ever before, the station density is still insufficient to provide validation for detailed propagation modeling. Much structure in the atmosphere is short-lived and occurs at spatial scales much smaller than the average distance between infrasound stations. Relatively large infrasound signals can be observed on seismic channels due to coupling at the Earth's surface. Recent research, using data from the 70-km spaced 400-station USArray and other seismic network deployments, has shown the value of dense seismic network data for filling in the gaps between infrasound arrays. The dense sampling of the infrasound wavefield has allowed us to observe complete travel-time branches of infrasound signals and shed more light on the nature of infrasound propagation. We present early results from our studies of impulsive atmospheric sources, such as series of UTTR rocket motor detonations in Utah. The Utah blasts have been well recorded by USArray seismic stations and infrasound arrays in Nevada and Washington State. Recordings of seismic signals from a series of six events in 2007 are used to pinpoint the shot times to < 1 second. Variations in the acoustic branches and signal arrival times at the arrays are used to probe variations in atmospheric structure. Although we currently use coupled signals we anticipate studying dense acoustic network recordings as the USArray is currently being upgraded with infrasound microphones. These new sensors will allow us to make semi-continental scale network recordings of infrasound signals free of concerns about how the signals observed on seismic channels were modified when being coupled to seismic.

  11. Engineering and development projects for the sustainment and enhancement of the IMS infrasound network

    NASA Astrophysics Data System (ADS)

    Marty, J.; Martysevich, P.; Kramer, A.; Haralabus, G.

    2012-04-01

    The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has a continuous interest in enhancing its capability in infrasound source localization and characterization. This capability is based on the processing of data recorded by the infrasound network of the International Monitoring System (IMS). This infrasound 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 infrasound station is composed of an array of infrasound 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 infrasound data. This includes the design of robust and reliable infrasound stations, the use of accurate and calibrated infrasound 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 infrasound engineering and development projects related to the testing and validation of wind noise reduction system models, the implementation of infrasound data QC tools, the definition of guidelines for the design of IMS power supply systems and the development of a portable infrasound calibrator and of field kits for site survey and certification.

  12. Spall Effects on Infrasound Generation

    NASA Astrophysics Data System (ADS)

    Jones, K. R.; Rodgers, A. J.; Whitaker, R. W.; Ezzedine, S. M.; Vorobiev, O.

    2014-12-01

    Spall effects from buried explosions are seen in near-source surface accelerations and depend on explosion yield, emplacement depth-of-burial and material strength. Investigations of infrasound 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 Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS) have been shown to generate spall signatures in local-distance infrasound (Jones et al. 2014). We are investigating the effects of spall on infrasound 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 source 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.

  13. Using large meteoroids as global infrasound reference events

    NASA Astrophysics Data System (ADS)

    Pilger, C.; Ceranna, L.; LE Pichon, A.; Brown, P.

    2015-12-01

    The explosive fragmentation of large meteoroids entering the Earth's atmosphere is one of the strongest sources of infrasonic waves and can be detected by infrasound 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 infrasound station on the one hand and of the complete global infrasound 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 infrasound detection capability are due to the directivity of the acoustic source 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 infrasound 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 infrasound at the more than 40 operational IMS infrasound stations are studied for the estimation of station and network performance and thus verification of nuclear test ban.

  14. The Temporal Morphology of Infrasound Propagation

    NASA Astrophysics Data System (ADS)

    Drob, Douglas P.; Garcés, Milton; Hedlin, Michael; Brachet, Nicolas

    2010-05-01

    Expert knowledge suggests that the performance of automated infrasound event association and source 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 infrasound 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 infrasound 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 infrasound propagation characteristics for robust automatic infrasound 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

  15. Integrated video and infrasound observations at Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Krzesni, D.; Johnson, J.; Kyle, P. R.

    2012-12-01

    Erebus volcano is ideally suited for infrasound 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 infrasound 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 infrasound wave. We assumed an acoustic monopole point source model where the volumetric acceleration was proportional to the radiated pressure waveform. In a comparison of synthetic and recorded infrasound we find a consistent match in both frequency and amplitude. The synthetic infrasound amplitude is generally greater than the amplitude of the observed infrasound. This suggests some non-linear decay in acoustic energy between the fluid ejection source and the infrasound recording sites. The infrasound 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 source overpressure respectively. For significantly asymmetric infrasound pulses, with large rarefactions compared to initial compression, we speculate that rupture occurs for bubble slugs with very low overpressures.

  16. Procedures for gathering ground truth information for a supervised approach to a computer-implemented land cover classification of LANDSAT-acquired multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Joyce, A. T.

    1978-01-01

    Procedures for gathering ground truth 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 ground truth forms and definitions and criteria of major land cover categories are provided in appendixes.

  17. Optical observations of meteors generating infrasound-I: Acoustic signal identification and phenomenology

    NASA Astrophysics Data System (ADS)

    Silber, Elizabeth A.; Brown, Peter G.

    2014-11-01

    We analyse infrasound signals from 71 bright meteors/fireballs simultaneously detected by video to investigate the phenomenology and characteristics of meteor-generated near-field infrasound (<300 km) and shock production. A taxonomy for meteor generated infrasound signal classification has been developed using the time-pressure signal of the infrasound arrivals. Based on the location along the meteor trail where the infrasound signal originates, we find most signals are associated with cylindrical shocks, with about a quarter of events evidencing spherical shocks associated with fragmentation episodes and optical flares. The video data indicate that all events with ray launch angles >117° from the trajectory heading are most likely generated by a spherical shock, while infrasound produced by the meteors with ray launch angles ≤117° can be attributed to both a cylindrical line source and a spherical shock. We find that meteors preferentially produce infrasound toward the end of their trails with a smaller number showing a preference for mid-trail production. Meteors producing multiple infrasound arrivals show a strong infrasound source height skewness to the end of trails and are much more likely to be associated with optical flares. We find that about 1% of all our optically-recorded meteors have associated detected infrasound and estimate that regional meteor infrasound events should occur on the order of once per week and dominate in numbers over infrasound associated with more energetic (but rarer) bolides. While a significant fraction of our meteors generating infrasound (~1/4 of single arrivals) are produced by fragmentation events, we find no instances where acoustic radiation is detectable more than about 60° beyond the ballistic regime at our meteoroid sizes (grams to tens of kilograms) emphasizing the strong anisotropy in acoustic radiation for meteors which are dominated by cylindrical line source geometry, even in the presence of fragmentation.

  18. Infrasound signals from the underground nuclear explosions of North Korea

    NASA Astrophysics Data System (ADS)

    Che, Il-Young; Park, Junghyun; Kim, Inho; Kim, Tae Sung; Lee, Hee-Il

    2014-07-01

    We investigated the infrasound 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 infrasound signals were detected not only by three infrasound network stations (KSGAR, ULDAR and YAGAR) in South Korea but also by two nearby International Monitoring System infrasound 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 source location of the epicentral infrasound 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 infrasound signals were observed from the second underground nuclear explosion in 2009. The exceptional detectability of the diffracted infrasound was a consequence of the temporal formation of a thin atmospheric inversion layer over the ocean surface when the event occurred.

  19. A procedure used for a ground truth study of a land use map of North Alabama generated from LANDSAT data

    NASA Technical Reports Server (NTRS)

    Downs, S. W., Jr.; Sharma, G. C.; Bagwell, C.

    1977-01-01

    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 ground truth study together with data from representative study areas is presented.

  20. SAGE ground truth plan: Correlative measurements for the Stratospheric Aerosol and Gas Experiment (SAGE) on the AEM-B satellite

    NASA Technical Reports Server (NTRS)

    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.

    1979-01-01

    The ground truth 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.

  1. The GSFC Mark-2 three band hand-held radiometer. [thematic mapper for ground truth data collection

    NASA Technical Reports Server (NTRS)

    Tucker, C. J.; Jones, W. H.; Kley, W. A.; Sundstrom, G. J.

    1980-01-01

    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 ground-truth 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.

  2. Infrasound research in Spitsbergen

    NASA Astrophysics Data System (ADS)

    Vinogradov, Yuri; Kremenetskaya, Elena

    2013-04-01

    KB GS RAS has a good experience of joint registration of seismic and infrasound events, their detection and classification. Since 1999 the observations at the seismic and infrasound array "Apatity" are carried out. The array is located in the center of Kola Peninsula. Since 2009 we also have started infrasound observations in Spitsbergen Archipelago. Until then we have assumed that such measurements are not informative because of extremely strong winds there. However, after noise level measurements at three points (Barentsburg, Pyramiden and Ny-Byen) it was found that registration of infrasound signals is possible at an average level of wind noise. In November, 2010 an infrasound array has been installed near the seismic station BRBB. The stations are located 4 km far from the settlement of Barentsburg to reduce man-made noise. The infrasound array consists of 3 low-frequency microphones. Each microphone is installed with a wind-reducing filter. It was supposed that the infrasound array will record signals from cleaving glaciers while the seismic station will register signals caused by glaciers movements. 132 glaciers are situated in the central and northern part of Spitsbergen, more than 90 of them are surging. Observation of seismicity of the continental part of the Archipelago has revealed a seasonal periodicity of weak seismic events. Maximal numbers of weak seismic events are registered during Septembers and Octobers. One of possible explanations of the periodicity could be seasonal changes of glaciers activity. It is known that ice breaks cause sharp sounds. Registration of these acoustic waves and their comparison with seismic signals also was the primary goal of our research. Two nearest surging glaciers, Esmark and Nansen, are located to the north and north-east from the stations at distances 20 and 24 kilometers respectively. These glaciers are rather small but a lot of seismic events has been registered in their areas in 2007 and in 2010. Single events

  3. Accuracies of facial soft tissue depth means for estimating ground truth skin surfaces in forensic craniofacial identification.

    PubMed

    Stephan, Carl N

    2015-07-01

    Facial soft tissue thickness means have long been used as a proxy to estimate the soft tissue envelope, over the skull, in craniofacial identification. However, estimation errors of these statistics are not well understood, making casework selection of the best performing estimation models impossible and overarching method accuracies controversial. To redress this situation, residuals between predicted and ground truth values were calculated in two experiments: (1) for 27 suites of means drawn from 10 recently published studies, all examining the same 10 landmarks (N ≥ 3051), and tested against six independent raw datasets of contemporary living adults (N = 797); and (2) pairwise tests of the above six, and five other, raw datasets (N = 1063). In total, 380 out-of-sample tests of 416 arithmetic means were conducted across 11 independent samples. Experiment 1 produced an overarching mean absolute percentage error (MAE) of 29% and a standard error of the estimate (S(est)) of 2.7 mm. Experiment 2 yielded MAE of 32% and S(est) of 2.8 mm. In any instance, MAE was always ≥20% of the ground truth value. The overarching 95% limits of the error, for contemporary samples, was large (11.4 mm). CT-derived means from South Korean males and Black South African females routinely performed well across the test samples and produced the smallest errors of any tests (but did so for Black American male reference samples). Sample-specific statistics thereby performed poorly despite discipline esteem. These results—and the practice of publishing means without prior model validation—demand major reforms in the field. PMID:25394746

  4. Contribution of the infrasound technology to characterize large scale atmospheric disturbances and impact on infrasound monitoring

    NASA Astrophysics Data System (ADS)

    Blanc, Elisabeth; Le Pichon, Alexis; Ceranna, Lars; Pilger, Christoph; Charlton Perez, Andrew; Smets, Pieter

    2016-04-01

    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 infrasound 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 infrasound 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 infrasound technology to characterize these large scale disturbances, including (i) wind fluctuations induced by gravity waves generating infrasound partial reflections and modifications of the infrasound 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 source location errors, and improve characterization methods.

  5. Detection and interpretation of seismoacoustic events at German infrasound stations

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Koch, Karl; Ceranna, Lars

    2016-04-01

    Three infrasound 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). Infrasound generated by seismoacoustic events is routinely detected at these infrasound arrays, but air-to-ground coupled acoustic waves occasionally show up in seismometer recordings as well. Different natural and artificial sources like meteoroids as well as industrial and mining activity generate infrasonic signatures that are simultaneously detected at microbarometers and seismometers. Furthermore, many near-surface sources 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 infrasound events or about the characterization of seismic events distinguishing man-made and natural origins. Furthermore, seismoacoustic studies help to improve the modelling of infrasound propagation and ducting in the atmosphere and allow quantifying the portion of energy coupled into ground and into air by seismoacoustic sources. An overview of different seismoacoustic sources and their detection by German infrasound stations as well as some conclusions on the benefit of a combined seismoacoustic analysis are presented within this study.

  6. Infrasound Studies at the USArray (Invited)

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, C. D.

    2013-12-01

    Many surface and atmospheric sources, both natural and anthropogenic, have generated infrasound signals that have been recorded on USArray transportable array (TA) seismometers at ranges up to thousands of kilometers. Such sources, including surface explosions, large bolides, mining events, and a space shuttle, have contributed to an understanding of infrasound propagation. We show examples of several atmospheric sources recorded at the TA. We first used USArray data to investigate infrasound 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 infrasound 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 infrasound 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, infrasound 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 source model, suggesting that the large size of the explosion

  7. Nonlinear synthesis of infrasound propagation through an inhomogeneous, absorbing atmosphere.

    PubMed

    de Groot-Hedlin, C D

    2012-08-01

    An accurate and efficient method to predict infrasound amplitudes from large explosions in the atmosphere is required for diverse source 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 infrasound 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 source amplitudes and atmospheric variability on infrasound waveforms and shock formation. Results show that infrasound waveforms steepen and their associated spectra are shifted to higher frequencies for nonlinear sources, leading to enhanced infrasound attenuation. Results also indicate that nonlinear infrasound 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. PMID:22894187

  8. Science results from a Mars drilling simulation (Río Tinto, Spain) and ground truth for remote science observations.

    PubMed

    Bonaccorsi, Rosalba; Stoker, Carol R

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" 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 %). GROUND TRUTH 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

  9. Science Results from a Mars Drilling Simulation (Río Tinto, Spain) and Ground Truth for Remote Science Observations

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, Rosalba; Stoker, Carol R.

    2008-10-01

    Science results from a field-simulated lander payload and post-mission laboratory investigations provided "ground truth" 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 (˜1:1, ˜1:2, and ˜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 (Corg <0.05 wt %) beneath the biologically active organic-rich soil horizon (Corg ˜3-11 wt %) in contrast to the phyllosilicate-rich zones (Corg ˜0.23 wt %). Ground truth 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 cores. Our manned vs. remote observations based on automated

  10. Geographic information system for fusion and analysis of high-resolution remote sensing and ground truth data

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony; Way, Jo Bea; Dubois, Pascale; Leberl, Franz

    1992-01-01

    We seek to combine high-resolution remotely sensed data with models and ground truth 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 ground truth 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

  11. BBN technical memorandum W1291 infrasound model feasibility study

    SciTech Connect

    Farrell, T., BBN Systems and Technologies

    1998-05-01

    The purpose of this study is to determine the need and level of effort required to add existing atmospheric databases and infrasound propagation models to the DOE`s Hydroacoustic Coverage Assessment Model (HydroCAM) [1,2]. The rationale for the study is that the performance of the infrasound 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 infrasound network are directly related to the variability of the atmosphere and the corresponding uncertainties in infrasound 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 infrasound 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 infrasound capability. The study approach was to talk to the acknowledged domain experts in the infrasound monitoring area to determine: 1. The major technical issues affecting infrasound monitoring network performance. 2. The need for an atmospheric database/infrasound propagation modeling capability similar to HydroCAM. 3. The state of existing infrasound 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 sources 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

  12. A 3-D view of field-scale fault-zone cementation from geologically ground-truthed electrical resistivity

    NASA Astrophysics Data System (ADS)

    Barnes, H.; Spinelli, G. A.; Mozley, P.

    2015-12-01

    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 ground-truth 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.

  13. Semi-automatic ground truth generation using unsupervised clustering and limited manual labeling: Application to handwritten character recognition

    PubMed Central

    Vajda, Szilárd; Rangoni, Yves; Cecotti, Hubert

    2015-01-01

    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 ground truth, 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

  14. The Numerical Simulation of Infrasound Generated by Convective Storms

    NASA Astrophysics Data System (ADS)

    Schecter, D.; Nicholls, M. E.

    2009-12-01

    Recent observations and theoretical considerations suggest that a developing tornado has a detectable signature in the infrasound of a severe weather system [A.J. Bedard Jr., Mon. Weather Rev., 133, 241 (2005)]. In order to reliably distinguish the vortex signal from extraneous noise, it is essential to advance current understanding of the various mechanisms that produce infrasound in atmospheric convection. Without detailed observations of the acoustic sources within a storm, numerical modeling may be the best method of investigation. Here, we consider the feasibility of using a special version of the Regional Atmospheric Modeling System (RAMS) that is customized to simulate aeroacoustics. Comparison to analytical results demonstrates that the customized model adequately generates the infrasound of tornado-like vortices, and of basic diabatic cloud processes. Sensitivity to the microphysics parameterization is briefly addressed. Provisional simulations suggest that a moderate-to-strong tornado can adiabatically generate infrasound of much greater intensity than the infrasound of a generic hail-producing thunderstorm, in the 0.1-3 Hz frequency range [D.A. Schecter et al., J. Atmos. Sci., 65, 685 (2008)]. More detailed numerical studies are underway to verify this conclusion, and to further understand the production of infrasound in a broad spectrum of convective systems, ranging from non-precipitating cumuli to tornadic thunderstorms.

  15. Infrasound from lightning: characteristics and impact on an infrasound station

    NASA Astrophysics Data System (ADS)

    Farges, T.; Blanc, E.

    2009-12-01

    More than two third of the infrasound 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, infrasound from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure infrasound from lightning when thunderstorms are close or far from the infrasound station. Main results concern detection range of infrasound from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, infrasound 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 infrasound signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. Infrasound 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 infrasound data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning

  16. Infrasound from lightning: characteristics and impact on an infrasound station

    NASA Astrophysics Data System (ADS)

    Farges, Thomas; Blanc, Elisabeth

    2010-05-01

    More than two third of the infrasound 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, infrasound from lightning and from sprites (which are transient luminous events occurring over thunderstorm). We examine the possibility to measure infrasound from lightning when thunderstorms are close or far from the infrasound station. Main results concern detection range of infrasound from lightning, amplitude vs. distance law, and characteristics of frequency spectrum. We show clearly that infrasound from lightning can be detected when the thunderstorm is within about 75 km from the station. In good noise conditions, infrasound 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 infrasound signal could reach several Pascal. The signal is then on average 30 dB over the noise level at 1 Hz. Infrasound 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 infrasound data in the last ten years and the appearance of global lightning detection network as the World Wide Lightning

  17. Probing the atmosphere with infrasound

    NASA Technical Reports Server (NTRS)

    Posmentier, E. S.; Donn, W. L.

    1969-01-01

    Recent studies are reported which have contributed to the knowledge of atmospheric structure and have established the practicality of infrasonic techniques for probing the atmosphere to heights of 120 km or more. Observations of a few types of infrasound are reviewed, and the theories used to account for the infrasound propagation and the deduced atmospheric structures are discussed.

  18. Grid-Search Location Methods for Ground-Truth Collection from Local and Regional Seismic Networks

    SciTech Connect

    Schultz, C A; Rodi, W; Myers, S C

    2003-07-24

    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 source-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

  19. Nonlinear Propagation of Infrasound from Large Explosions

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine

    2015-04-01

    Atmospheric explosions release immense quantities of infrasound 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 source energy from remote recordings of infrasound signals use simplified empirical source-yield relations that account for stratospheric winds along the source-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 source-yield formulations for realistic sound and wind speed profiles. However, these methods assume linear infrasound 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 infrasound frequencies, velocities and amplitudes, and thus can affect derived source yield estimates. For realistic atmospheric profiles, nonlinearity can be significant both in the vicinity of a large explosive source 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 infrasound 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 infrasound 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 source in a fully 3D model with rotational

  20. Long-range infrasound monitoring of eruptive volcanoes.

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Innocenti, Lorenzo; Ulivieri, Giacomo; Lacanna, Giorgio; Ripepe, Maurizio

    2016-04-01

    The efficient long-range propagation in the atmosphere makes infrasound of active volcanoes extremely promising and opens new perspectives for volcano monitoring at large scale. In favourable propagation conditions, long-range infrasound 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 source term is still debated. We present results of comparing five years of infrasound of eruptive activity at Mt.Etna volcano (Italy) recorded both at local (~5 km) and at regional distances (~600 km) from the source. Infrasound 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 source 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 infrasound, 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.

  1. Explosion Source Location Study Using Collocated Acoustic and Seismic Networks in Israel

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Gitterman, Y.; Arrowsmith, S.; Ben-Horin, Y.

    2013-12-01

    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 ground-truth 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 infrasound waves (up to 300 km), is also analyzed. For all of these events the ground-truth 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 ground-truth event recordings and the preliminary results obtained have been compared to the ground-truth 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

  2. Using infrasound to constrain ash plume height

    NASA Astrophysics Data System (ADS)

    Lamb, Oliver; De Angelis, Silvio; Lavallée, Yan

    2016-04-01

    Airborne volcanic ash advisories are currently based on analyses of satellite imagery with relatively low temporal resolution, and numerical simulations of atmospheric plume dispersion. These simulations rely on key input parameters such as the maximum height of eruption plumes and the mass eruption rate at the vent, which remain loosely constrained. In this study, we present a proof-of-concept workflow that incorporates the analysis of volcanic infrasound with numerical modelling of volcanic plume rise in a realistic atmosphere. We analyse acoustic infrasound records from two explosions during the 2009 eruption of Mt. Redoubt, USA, that produced plumes reaching heights of 12-14 km. We model the infrasonic radiation at the source under the assumptions of linear acoustic theory and calculate variations in mass ejection velocity at the vent. The estimated eruption velocities serve as the input for numerical models of plume rise. The encouraging results highlight the potential for infrasound measurements to be incorporated into numerical modelling of ash dispersion, and confirm their value for volcano monitoring operations.

  3. Infra-sound Signature of Lightning

    NASA Astrophysics Data System (ADS)

    Arechiga, R. O.; Badillo, E.; Johnson, J.; Edens, H. E.; Rison, W.; Thomas, R. J.

    2012-12-01

    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 infra-sound and audio-range portion of thunder is thought to come from the gas dynamic expansion, and the electrostatic mechanism gives rise to a signature infra-sound pulse peaked at a few Hz. More than 50 signature infra-sound 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 infra-sound pulses at different times and acoustic source reconstruction to demonstrate the beaming effect.

  4. I37NO: an IMS infrasound array in northern Norway for optimal monitoring of infrasound on global and regional scales

    NASA Astrophysics Data System (ADS)

    Kvaerna, Tormod; Gibbons, Steven; Fyen, Jan; Roth, Michael

    2014-05-01

    The IMS infrasound array I37NO near Bardufoss in northern Norway became operational in October 2013 and was certified on December 19, 2013. The 10-element array has an aperture of approximately 1.5 km and is deployed in low-lying woodland about 2.5 degrees north of the Arctic Circle. Its location in the European Arctic means that the array fills an important gap in the global IMS infrasound monitoring network. In addition, I37NO extends significantly the network of infrasound stations in northern Norway, Sweden, Finland, and Russia: operated by NORSAR, the Swedish Institute for Space Physics, and the Kola Regional Seismological Center in Apatity. The geometry is based on the highly successful classical design for regional seismic arrays with sensors arranged in two approximately concentric rings surrounding a central site. A 4-site subarray with an aperture of approximately 450 meters, comprising the central element and the inner ring of 3 sites, provides an excellent array response function and detection capability for relatively high frequency (2-4 Hz) signals. Such signals are usually generated by events at distances within 1000 km and often lack energy in the lower frequency bands for which the larger aperture arrays provide signal coherence. These so-called regional signals are of increasing importance in civil applications and the need to characterize the infrasonic wavefield over these distances is increasingly important in the remote monitoring of natural hazards. I37NO will provide good characterization of Ground Truth industrial and military explosions in the region which are well-constrained by seismic data. The full array aperture provides excellent backazimuth and slowness resolution for lower frequency signals and it is anticipated that I37NO will contribute significantly to the detection and association of signals on a global scale. Already within the first few months of operation, we have examples of high-quality recordings from meteors, accidental

  5. Results of Infrasound Interferometry in Netherlands

    NASA Astrophysics Data System (ADS)

    Fricke, J. T.; Ruigrok, E. N.; Evers, L. G.; Simons, D. G.; Wapenaar, K.

    2012-04-01

    The travel time of infrasound through the atmosphere depends on the temperature and the wind. These atmospheric conditions could be estimated by measuring the travel times between different receivers (microbarometers). For such an estimation an inverse model of the propagation of infrasound through the atmosphere is essential. In the first step it is useful to build a forward model. The inputs of our raytracing model are the atmospheric conditions and the positions of source and receiver. The model consists of three elements the source, the channel and the receiver. The source is a blast wave or microbaroms. The channel is the atmosphere and it takes into account the travel time along the eigen ray, the attenuation of the different atmospheric layers, the spreading of the rays and the influence of caustics. Each receiver is reached by different rays (eigen rays). To determine the eigen rays is part of the receiver element. As output the model generates synthetic barograms. The synthetic barograms can be used to explain measured barograms. Furthermore the synthetic barograms can also be used to evaluate the determination of the travel time. The accurate travel time is for the inverse model as input essential. Since small changes of the travel time lead to big changes of the output (temperature and wind). The travel time between two receivers is determined by crosscorrelating the barograms of these two receivers. This technique was already successfully applied in the troposphere (Haney, 2009). We show that the same can be achieved with more complicated stratospheric phases. Now we compare the crosscorrelation of synthetic barograms with the crosscorrelation of measured barograms. These barograms are measured with the 'Large Aperture Infrasound Array' (LAIA). LAIA is being installed by the Royal Netherlands Meteorological Institute (KNMI) in the framework of the radio-astronomical 'Low Frequency Array' (LOFAR) initiative. LAIA will consist of thirty microbarometers

  6. Geological "Ground Truth" of Sea-level Highstand Events During Warm Interglaciations (MIS 11 and 5e): Taking the Punch out of Proxy Precision

    NASA Astrophysics Data System (ADS)

    Hearty, P. J.

    2005-12-01

    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 ground truth 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

  7. Constraining the Spatial and Temporal Variability of Atmospheric Conditions to Explore the Infrasound Detection of Volcanic Eruptions in Alaska

    NASA Astrophysics Data System (ADS)

    Iezzi, A. M.; Schwaiger, H. F.; Fee, D.; Haney, M. M.

    2015-12-01

    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 infrasound sensors. Infrasound is an especially crucial tool in this area because infrasound data collection is not obstructed by frequent cloud cover (as in satellite imagery) and infrasound waves can travel hundreds to thousands of kilometers. However, infrasound station coverage is relatively sparse and strong wind and temperature gradients in the atmosphere create multiple waveguides and shadow zones where the propagation of infrasound is enhanced and diminished, respectively. To accurately constrain volcanic source information and the long-range propagation of infrasound 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 infrasound waves to model the propagation of infrasound. Here we present the first results of a re-analysis system constructed by the Alaska Volcano Observatory to accurately characterize and model long-range infrasound propagation from volcanic eruptions. We select a number of case studies to examine infrasound 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 infrasound propagation modeling.Drob, Douglas P., J. M. Picone

  8. Ground-Truthing Moderate Resolution Satellite Imagery with Near-Surface Canopy Images in Hawai'i's Tropical Cloud Forests

    NASA Astrophysics Data System (ADS)

    Bergstrom, R.; Miura, T.; Lepczyk, C.; Giambelluca, T. W.; Nullet, M. A.; Nagai, S.

    2012-12-01

    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 ground-truthing. 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

  9. Validation of the Carotid Intima-Media Thickness Variability: Can Manual Segmentations Be Trusted as Ground Truth?

    PubMed

    Meiburger, Kristen M; Molinari, Filippo; Wong, Justin; Aguilar, Luis; Gallo, Diego; Steinman, David A; Morbiducci, Umberto

    2016-07-01

    difference in both the no variability and large variability cases. Moreover, the error range between the reader and automatic IMTV values was approximately 0.15 mm, which is on the same order of small IMTV values, indicating that manual and automatic IMTV readings should be not used interchangeably in clinical practice. On the basis of our findings, we conclude that expert manual tracings should not be considered reliable in IMTV measurement and, therefore, should not be trusted as ground truth. On the other hand, our automated algorithm was found to be more reliable, indicating how automated techniques could therefore foster analysis of the carotid artery intima-media thickness irregularity. PMID:27072077

  10. Remote Sensing across the Globe: Best Practices in Bringing Together Satellite Imagery, Telecommunications and Ground-Truth Observations

    NASA Astrophysics Data System (ADS)

    Probst, R.; Walker, C. E.; Martin, C.; Dorame, B.; Ochoa, H.; Orellana, D.; Isbell, D. M.; Pompea, S. M.

    2006-12-01

    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 ground-truth. 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

  11. Deep infrasound radiated by the Sumatra earthquake and tsunami

    NASA Astrophysics Data System (ADS)

    Garcés, M.; Caron, P.; Hetzer, C.; Le Pichon, A.; Bass, H.; Drob, D.; Bhattacharyya, J.

    Infrasound arrays in the Pacific and Indian oceans that are part of the International Monitoring System (IMS) of the Comprehensive Nuclear Test Ban Treaty (CTBT) recorded distinct signatures associated with the 26 December 2004 Sumatra earthquake (M/9, http://earthquake.usgs.gov/) and tsunami. Although the radiation of infrasound from large continental earthquakes is established [e.g., Le Pichon et al., 2003], the results presented in the present article indicate that islands undergoing significant surface displacements from submarine earthquakes can produce infrasound.Far more intriguing is the possibility that the initiation and propagation of a tsunami may produce low-frequency sound near the source as well as along coastlines and basins. Since distant sound effectively propagates at ˜300 m/s and tsunamis propagate at ˜200 m/s, precursory sound could potentially be used as a discriminant for tsunami genesis.

  12. Characteristics and Applications of a High Performance, Miniaturized, Infrasound Sensor

    NASA Astrophysics Data System (ADS)

    Rothman, J. L.; Marriott, D. A.

    2015-12-01

    Infrasound Sensors have been used for many years to monitor a large number of geophysical phenomena and manmade sources. 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, infrasound microphone has been developed to enable mobile infrasound 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.

  13. Infrasound from Rock Fall at Santiaguito Volcano, Guatemala

    NASA Astrophysics Data System (ADS)

    Ronan, T.; Terbush, B.; Miller, A. J. C.; Anderson, J.; Johnson, J. B.

    2014-12-01

    Volcanoes generate infrasound from incidental rock fall and from rock fall directly associated with eruptions. This study demonstrates that arrays of infrasound 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 infrasound 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, sources 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 source of infrasound (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 infrasound, 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 infrasound array remote sensing for detecting volcanic unrest in the form of rock fall, which is common at most active silicic domes.

  14. Study of IDC infrasound REB solutions using Egyptian National Seismic Network data

    NASA Astrophysics Data System (ADS)

    Ali, Sherif M.; Polich, Paul

    2015-04-01

    infragenic sources within Egypt and regional surroundings, and benchmark the detection capability of the ENSN by its concurrence with IMS infrasound data.

  15. Estimation of snowpack matching ground-truth data and MODIS satellite-based observations by using regression kriging

    NASA Astrophysics Data System (ADS)

    Juan Collados-Lara, Antonio; Pardo-Iguzquiza, Eulogio; Pulido-Velazquez, David

    2016-04-01

    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 ground-truth 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

  16. Hyperion 5113/A Infrasound Sensor Evaluation

    SciTech Connect

    Merchant, Bion John

    2015-09-01

    Sandia National Laboratories has tested and evaluated an infrasound sensor, the 5113/A manufactured by Hyperion. These infrasound sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, and dynamic range. The 5113/A infrasound sensor is a new revision of the 5000 series intended to meet the infrasound application requirements for use in the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).

  17. Urban Infrasound Observations - Examples from July 4th 2012

    NASA Astrophysics Data System (ADS)

    McComas, S.; Hayward, C.; Golden, P.; McKenna, M.; Simpson, C.

    2012-12-01

    Historical observations indicate that urban environments are rich in infrasound signals and thus provide the opportunity to characterize sources, monitor propagation path effects, and document diurnal and seasonal variability in the urban acoustical noise environment. If infrasound 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 sources of infrasound 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 sources be well differentiated? (3) Does infrasound 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 infrasound noise and propagation effects. Such studies differ from typical infrasound work in that the propagation paths are short, i.e. ~1- 100 km, and signal frequencies can extend from the infrasound band to the low frequency acoustic band (100 Hz). We have begun a study to address some of the unique infrasound research questions and sources found in an urban environment. Our initial investigation of the data and a description of the identified noise and source 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 infrasound 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

  18. Global Infrasound Association Based on Probabilistic Clutter Categorization

    NASA Astrophysics Data System (ADS)

    Arora, N. S.; Mialle, P.

    2015-12-01

    The IDC collects waveforms from a global network of infrasound 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 sources such as microbaroms (from standing waves in the oceans), waterfalls, dams, gas flares, surf (ocean breaking waves) etc. These sources 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 infrasound 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 sources as well as other sources of infrasound clutter. A diverse clutter-field such as this one is quite common for most IMS infrasound stations, and it highlights the dangers of forming events without due consideration of this source of noise. References: [1] Infrasound 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.

  19. Global Infrasound Association Based on Probabilistic Clutter Categorization

    NASA Astrophysics Data System (ADS)

    Arora, Nimar; Mialle, Pierrick

    2016-04-01

    The IDC advances its methods and continuously improves its automatic system for the infrasound 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 infrasound 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 sources such as microbaroms, waterfalls, dams, gas flares, surf (ocean breaking waves) etc. These sources 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 infrasound processing built on a unified probabilistic framework. References: [1] Infrasound 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

  20. Assessing and optimizing infrasound network performance: application to remote volcano monitoring

    NASA Astrophysics Data System (ADS)

    Tailpied, D.; LE Pichon, A.; Marchetti, E.; Kallel, M.; Ceranna, L.

    2014-12-01

    Infrasound is an efficient monitoring technique to remotely detect and characterize explosive sources such as volcanoes. Simulation methods incorporating realistic source 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 infrasound propagation. Recent studies have shown that remote infrasound 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 source 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 source to test and optimize detection and simulation methods. The closest infrasound 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 infrasound 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 infrasound monitoring.

  1. Up-Scaling Field Observations to Ground Truth Seismic Interpretations and Test Dynamic Models of Deep Water Rifted Margins: What are the Challenges?

    NASA Astrophysics Data System (ADS)

    Manatschal, G.; Nirrengarten, M.; Epin, M. E.

    2015-12-01

    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 ground truth 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 ground truth 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

  2. Characterization and diagnostic methods for geomagnetic auroral infrasound waves

    NASA Astrophysics Data System (ADS)

    Oldham, Justin J.

    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 infrasound. Persistent periods of infrasonic activity associated with geomagnetic sub-storms have been termed geomagnetic auroral infrasound 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 infrasound 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 infrasound 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 source 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 sources of much of the observed infrasound, with

  3. Infrasound associated with the deep M 7.3 northeastern China earthquake of June 28, 2002

    NASA Astrophysics Data System (ADS)

    Che, Il-Young; Kim, Geunyoung; Pichon, Alexis Le

    2013-02-01

    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 infrasound signal that was observed by the remote infrasound array (CHNAR), 682 km from the epicenter, in South Korea. Coherent infrasound 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 source area of the infrasonic signals that arrived earlier were located along the eastern coastal areas of North Korea and Russia, whereas later signals were sourced throughout Japan. The geographically-constrained, and discrete, distribution of the sources identified is explained by infrasound 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 infrasound to include deep earthquakes, and also supports the possibility that infrasound measurements could help determine the depth of earthquakes.

  4. IDC Infrasound Pipeline initiative for technology development

    NASA Astrophysics Data System (ADS)

    Mialle, Pierrick; Bittner, Paulina; Brown, David; Given, Jeffrey

    2013-04-01

    The first atmospheric event built only from infrasound 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 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The growing amount of infrasound data and detections produced by the automatic system challenged the station and network processing at the IDC, which require the Organization to continually improve the infrasound data processing. For 3 years, the IDC resumed automatic processing of infrasound data reviewed by interactive analysis; the detected and located events are being systematically included in the Late Event Bulletin (LEB) and REB. Approximately 16% of SEL3 (Selected Event List 3, produced 6 hours after real-time) events with an infrasound component make it to the IDC bulletins. 41% of SEL3 events rejected after review are built including only 2 associated infrasound phases (with the potential addition of seismic and hydroacoustic detections). Therefore, the process whereby infrasound and seismic detections are associated into an event needed to be investigated further. The IDC works on enhancing the automatic system for the identification of valid signals and the optimization of the network detection threshold. Thus the IDC investigates ways to refine the signal characterization methodology and the association criteria. The objective of this study is to reduce the number of associated infrasound arrivals that are rejected from the SEL3 pipeline when generating the LEB and REB bulletins. The study is twofold, the first part consist of improving the detection accuracy at the station processing stage in the IDC development area by enhancing the infrasound signal detector DFX-PMCC (Detection and Feature eXtraction - Progressive Multi-Channel Correlation) used at the IDC. The second part is

  5. Derivation from the Landsat 7 NDVI and ground truth validation of LAI and interception storage capacity for wetland ecosystems in Biebrza Valley, Poland

    NASA Astrophysics Data System (ADS)

    Suliga, Joanna; Chormański, Jarosław; Szporak-Wasilewska, Sylwia; Kleniewska, Małgorzata; Berezowski, Tomasz; van Griensven, Ann; Verbeiren, Boud

    2015-10-01

    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 ground truthing 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. Ground truthing 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.

  6. Databases for Studies of Infrasound Propagation in the European Arctic

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Ringdal, Frode

    2010-05-01

    Industrial and military sources in northern Fennoscandia and NW Russia generate both seismic and infrasound 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 infrasound 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 infrasound 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 infrasound 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. Infrasound 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

  7. Hyperion 5113/GP Infrasound Sensor Evaluation.

    SciTech Connect

    Merchant, Bion J.

    2015-08-01

    Sandia National Laboratories has tested and evaluated an infrasound sensor, the 5113/GP manufactured by Hyperion. These infrasound sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the infrasound 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.

  8. MB3a Infrasound Sensor Evaluation.

    SciTech Connect

    Merchant, Bion J.; McDowell, Kyle D.

    2014-11-01

    Sandia National Laboratories has tested and evaluated a new infrasound sensor, the MB3a, manufactured by Seismo Wave. These infrasound 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 infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, seismic sensitivity, and self- calibration ability. The MB3a infrasound sensors are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

  9. Infrasound research at Kola Regional Seismological Centre, Russia

    NASA Astrophysics Data System (ADS)

    Asming, Vladimir; Kremenetskaya, Elena

    2013-04-01

    A small-aperture infrasound 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 infrasound 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 infrasound signals of different natures has been collected. It contains recordings of microbaromes, industrial and military explosions, airplane shock waves, infrasound 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 infrasound signals and preliminary location of infrasound events by several arrays. It was tested with Apatity data together with data of Sweden - Finnish infrasound 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 infrasound 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 source of repeating infrasound signals of the same magnitude and origin. We recorded several hundreds of such explosions. The signals have been used for testing our location routines

  10. Detecting and characterizing infrasound signals with optical fiber infrasound sensors

    NASA Astrophysics Data System (ADS)

    Walker, Kristoffer; Zumberge, Mark; Berger, Jonathan; Hedlin, Michael; Arrowsmith, Stephen

    2005-04-01

    Optical Fiber Infrasound Sensors (OFIS) are long compliant tubes wrapped with two optical fibers that interferometrically measure the differential pressure variation along the length of the tube. Because each sensor averages spatially along the length of the tube, the frequency response of the recorded pressure variation is a function of the orientation of the OFIS sensor relative to the back azimuth and incidence angle of the incoming wave. We have exploited this property to investigate the ability of various OFIS geometries to determine the back azimuth of infrasound signals. We have found that an OFIS comprised of two orthogonal 89-m-long arms having their centers separated by 63 m can resolve the back azimuth of most infrasound signals with a good signal-to-noise ratio. We find a good match between the back azimuths determined with our technique and those determined for the same signals recorded on the co-located pipe array I57US with the Progressive Multichannel Cross-Correlation technique. Based on these results and additional synthetic tests, we have built and are testing a larger OFIS with several arms that will be able to resolve signals from all directions and with small signal-to-noise ratios.

  11. IPLOR performance in detecting infrasound from volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Popa, Mihaela

    2016-04-01

    Plostina infrasound 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 infrasound signals produced by natural and anthropogenic impulsive sources. 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 infrasound source 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 infrasound 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

  12. Could the IMS Infrasound Stations Support a Global Network of Small Aperture Seismic Arrays?

    NASA Astrophysics Data System (ADS)

    J, Gibbons, Steven; Kværna, Tormod; Mykkeltveit, Svein

    2015-04-01

    find such added capabilities valuable from a national perspective. In addition, the seismic recordings may also help to identify the sources of infrasound signals with consequences for improved event screening and evaluating models of infrasound propagation and atmospheric properties.

  13. Infrasound Sensor Models and Evaluations

    SciTech Connect

    KROMER,RICHARD P.; MCDONALD,TIMOTHY S.

    2000-07-31

    Sandia National Laboratories has continued to evaluate the performance of infrasound 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 Infra-sound Monitoring and the International Exchange of Infrasound 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.

  14. Infrasound and the avian navigational map

    USGS Publications Warehouse

    Hagstrum, J.T.

    2001-01-01

    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 infrasound down to 0??05 Hz, and an acoustic avian map is proposed consisting of infrasonic cues radiated from steep-sided topographic features. The source 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.

  15. Miniaturization and Autonomous Deployment of the Optical Fiber Infrasound Sensor

    NASA Astrophysics Data System (ADS)

    DeWolf, S.; Walker, K. T.; Zumberge, M. A.

    2010-12-01

    A key difficulty in infrasound signal detection is the noise created by spatially incoherent turbulence that is usually present in wind. Increasing wind speeds correlate with increasing noise levels across the entire infrasound band. Spatial separation of sensors with array processing provides only limited signal-to-noise improvement. Mechanical wind filters, like rosette pipe arrays, also help to reduce wind noise, but the rosette infrasound response depends on the apparent speed and frequency of the signal that propagates across the ports as well as the rosette size. This response places an upper limit of about 70 m on the diameter of rosettes; larger rosettes, while better at wind noise reduction, attenuate important infrasound signals arriving from all directions. Optical fiber infrasound sensors (OFIS) are line microphones that instantaneously integrate pressure along their lengths with laser interferometry. We have developed and tested computationally efficient beamforming techniques that permit the rapid estimation of back azimuth using an array of OFIS arms as well as an array deconvolution technique that accurately stacks weighted versions of the recordings to obtain the infrasound signal. In this presentation we report on the major changes to our OFIS deployment strategies to accommodate a recent installment of a four element array in the Big Chico Creek Ecological Reserve, near Chico, CA. This includes significant improvement of the data acquisition and real-time digital signal processing systems, development of a robust and low-noise laser source, reduction of the power budget to that compatible with solar power, and data telemetry that enables each sensor to run autonomously. We also demonstrate that the sensitivity of the OFIS is linear over a wide range of pressures, which combined with the dynamic range of the digitizer, also makes the OFIS suitable for impulsive, near-field source studies. Using one of the aforementioned beamforming techniques, we

  16. Infrasound from the Chelyabinsk Meteor recorded at the USArray

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, C. D.; Hedlin, M. A.

    2013-12-01

    A small asteroid that entered Earth's atmosphere near the city of Chelyabinsk, Russia, generated infrasound signals that were recorded by USArray barometers at distances from 6000-10000 km from the source. The infrasound recordings made of this event by these arrays are unprecedented, due to the high density of the networks and their spatial extent. Signal characteristics vary across the network; infrasound arrivals recorded in Alaska and along the U.S. northwest coast had higher velocities and higher frequency content than those recorded in the eastern part of the network. Waveform amplitudes at Alaska sites were approximately ten times larger than for the remaining stations, much more than expected due solely to their shorter travel paths. Atmospheric specifications of global wind and sound speeds indicate the presence of a stratospheric duct for propagation to Alaska and stations along the northwest coast; however, most USarray stations lie within a thermospheric duct. Raytrace modeling confirms that, at stations in Alaska and the northwest U.S., the arrival times and durations of stratospherically ducted rays are consistent with observed arrivals at frequencies above the microbarom band. At lower frequencies, arrival times are consistent with thermospheric ducting at stations across the network. An attenuation formula derived from parabolic equation simulations is used to estimate infrasound transmission losses at all USArray stations, using simplified models of the effective sound speed along each source-receiver path. Results indicate that, under the assumption of an isotropic source, attenuation estimates for most USArray sites are in agreement with observed variations in waveform amplitudes. However, stations in the northwest U.S, which lie along a geographic boundary between stratospheric and thermospheric ducting, have lower than expected amplitudes.

  17. Simulation and Analysis of Infrasound Generated by Convective Storms and Tornadoes

    NASA Astrophysics Data System (ADS)

    Schecter, D.; Nicholls, M.

    2011-12-01

    Observational studies have shown that severe storms can emit abnormally strong, sustained infrasound 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 infrasound of non-tornadic sources within a storm. There is a pressing need to advance our fundamental understanding of the different mechanisms that generate infrasound 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 sources of infrasound 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 infrasound 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 infrasound 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 source of discernible infrasound. Apparent deficiencies of earlier theories that predicted otherwise will be addressed. This work was supported by NSF grant AGS-0832320.

  18. Assessing and optimizing infrasound network performance: application to remote volcano monitoring

    NASA Astrophysics Data System (ADS)

    Tailpied, Dorianne; Le Pichon, Alexis; Marchetti, Emanuele; Ceranna, Lars; Pilger, Christopher

    2015-04-01

    Interest in infrasound 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 infrasound 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 source 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 infrasound propagation. Recent studies have shown that remote infrasound 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 source 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 source 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 infrasound 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 infrasound 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 infrasound monitoring.

  19. Atmospheric Infrasound from Hurricanes Felicia and Neki of 2009

    NASA Astrophysics Data System (ADS)

    Stopa, J. E.; Cheung, K.; Garces, M. A.; Badger, N. B.

    2011-12-01

    Microbaroms are infrasound signals with a dominant frequency at 0.2 Hz. Monitoring stations around the globe continuously detected strong microbaroms across the ocean. Hurricanes Felicia and Neki were well recorded in 2009 at the International Monitoring System's IS59 array located in Kailua-Kona. A theoretical acoustic source model is utilized to estimate the intensity and spatial distribution of microbaroms produced by surface waves in the open ocean. The tropical cyclone sea state is created by utilizing a spectral ocean wave model and blended wind fields of different spatial scales that include the global winds from NCEP's final analysis, regional winds from University of Hawaii Meteorology Department's Weather and Forecasting model, and high resolution tropical cyclone winds from a parametric hurricane model. The computed wave data is validated with altimetry measurements. The strong correlation between the microbarom estimates and the IS59 measurements supports the potential use of infrasound signals for warning of hazardous wave conditions.

  20. Comparing different methods for assessing ground truth of rover data analysis for the 2005 season of the Life in the Atacama Project

    NASA Astrophysics Data System (ADS)

    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.

    2007-12-01

    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 ground truth 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.

  1. Characterization of NCPA Infrasound Sensors

    NASA Astrophysics Data System (ADS)

    Hart, D. M.; Jones, K. R.; Sauter, A.

    2011-12-01

    By adding NCPA (National Center for Physical Acoustics) Infrasound sensors to the eastern-half of the Transportable Array, the scientific community has gained another powerful tool for studying natural processes. In an effort to characterize the sensors, including the effect of the wind filter and acoustical porting, researchers at Sandia National Labs (SNL) FACT Site and IRIS PASSCAL have performed a series of tests that resulted in good agreement with the NCPA-provided response (20mV/Pa +-10%, .007Hz high-pass corner frequency). Through independent testing and verification we have gained confidence in the sensor's linearity over the pressure range tested, a measure of power usage, and a measure of the dynamic range the sensors are capable of delivering, indicating the instruments can measure signals well below the Bowman (2005) Acoustic Low Noise Model up to 8Hz. Researchers at the SNL Fact site have the capabilities not only to test the NCPA sensor in an acoustic pressure chamber, but also to test the equivalent of the entire infrasound system used in the TA stations: NCPA sensor, tubing, and wind reduction design (a PVC filter buried in a bag of pumice stone). SNL tests with this fully-ported infrasound system characterize the full system response. We found that the tubing used to port the sensor to the external wind reduction device adds a measurable 15Hz resonance to the response and influences the high-frequency roll-off point. At PASSCAL, we have performed an acceptance test on more than 350 NCPA sensors, and in the process, have collected statistics on their relative gains. The standard deviation of the relative gain for all measured sensors is 5.32%. For 59 repeated tests of the two NCPA sensors used as references, the standard deviation is .15%, which suggests that acceptance testing can be used to constrain the gain of individual NCPA sensors much tighter than the population deviation.

  2. Infrasound workshop for CTBT monitoring: Proceedings

    SciTech Connect

    Christie, D.; Whitaker, R.

    1998-11-01

    It is expected that the establishment of new infrasound 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 infrasound 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 infrasound 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 infrasound array station that will reliably detect and locate infrasound 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 infrasound 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 infrasound 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.

  3. USArray recordings of infrasound generated by the Chelyabinsk Meteor and other, smaller bolides

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine; Hedlin, Michael

    2014-05-01

    A small asteroid that entered Earth's atmosphere near the city of Chelyabinsk, Russia, generated infrasound signals that were recorded by USArray barometers at distances from 6000-10000 km from the source. The infrasound recordings made of this event by these arrays are unprecedented, due to rarity of this type of event and the high density and spatial extent of the recording network. Signal characteristics vary across the network; infrasound arrivals recorded in Alaska and along the U.S. northwest coast had higher velocities and higher frequency content than those recorded in the eastern part of the network. The recorded pressure amplitudes at Alaska sites were significantly larger than for the remaining stations. Atmospheric specifications of global wind and sound speeds indicate the presence of a stratospheric duct for propagation to Alaska and stations along the northwest coast; however, most USarray stations lie within a thermospheric duct. Raytrace modeling confirms that, at stations in Alaska and the northwest U.S., the arrival times and durations of stratospherically ducted rays are consistent with observed arrivals at frequencies above the microbarom band. At lower frequencies, arrival times are consistent with thermospheric ducting at stations across the network. Estimates of infrasound attenuation from the Chelyabisk meteor to the recording sites were made using an attenuation formula derived from parabolic equation simulations. The results suggest that, under the assumption that infrasound was radiated isotropically from the Chelyabinsk meteor, thermospheric returns have higher than expected amplitudes as compared to stratospheric returns at the same frequencies. We examine in greater detail our assumption of isotropic infrasound radiation from a bolide explosion using a number of much smaller fireball events observed at seismic and infrasound sensors at the USArray.

  4. Modeling propagation of infrasound signals observed by a dense seismic network.

    PubMed

    Chunchuzov, I; Kulichkov, S; Popov, O; Hedlin, M

    2014-01-01

    The long-range propagation of infrasound 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 source. The simulation shows the evolution of several branches of stratospheric and thermospheric signals with increasing range from the source. Infrasound 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 infrasound arrivals are compared with those of seismic recordings. This study illustrates the utility of dense seismic networks for mapping an infrasound field with high spatial resolution. The parabolic equation calculations capture both the effect of scattering of infrasound into geometric acoustic shadow zones and significant temporal broadening of the arrivals. PMID:24437743

  5. Eruptions of Mount Erebus Volcano Constrained with Infrasound, Video, and Doppler Radar

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Jones, K. R.; Aster, R.; Kyle, P.; McIntosh, W.; Gerst, A.

    2008-12-01

    Co-eruptive infrasound 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 infrasound 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 infrasound generation mechanisms, which include both pre- eruptive distension of the lava lake surface and gas expansion and jetting following large explosive bubble bursts. Network infrasound 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. Infrasound 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 source) and gas jetting (dipole source) and corroborate this explosive asymmetry with video and Doppler radar observations.

  6. IMPROVED GROUND TRUTH IN SOUTHERN ASIA USING IN-COUNTRY DATA, ANALYST WAVEFORM REVIEW, AND ADVANCED ALGORITHMS

    SciTech Connect

    Engdahl, Eric, R.; Bergman, Eric, A.; Myers, Stephen, C.; Ryall, Floriana

    2009-06-19

    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-source 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-source 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

  7. Archaeological Evidence for Abrupt Cimate Change: Results from Satellite Imagery Analysis and Subsequent Ground-Truthing in the El-Manzalah Region, Northeast Egyptian Delta

    NASA Astrophysics Data System (ADS)

    Parcak, S. H.

    2003-12-01

    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 ground-truthing 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

  8. Comparison of ground truth location of earthquake from InSAR and from ambient seismic noise: A case study of the 1998 Zhangbei earthquake

    NASA Astrophysics Data System (ADS)

    Xie, Jun; Zeng, Xiangfang; Chen, Weiwen; Zhan, Zhongwen

    2011-04-01

    Because ambient seismic noise provides estimated Green's function (EGF) between two sites with high accuracy, Rayleigh wave propagation along the path connecting the two sites is well resolved. Therefore, earthquakes which are close to one seismic station can be well located with calibration extracting from EGF. We test two algorithms in locating the 1998 Zhangbei earthquake, one algorithm is waveform-based, and the other is traveltime-based. We first compute EGF between station ZHB (a station about 40 km away from the epicenter) and five IC/IRIS stations. With the waveform-based approach, we calculate 1D synthetic single-force Green's functions between ZHB and other four stations, and obtain traveltime corrections by correlating synthetic Green's functions with EGFs in period band of 10-30 s. Then we locate the earthquake by minimizing the differential travel times between observed earthquake waveform and the 1D synthetic earthquake waveforms computed with focal mechanism provided by Global CMT after traveltime correction from EGFs. This waveform-based approach yields a location which error is about 13 km away from the location observed with InSAR. With the traveltime-based approach, we begin with measuring group velocity from EGFs as well as group arrival time on observed earthquake waveforms, and then locate the earthquake by minimizing the difference between observed group arrival time and arrival time measured on EGFs. This traveltime-based approach yields accuracy of 3 km, Therefore it is feasible to achieve GT5 (ground truth location with accuracy 5 km) with ambient seismic noises. The less accuracy of the waveform-based approach was mainly caused by uncertainty of focal mechanism.

  9. Infrasound from lightning measured in Ivory Coast

    NASA Astrophysics Data System (ADS)

    Farges, T.; Matoza, R. S.

    2011-12-01

    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 infrasound 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 infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound 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 infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound 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 infrasound 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 infrasound 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).

  10. Observing Infrasound and Atmospheric Pressure with the NSF EarthScope USArray Transportable Array

    NASA Astrophysics Data System (ADS)

    Vernon, F. L.; Hedlin, M. A.; Busby, R. W.; Woodward, R.

    2010-12-01

    We are creating a real-time infrasound array whose sensing elements are co-located with the 400 seismic stations in the USArray Transportable Array component of the NSF EarthScope program. This continuously sampled array, of an unprecedented scale, will provide opportunities for groundbreaking and interdisciplinary research in atmospheric acoustics, atmospheric science, and seismology. Such an array will sample mean (absolute) values and fluctuations of the surface air pressure with nominal 70 km station spacing, with a dynamic range of about 7 orders of magnitude, and with a sampling frequency of up to 40 Hz. All samples will be synchronized to UTC. This dense network of infrasound sensors will permit us to study the nature of long-range infrasound propagation from regional to continental distances, and study the sources of infrasound signals, using actual acoustic data, free of concerns about seismic-to-acoustic coupling. All new TA stations deployed starting this fall will have a Quanterra Environmental Processor with internal VTI SCP1000 MEMS barometric pressure gauge, Setra 278 absolute microbarometer, and NCPA Infrasound Microphone. We will present data from field tests and from the newly deployed instrumentation.

  11. Charting a Course for the Infrasound Renaissance

    NASA Astrophysics Data System (ADS)

    Garces, M.; Bass, H.; Hedlin, M.; Hayward, C.; Bowman, R.; Brown, D.; Businger, S.; Butler, R.; Chouet, B.; Drob, D.; Hetzer, C.; Koyanagi, S.; Mattioli, G.; McCormack, D.; Merrifield, M.; Pack, D.; Swanson, D.; Veith, K.; Voight, B.; Willis, M.

    2003-12-01

    The turn of the 21st century marks the onset of a renaissance in the field of infrasound, which had been dormant for ~30 years. The ongoing deployment of a global infrasound network has reawakened the field to a world of high-resolution digital array data, rapid communication, and seemingly unlimited growth in computing power. Complex phenomena that could only be addressed in general terms three decades ago can now be measured, analyzed, and modeled with unprecedented fidelity. Many fundamental problems in infrasound are now being revisited, and infrasonic observations are being integrated with other technologies (such as seismic, strainmeter and infrared) for the discovery of new phenomena or the refinement of geophysical studies. On July 24-25, 2003, the National Science Foundation sponsored a group of infrasound experts and interdisciplinary researchers to convene in Waikoloa, Hawaii, and chart a course for basic US infrasound research. The conveners selected key projects that would lead to significant advances in our understanding of infrasound generated by effusive and explosive volcanoes, ocean swells, bolides, fauna, severe weather, and long-period atmospheric instabilities. Projects were also proposed to refine our knowledge of atmospheric dynamics and transport mechanisms. A sampling of these projects is discussed in light of their contributions to our fundamental scientific understanding and their impact on the geophysical community.

  12. Infrasound detection of the Chelyabinsk meteor at the USArray

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine D.; Hedlin, Michael A. H.

    2014-09-01

    On February 15, 2013 a small asteroid entered Earth's atmosphere near Chelyabinsk, Russia. This extremely rare event was recorded by the 400-station USArray deployed in the continental United States and Alaska. These stations recorded infrasound signals from the event at distances from 6000 to 10 000 km across a sector spanning 55° that encompassed the North Pole. This dense, extensive network permitted a detailed study of long-range infrasound propagation and source characteristics. We observe long wavetrains at all stations (ranging to over 100 min) but clear variations in the character of the wavetrains across the network. Ray-tracing through a spatially and temporally varying atmospheric model indicates the source excited resonance in the thermospheric duct to all stations. Resonance was also excited in a persistent stratospheric duct between the source and stations in Alaska and along the west coast of the United States due to favorable winds at those azimuths, leading to higher group velocities and frequency content at these stations than those to the east. An attenuation formula derived from parabolic equation simulations is used to estimate infrasound transmission losses at all stations, using simplified models of the effective sound speed along each source-receiver path. Observed variations in signal energies from higher than expected at stations in the thermospheric duct in the eastern United States, to lower than expected in Alaska, at azimuths nearly orthogonal to the asteroid's Mach cone, lead us to conclude that (1) the source was dominantly isotropic and (2) the model overestimates attenuation in the thermospheric duct.

  13. Airborne infrasound: A new way to explore the 3D acoustic wavefield

    NASA Astrophysics Data System (ADS)

    Jones, K. R.

    2015-12-01

    As a part of the Source Physics Experiment (SPE) site characterization and explosive test series, we developed and deployed an airborne octocopter infrasound platform. Traditionally, infrasound data is collected with sensors and arrays that are installed on the ground. For most applications this is sufficient but can be limiting when observing non-isotropic sources, such as underground explosions, at close range. To develop and test the airborne infrasound platform we recorded data from a seismo-acoustic hammer source at the Nevada National Security Site (NNSS). During early field-testing of the hammer source we found that, as the 13 metric ton mass hit the ground, a significant downward deflection of the surrounding surface imparted an observable infrasound pressure wave into the atmosphere. We compared waveforms collected at various vertical and horizontal offsets from the hammer source and found that the peak frequencies differed when observed directly above the source compared to the horizontal offsets. 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.

  14. Experimental Infrasound Studies in Nevada

    NASA Astrophysics Data System (ADS)

    Herrin, E. T.; Negraru, P. T.; Golden, P.; Williams, A.

    2009-12-01

    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 infrasound 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 infrasound 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.

  15. Large meteoroid detection using the global IMS infrasound system

    SciTech Connect

    ReVelle, D. O.

    2002-01-01

    Numerous signals will be routinely detected using the 60 array, global IMS (International Monitoring System) infrasound 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 sources of infrasound 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 infrasound signals from bolides. This summary will include the generation of the signals at the complex, quasi-cylindrical line source, 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 source properties, Le., source altitude, blast radius (see below) and the source energy, etc. In addition, we will use infrasound from energetic bolides to estimate the expected steady state

  16. Infrasound induced instability by modulation of condensation process in the atmosphere.

    PubMed

    Naugolnykh, Konstantin; Rybak, Samuil

    2008-12-01

    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 infrasound, which is detectable at large distances from the source. The wave-condensation instability can lead to variation in the level of infrasound radiation by a developing cyclone, and this can be as a precursor of these intense atmospheric events. PMID:19206769

  17. The Complementary Nature of Seismic and Infrasound Technologies in Regional Monitoring (Invited)

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Under current CTBTO event detection and location operating conditions, signal detection is a station-centric decision (was an event phase detected at this station?), rather than a global hypothesis test. Currently, infrasound and seismic detection use signal detectors run independently on each technology. It is only after event formation that the observations and inferences are merged. Development of this independent processing is a result of the vastly different signal and noise characteristics of these two waveform technologies. However, for specific signals there may be a utility to a joint seismic-infrasound detector. For example, noise estimates from one technology may help characterize or identify the noise on another technology (wind couples to both infrasound and seismic). Back-projection methods for both seismic and infrasound could easily be combined to produce a common seismo-acoustic detection and associated event location. The opportunity exists to integrate detection and location into a single multi-disciplinary approach. One such example is the ongoing infrasound detection and location procedure that utilizes an adaptive F-detector as input into the Bayesian Infrasonic Source Location (BISL, Modrak et al. 2010) procedure that provides an estimate of source location using assigned prior probabilities based on what is known of the propagation path and on the signal detector estimates (arrival time, phase velocity and azimuth). As the atmospheric model is better defined these priors may be changed, thus linking improved location estimates directly to improvements in atmospheric models. The final step following event location is identification. Seismic and infrasound observations and their interpretation for the recent set of North Korean nuclear explosions in 2006, 2009, and 2013 provide a motivation for multiple disciplinary approach to this step as well. Seismic analysis of these tests have documented that for existing parameterized source models

  18. Infrasound emission generated by wind turbines

    NASA Astrophysics Data System (ADS)

    Ceranna, Lars; Pilger, Christoph

    2014-05-01

    Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound 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 infrasound 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 infrasound array's detection capability. This aspect is particularly important for the other two sites of the German infrasound 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 infrasound stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned infrasound 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 infrasound array.

  19. Infrasounds and biorhythms of the human brain

    NASA Astrophysics Data System (ADS)

    Panuszka, Ryszard; Damijan, Zbigniew; Kasprzak, Cezary; McGlothlin, James

    2002-05-01

    Low Frequency Noise (LFN) and infrasound 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 sources such as streams and waterfalls.

  20. Application of ground-truth for classification and quantification of bird movements on migratory bird habitat initiative sites in southwest Louisiana: final report

    USGS Publications Warehouse

    Barrow, Wylie C.; Baldwin, Michael J.; Randall, Lori A.; Pitre, John; Dudley, Kyle J.

    2013-01-01

    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, ground-truthing is required to identify radar echoes to species or species group. We designed a field study to ground-truth 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

  1. Responses of the ear to low frequency sounds, infrasound and wind turbines.

    PubMed

    Salt, Alec N; Hullar, Timothy E

    2010-09-01

    Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external sources, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that infrasound 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 infrasound. Structures that are involved in endolymph volume regulation are also known to be influenced by infrasound, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to infrasound. In most cases, the inner ear's responses to infrasound 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

  2. ECMWF SSW forecast evaluation using infrasound

    NASA Astrophysics Data System (ADS)

    Smets, P. S. M.; Assink, J. D.; Le Pichon, A.; Evers, L. G.

    2016-05-01

    Accurate prediction of Sudden Stratospheric Warming (SSW) events is important for the performance of numerical weather prediction due to significant stratosphere-troposphere coupling. In this study, for the first time middle atmospheric numerical weather forecasts are evaluated using infrasound. A year of near-continuous infrasound from the volcano Mount Tolbachik (Kamchatka, Russian Federation) is compared with simulations using high-resolution deterministic forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF). For the entire time span the nowcast generally performs best, indicated by a higher continuity of the predicted wavefront characteristics with a minimal back azimuth difference. Best performance for all forecasts is obtained in summer. The difference between the infrasound observations and the predictions based on the forecasts is significantly larger during the 2013 SSW period for all forecasts. Simulations show that the SSW onset is better captured by the 10 day forecast while the recovery is better captured by the nowcast.

  3. Infrasound from lightning measured in Ivory Coast

    NASA Astrophysics Data System (ADS)

    Farges, T.; Millet, C.; Matoza, R. S.

    2012-04-01

    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 infrasound 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 infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound 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 infrasound from thunderstorms within a range of distances from the infrasound station. Infrasound 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 infrasound 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 infrasound 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

  4. ECMWF SSW forecast evaluation using infrasound

    NASA Astrophysics Data System (ADS)

    Smets, Pieter; Assink, Jelle; Le Pichon, Alexis; Evers, Läslo

    2016-04-01

    Accurate prediction of Sudden Stratospheric Warming (SSW) events is important for the performance of numerical weather prediction due to significant stratosphere--troposphere coupling. In this study, for the first time middle atmospheric numerical weather forecasts are evaluated using infrasound. A year of near continuous infrasound from Mt. Tolbachik (Kamchatka, Russian Federation) is compared with simulations using high resolution deterministic forecasts of the European Centre for Medium-range Weather Forecasts (ECMWF). For the entire timespan the nowcast generally performs best, indicated by a higher continuity and and smaller bearing difference. However, focussing on the period around the 2013 major SSW shows that while the SSW onset is better captured by the ten day forecast, the recovery is better captured by the nowcast. As such, this study demonstrates the use of infrasound in the evaluation of middle atmospheric weather forecasts and therefore its potential in the assessment of tropospheric forecast skill.

  5. Inferring atmospheric weather conditions in volcanic environments using infrasound

    NASA Astrophysics Data System (ADS)

    Ortiz, H. D.; Johnson, J. B.; Ruiz, M. C.

    2015-12-01

    We use infrasound 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 infrasound 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 source 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 infrasound 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.

  6. The effects of high level infrasound

    SciTech Connect

    Johnson, D.L.

    1980-02-01

    This paper will attempt to survey the current knowledge on the effects of relative high levels of infrasound 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 infrasound 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.

  7. Archaeogeophysical data acquisition and analysis at Tel Burna, Israel: a valuable opportunity for ongoing ground-truth investigation and collaboration (Invited)

    NASA Astrophysics Data System (ADS)

    Pincus, J. A.

    2013-12-01

    , 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 ground-truthing 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.

  8. The coherent field of infrasound - a global view with the IMS

    NASA Astrophysics Data System (ADS)

    Ceranna, Lars; Le Pichon, Alexis

    2016-04-01

    In this study we are going to present preliminary results of global coherent infrasound measured at IMS infrasound stations and its correlation with atmospheric dynamics. A new implementation of the Progressive Multi-Channel Correlation (PMCC) algorithm has been used, which enables a better characterization of all received signals in their wave parameter space (e.g., frequency-azimuth space, frequency-trace-velocity space). This, in-turn, allows an accurate signal discrimination, as well as source and propagation studies. For instance, we are using the processing for microbarom source and propagation studies and for analysing the occurrence of mountain associated waves. We are currently performing re-processing of the entire previous IMS infrasound database covering the time period from January 2003 to December 2015; whereas the number of stations has increased from 6 to 48. Results so far indicate a continuous spectrum of coherent signals at IMS stations within the 0.02 to 5.0 Hz band. Moreover, these results could be used for estimating network detection capability based on empirical station coherent infrasound noise models.

  9. Vent geometry detected from infrasound observation on Villaricca volcano, Chile

    NASA Astrophysics Data System (ADS)

    Goto, A.; Johnson, J. B.; Sanderson, R. W.; Anderson, J.; Varley, N. R.

    2010-12-01

    Volcan Villarrica in the southern Andes, Chile, is an active stratovolcano that hosts a convecting lava lake in the summit crater. Activity is characterized by persistent degassing and bubble bursting at the surface of lava lake. Between the 21st and 23rd of Jan 2010 we recorded monotonic infrasound with a stable dominant frequency at 0.7 to 0.8 Hz. Associated video imagery of the active lava lake, taken by a camera suspended from a wire across the crater, showed active convection and degassing, but gas release events were not directly correlated with infrasound transients. Continuous monotonic infrasound strongly suggests a resonant phenomena associated with a stable conduit and vent system. In the present study we attempt to estimate the vent geometry of Villarrica volcano based on the observed infrasound. We deployed four stations consisting of infrasound microphones, audible microphone, three components seismometers and weather stations, two of which were on the eastern and western rim of the crater, while the other two were on the flanks of volcano 2.7 and 3.8 km NNW of the crater, respectively. Despite amplitude variations the observed waveforms were very well correlated among the four stations indicating sound originating in the crater. From our video image and the past studies we inferred a cavity between the lava lake and overhanging spatter roof with a skylight in its center. In this case Helmholtz resonance is plausible as the source of observed monotonic infrasound. An idealized Helmholtz resonance model is manifested by a simple harmonic motion of air pistoning within the skylight neck that separates the inner cavity from external atmosphere. The frequenc f is given by: f=(c/2π)(S/VL)1/2 where c is sound velocity, S is neck cross sectional area, L is neck length and V is cavity volume. In the present case L corresponds to skylight depth. In practice, an extra volume proportional to neck radius moves together with the air above and below the neck

  10. Unraveling Structural Infrasound: understanding the science for persistent remote monitoring of critical infrastructure (Invited)

    NASA Astrophysics Data System (ADS)

    McKenna, S. M.; Diaz-Alvarez, H.; McComas, S.; Costley, D.; Whitlow, R. D.; Jordan, A. M.; Taylor, O.

    2013-12-01

    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 infrasound. 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 source 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 infrasound bandwidth and the correlation to scour of embedment material. The Urban infrasound program is infrasound 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 infrasound environment. Structural sources within 15 km of the arrays have been identified through signal processing and confirmed through acoustical models. Infrasound is also being studied as a means of

  11. Evolution of the CTBTO Infrasound Technology Roadmap

    NASA Astrophysics Data System (ADS)

    Garces, Milton; Haralabus, Georgios; Noack, Patrick; Grenard, Patrick

    2013-04-01

    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 Infrasound 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 infrasound 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 infrasound community, with a 93% response rate. We present the statistical results from our survey as well as the highlights of the draft Infrasound Technology Roadmap Document.

  12. Evaluation of Infrasound and Strobe Lights for Eliciting Avoidance Behavior in Juvenile Salmon and Char

    SciTech Connect

    Mueller, Robert P. ); Neitzel, Duane A. ); Amidan, Brett G. )

    2001-12-01

    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 infrasound (< 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 source of infrasound. Rainbow and eastern brook trout (25-100 mm TL) did not respond with avoidance or other behaviors to infrasound. Evidence of habituation to the infrasound source was evident for chinook salmon during repeated exposures. Wild and hatchery chinook displayed a higher proportion of movement during the initial exposures to infrasound 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.

  13. How to estimate yield using remote infrasound recordings?

    NASA Astrophysics Data System (ADS)

    Ceranna, L.; Le Pichon, A.

    2012-04-01

    Currently, estimates of radiated source energy or yield are based on empirical yield-scaling relations, which account for prevailing stratospheric winds. The most commonly used relation is derived from a high explosive dataset (Whitaker & Mutschlecner, 2008). However, limitations of this approach have been found by comparisons with reference events where problems arise either due to a fixed stratospheric wind speed or by an over-estimate of a known yield (e.g., Green et al., 2010). More realistic predictions can be achieved by using improved atmospheric specifications and measured station noise characteristics, as well as attenuation relations derived from operational propagation tools. An improved yield-scaling relation is considered (Le Pichon et al., 2012) which accounts for near-real time atmospheric up-dates and background noise calculations at various times of day for each month. This relation depends on a limited number of parameters describing the source (source altitudes between 0 and 30 km, dominant frequencies between 0.01 and 4.0 Hz) and the atmosphere (including naturally occurring gravity waves, altitude and strength of the stratospheric wind jet). All these parameters have a significant impact on infrasound propagation. We present a first approach for source energy (yield) estimates by combining all this information which provides a realistic picture of both station specific recording conditions and infrasound propagation from source to receiver. The spectrum of a full wave-train, whereas the local background noise is removed, can be inverted to a noise-free source spectrum at a certain reference distance, which is in turn related to certain yield based on empirical relations (e.g., Kinney & Graham, 1985). The capability of our approach is demonstrated for the two Sayarim explosion data-sets.

  14. Infrasound as a Detector of Local and Remote Turbulence

    NASA Astrophysics Data System (ADS)

    Cuxart, J.; Tatrai, D.; Weidinger, T.; Kircsi, A.; Józsa, J.; Kiss, M.

    2016-05-01

    Infrasound measurements are used to detect seismic waves and a large effort is devoted to eliminating the turbulence-related infrasound signal, usually considered as noise. Here we take a complementary approach, investigating whether infrasound can provide information on atmospheric turbulence. Microphone measurements of infrasound from an experimental campaign in Hungary in 2013 are used, together with data from a nearby sonic anemometer and a sodar. The comparison of infrasound 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 infrasound when the sodar showed a low-level jet above the surface inversion, indicating that microphones may be used as detectors of elevated turbulence.

  15. On infrasound generated by wind farms and its propagation in low-altitude tropospheric waveguides

    NASA Astrophysics Data System (ADS)

    Marcillo, Omar; Arrowsmith, Stephen; Blom, Philip; Jones, Kyle

    2015-10-01

    Infrasound from a 60-turbine wind farm was found to propagate to distances up to 90 km under nighttime atmospheric conditions. Four infrasound sensor arrays were deployed in central New Mexico in February 2014; three of these arrays captured infrasound 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 infrasound. 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 infrasound from a quasi-continuous source with the potential for long-range propagation that could be used to monitor the lower part of the atmospheric boundary layer.

  16. Assessing Infrasound Network Performance Using the Ambient Ocean Noise

    NASA Astrophysics Data System (ADS)

    Stopa, J. E.; Cheung, K.; Garces, M. A.; Williams, B.; Le Pichon, A.

    2013-12-01

    Infrasonic microbarom signals are attributed to the nonlinear resonant interaction of ocean surface waves. IMS stations around the globe routinely detect microbaroms with a dominant frequency of ~0.2 Hz from regions of marine storminess. We have produced the predicted global microbarom source field for 2000-2010 using the spectral wave model WAVEWATCH III in hindcast mode. The wave hindcast utilizes NCEP's Climate Forecast System Reanalysis (CFSR) winds to drive the ocean waves. CFSR is a coupled global modeling system created by a state-of-the-art numerical models and assimilation techniques to construct a homogenous dataset in time and space at 0.5° resolution. The microbarom source model of Waxler and Gilbert (2005) is implemented to estimate the ocean noise created by counter-propagating waves with similar wave frequencies. Comparisons between predicted and observed global microbarom fields suggest the model results are reasonable; however, further error analysis between the predicted and observed infrasound signals is required to quantitatively assess the predictions. The 11-year hindcast suggests global sources are stable in both magnitude and spatial distribution. These statistically stable features represent the ambient microbarom climatology of the ambient ocean noise. This supports the use of numerical forecast models to assess the IMS infrasound network performance and explosion detection capabilities in the 0.1-0.4 Hz frequency band above the ambient ocean noise. Theoretical/modeled microbarom source strength (colors) versus infrasonic observations from the IMS network (directional histograms). The contours represent the maximum intersections from the recorded acoustic signals for a large extra-tropical event on December 7, 2009.

  17. Development of the IDC Infrasound Event Detection Pipeline

    NASA Astrophysics Data System (ADS)

    Mialle, P.; Bittner, P.; Brown, D.; Given, J. W.

    2012-12-01

    The first atmospheric event built only from infrasound 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 subsequent decade, 45 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting continuous data to the IDC. The growing amount of infrasound data and detections produced by the automatic system challenges the station and network processing at the IDC and requires the Organization to improve the infrasound data processing. In 2010, the IDC began full-time operational automatic processing of infrasound data followed by interactive analysis. The detected and located events are systematically included in the analyst-reviewed Late Event Bulletin (LEB) and REB. Approximately 16% of SEL3 (Selected Event List 3, automatically produced 6 hours after real-time) events with associated infrasound signals pass interactive analysis and make it to the IDC bulletins. 41% of those SEL3 events rejected after review have only 2 associated infrasound phases (and possibly other seismic and hydro-acoustic detections). Therefore, the process whereby infrasound detections are associated with events needs to be investigated further. The objective of this study is to reduce the number of associated infrasound arrivals that are falsely associated during the creation of the SEL3. There are two parts to the study. First, the detection accuracy at the infrasound arrays is improved by improving the infrasound signal detector, which is based on the PMCC (Progressive Multi-Channel Correlation) algorithm. The second part focuses on improving the reliability of the association algorithm. The association algorithm is enhanced to include better characterization of the variable atmospheric phenomena, which profoundly affect the detection patterns of the infrasound signals. The algorithm is then further tuned to reduce the

  18. Infrasound From Explosions: Large, Medium and Small

    NASA Astrophysics Data System (ADS)

    Whitaker, R. W.; Sandoval, T. D.; Mutschlecner, J. P.

    2003-12-01

    We will present analysis of infrasound signals of some recent high explosive (HE) events. The events include a recent explosive test, Watusi, at the Nevada Test Site (NTS) as well as some small explosions done under a Department of Defense (DOD) program, also at the NTS. Watusi, with a charge weight of 19 tons, was recorded at four Los Alamos National Laboratory/Department of Energy (LANL/DOE) infrasound arrays. Summary results will be presented, followed by a comparison to earlier HE data recorded by LANL arrays. These earlier data were from larger tests undertaken by the former Defense Nuclear Agency, now Defense Threat Reduction Agency. The Watusi data fit well with the earlier results for wind corrected amplitude versus scaled range. We also have recorded, from calendar year 2000 to the present, infrasound signals from 1000 to 2000 lb explosions executed at the NTS. These events were recorded at a range of 45 km by the LANL NTS array. These results show that detection at this range is fairly robust.

  19. Infrasound records from U.S. atmospheric tests

    SciTech Connect

    Chael, E.P.; Lohr, R.D.

    1998-07-01

    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. Infrasound 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; source 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 source function, yield scaling and regional propagation of infrasound 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.

  20. Atmospheric infrasound from nonlinear wave interactions during Hurricanes Felicia and Neki of 2009

    NASA Astrophysics Data System (ADS)

    Stopa, Justin E.; Cheung, Kwok Fai; GarcéS, Milton A.; Badger, Nickles

    2012-12-01

    Monitoring stations around the globe routinely detect microbarom signals with a dominant frequency of ˜0.2 Hz from regions of marine storminess. International Monitoring System (IMS) infrasound array IS59 in Kailua-Kona, Hawaii recorded clear signals in close proximity of Hurricanes Felicia and Neki of 2009 for a first-hand investigation of the detailed source mechanism through a hindcast analysis. A spectral wave model describes the tropical cyclone and ambient sea states through a system of two-way nested grids with forcing from a blended data set of global, regional, and cyclonic winds. The computed wave conditions are validated with altimetry measurements and utilized in an acoustic model to estimate the intensity and spatial distribution of the microbarom source. The model results elucidate origins of infrasound signals from the tropical cyclone waves as well as their interactions with the ambient conditions consisting of swells, wind seas, and storm waves from nearby systems. The positive correlation between the IS59 observations and the theoretical microbarom estimates, and the saturation of recorded signals from high-energy sources support the use of infrasound signals for inference of tropical cyclone waves.

  1. Neural network approach to classification of infrasound signals

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Chang

    As part of the International Monitoring Systems of the Preparatory Commissions for the Comprehensive Nuclear Test-Ban Treaty Organization, the Infrasound Group at the University of Alaska Fairbanks maintains and operates two infrasound 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 infrasound 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 sources 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

  2. Detection of infrasound and linear acceleration in fishes.

    PubMed Central

    Sand, O; Karlsen, H E

    2000-01-01

    Fishes have an acute sensitivity to extremely low-frequency linear acceleration, or infrasound, even down to below 1 Hz. The otolith organs are the sensory system responsible for this ability. The hydrodynamic noise generated by swimming fishes is mainly in the infrasound range, and may be important in courtship and prey predator interactions. Intense infrasound has a deterring effect on some species, and has a potential in acoustic barriers. We hypothesize that the pattern of ambient infrasound in the oceans may be used for orientation in migratory fishes, and that pelagic fishes may detect changes in the surface wave pattern associated with altered water depth and distant land formations. We suggest that the acute sensitivity to linear acceleration could be used for inertial guidance, and to detect the relative velocity of layered ocean currents. Sensitivity to infrasound may be a widespread ability among aquatic organisms, and has also been reported in cephalopods and crustaceans. PMID:11079418

  3. Detection of volcanic infrasound with a ring laser interferometer

    NASA Astrophysics Data System (ADS)

    Dunn, Robert W.; Hosman, Ashley R.

    2014-11-01

    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 infrasound emissions from explosive volcanic eruptions. Volcanic infrasound is reported from representative eruptions of volcanoes Kelut (Kelud), Klyuchevskaya (Kliuchevskoi), Puyehua, Santa Maria, Sakurajima, and Tungurahua. The detected infrasound 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 infrasound. Signatures of the infrasound are found in the frequency modulated side bands.

  4. Infrasound sensitizes human glioblastoma cells to cisplatin-induced apoptosis.

    PubMed

    Rachlin, Kenneth; Moore, Dan H; Yount, Garret

    2013-11-01

    The development of nontoxic agents that can selectively enhance the cytotoxicity of chemotherapy is an important aim in oncology. This study evaluates the ability of infrasound exposure to sensitize glioblastoma cells to cisplatin-induced apoptosis. The infrasound was delivered using a device designed to replicate the unique infrasound emissions measured during external Qigong treatments. Human glioblastoma cell lines harboring wild-type p53 (U87) or mutant p53 (U251, SF210, and SF188) were treated in culture with cisplatin, infrasound emissions, or the combination of the 2 agents. Induction of apoptosis was quantified after 24 hours by flow cytometry following annexin V/propidium iodide staining. Infrasound emissions alone, delivered at moderate levels (~10 mPa) with dynamic frequency content (7-13 Hz), did not induce apoptosis, yet combining infrasound with cisplatin augmented the induction of apoptosis by cisplatin in all the 4 cell lines (P < .05). Increased cellular uptake of the fluorophore calcein associated with infrasound exposure was quantified by fluorescence microscopy as well as flow cytometry, demonstrating increased cell membrane permeability. The 4 cell lines differed in the degree to which infrasound exposure increased calcein uptake, and these differences were predictive of the extent to which infrasound enhanced cisplatin-induced apoptosis. When exposed to specific frequencies, membrane permeabilization also appeared to be differentially responsive for each cell line, suggesting the potential for selective targeting of tissue types using isolated infrasonic frequencies. Additionally, the pressure amplitudes used in this study were several orders of magnitude less than those used in similar studies involving ultrasound and shock waves. The results of this study provide support for using infrasound to enhance the chemotherapeutic effects of cisplatin in a clinical setting. PMID:23165942

  5. Capability of the CTBT infrasound stations detecting the 2013 Russian fireball

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; Le Pichon, Alexis; Mialle, Pierrick; Garces, Milton

    2015-04-01

    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 infrasound 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 infrasound 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 source 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.

  6. Responses of the ear to low frequency sounds, infrasound and wind turbines

    PubMed Central

    Salt, Alec N.; Hullar, Timothy E.

    2010-01-01

    Infrasonic sounds are generated internally in the body (by respiration, heartbeat, coughing, etc) and by external sources, such as air conditioning systems, inside vehicles, some industrial processes and, now becoming increasingly prevalent, wind turbines. It is widely assumed that infrasound 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 infrasound. Structures that are involved in endolymph volume regulation are also known to be influenced by infrasound, but their sensitivity is also thought to be low. There are, however, abnormal states in which the ear becomes hypersensitive to infrasound. In most cases, the inner ear’s responses to infrasound can be considered normal, but they could be associated with unfamiliar sensations or subtle changes in physiology. This raises the possibility that

  7. The case for infrasound as the long-range map cue in avian navigation

    USGS Publications Warehouse

    Hagstrum, J.T.

    2007-01-01

    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 infrasounds are proposed as the elusive longrange cues constituting the avian navigational map. Although infrasounds 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 sources (microbaroms, sonic booms), respectively. A source of continuous geographic infrasound 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.

  8. Peculiar transient phenomena observed by HF Doppler sounding on infrasound time scales

    NASA Astrophysics Data System (ADS)

    Chum, J.; Lastovicka, J.; Sindelárová, T.; Buresová, D.; Hruska, F.

    2008-04-01

    Compared to investigations of the influence of gravity and planetary waves on the ionosphere, the effects of infrasound (periods from about 0.01 s to several minutes) variations have not been studied very much in the last 20 years. Here we present some recent results on peculiar transient phenomena occurring at infrasound timescales, as observed by HF Doppler sounding in the Czech Republic. After a brief description of the measuring equipment for continuous HF Doppler sounding of the ionosphere, we deal with the observations of short-time transient changes that are observed in the Doppler spectrograms in time intervals of a minute or less, and therefore cannot be observed by ionosondes. First, we present examples of S-shaped traces and examine the diurnal and seasonal variation of their occurrence. We show that S-shape phenomena appear to be concentrated near sunset and sunrise. We also discuss the possible source of these disturbances and their relationship to gravity and infrasound waves. Then we show rare patterns with Doppler shifts corresponding to quasi-linear shape (QLS) phenomena in the time-frequency space. Their slope may be positive or negative. We present some of their properties and discuss the possible origin of such a phenomenon. Several potential sources of QLSs were excluded, such as aircrafts, satellites, bolides, meteors, meteorites, thunderstorms or geomagnetic storms. We speculate that QLSs may correspond to the radio waves in the Z-mode reflected at the upper hybrid resonance frequency.

  9. Comparison of seismic and infrasound wave fields generated by snow avalanches

    NASA Astrophysics Data System (ADS)

    Suriñach, Emma; Tapia, Mar; Pérez-Guillén, Cristina; Khazaradze, Giorgi; Roig, Pere

    2016-04-01

    Snow avalanches are a source of waves that are transmitted through the ground and the air. These wave fields are detected by seismic and infrasound 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 infrasound 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 infrasound 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 infrasound and seismic waves enables us to obtain valuable information about the internal parts of the avalanche as a source 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).

  10. Infrasound of basaltic effusive activity at Piton de la Fournaise Volcano

    NASA Astrophysics Data System (ADS)

    Genco, Riccardo; Valade, Sebastien; Villeneuve, Nicolas; Peltier, Aline; Ferrazzini, Valérie; Di Muro, Andrea; Ripepe, Maurizio

    2016-04-01

    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, infrasound 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 infrasound 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 source 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 infrasound can be succesfully used to locate the source, 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 infrasound dataset reported for this style of basaltic volcanic activity.

  11. Infrasound from the 2012-2013 Plosky Tolbachik, Kamchatka fissure eruption

    NASA Astrophysics Data System (ADS)

    Albert, Sarah; Fee, David; Firstov, Pavel; Makhmudov, Evgeniy; Izbekov, Pavel

    2015-12-01

    We use both regional and local infrasound data to investigate the dynamics of the 2012-2013 eruption of Tolbachik Volcano, Kamchatka, Russia during select periods of time. Analysis of regional data recorded at the IMS array IS44 in southern Kamchatka, ~ 384 km from the vent focuses on the eruption onset in November 2012, while analysis of local data focuses on activity in February and August 2013. Signals recorded from Tolbachik suggest a change in eruptive intensity possibly occurred from November 27-30, 2012. Local infrasound data recorded at distances of 100-950 m from the vent are characterized primarily by repeated, transient explosion signals indicative of gas slug bursts. Three methods are employed to pick slug burst events in February and August. The nature of slug bursts makes a monopole acoustic source model particularly fitting, permitting volume outflux and slug radius calculations for individual events. Volume outfluxes and slug radii distributions provide three possible explanations for the eruption style of Tolbachik Volcano from mid-February to late August. Cumulative outflux for slug bursts (i.e. mass of emissions from individual bursts) derived by infrasound for both February and August range from < 100 to ~ 3000 kg. These values are greater than infrasound-derived emissions calculated at Pacaya Volcano, but less than those calculated at Mt. Erebus Volcano. From this, we determine slug bursts at Tolbachik Volcano in February and August were larger on average than those at Pacaya Volcano in 2010, but smaller on average than those at Mt. Erebus in 2008. Our overall emissions estimates are in general agreement with estimates from satellite observations. This agreement supports the monopole source inversion as a potential method for estimating mass of emissions from slug burst events.

  12. Evaluation of Infrasound and Strobe Lights to Elicit Avoidance Behavior in Juvenile Salmon and Char.

    SciTech Connect

    Mueller, Robert, P.; Neitzel, Duane A.; Amidan, Brett G.

    1999-02-01

    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 infrasound (<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 source. Rainbow and eastern brook trout (25-100 mm) did not respond with avoidance or other behaviors to infrasound. Habituation to the infrasound source was evident for chinook salmon during repeated exposures. Wild and hatchery chinook displayed a higher proportion of movement during the initial exposures to infrasound 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

  13. Contribution of Infrasound to IDC Reviewed Event Bulletin

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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 but infrasound 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 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 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 and large earthquakes belong to events primarily recorded at seismic stations of the IMS network but often detected at the infrasound stations. Presence of infrasound 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 infrasound data to IDC bulletins and provide examples of events recorded at the IMS infrasound network. Results of this study may help to improve location of small events with observations on infrasound stations.

  14. Infrasound from the 2007 fissure eruptions of Kīlauea Volcano, Hawai'i

    USGS Publications Warehouse

    Fee, D.; Garces, M.; Orr, T.; Poland, M.

    2011-01-01

    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 source 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 infrasound arrays. The 19 June eruption from a fissure approximately mid-way between Kīlauea's summit and Pu'u 'O'o produced infrasound for ~30 minutes-the only observed geophysical signal associated with the fissure opening. The infrasound 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.

  15. Frequency-wavenumber processing for infrasound distributed arrays.

    PubMed

    Costley, R Daniel; Frazier, W Garth; Dillion, Kevin; Picucci, Jennifer R; Williams, Jay E; McKenna, Mihan H

    2013-10-01

    The work described herein discusses the application of a frequency-wavenumber signal processing technique to signals from rectangular infrasound arrays for detection and estimation of the direction of travel of infrasound. Arrays of 100 sensors were arranged in square configurations with sensor spacing of 2 m. Wind noise data were collected at one site. Synthetic infrasound 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. PMID:24116535

  16. Study of the wind velocity-layered structure in the stratosphere, mesosphere, and lower thermosphere by using infrasound probing of the atmosphere

    NASA Astrophysics Data System (ADS)

    Chunchuzov, I.; Kulichkov, S.; Perepelkin, V.; Popov, O.; Firstov, P.; Assink, J. D.; Marchetti, E.

    2015-09-01

    The wind velocity structure in the upper stratosphere, mesosphere, and lower thermosphere (MLT) is studied with the recently developed method of infrasound probing of the atmosphere. The method is based on the effect of infrasound scattering from highly anisotropic wind velocity and temperature inhomogeneities in the middle and upper atmosphere. The scattered infrasound 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 infrasound signals generated by explosive sources 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 infrasound 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 sources 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.

  17. Regional Localization with the Hawaii Island Infrasound Network

    NASA Astrophysics Data System (ADS)

    Perttu, A. B.; Garces, M. A.; Thelen, W. A.

    2013-12-01

    The Big Island of Hawaii is home to an extensive network of infrasound 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 source location, onset time, duration, and source energetics from regional infrasonic signals, with an emphasis on improving signal characterization. Diverse persistent natural and anthropogenic regional sources 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 source characterization.

  18. Comparing Volcano Infrasound and Aeroacoustics Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Ogden, D. E.; Matoza, R. S.; Fee, D.

    2012-12-01

    The production of acoustic noise by fluid flows has been studied experimentally within engineering aeroacoustics for over 50 years. These works aim to correlate flow properties and dynamics with the produced acoustic spectra (i.e., patterns of frequencies and amplitude). These correlations are used to design flow fields in man-made jet engines and other machines to reduce the production of harmful acoustic signals and resulting hearing loss. Many of the flow fields in these man-made systems are analogous to those in volcanic eruptions. We postulate that the acoustic signals generated by these flows are also analogous and the aeroacoustics experimental results provide a starting point for modeling the noise generated by volcanic flow fields. Application of empirical results from these experiments to volcanic flow fields is non-trivial. Volcanic eruptions involve complexities not present in man-made experiments including but not limited to multiphase flow, buoyancy forces, and non-uniform atmosphere. This work explores methods by which some of the empirical results from aeroacoustics experiments can be modified for application to volcanic eruptions. Results are compared with observations of volcano infrasound. Preliminary comparison to numerical simulations of volcano infrasound may also be presented.

  19. Upgrade of the Plostina infrasound array

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Ionescu, Constantin; Tataru, Stefan

    2014-05-01

    Plostina infrasound station (IPLOR) is a large aperture array deployed in the central part of Romania since 2009, by National Institute for Earth Physics (NIEP). The initial set-up consisted of 3 elements (IPH4, IPH5, IPH6); in 2010, a fourth element (IPH7) was added; during 2012, two more sensors were installed in IPH2 and IPH3 sites. All 6 elements are equipped with Chaparral Physics Model 25 sensors. Upgrading works are currently ongoing at IPLOR, aiming to enhance the station performance in terms of automatic signal detection and characterization in the routine processing using PMCC algorithm. The infrasound data quality is improved through station design optimization and installation of more efficient wind-noise reduction systems. Solutions adopted took in account the recommendations provided by the 2011 Expert Group Meeting for the design of IMS infrasound stations, as well as the knowledge acquired during the NIEP participation, as associated member, to the ARISE design study project. After upgrading the IPLOR station to a 6-element array, the analysis of the data shows a visibly enhancement of the detection capability by increasing the lower frequency resolution (below 0.5 Hz). The improved array response indicates reducing spatial aliasing of higher frequency signals and increasing the degree of signal correlation between array elements, which are observed in a better characterization of the signal in terms of back-azimuth and horizontal trace velocity. In September 2013, NIEP started the works to improve the wind-noise reduction conditions at IPLOR station. The pipes and air-inlets installed at IPH4 element were replaced, in order to eliminate the potential points of air leak. The porous hoses at IPH5, IPH6 and IPH7 sites were replaced with new rosette pipe array systems: 20-port rosette design at IPH5 and IPH6, and 19-port rosette design at IPH7. The two circular porous hoses located at the IPH2 and IPH3 sites are scheduled for replacing in 2014. The new

  20. The Use of Uas for Assessing Agricultural Systems in AN Wetland in Tanzania in the - and Wet-Season for Sustainable Agriculture and Providing Ground Truth for Terra-Sar X Data

    NASA Astrophysics Data System (ADS)

    Thamm, H.-P.; Menz, G.; Becker, M.; Kuria, D. N.; Misana, S.; Kohn, D.

    2013-08-01

    The paper describes the assessment of the vegetation and the land use systems of the Malinda Wetland in the Usambara Mountains in Tanzania with the parachute UAS (unmanned aerial system) SUSI 62. The area of investigation was around 8 km2. In two campaigns, one in the wet season and one in the dry season, approximately 2600 aerial photos of the wetland were taken using the parachute UAS SUSI 62; of these images, ortho-photos with a spatial resolution of 20 cm x 20 cm, were computed with an advanced block bundle approach. The block bundles were geo-referenced using control points taken with differential GPS. As well a digital surface model (DSM) of the wetland was created out of the UAS photos. Using the ortho-photos it is possible to assess the different land use systems; the differences in the phenology of the vegetation between wet and dry season can be investigated. In addition, the regionalisation of bio mass samples on smaller test plots was possible. The ortho-photos and the DSM derived from the UAS proved to be a valuable ground truth for the interpretation of Terra-SAR X images. The campaigns demonstrated that SUSI 62 was a suitable, robust tool to obtain the valuable information under harsh conditions.

  1. Collective bubble oscillations as a component of surf infrasound.

    PubMed

    Park, Joseph; Garcés, Milton; Fee, David; Pawlak, Geno

    2008-05-01

    Plunging surf is a known generator of infrasound, though the mechanisms have not been clearly identified. A model based on collective bubble oscillations created by demise of the initially entrained air pocket is examined. Computed spectra are compared to infrasound data from the island of Kauai during periods of medium, large, and extreme surf. Model results suggest that bubble oscillations generated by plunging waves are plausible generators of infrasound, and that dynamic bubble plume evolution on a temporal scale comparable to the breaking wave period may contribute to the broad spectral lobe of dominant infrasonic energy observed in measured data. Application of an inverse model has potential to characterize breaking wave size distributions, energy, and temporal changes in seafloor morphology based on remotely sensed infrasound. PMID:18529169

  2. In search of discernible infrasound emitted by numerically simulated tornadoes

    NASA Astrophysics Data System (ADS)

    Schecter, David A.

    2012-09-01

    The comprehensive observational study of Bedard (2005) provisionally found that the infrasound of a tornado is discernible from the infrasound of generic cloud processes in a convective storm. This paper discusses an attempt to corroborate the reported observations of distinct tornado infrasound with numerical simulations. Specifically, this paper investigates the infrasound of an ordinary tornado in a numerical experiment with the Regional Atmospheric Modeling System, customized to simulate acoustic phenomena. The simulation has no explicit parameterization of microphysical cloud processes, but creates an unsteady tornado of moderate strength by constant thermal forcing in a rotational environment. Despite strong fluctuations in the lower corner flow and upper outflow regions, a surprisingly low level of infrasound is radiated by the vortex. Infrasonic pressure waves in the 0.1 Hz frequency regime are less intense than those which could be generated by core-scale vortex Rossby (VR) waves of modest amplitude in similar vortices. Higher frequency infrasound is at least an order of magnitude weaker than expected based on infrasonic observations of tornadic thunderstorms. Suppression of VR waves (and their infrasound) is explained by the gradual decay of axial vorticity with increasing radius from the center of the vortex core. Such non-Rankine wind-structure is known to enable the rapid damping of VR waves by inviscid mechanisms, including resonant wave-mean flow interaction and "spiral wind-up" of vorticity. Insignificant levels of higher frequency infrasound may be due to oversimplifications in the computational setup, such as the neglect of thermal fluctuations caused by phase transitions of moisture in vigorous cloud turbulence.

  3. Infrasound array criteria for automatic detection and front velocity estimation of snow avalanches: towards a real-time early-warning system

    NASA Astrophysics Data System (ADS)

    Marchetti, E.; Ripepe, M.; Ulivieri, G.; Kogelnig, A.

    2015-11-01

    Avalanche risk management is strongly related to the ability to identify and timely report the occurrence of snow avalanches. Infrasound has been applied to avalanche research and monitoring for the last 20 years but it never turned into an operational tool to identify clear signals related to avalanches. We present here a method based on the analysis of infrasound signals recorded by a small aperture array in Ischgl (Austria), which provides a significant improvement to overcome this limit. The method is based on array-derived wave parameters, such as back azimuth and apparent velocity. The method defines threshold criteria for automatic avalanche identification by considering avalanches as a moving source of infrasound. We validate the efficiency of the automatic infrasound detection with continuous observations with Doppler radar and we show how the velocity of a snow avalanche in any given path around the array can be efficiently derived. Our results indicate that a proper infrasound array analysis allows a robust, real-time, remote detection of snow avalanches that is able to provide the number and the time of occurrence of snow avalanches occurring all around the array, which represent key information for a proper validation of avalanche forecast models and risk management in a given area.

  4. Large Bubble Growth Quantified By Video and Infrasound at Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Miller, A. J. C.; Johnson, J. B.

    2014-12-01

    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 infrasound and time synchronized video data recording at ~30 FPS. Video footage is used to synthesize pressure time series during eruptions assuming a simple acoustic source. These synthetic pressure records are directly compared to infrasound pressure records collected at two sites located ~300 m from the lava lake source. A scaled relationship exists between infrasound and video derived pressures where video generally overestimates the volumetrically expanding source. 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 source 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 source 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.

  5. Microseism and infrasound generation by cyclones.

    PubMed

    Bowen, Samuel P; Richard, Jacques C; Mancini, Jay D; Fessatidis, Vassilios; Crooker, Benjamin

    2003-05-01

    A two-dimensional cylindrical shear-flow wave theory for the generation of microseisms and infrasound by hurricanes and cyclones is developed as a linearized theory paralleling the seminal work by Longuet-Higgins which was limited to one-dimensional plane waves. Both theories are based on Bernoulli's principle. A little appreciated consequence of the Bernoulli principle is that surface gravity waves induce a time dependent pressure on the sea floor through a vertical column of water. A significant difference exists between microseisms detected at the bottom of each column and seismic signals radiated into the crust through coherence over a region of the sea floor. The dominant measured frequency of radiated microseisms is matched by this new theory for seismic data gathered at the Fordham Seismic Station both for a hurricane and a mid-latitude cyclone in 1998. Implications for Bernoulli's principle and this cylindrical stress flow theory on observations in the literature are also discussed. PMID:12765375

  6. The stratospheric arrival pair in infrasound propagation.

    PubMed

    Waxler, Roger; Evers, Läslo G; Assink, Jelle; Blom, Phillip

    2015-04-01

    The ideal case of a deep and well-formed stratospheric duct for long range infrasound 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. PMID:25920837

  7. Development and Application of First- and Second-Pass Clutter-Reduction Techniques for Nuclear Blast Detection at Infrasound Stations

    NASA Astrophysics Data System (ADS)

    Hetzer, C. H.; Waxler, R.

    2009-12-01

    The number of spurious arrivals observed at infrasound stations worldwide, often tens to hundreds per day per station, places great strain on human analysts tasked to eliminate arrivals of non-interest. Reliable automated arrival-classification systems are necessary for any effective real-time or near-real-time monitoring regime. We explore the utility and effectiveness of processor-based and physics-based techniques exploiting the strengths of the PMCC processor and the theoretical effects of propagation and attenuation on the spectra of explosive sources, both in terms of reducing the clutter volume at a continuously-operating research infrasound array in central Mississippi, and at preserving signals from known explosive sources recorded in Nevada. Possible fallacies in the assumptions underlying some common techniques will also be discussed.

  8. Sub-Surface Windscreen for the Measurement of Outdoor Infrasound

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Burkett, Cecil G., Jr.; Comeaux, Toby; Zuckerwar, Allan J.; Weistroffer, George R.

    2008-01-01

    A windscreen has been developed that features two advantages favorable for the measurement of outdoor infrasound. 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 sources, 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.

  9. Joint interpretation of infrasound, acoustic, and seismic waves from meteorites: Chelyabinsk bolide and other events

    NASA Astrophysics Data System (ADS)

    Kitov, Ivan; Rozhkov, Mikhail; Bobrov, Dmitry; Ovtchinnikov, Vladimir

    2014-05-01

    Meteorites are always the events that testing the capability of the International Monitoring System to measure and the International Data Centre to analyze sources similar to nuclear explosions. Monitoring of the Comprehensive Nuclear-Test-Ban Treaty suggests the possibility to detect infrasound (acoustic) and seismic signals from atmospheric and underground events and to locate their sources. 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 infrasound 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 infrasound 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 source 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 infrasound 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

  10. AVE/VAS experiment: Ground truth network

    NASA Technical Reports Server (NTRS)

    Scoggins, J. R.

    1983-01-01

    The visible/infrared spin scan radiometer (VISSR) atmospheric sounder (VAS) rawinsonde field program is discussed. Specific items covered include: planning, personnel requirements and training, operational requirement and procedures, sounding times and dates, methods of data processing, data inventory, and status of data processing.

  11. Design and Operation of Infrasound Stations for Hazardous Weather Detection

    NASA Astrophysics Data System (ADS)

    Pepyne, D.

    2012-04-01

    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 infrasound 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 infrasound 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 infrasound with active tracking of the parent storms that carry the tornadoes with its weather radars. In the spring of 2011 CASA conducted an infrasound 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 infrasound experiment, the goal of the field-test was to gain an understanding of the issues involved in the design and operation of infrasound stations for severe weather monitoring and early warning. In this application, it is not so much the ability of infrasound 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 infrasound "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

  12. Remote infrasound monitoring of Mount Etna: Observed and predicted network detection capability

    NASA Astrophysics Data System (ADS)

    Tailpied, Dorianne; Le Pichon, Alexis; Marchetti, Emanuele; Ripepe, Maurizio; Kallel, Mohamed; Ceranna, Lars

    2013-04-01

    Volcanic eruptions are unique and valuable calibrating sources 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 infrasound 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 source 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 infrasound propagation and allow predicting fine temporal fluctuations in the European infrasound network performance with potential application for civil aviation safety.

  13. Evaluation of Inter-Mountain Labs infrasound sensors : July 2007.

    SciTech Connect

    Hart, Darren M.

    2007-10-01

    Sandia National Laboratories has tested and evaluated three Inter Mountain Labs infrasound 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 infrasound 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) infrasound 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.

  14. Detecting blast-induced infrasound in wind noise.

    PubMed

    Howard, Wheeler B; Dillion, Kevin L; Shields, F Douglas

    2010-03-01

    Current efforts seek to monitor and investigate such naturally occurring events as volcanic eruptions, hurricanes, bolides entering the atmosphere, earthquakes, and tsunamis by the infrasound they generate. Often, detection of the infrasound signal is limited by the masking effect of wind noise. This paper describes the use of a distributed array to detect infrasound 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. PMID:20329823

  15. Steps toward quantitative infrasound propagation modeling

    NASA Astrophysics Data System (ADS)

    Waxler, Roger; Assink, Jelle; Lalande, Jean-Marie; Velea, Doru

    2016-04-01

    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, infrasound, 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.

  16. Detectability of Tengchong infrasound array in China

    NASA Astrophysics Data System (ADS)

    Su, Wei; Yuan, Songyong

    2016-04-01

    The Tengchong seismo-acoustic array located in southwest of China has been running for 5 years. We perform broadband (0.01-5 Hz) array processing with the infrasound continuous waveform data (from 1 January 2011 to 31 December 2015) using the Progressive Multi-Channel Correlation algorithm in 15 log-spaced frequency bands defined by Matoza et al.(2013).The detection results show microbaroms [0.1-0.5 Hz] come from azimuth between 180 and 240°during April to October related to the significant wave height in southern India ocean,but microbaroms come from azimuth between 30 and 90°during September to March related to the significant wave height in northern Pacific ocean. MAWs [0.01-0.1 Hz] come from azimuth between 270 and 360°,and between 90 and 160°. The detections with azimuth between 100 and 150° in December 2014 to January 2015 may be related to the several typhoons from the Western Pacific ocean. The PMCC results confirm that the coherent signals typically exhibit systematic seasonal variations.

  17. Seismo-acoustic Signals Recorded at KSIAR, the Infrasound Array Installed at PS31

    NASA Astrophysics Data System (ADS)

    Kim, T. S.; Che, I. Y.; Jeon, J. S.; Chi, H. C.; Kang, I. B.

    2014-12-01

    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 infrasound 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 infrasound array at KS07. The infrasound 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 sources 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.

  18. Tracking near-surface atmospheric conditions using an infrasound network.

    PubMed

    Marcillo, O; Johnson, J B

    2010-07-01

    Continuous volcanic infrasound 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 infrasound for tracking local averaged meteorological conditions, which has implications for modeling plume dispersal and quantifying gas flux. PMID:20649183

  19. 2013 Russian Fireball Largest Ever Detected by CTBTO Infrasound Sensors (Invited)

    NASA Astrophysics Data System (ADS)

    Pilger, C.; Ceranna, L.; Le Pichon, A.; Herry, P.; Brachet, N.; Mialle, P.; Brown, D.

    2013-12-01

    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 infrasound 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, infrasound 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 source and a line source is performed.

  20. Location of space debris by infrasound

    NASA Astrophysics Data System (ADS)

    Asming, Vladimir; Vinogradov, Yuri

    2013-04-01

    After an exhausted stage has separated from a rocket it comes back to the dense atmosphere. It burns and divides into many pieces moving separately. Ballisticians can calculate an approximate trace of a falling stage and outline a supposed area where the debris can fall (target ellipse). Such ellipses are usually rather big in sizes (something like 60 x 100 km). For safety reasons all local inhabitants should be evacuated from a target area during rocket's launch. One of problems is that the ballistician can not compute the traces and areas exactly. There were many cases when debris had fallen outside the areas. Rescue teams must check such cases to make changes in rockets. The largest pieces can contain remains of toxic rocket fuel and therefore must be found and deactivated. That is why the problem of debris location is of significant importance for overland fall areas. It is more or less solved in Kazakhstan where large fragments of 1st stages can be seen in the Steppe but it is very difficult to find fragments of 2nd stages in Altai, Tomsk region and Komi republic (taiga, mountains, swamps). The rocket debris produces strong infrasonic shock waves during their reentry. Since 2009 the Kola Branch of Geophysical Survey of RAS participates in joint project with Khrunichev Space Center concerning with infrasound debris location. We have developed mobile infrasound arrays consisting of 3 microphones, analog-to-digit converter, GPS and notebook. The aperture is about 200 m, deployment time is less than 1 hour. Currently we have 4 such arrays, one of them is wireless and consists of 3 units comprising a microphone, GPS and radio-transmitter. We have made several field measurements by 3 or 4 such arrays placed around target ellipses of falling rocket stages in Kazakhstan ("Soyuz" rocket 1st stage), Altai and Tomsk region ("Proton" rocket 2nd stages). If was found that a typical 2nd stage divides into hundreds of pieces and each one generates a shock wave. This is a

  1. Epigallocatechin gallate (EGCG) attenuates infrasound-induced neuronal impairment by inhibiting microglia-mediated inflammation.

    PubMed

    Cai, Jing; Jing, Da; Shi, Ming; Liu, Yang; Lin, Tian; Xie, Zhen; Zhu, Yi; Zhao, Haibo; Shi, Xiaodan; Du, Fang; Zhao, Gang

    2014-07-01

    Infrasound, a kind of common environmental noise and a major contributor of vibroacoustic disease, can induce the central nervous system (CNS) damage. However, no relevant anti-infrasound drugs have been reported yet. Our recent studies have shown that infrasound resulted in excessive microglial activation rapidly and sequential inflammation, revealing a potential role of microglia in infrasound-induced CNS damage. Epigallocatechin gallate (EGCG), a major bioactive component in green tea, has the capacity of protecting against various neurodegenerative diseases via an anti-inflammatory mechanism. However, it is still unknown to date whether EGCG acts on infrasound-induced microglial activation and neuronal damage. We showed that, after 1-, 2- or 5-day exposure of rats to 16 Hz, 130 dB infrasound (2 h/day), EGCG significantly inhibited infrasound-induced microglial activation in rat hippocampal region, evidenced by reduced expressions of Iba-1 (a marker for microglia) and proinflammatory cytokines (IL-1β, IL-6, IL-18 and TNF-α). Moreover, infrasound-induced neuronal apoptosis in rat hippocampi was significantly suppressed by EGCG. EGCG also inhibited infrasound-induced activation of primary microglia in vitro and decreased the levels of proinflammatory cytokines in the supernatants of microglial culture, which were toxic to cultured neurons. Furthermore, EGCG attenuated infrasound-induced increases in nuclear NF-κB p65 and phosphorylated IκBα, and ameliorated infrasound-induced decrease in IκB in microglia. Therefore, our study provides the first evidence that EGCG acts against infrasound-induced neuronal impairment by inhibiting microglia-mediated inflammation through a potential NF-κB pathway-related mechanism, suggesting that EGCG can be used as a promising drug for the treatment of infrasound-induced CNS damage. PMID:24746834

  2. Using Infrasound and Machine Learning for Monitoring Plinian Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Ham, F. M.; Iyengar, I.; Hambebo, B. M.; Garces, M. A.; Deaton, J.; Perttu, A.; Williams, B.

    2012-12-01

    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 infrasound array network. To reduce potential hazards for commercial aviation from volcanic ash, these infrasound 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 infrasound 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 infrasound 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 infrasound 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

  3. A dedicated pistonphone for absolute calibration of infrasound sensors at very low frequencies

    NASA Astrophysics Data System (ADS)

    He, Wen; He, Longbiao; Zhang, Fan; Rong, Zuochao; Jia, Shushi

    2016-02-01

    Aimed at the absolute calibration of infrasound 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 infrasound source in the frequency range from 0.001 Hz to 20 Hz. The low frequency property of the pistonphone has been verified through calibrating low frequency microphones. Comparison tests with the reciprocity method have shown that the pressure sensitivities from the pistonphone are not only reliable at common frequencies but also have smaller uncertainties at low frequencies.

  4. CTBT infrasound network performance to detect the 2013 Russian fireball event

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; Le Pichon, Alexis; Mialle, Pierrick; Garcés, Milton A.

    2015-04-01

    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 infrasound 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 infrasound 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 source 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.

  5. Kernel-based machine learning techniques for infrasound signal classification

    NASA Astrophysics Data System (ADS)

    Tuma, Matthias; Igel, Christian; Mialle, Pierrick

    2014-05-01

    Infrasound monitoring is one of four remote sensing technologies continuously employed by the CTBTO Preparatory Commission. The CTBTO's infrasound network is designed to monitor the Earth for potential evidence of atmospheric or shallow underground nuclear explosions. Upon completion, it will comprise 60 infrasound array stations distributed around the globe, of which 47 were certified in January 2014. Three stages can be identified in CTBTO infrasound data processing: automated processing at the level of single array stations, automated processing at the level of the overall global network, and interactive review by human analysts. At station level, the cross correlation-based PMCC algorithm is used for initial detection of coherent wavefronts. It produces estimates for trace velocity and azimuth of incoming wavefronts, as well as other descriptive features characterizing a signal. Detected arrivals are then categorized into potentially treaty-relevant versus noise-type signals by a rule-based expert system. This corresponds to a binary classification task at the level of station processing. In addition, incoming signals may be grouped according to their travel path in the atmosphere. The present work investigates automatic classification of infrasound arrivals by kernel-based pattern recognition methods. It aims to explore the potential of state-of-the-art machine learning methods vis-a-vis the current rule-based and task-tailored expert system. To this purpose, we first address the compilation of a representative, labeled reference benchmark dataset as a prerequisite for both classifier training and evaluation. Data representation is based on features extracted by the CTBTO's PMCC algorithm. As classifiers, we employ support vector machines (SVMs) in a supervised learning setting. Different SVM kernel functions are used and adapted through different hyperparameter optimization routines. The resulting performance is compared to several baseline classifiers. All

  6. Infrasound and Seismic Observation of Hayabusa Reentry as An Artificial Meteorite Fall

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Hiramatsu, Y.; Yamamoto, M.; Furumoto, M.; Fujita, K.

    2011-12-01

    The Hayabusa, the world first sample-return minor body explorer, came back to the Earth, and reentered into the Earth's atmosphere on June 13, 2010. Following the reentries of the Genesis in 2004 and the Stardust in 2006, the return of the Hayabusa Sample Return Capsule (H-SRC) was the third direct reentry event from the interplanetary transfer orbit to the Earth at a velocity of over 11.2 km/s. In addition, it was the world first case of the direct reentry of the spacecraft (H-S/C) itself from the interplanetary transfer orbit. The H-SRC and the H-S/C reentries are very good analogue for studying bolide size meteors and meteorite falls. We, therefore, conducted a ground observation campaign for aspects of meteor sciences. We carried out multi-site ground observations of the Hayabusa reentry in the Woomera Prohibited Area (WPA), Australia. The observations were configured with optical imaging with still and video recordings, spectroscopies, and shockwave detection with infrasound and seismic sensors. In this study, we report details of the infrasound/seismic observations and those results. To detect shockwaves from the H-SRC and the H-S/C, we installed three small aperture infrasound/seismic arrays as the main stations. In addition, we also installed three single component seismic sub stations and an audible sound recorder. The infrasound and seismic sensors clearly recorded sonic boom type shockwaves from the H-SRC and disrupted fragments of the H-S/C itself. The audible recording also detected those shockwave sounds in the human audible band. Positive overpressure values of shockwaves (corresponding to the H-SRC) recorded at three main stations are 1.3 Pa, 1.0 Pa, and 0.7 Pa with the slant distance of 36.9 km, 54.9 km, and 67.8 km (i.e., the source altitude of 36.5 km, 38.9km, and 40.6 km), respectively. These amplitudes of shockwave overpressures are systematically smaller than those of theoretical predictions. We tried to identify the sources of shockwaves

  7. The Chelyabinsk Meteorite as a multiple source of acoustic and seismic waves

    NASA Astrophysics Data System (ADS)

    Kitov, I. O.; Bobrov, D. I.; Ovchinnikov, V. M.; Rozhkov, M. V.

    2016-05-01

    Shock waves and impact of the Chelyabinsk Meteorite fragments on the ground initiated various waves in the atmosphere and the earth. Three different sources of seismic and infrasound waves were found by arrival time and azimuth of seismic and infrasound waves recorded by the International Monitoring System.

  8. Monitoring of Ash Ejection from Ecuadorean Volcanoes Using Infrasound

    NASA Astrophysics Data System (ADS)

    Hetzer, C.; Garces, M.; Fee, D.; Bass, H.; McCormack, D.

    2007-12-01

    Two infrasound arrays with 100-meter apertures have been deployed in Ecuador in order to monitor volcanic eruptions that may produce ash clouds. Data is collected continuously and streamed via satellite and internet links to processing centers that apply array processing techniques to display acoustic detections of volcanic eruptions in near-real-time. These data products are delivered to the DC Volcanic Ash Advisory Center (VAAC), and have been used as additional confirmation of an eruption in ash advisories provided by the VAAC to commercial aircraft. Considerable research has been put into identifying the types of acoustic signals that indicate ash injection, as well as eliminating false alarms and reducing the latency between data collection and notification. Research conducted to date will be discussed, as well as several case studies wherein infrasound data proved useful for quick detection of eruptions. A brief summary of the advantages gained from use of this technique will also be presented.

  9. Test definitions for the evaluation of infrasound sensors.

    SciTech Connect

    Kromer, Richard Paul; Hart, Darren M.; Harris, James Mark

    2007-07-01

    Most test methodologies referenced in this Test Definition and Test Procedures were designed by Sandia specifically for geophysical instrumentation evaluation. When appropriate, test instrumentation calibration is traceable to the National Institute for Standards Technology (NIST). The objectives are to evaluate the overall technical performance of the infrasound sensor. The results of these evaluations can be compared to the manufacturer's specifications and any relevant application requirements or specifications.

  10. Trans-Mediterranean Infrasound Propagation in Summer: Theory and Observations

    NASA Astrophysics Data System (ADS)

    Garces, M. A.; Fee, D.; Waxler, R.; Hetzer, C. H.; Assink, J.; Drob, D. P.; Le Pichon, A.; Hofstetter, A.; Gitterman, Y.

    2009-12-01

    The ground surface detonation of ~82 tons of high explosives was successfully conducted on 26 August 2009 by the Geophysical Institute of Israel at the Sayarim Military Range in the Negev desert. The measured detonation time was 6:31:54 GMT, and the GPS coordinates of the surface explosion are 30.00057°N, 34.81351°E, 556 m altitude. The primary goal of the experiment was to transmit low-frequency sound across the Mediterranean to improve our understanding of infrasound propagation in the Middle East and Mediterranean regions. Multiple infrasound arrays were deployed by collaborating institutions, which will also cooperate in the analysis and modeling of the recorded signals. The following organizations participated in temporary infrasound microphone and array deployments in the Mediterranean and Middle East: The Geophysical Institute of Israel and the University of Mississippi (Israel and Cyprus), University of Alaska (Israel), Geological Survey of Cyprus (Cyprus), National Observatory of Athens and University of Hawaii (Rhodes, Crete, and Peloponnese, Greece), University of Florence (Calabria, Italy), CEA/DAM (Provence and Paris, France), and the United Nations (N. Italy, Austria, Germany, and Tunisia). All these station recorded acoustic signals, with ranges from ~100 m (Sayarim, Israel) to ~3500 km (Paris, France). The observations validate the predicted acoustic returns from refraction in the stratosphere and thermosphere during Summer, and are used to further refine sound propagation models and atmospheric specifications.

  11. The developement of the Romanian infrasound network array

    NASA Astrophysics Data System (ADS)

    Ionescu, C.; Moldovan, A. S.; Moldovan, I. A.; Grigore, A. G.

    2009-04-01

    The infrasound technology in Romania was developed in the framework of three national projects in the field of Monitoring of anomalous phenomena associated with earthquakes, explosions and storms with the very start in 2005. In the last years we have developed in the epicentral zone two triangle-shaped infrasound arrays, the first one having 400 m aperture and the second one 2.5 km aperture. The sites are also equipped with seismic, electric and triaxial fluxgate magnetic sensors. First configuration, surrounding a central point (Plostina-Vrancea) have been completed with other three sites with a larger aperture, needed for a better event azimuth identification. In one site there are installed two types os sensors for reliability studies. At present the infrasound array from Plostina consists in 6 elements: three elements built in Basic Design Requirements for Pipe Arrays with Chaparral sensors (Model25, 0.1Hz to 200 Hz) and Quantera 330 digitizer with porous pipe garden house installed on external ring and the other three with MBAZEL2007 (+/-50Pa) microbarometer with porous pipe and Hi6 digitizer.

  12. Impact of mountain gravity waves on infrasound propagation

    NASA Astrophysics Data System (ADS)

    Damiens, Florentin; Lott, François; Millet, Christophe

    2016-04-01

    Linear theory of acoustic propagation is used to analyze how mountain waves can change the characteristics of infrasound signals. The mountain wave model is based on the integration of the linear inviscid Taylor-Goldstein equation forced by a nonlinear surface boundary condition. For the acoustic propagation we solve the wave equation using the normal mode method together with the effective sound speed approximation. For large-amplitude mountain waves we use direct numerical simulations to compute the interactions between the mountain waves and the infrasound component. It is shown that the mountain waves perturb the low level waveguide, which leads to significant acoustic dispersion. The mountain waves also impact the arrival time and spread of the signals substantially and can produce a strong absorption of the wave signal. To interpret our results we follow each acoustic mode separately and show which mode is impacted and how. We also show that the phase shift between the acoustic modes over the horizontal length of the mountain wave field may yield to destructive interferences in the lee side of the mountain, resulting in a new form of infrasound absorption. The statistical relevance of those results is tested using a stochastic version of the mountain wave model and large enough sample sizes.

  13. In-situ comparison calibration of infrasound array elements

    NASA Astrophysics Data System (ADS)

    Gabrielson, T. B.

    2009-12-01

    A typical infrasound array element consists of an infrasonic sensor connected to a multiple-pipe or porous-hose system for reduction of wind noise. While the frequency response of the sensor itself may be known, the wind-noise reduction system can modify that response. One approach to measuring the actual frequency response in situ is to perform a comparison calibration using ambient noise. The reference sensor must have a sufficiently low self noise and have a well characterized frequency response over the band of interest. In the cases presented here, three reference sensors are placed and summed to form a virtual reference at the geometric center of the pipe system. Under low-wind conditions, coherence between the virtual reference and the infrasound element is typically greater than 0.8 from 0.01 to 8 Hz. Proper combination of auto- and cross-spectral averages over a several-hour period produces an estimate of the response of the infrasound system relative to that of the virtual reference. Measured coherence and the consistency between the magnitude and the phase provide quality checks on the process. [Funded by the US Army Space and Missile Defense Command

  14. Effects of infrasound on the growth of bone marrow mesenchymal stem cells: a pilot study.

    PubMed

    He, Renhong; Fan, Jianzhong

    2014-11-01

    Poor viability of transplanted bone marrow mesenchymal stem cells (BMSCs) is well‑known, but developing methods for enhancing the viability of BMSCs requires further investigation. The aim of the present study was to elucidate the effects of infrasound on the proliferation and apoptosis of BMSCs, and to determine the association between survivin expression levels and infrasound on BMSCs. Primary BMSCs were derived from Sprague Dawley rats. The BMSCs, used at passage three, were divided into groups that received infrasound for 10, 30, 60, 90 or 120 min, and control groups, which were exposed to the air for the same durations. Infrasound was found to promote proliferation and inhibit apoptosis in BMSCs. The results indicated that 60 min was the most suitable duration for applied infrasound treatment to BMSCs. The protein and mRNA expression levels of survivin in BMSCs from the two treatment groups that received 60 min infrasound or air, were examined by immunofluorescence and quantitative polymerase chain reaction. Significant differences in survivin expression levels were identified between the two groups, as infrasound enhanced the expression levels of survivin. In conclusion, infrasound promoted proliferation and inhibited apoptosis in BMSCs, and one mechanisms responsible for the protective effects may be the increased expression levels of survivin. PMID:25175368

  15. Finite-difference time-domain modeling of infrasound from pulsating auroras and comparison with recent experiments

    NASA Astrophysics Data System (ADS)

    de Larquier, S.; Pasko, V. P.; Stenbaek-Nielsen, H. C.; Wilson, C. R.; Olson, J. V.

    2009-12-01

    Atmospheric infrasonic waves are acoustic waves with frequencies ranging from 0.02 to 10 Hz, slightly higher than the acoustic cut-off frequency (approximately 0.032 Hz), but lower than the audible frequencies (typically 20 Hz-15 kHz) [e.g., Blanc, Ann. Geophys., 3, 673, 1985]. A number of natural events have been identified as generating atmospheric infrasound, such as volcanoes, tornadoes, avalanches, earthquakes [e.g., Bedard and Georges, Physics Today, S3, 32, 2000], ocean surfaces [e.g., Gossard and Hooke, Waves in the Atmosphere, Elsevier, 1975, Ch. 9], lightning [e.g., Assink et al., GRL, 35, L15802, 2008; Pasko, JGR, 114, D08205, 2009], or transient luminous events in the middle atmosphere termed sprites [e.g., Farges, Lightning: Principles, Instruments and Applications, H.D. Betz et al. (eds), Springer, 2009, Ch. 18]. The importance of infrasound studies has been emphasized in the past ten years from the Comprehensive Nuclear-Test-Ban Treaty verification perspective [e.g., Le Pichon et al., JGR, 114, D08112, 2009]. A proper understanding of infrasound propagation in the atmosphere is required for identification and classification of different infrasonic waves and their sources [Drob et al., JGR, 108, D21, 4680, 2003]. The goal of the present work is to provide a quantitative interpretation and explanation of infrasonic signatures from pulsating auroras reported recently by Wilson et al. [GRL, 32, L14810, 2005]. The infrasound signals observed with an infrasonic array at Fairbanks, Alaska had a mean amplitude of 0.05 Pa, a delay of about 5 minutes from the pulsating aurora, and an almost normal incidence on the ground plane [Wilson et al., 2005]. We employ a finite-difference time-domain (FDTD) model of infrasound propagation in a realistic atmosphere. We use the absorption model of infrasound introduced by Sutherland and Bass [J. Acoust. Soc. Am., 115, 1012, 2004]. Classical absorption mechanisms as well as molecular relaxation mechanisms are taken into

  16. A Tribute to Hank Bass: The Past, Present, and Future of US Infrasound Research

    NASA Astrophysics Data System (ADS)

    Garces, M.; Drob, D.; Golden, P.; Hedlin, M.; Szuberla, C.; Waxler, R.; Whitaker, R.

    2008-12-01

    The deployment of the International Monitoring System (IMS) global infrasound network at the turn of the 21st century inspired a renaissance in innovation, development, and application of infrasound technology. In the United States, Hank Bass (1944-2008) was responsible for defining and directing the scientific agenda. Under his leadership, US research teams in academia, industry, and government evaluated and developed the infrastructure to deploy, maintain, and make optimal use of infrasound arrays in the IMS and national networks. Case studies of national and international interest, such as the April 23, 2001 megabolide, the February 1, 2003 Columbia disaster, and the 2004 Sumatra earthquake and tsunami, integrated monitoring technologies and renewed the value of infrasound in covering observational gaps. Dramatic technological improvements have extended the use of infrasound to new natural hazard and national security applications, which will be discussed within the context of nuclear explosion monitoring.

  17. Infrasound Generation from the HH Seismic Hammer.

    SciTech Connect

    Jones, Kyle Richard

    2014-10-01

    The HH Seismic hammer is a large, "weight-drop" source for active source seismic experiments. This system provides a repetitive source that can be stacked for subsurface imaging and exploration studies. Although the seismic hammer was designed for seismological studies it was surmised that it might produce energy in the infrasonic frequency range due to the ground motion generated by the 13 metric ton drop mass. This study demonstrates that the seismic hammer generates a consistent acoustic source that could be used for in-situ sensor characterization, array evaluation and surface-air coupling studies for source characterization.

  18. Current Status of Infrasound Pilot Observation at Japanese Islands and SYOWA Antarctica, and Development of New Infrasound Sensor using Optical Sensing Method

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Yamamoto, M.; Kanao, M.

    2009-12-01

    Infrasound is sub audible sound (pressure wave), and that frequency range is cut-off frequency of sound (e.g., 3.21 mHz for 15 degree Celsius isothermal atmosphere) to 20 Hz (that is lowest frequency of human audible band). This frequency range is one of the new horizons of the remote sensing in the Earth’s atmosphere, for example, a large earthquake in Sumatra region generated great Tsunami also produced such kinds of waves in atmosphere and shaking Earth itself by free vibration mode as well as affected even upon the upper atmosphere. Last decade, for the purpose of monitoring nuclear tests, a global infrasound network is constructed by CTBTO. The CTBT-IMS infrasound network has 60 infrasound stations and each station contains at least 4 infrasound sensors (arrayed station), they can detect a some-kiloton TNT level atmospheric explosion in range of some 1000 kilometers. This network is enough for monitoring nuclear tests, but much sparse for detecting and analyzing in detail of natural infrasound phenomena. Observation of infrasound in Japan began in 1980’s by Tahira at Aichi University of Educational with using three arrayed sensors of Chaparral Physics’ Model-2. They reported infrasound waves by volcanic eruptions, ocean waves, earthquakes, airplane passages, etc. Recently, infrasound waves possibly generated by thunders, sprites, fireballs / meteorite fall, and artificial reentry of vehicles, and auroral activities have been reported in several papers. In 2004, we began to study infrasound and discussed with Prof. Tahira, then just after his retirement of his university, these three arrayed sensors tested again at Tohoku University in 2005. Network observation of infrasound is significant in studying geophysical phenomena, however, the sensors are too expensive to buy for further several arrayed stations to distribute in Japan. In 2006, we began to develop new types of infrasound sensors by piezo films and firstly tested in field in 2007, comparing with

  19. Classification, Characterization, and Automatic Detection of Volcanic Explosion Complexity using Infrasound

    NASA Astrophysics Data System (ADS)

    Fee, D.; Matoza, R. S.; Lopez, T. M.; Ruiz, M. C.; Gee, K.; Neilsen, T.

    2014-12-01

    Infrasound signals from volcanoes represent the acceleration of the atmosphere during an eruption and have traditionally been classified into two end members: 1) "explosions" consisting primarily of a high amplitude bi-polar pressure pulse that lasts a few to tens of seconds, and 2) "tremor" or "jetting" consisting of sustained, broadband infrasound lasting for minutes to hours. However, as our knowledge and recordings of volcanic eruptions have increased, significant infrasound signal diversity has been found. Here we focus on identifying and characterizing trends in volcano infrasound data to help better understand eruption processes. We explore infrasound signal metrics that may be used to quantitatively compare, classify, and identify explosive eruptive styles by systematic analysis of the data. We analyze infrasound data from short-to-medium duration explosive events recorded during recent infrasound deployments at Sakurajima Volcano, Japan; Karymsky Volcano, Kamchatka; and Tungurahua Volcano, Ecuador. Preliminary results demonstrate that a great variety of explosion styles and flow behaviors from these volcanoes can produce relatively similar bulk acoustic waveform properties, such as peak pressure and event duration, indicating that accurate classification of physical eruptive styles requires more advanced field studies, waveform analyses, and modeling. Next we evaluate the spectral and temporal properties of longer-duration tremor and jetting signals from large eruptions at Tungurahua Volcano; Redoubt Volcano, Alaska; Augustine Volcano, Alaska; and Nabro Volcano, Eritrea, in an effort to identify distinguishing infrasound features relatable to eruption features. We find that unique transient signals (such as repeated shocks) within sustained infrasound signals can provide critical information on the volcanic jet flow and exhibit a distinct acoustic signature to facilitate automatic detection. Automated detection and characterization of infrasound associated

  20. Atmospheric Infrasound Propagation Modelling Using the Reflectivity Method

    NASA Astrophysics Data System (ADS)

    Näsholm, Sven Peter; Schweitzer, Johannes; Gibbons, Steven J.; Kvaerna, Tormod

    2015-04-01

    We demonstrate that the reflectivity method can be applied to the modelling of infrasound propagation. The reflectivity method is a slowness (or wavenumber) integration method widely applied in the seismological community to generate synthetic seismograms in layered media. The integrated function essentially describes the reflection coefficients between the layers. The method models P- and S-wave propagation and includes refractions and reflections, multiples, caustics, mode conversion, absorption and dispersion. Some limitations of conventional ray tracing are circumvented since head waves are represented and shadow zones are more correctly modelled. We apply a 2.5-D ray-tracing engine and a slightly modified version of Müller's reflectivity code to the atmospheric wind and temperature conditions at the time of the Drevja accidental explosion on December 17, 2013, in Northern Norway. The infrasound modelling results are compared with signals observed at the IS37 array station in Bardufoss, situated around 400 km north-east of the event. The effective sound speed approximation is applied, where the altitude-varying and range-independent sound speed is given by sum of the adiabatic sound speed and the wind projected in the horizontal propagation direction. An important observation is that an infrasound arrival, clearly observed in the IS37 data approximately 20 minutes after the explosion time, is predicted by the reflectivity method and not by ray-tracing, even for very densely sampled ray emission elevation angles. However at shorter ranges (~300 km), the corresponding phase is predicted by both modelling methods. There, the ray tracing shows this arrival as resulting from of a ray turning once in the stratosphere.

  1. Infrasound Waveform Classification and Emissions Correlation at Karymsky and Sakurajima Volcanoes

    NASA Astrophysics Data System (ADS)

    Albert, S.; Fee, D.; Lopez, T. M.; Firstov, P. P.; Makhmudov, E.

    2014-12-01

    Infrasound (sound between ~0.01-20 Hz) is often used to monitor volcanoes and provide insight into eruption dynamics. Of the main goals in the volcano infrasound community, associating volcanic emissions with specific infrasound features remains of importance. Here we focus on infrasound collected during two separate field campaigns at Karymsky Volcano, Kamchatka, Russia and Sakurajima Volcano, Japan. Both volcanoes are andesitic and produce frequent eruptions. Recent Karymsky eruptions have been classified into four main eruption types: discrete ash explosions, pulsatory gas emissions, gas jetting, and quiescence followed by an explosion. Sakurajima eruptions are typically ash-rich and are dominantly Vulcanian in character. We use a waveform cross correlation scheme to identify infrasound waveform families from recent eruptions at each volcano. We also identify changes in eruption dynamics by tracking the number and occurrence of these families though time. This can be done on a large scale (changes in relation to the families) as well as on a smaller scale (changes in relation to the subfamilies). During these field campaigns volcanic emissions data were also collected using ground-based sampling, and visual, ultraviolet, and infrared remote sensing techniques. The infrasound waveform families are then correlated with volcanic emissions data to determine unique signatures of volcanic emissions. By comparing model calculations and physical data, this information will hopefully lead to improved monitoring and characterization of volcanic eruptions using infrasound in particular at remote, difficult to monitor volcanoes.

  2. Monitoring volcanic activities using correlation patterns between infrasound and ground motion

    NASA Astrophysics Data System (ADS)

    Ichihara, M.; Takeo, M.; Yokoo, A.

    2012-04-01

    This paper presents a simple method to distinguish infrasonic signals from wind noise using a cross-correlation function of signals from a microphone and a co-located seismometer. The method makes use of a particular feature of the cross-correlation function of vertical ground motion generated by infrasound, and the infrasound itself. Contribution of wind noise to the correlation function is effectively suppressed by separating the microphone and the seismometer by several meters because the correlation length of wind noise is much shorter than wavelengths of infrasound. The method is tested with data from volcanoes, and demonstrates that the method effectively detects not only the main eruptions, but also minor activity generating weak infrasound hardly visible in the wave traces. In addition, the correlation function gives more information about volcanic activity than infrasound alone. The correlation pattern changes when the spectral feature of the infrasound and/or the seismic wave changes and the relative strength of infrasound and seismic wave changes, both of which are expected to be accompanied by change in eruptive activity. Therefore, a graphical presentation of temporal variation in the cross-correlation function enables to see qualitative changes of eruptive activities at a glance. This method is particularly useful when available sensors are limited, and will extend the utility of a single microphone and seismometer in monitoring and understanding volcanic activity. The method is used to analyze sequences of two recent eruptions of Asama and Shinmoe-dake volcanoes, Japan.

  3. Hardware design document for the Infrasound Prototype for a CTBT IMS station

    SciTech Connect

    Breding, D.R.; Kromer, R.P.; Whitaker, R.W.; Sandoval, T.

    1997-11-01

    The Hardware Design Document (HDD) describes the various hardware components used in the Comprehensive Test Ban Treaty (CTBT) Infrasound Prototype and their interrelationships. It divides the infrasound prototype into hardware configurations items (HWCIs). The HDD uses techniques such as block diagrams and parts lists to present this information. The level of detail provided in the following sections should be sufficient to allow potential users to procure and install the infrasound system. Infrasonic monitoring is a low cost, robust, and effective technology for detecting atmospheric explosions. Low frequencies from explosion signals propagate to long ranges (few thousand kilometers) where they can be detected with an array of sensors.

  4. [Hygienic estimation of combined influence of noise and infrasound on the organism of military men].

    PubMed

    Akhmetzianov, I M; Zinkin, V N; Petreev, I V; Dragan, S P

    2011-11-01

    Hygienic estimation of combined influence of noise and infrasound on the organism of military men. Combined influence of noise and infrasound is accompanied by essential increase of risk of development neurosensory deafness and hypertensive illness. At combined influence of noise and infrasound with a maximum of a spectrum in the field of a sound range the probability of development neurosensory deafness will prevail. Thus probability of development of pathology of ear above the values established ISO 1999:1990. In a case if the spectrum maximum is necessary on an infrasonic range the probability of development of a hypertensive illness. PMID:22329172

  5. Acoustic multipole source model for volcanic explosions and inversion for source parameters

    NASA Astrophysics Data System (ADS)

    Kim, Keehoon; Lees, Jonathan M.; Ruiz, Mario

    2012-12-01

    Volcanic explosions are accompanied by strong acoustic pressure disturbances in the atmosphere. With a proper source model, these acoustic signals provide invaluable information about volcanic explosion dynamics. Far-field solutions to volcanic infrasound radiation have been derived above a rigid half-space boundary, and a simple inversion method was developed based on the half-space model. Acoustic monopole and dipole sources were estimated simultaneously from infrasound waveforms. Stability of the inversion procedure was assessed in terms of variances of source parameters, and the procedure was reliable with at least three stations around the infrasound source. Application of this method to infrasound observations recorded at Tungurahua volcano in Ecuador successfully produced a reasonable range of source parameters with acceptable variances. Observed strong directivity of infrasound radiation from explosions at Tungurahua are successfully explained by the directivity of a dipole source model. The resultant dipole axis, in turn, shows good agreement with the opening direction of the vent at Tungurahua, which is considered to be the origin of the dipole source. The method is general and can be utilized to study any monopole, dipole or combined sources generated by explosions.

  6. Infrasound analysis using Fisher detector and Hough transform

    NASA Astrophysics Data System (ADS)

    Averbuch, Gil; Assink, Jelle D.; Smets, Pieter S. M.; Evers, Läslo G.

    2016-04-01

    Automatic detection of infrasound signals from the International Monitoring System (IMS) from the Comprehensive Nuclear-Test-Ban Treaty requires low rates of both false alarms and missed events. The Fisher detector is a statistical method used for detecting such infrasonic events. The detector aims to detect coherent signals after Beamforming is applied on the recordings. A detection is defined to be above a threshold value of Fisher ratio. The Fisher distribution for such a detection is affected by the SNR. While events with high Fisher ratio and SNR can easily be detected automatically, events with lower Fisher ratios and SNRs might be missed. The Hough transform is a post processing step. It is based on a slope-intercept transform applied to a discretely sampled data, with the goal of finding straight lines (in apparent velocity and back azimuth). Applying it on the results from the Fisher detector is advantageous in case of noisy data, which corresponds to low Fisher ratios and SNRs. Results of the Hough transform on synthetic data with SNR down to 0.7 provided a lower number of missed events. In this work, we will present the results of an automatic detector, based on both methods. Synthetic data with different lengths and SNRs are evaluated. Furthermore, continuous data from the IMS infrasound station I18DK will be analyzed. We will compare the performances of both methods and investigate their ability in reducing the number of missed events.

  7. Sound, infrasound, and sonic boom absorption by atmospheric clouds.

    PubMed

    Baudoin, Michaël; Coulouvrat, François; Thomas, Jean-Louis

    2011-09-01

    This study quantifies the influence of atmospheric clouds on propagation of sound and infrasound, based on an existing model [Gubaidulin and Nigmatulin, Int. J. Multiphase Flow 26, 207-228 (2000)]. Clouds are considered as a dilute and polydisperse suspension of liquid water droplets within a mixture of dry air and water vapor, both considered as perfect gases. The model is limited to low and medium altitude clouds, with a small ice content. Four physical mechanisms are taken into account: viscoinertial effects, heat transfer, water phase changes (evaporation and condensation), and vapor diffusion. Physical properties of atmospheric clouds (altitude, thickness, water content and droplet size distribution) are collected, along with values of the thermodynamical coefficients. Different types of clouds have been selected. Quantitative evaluation shows that, for low audible and infrasound frequencies, absorption within clouds is several orders of magnitude larger than classical absorption. The importance of phase changes and vapor diffusion is outlined. Finally, numerical simulations for nonlinear propagation of sonic booms indicate that, for thick clouds, attenuation can lead to a very large decay of the boom at the ground level. PMID:21895057

  8. Lahar Infrasound Associated with Villarrica's March 3, 2015 Eruption

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Palma, J.

    2015-12-01

    The paroxysmal eruption of Volcan Villarrica on March 3rd, 2015 produced a moderate-sized lahar, which descended more than 20 km within the Rio Correntoso/Turbio drainage. A three-element infrasound array 10 km from the summit, and 4 km from the lahar's closest approach, was used to track the flow's evolution as it progressed downstream. Array processing using cross correlation lag times as well as semblance techniques places important constraints on the lahar's dynamics, including the detection of an early flow pulse that traveled from 3 to 13 km at an average speed of 36 m/s. After the first six minutes of lahar advancement the signal evolves into a relatively stationary infrasonic tremor located ~11.5 km downstream and consistent with a notch in intervening topography. Diminishing tremor amplitude over the course of more than two hours constrain the flow duration and indicates progressively decreasing flow energy and/or confinement of the flow to more distant reaches. This study demonstrates the powerful capabilities of infrasound arrays for lahar study and suggests its potential implementation for hazard monitoring.

  9. Infrasound from the El Paso super-bolide of October 9, 1997

    SciTech Connect

    ReVelle, D.O.; Whitaker, R.W.; Armstrong, W.T.

    1998-12-31

    During the noon hour on October 9, 1997 an extremely bright fireball ({approx}-21.5 in stellar magnitude putting it into the class of a super-bolide) was observed over western Texas with visual sightings from as far away as Arizona to northern Mexico and even in northern New Mexico over 300 miles away. This event produced tremendously loud sonic boom reports in the El Paso area. It was also detected locally by 4 seismometers which are part of a network of 5 seismic stations operated by the University of Texas at El Paso (UTEP). Subsequent investigations of the data from the six infrasound arrays used by LANL (Los Alamos National Laboratory) and operated for the DOE (Department of Energy) as a part of the CTB (Comprehensive Test Ban) Research and Development program for the IMS (International Monitoring System) showed the presence of an infrasonic signal from the proper direction at the correct time for this super-bolide from two of the six arrays. Both the seismic and infrasound recordings indicated that an explosion occurred in the atmosphere at source heights from 28--30 km, having its epicenter slightly to the northeast of Horizon City, Texas. The signal characteristics, analyzed from {approx}0.1 to 5.0 Hz, include a total duration of {approx}4 min (at Los Alamos, LA) to >{approx}5 min at Lajitas, Texas, TXAR, another CTB IMS array operated by E. Herrin at Southern Methodist University (SMU) for a source directed from LA toward {approx}171--180 deg and from TXAR of {approx}321-4 deg respectively from true north. The observed signal trace velocities (for the part of the recording with the highest cross-correlation) at LA ranged from 300--360 m/sec with a signal velocity of 0.30 {+-} 0.03 km/sec, implying a Stratospheric (S Type) ducted path. The dominant signal frequency at LA was from 0.20 to 0.80 Hz, with a peak near 0.3 Hz. These highly correlated signals at LA had a very large, peak to peak, maximum amplitude of 21.0 microbars (2.1 Pa). The analysis, using

  10. A study of infrasound propagation based on high-order finite difference solutions of the Navier-Stokes equations.

    PubMed

    Marsden, O; Bogey, C; Bailly, C

    2014-03-01

    The feasibility of using numerical simulation of fluid dynamics equations for the detailed description of long-range infrasound propagation in the atmosphere is investigated. The two dimensional (2D) Navier Stokes equations are solved via high fidelity spatial finite differences and Runge-Kutta time integration, coupled with a shock-capturing filter procedure allowing large amplitudes to be studied. The accuracy of acoustic prediction over long distances with this approach is first assessed in the linear regime thanks to two test cases featuring an acoustic source placed above a reflective ground in a homogeneous and weakly inhomogeneous medium, solved for a range of grid resolutions. An atmospheric model which can account for realistic features affecting acoustic propagation is then described. A 2D study of the effect of source amplitude on signals recorded at ground level at varying distances from the source is carried out. Modifications both in terms of waveforms and arrival times are described. PMID:24606252

  11. Degassing Dynamics from Long-Period and Very-Long-Period Seismicity and Infrasound at Mt. Pagan Volcano

    NASA Astrophysics Data System (ADS)

    Lyons, J. J.; Haney, M. M.; Fee, D.; Werner, C. A.; Kern, C.; Kelly, P. J.

    2014-12-01

    Mt. Pagan is a small (570 m ASL), active basaltic cone filling a caldera that sits atop one of the largest (2160 km3) volcanoes in the Mariana Arc Front. A VEI 4 eruption in 1981 that forced the evacuation of the island was the most recent serious activity, although low-level activity persists with a robust degassing plume and occasional small ash explosions. A new monitoring network was installed in 2013, consisting of 7 intermediate band seismometers, 2 6-component infrasound arrays, and 2 web cameras. Additionally, 12 campaign broadband seismometers recorded for 10 months in 2013-2014. Crater-rim multi-GAS sampling and remote sensing of the volcanic plume indicate a shallowly degassing magmatic system producing ~600 tonnes/day of sulfur dioxide (SO2). The seismic activity to date is dominated by frequent long-period (LP) events (~1000 events/day) with energy peaked from 0.6-2 Hz. These events are accompanied by a 3 s very-long-period (VLP) signal in the infrasound. Continuous beamforming of waveforms from the infrasound arrays shows that degassing from the summit vent is an impressive source of nearly continuous, low frequency sound. The network has also recorded infrequent, extended (minutes duration), emergent seismo-acoustic signals associated with minor ash emissions. These small explosions are accompanied by VLP seismic signals with a period of 70 s and duration of ~200 s. In order to understand how the shallow conduit system produces nearly continuous degassing as well as discrete explosions, we performed full waveform inversions of the LP and VLP seismicity with a combination of campaign and permanent stations. The best-fit location for a 6 moment plus 3 force source mechanism lies at ~500 m beneath and at the western margin of the summit vent. The source time function is dominated by the diagonal components of the moment tensor with a minor contribution from the vertical single force. We suggest that these signals are caused by fluid transport through

  12. Long-range propagation of nonlinear infrasound waves through an absorbing atmosphere.

    PubMed

    de Groot-Hedlin, C D

    2016-04-01

    The Navier-Stokes equations are solved using a finite-difference, time-domain (FDTD) approach for axi-symmetric environmental models, allowing three-dimensional acoustic propagation to be simulated using a two-dimensional Cylindrical coordinate system. A method to stabilize the FDTD algorithm in a viscous medium at atmospheric densities characteristic of the lower thermosphere is described. The stabilization scheme slightly alters the governing equations but results in quantifiable dispersion characteristics. It is shown that this method leaves sound speeds and attenuation unchanged at frequencies that are well resolved by the temporal sampling rate but strongly attenuates higher frequencies. Numerical experiments are performed to assess the effect of source strength on the amplitudes and spectral content of signals recorded at ground level at a range of distances from the source. It is shown that the source amplitudes have a stronger effect on a signal's dominant frequency than on its amplitude. Applying the stabilized code to infrasound propagation through realistic atmospheric profiles shows that nonlinear propagation alters the spectral content of low amplitude thermospheric signals, demonstrating that nonlinear effects are significant for all detectable thermospheric returns. PMID:27106305

  13. Study on osteogenesis promoted by low sound pressure level infrasound in vivo and some underlying mechanisms.

    PubMed

    Long, Hua; Zheng, Liheng; Gomes, Fernando Cardoso; Zhang, Jinhui; Mou, Xiang; Yuan, Hua

    2013-09-01

    To clarify the effects of low sound pressure level (LSPL) infrasound on local bone turnover and explore its underlying mechanisms, femoral defected rats were stabilized with a single-side external fixator. After exposure to LSPL infrasound for 30min twice everyday for 6 weeks, the pertinent features of bone healing were assessed by radiography, peripheral quantitative computerized tomography (pQCT), histology and immunofluorescence assay. Infrasound group showed a more consecutive and smoother process of fracture healing and modeling in radiographs and histomorphology. It also showed significantly higher average bone mineral content (BMC) and bone mineral density (BMD). Immunofluorescence showed increased expression of calcitonin gene related peptide (CGRP) and decreased Neuropeptide Y (NPY) innervation in microenvironment. The results suggested the osteogenesis promotion effects of LSPL infrasound in vivo. Neuro-osteogenic network in local microenvironment was probably one target mediating infrasonic osteogenesis, which might provide new strategy to accelerate bone healing and remodeling. PMID:23770453

  14. An analysis of three new infrasound arrays around Kīlauea Volcano

    USGS Publications Warehouse

    Thelen, Weston A.; Cooper, Jennifer

    2015-01-01

    A network of three new infrasound station arrays was installed around Kīlauea Volcano between July 2012 and September 2012, and a preliminary analysis of open-vent monitoring has been completed by Hawaiian Volcano Observatory (HVO). Infrasound is an emerging monitoring method in volcanology that detects perturbations in atmospheric pressure at frequencies below 20 Hz, which can result from volcanic events that are not always observed optically or thermally. Each array has the capability to detect various infrasound events as small as 0.05 Pa as measured at the array site. The infrasound monitoring network capabilities are demonstrated through case studies of rockfalls, pit collapses, and rise-fall cycles at Halema'uma'u Crater and Pu'u 'Ōʻō.

  15. A system for verifying models and classification maps by extraction of information from a variety of data sources

    NASA Technical Reports Server (NTRS)

    Norikane, L.; Freeman, A.; Way, J.; Okonek, S.; Casey, R.

    1992-01-01

    Recent updates to a geographical information system (GIS) called VICAR (Video Image Communication and Retrieval)/IBIS are described. The system is designed to handle data from many different formats (vector, raster, tabular) and many different sources (models, radar images, ground truth surveys, optical images). All the data are referenced to a single georeference plane, and average or typical values for parameters defined within a polygonal region are stored in a tabular file, called an info file. The info file format allows tracking of data in time, maintenance of links between component data sets and the georeference image, conversion of pixel values to `actual' values (e.g., radar cross-section, luminance, temperature), graph plotting, data manipulation, generation of training vectors for classification algorithms, and comparison between actual measurements and model predictions (with ground truth data as input).

  16. Infrasound array observations in the Lützow-Holm Bay region, East Antarctica

    NASA Astrophysics Data System (ADS)

    Murayama, Takahiko; Kanao, Masaki; Yamamoto, Masa-Yuki; Ishihara, Yoshiaki; Matsushima, Takeshi; Kakinami, Yoshihiro

    2015-03-01

    The characteristic features of infrasound waves observed in Antarctica reveal a physical interaction involving surface environmental variations in the continent and the surrounding Southern Ocean. A single infrasound sensor has been making continuous recordings since 2008 at Syowa Station (SYO; 69.0S, 39.6E) in the Lützow-Holm Bay (LHB) of East Antarctica. The continuously recorded data clearly show the contamination of background oceanic signals (microbaroms) throughout all seasons. In austral summer 2013, several field stations with infrasound sensors were established along the coast of the LHB. Two infrasound arrays of different diameters were set up: one at SYO (with a 100-m spacing triangle) and one in the S16 area on the continental ice sheet (with a 1000-m spacing triangle). In addition to these arrays, isolated single stations were deployed at two outcrops in the LHB. These newly established arrays clearly detected the propagation direction and frequency content of microbaroms from the Southern Ocean. Microbarom measurements are a useful tool for characterizing ocean wave climates, complementing other oceanographic and geophysical data from the Antarctic. In addition to the microbaroms, several other remarkable infrasound signals were detected, including regional earthquakes, and airburst shock waves emanating from a meteoroid entering the atmosphere over the Russian Republic on 15 February 2013. Detailed and continuous measurements of infrasound waves in Antarctica could prove to be a new proxy for monitoring regional environmental change as well as temporal climate variations in high southern latitudes.

  17. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-couples airwaves

    USGS Publications Warehouse

    De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David

    2012-01-01

    In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and infrasound observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by infrasound sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. Infrasound and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic infrasound and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow infrasound to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in infrasound monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.

  18. Improved source term estimation using blind outlier detection

    NASA Astrophysics Data System (ADS)

    Martinez-Camara, Marta; Bejar Haro, Benjamin; Vetterli, Martin; Stohl, Andreas

    2014-05-01

    Emissions of substances into the atmosphere are produced in situations such as volcano eruptions, nuclear accidents or pollutant releases. It is necessary to know the source term - how the magnitude of these emissions changes with time - in order to predict the consequences of the emissions, such as high radioactivity levels in a populated area or high concentration of volcanic ash in an aircraft flight corridor. However, in general, we know neither how much material was released in total, nor the relative variation of emission strength with time. Hence, estimating the source term is a crucial task. Estimating the source term generally involves solving an ill-posed linear inverse problem using datasets of sensor measurements. Several so-called inversion methods have been developed for this task. Unfortunately, objective quantitative evaluation of the performance of inversion methods is difficult due to the fact that the ground truth is unknown for practically all the available measurement datasets. In this work we use the European Tracer Experiment (ETEX) - a rare example of an experiment where the ground truth is available - to develop and to test new source estimation algorithms. Knowledge of the ground truth grants us access to the additive error term. We show that the distribution of this error is heavy-tailed, which means that some measurements are outliers. We also show that precisely these outliers severely degrade the performance of traditional inversion methods. Therefore, we develop blind outlier detection algorithms specifically suited to the source estimation problem. Then, we propose new inversion methods that combine traditional regularization techniques with blind outlier detection. Such hybrid methods reduce the error of reconstruction of the source term up to 45% with respect to previously proposed methods.

  19. Cardiac peroxisome proliferator-activated receptor-γ expression is modulated by oxidative stress in acutely infrasound-exposed cardiomyocytes.

    PubMed

    Pei, Zhaohui; Meng, Rongsen; Zhuang, Zhiqiang; Zhao, Yiqiao; Liu, Fangpeng; Zhu, Miao-Zhang; Li, Ruiman

    2013-12-01

    The aim of the present study was to examine the effects of acute infrasound exposure on oxidative damage and investigate the underlying mechanisms in rat cardiomyocytes. Neonatal rat cardiomyocytes were cultured and exposed to infrasound for several days. In the study, the expression of CAT, GPx, SOD1, and SOD2 and their activities in rat cardiomyocytes in infrasound exposure groups were significantly decreased compared to those in the various time controls, along with significantly higher levels of O2 (-) and H2O2. Decreased cardiac cell viability was not observed in various time controls. A significant reduction in cardiac cell viability was observed in the infrasound group compared to the control, while significantly increased cardiac cell viability was observed in the infrasound exposure and rosiglitazone pretreatment group. Compared to the control, rosiglitazone significantly upregulated CAT, GPx, SOD1, and SOD2 expression and their activities in rat cardiomyocytes exposed to infrasound, while the levels of O2 (-) or H2O2 were significantly decreased. A potential link between a significant downregulation of PPAR-γ expression in rat cardiomyocytes in the infrasound group was compared to the control and infrasound-induced oxidative stress. These findings indicate that infrasound can induce oxidative damage in rat cardiomyocytes by inactivating PPAR-γ. PMID:23632742

  20. Source and Propagation Characteristics of Explosive and Other Seismic Sources

    SciTech Connect

    Ni, X; Chan, W; Wagner, R; Walter, W R; Matzel, E M

    2005-07-14

    Understanding of the source and propagation characteristics of seismic events of different types including earthquakes, explosions and mining-induced events is essential for successful discrimination of nuclear explosions. We are compiling a data set of mining related seismic events in east Eurasia. Natural earthquake data in the same region are also collected for comparison study between mining related events and earthquakes. The ground-truth data set will provide a unique and valuable resource for monitoring research. We will utilize the data set to investigate the source and propagation characteristics of seismic sources of different types including mine blasts, tremors, collapses and earthquakes. We will use various seismological techniques including spectral analysis, and waveform modeling to conduct the investigation. The research will improve our understanding of the S-wave excitation and propagation characteristics of chemical explosions and other source types.

  1. Long period seismicity and very long period infrasound driven by shallow magmatic degassing at Mount Pagan, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Lyons, John J.; Haney, Matthew M.; Werner, Cynthia; Kelly, Peter; Patrick, Matthew; Kern, Christoph; Trusdell, Frank

    2016-01-01

    Long period (LP) seismicity and very long period infrasound (iVLP) were recorded during continuous degassing from Mount Pagan, Mariana Islands, in July 2013 to January 2014. The frequency content of the LP and iVLP events and delay times between the two arrivals were remarkably stable and indicate nearly co-located sources. Using phase-weighted stacking over similar events to dampen noise, we find that the LP source centroid is located 60 m below and 180 m west of the summit vent. The moment tensor reveals a volumetric source modeled as resonance of a subhorizontal sill intersecting a dike. We model the seismoacoustic wavefields with a coupled earth-air 3-D finite difference code. The ratios of pressure to velocity measured at the infrasound arrays are an order of magnitude larger than the synthetic ratios, so the iVLP is not the result of LP energy transmitting into the atmosphere at its epicenter. Based on crater shape and dimensions determined by structure from motion, we model the iVLP as acoustic resonance of an exponential horn. The source of the continuous plume from gas analysis is shallow magmatic degassing, which repeatedly pressurized the dike-sill portion of the conduit over the 7 months of observation. Periodic gas release caused the geologically controlled sill to partially collapse and resonate, while venting of gas at the surface triggered resonance in the crater. LP degassing only accounts for ~12% of total degassing, indicating that most degassing is relatively aseismic and that multiple active pathways exist beneath the vent.

  2. Tropical cyclone waves detected with infrasound sensor array

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-02-01

    The strong winds of a tropical cyclone whip up the sea surface, driving ocean waves a dozen meters high. When one such ocean wave runs into another wave that has an equal period but is traveling in the opposite direction, the interaction produces low-frequency sound waves that can be detected thousands of kilometers away. The infrasound signals produced by interacting ocean surface waves—known as microbarom—have typical frequencies around 0.2 hertz. Researchers previously determined that as a hurricane travels along its track, early waves generated by the storm will interact with those generated later on, producing a strong microbarom signal in the storm's wake. Researchers also found, however, that microbarom signals are produced by regular surface ocean behavior, including swell, surface waves, and nontropical cyclone storms.

  3. The correction of infrasound signals for upper atmospheric winds

    SciTech Connect

    Mutschlecner, J.P.; Whitaker, R.W.

    1990-01-01

    Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. It is our purpose to obtain a method for the correction of this effect.

  4. Characterisation of wind farm infrasound and low-frequency noise

    NASA Astrophysics Data System (ADS)

    Zajamšek, Branko; Hansen, Kristy L.; Doolan, Con J.; Hansen, Colin H.

    2016-05-01

    This paper seeks to characterise infrasound and low-frequency noise (ILFN) from a wind farm, which contains distinct tonal components with distinguishable blade-pass frequency and higher harmonics. Acoustic measurements were conducted at dwellings in the vicinity of the wind farm and meteorological measurements were taken at the wind farm location and dwellings. Wind farm ILFN was measured frequently under stable and very stable atmospheric conditions and was also found to be dependent on the time of year. For noise character assessment, wind farm ILFN was compared with several hearing thresholds and also with the spectra obtained when the wind farm was not operating. Wind farm ILFN was found to exceed the audibility threshold at distances up to 4 km from the wind farm and to undergo large variations in magnitude with time.

  5. Impact of gravity waves on long-range infrasound propagation

    NASA Astrophysics Data System (ADS)

    Millet, Christophe; Lott, François; De La Camara, Alvaro

    2016-04-01

    In this work we study infrasound propagation in acoustic waveguides that support a finite number of propagating modes. We analyze the effects of gravity waves on these acoustic waveguides. Testing sound propagation in such perturbed fields can potentially be used to improve the gravity wave models. A linear solution modeling the interaction between an incoming acoustic wave and a randomly perturbed atmosphere is developed, using the forward-scattering approximation. The wave mode structure is determined by the effective sound speed profile which is strongly affected by gravity wave breaking. The random perturbations are described by a stochastic field predicted by a multiwave stochastic parameterization of gravity waves, which is operational in the LMDz climate model. The justification for this approach is two fold. On the one hand, the use of a few monochromatic waves mimics the observations of rather narrow-banded gravity wave packets in the lower stratosphere. On the other hand, the stochastic sampling of the gravity wave field and the random choice of wave properties deals with the inherent unpredictability of mesoscale dynamics from large scale conditions provided by the meteorological reanalysis. The transmitted acoustic signals contain a stable front and a small-amplitude incoherent coda. A general expression for the stable front is derived in terms of saddle-point contributions. The saddle-points are obtained from a WKB approximation of the vertical eigenvalue problem. This approach extract the dominant effects in the acoustic - gravity wave interaction. We present results that show how statistics of the transmitted signal are related to a few saddle-points and how the GW field can trigger large deviations in the acoustic signals. While some of the characteristics of the stable front can be directly related to that of a few individual gravity waves, it is shown that the amount of the launched gravity waves included in climate models can be estimated using

  6. Recording of remote ground explosions in the Barents Region by the Seismic &Infrasound Integrated Array "Apatity"

    NASA Astrophysics Data System (ADS)

    Vinogradov, Y.; Vinogradov, A.

    2003-04-01

    velocities (apparent velocities) range between 330-400 m/s, with the lowest values for the Iw phases and the highest values for the It phases. Seismic signals from the explosion were very low, and only P-waves were recorded. In contrary to the infrasound data the seismic ones were insufficient for a correct location of source, but allowed to determinate the origin time of explosion. We should note that a detection of infrasonic phases is very dependent on background atmospheric conditions, and that such phases are usually observed only during relatively quiet wind conditions. Our future plans include the installation of additional wind-noise-reducing pipe array to improve the delectability during windy conditions. After the projected infrasonic array in Karasjok, northern Norway, is installed, we plan to carry out joint processing of data from these two arrays in co-operation with NORSAR, Norway.

  7. Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory's Source Region Program

    SciTech Connect

    Whitaker, R.W.; Noel, S.D.

    1992-12-01

    The summary report by Tom Weaver gives the overall background for the series of IVE (Integrated Verification Experiment) experiments including information on the full set of measurements made. This appendix presents details of the infrasound data for the and discusses certain aspects of a few special experiments. Prior to FY90, the emphasis of the Infrasound Program was on underground nuclear test (UGT) detection and yield estimation. During this time the Infrasound Program was a separate program at Los Alamos, and it was suggested to DOE/OAC that a regional infrasound network be established around NTS. The IVE experiments took place in a time frame that allowed simultaneous testing of possible network sites and examination of propagation in different directions. Whenever possible, infrasound stations were combined with seismic stations so that a large number could be efficiently fielded. The regional infrasound network was not pursued by DOE, as world events began to change the direction of verification toward non-proliferation. Starting in FY90 the infrasound activity became part of the Source Region Program which has a goal of understanding how energy is transported from the UGT to a variety of measurement locations.

  8. Glial cell-expressed mechanosensitive channel TRPV4 mediates infrasound-induced neuronal impairment.

    PubMed

    Shi, Ming; Du, Fang; Liu, Yang; Li, Li; Cai, Jing; Zhang, Guo-Feng; Xu, Xiao-Fei; Lin, Tian; Cheng, Hao-Ran; Liu, Xue-Dong; Xiong, Li-Ze; Zhao, Gang

    2013-11-01

    Vibroacoustic disease, a progressive and systemic disease, mainly involving the central nervous system, is caused by excessive exposure to low-frequency but high-intensity noise generated by various heavy transportations and machineries. Infrasound is a type of low-frequency noise. Our previous studies demonstrated that infrasound at a certain intensity caused neuronal injury in rats but the underlying mechanism(s) is still largely unknown. Here, we showed that glial cell-expressed TRPV4, a Ca(2+)-permeable mechanosensitive channel, mediated infrasound-induced neuronal injury. Among different frequencies and intensities, infrasound at 16 Hz and 130 dB impaired rat learning and memory abilities most severely after 7-14 days exposure, a time during which a prominent loss of hippocampal CA1 neurons was evident. Infrasound also induced significant astrocytic and microglial activation in hippocampal regions following 1- to 7-day exposure, prior to neuronal apoptosis. Moreover, pharmacological inhibition of glial activation in vivo protected against neuronal apoptosis. In vitro, activated glial cell-released proinflammatory cytokines IL-1β and TNF-α were found to be key factors for this neuronal apoptosis. Importantly, infrasound induced an increase in the expression level of TRPV4 both in vivo and in vitro. Knockdown of TRPV4 expression by siRNA or pharmacological inhibition of TRPV4 in cultured glial cells decreased the levels of IL-1β and TNF-α, attenuated neuronal apoptosis, and reduced TRPV4-mediated Ca(2+) influx and NF-κB nuclear translocation. Finally, using various antagonists we revealed that calmodulin and protein kinase C signaling pathways were involved in TRPV4-triggered NF-κB activation. Thus, our results provide the first evidence that glial cell-expressed TRPV4 is a potential key factor responsible for infrasound-induced neuronal impairment. PMID:24002225

  9. The 2013 Chelyabinsk meteorite: global detection performance of the CTBTO infrasound network

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Ceranna, Lars; Le Pichon, Alexis; Mialle, Pierrick; Garces, Milton

    2014-05-01

    The explosive fragmentation of the Chelyabinsk meteorite of 15 February 2013 over the Ural Mountains, Russia, generated a large airburst with an equivalent explosive yield of half a megaton of TNT. It is the most energetic event recorded by the infrasound component of the International Monitoring System (IMS) network operated by the Comprehensive Nuclear-Test-Ban Treaty Organization. The event was detected by 20 out of 45 stations of the operational IMS network and propagation paths from the event to the stations ranged between 500 km and 87000 km, traveling more than twice around the globe. The current study in the framework of the ARISE project (http://arise-project.eu/) performs a detailed station-by-station estimation to address why infrasonic signals were clearly detected at some of the stations over very large distances whereas they were not detected at other stations at shorter distances. One potential explanation investigated within this study is the directivity of the signal energy radiated from the meteorite's line source, where azimuth directions at stations perpendicular to the trajectory are favored compared to parallel directions. Another explanation might be different noise and data quality levels at each station, which not only depend on frequency and sensor response, but also on diurnal, seasonal and weather variability. The presentation will provide a station-dependent overview on these parameters compared to the detections of the meteorite event.

  10. Infrasound and seismic signals from Baikonur spaceport rocket launches recorded by Kazakh stations

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexandr; Sokolova, Inna; Mikhailova, Natalya

    2015-04-01

    The monitoring network of the Institute of Geophysical Researches, Kazakhstan consists of 2 infrasound arrays, 8 seismic arrays and 7 3C stations. 5 of these stations are a part of IMS CTBTO. The Institute of Geophysical Researches monitors round-the-clock many sorts of seismoacoustic events. Tens of rockets are launched every year from Baikonur spaceport located in Central Kazakhstan. Baikonur rockets fly over several regions of Kazakhstan. Kazakh monitoring stations record launches, rocket stage falls, satellite recovery and sometimes accidents. A catalog of events associated with such activity is built. Some waveform features are collected. The catalog also contains some kinematic and dynamic parameters of the events sources. The signals from accidents of Dnepr rocket of July 26, 2006 and Proton rocket of September 5, 2007 and of July 2, 2013 were studied in details. Discrimination of the events associated with spaceport activity and its exclusion from seismic bulletins allows improving the bulletins quality. And in case of accident this information helps to estimate the event parameters and to start recovery procedures in proper time.

  11. Estimation Source Parameters of Large-Scale Chemical Surface Explosions and Recent Underground Nuclear Tests

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Kim, S.; Hofstetter, R.

    2013-12-01

    spectra of teleseismic P-waves. For a ground-truth explosion with a shallow source depth (relatively to an earthquake), this phenomenon can be interpreted in terms of the interference between the down-going P-wave energy and the pP phase reflected from the Earth's surface. A similar effect was observed before at ISN stations for the Pakistan explosion (28.05.98) at a different frequency 1.7 Hz indicating the source- and not site-effect. Based on the null frequency dependency on the near-surface acoustic velocity and the source depth, the depth of the both North Korea tests was estimated ~2 km, different from the value ~1 km informed by USGS. This depth estimation is based only on several closely placed teleseismic ISN stations and should be verified at other local networks on similar directions and distances from the test site.

  12. Infrasound from lightning measured in Ivory Coast from 2004 to 2014

    NASA Astrophysics Data System (ADS)

    Farges, Thomas; Le Pichon, Alexis; Ceranna, Lars; Diawara, Adama

    2016-04-01

    It is well established that more than 2,000 thunderstorms occur continuously around the world and that about 45 lightning flashes are produced per second over the globe. 80 % of the infrasound stations of the International Monitoring System (IMS) of the CTBTO (Comprehensive nuclear Test Ban Treaty Organisation) are now certified and routinely measure signals due to natural activity (e.g., airflow over mountains, aurora, microbaroms, surf, volcanoes, severe weather including lightning flashes …). Some of the IMS stations are located where lightning activity is high (e.g. Africa, South America). These infrasound stations are well localised to study lightning flash activity and its disparity, which is a good proxy for global warming. Progress in infrasound array data processing over the past ten years makes such lightning studies possible. Assink et al. (2008) and Farges and Blanc (2010) show clearly that it is possible to measure lightning infrasound from thunderstorms within 300 km. One-to-one correlation is possible when the thunderstorm is within about 75 km from the station. When the lightning flash occurs within 20 km, it is also possible to rebuild the 3D geometry of the discharges when the network size is less than 100 m (Arechiga et al., 2011; Gallin, 2014). An IMS infrasound station has been installed in Ivory Coast since 2002. The lightning rate of this region is 10-20 flashes/km²/year from space-based instrument OTD (Christian et al., 2003). Ivory Coast is therefore a good place to study infrasound data associated with lightning activity and its temporal variation. First statistical results will be presented in this paper based on 10 years of data (2005-2014). Correlation between infrasound having a mean frequency higher than 1 Hz and lightning flashes detected by the World Wide Lightning Location Network (WWLLN) is systematically looked for. One-to-one correlation is obtained for flashes occurring within about 100 km. An exponential decrease of the

  13. Merging Infrasound and Electromagnetic Signals as a Means for Nuclear Explosion Detection

    NASA Astrophysics Data System (ADS)

    Ashkenazy, Joseph; Lipshtat, Azi; Kesar, Amit S.; Pistinner, Shlomo; Ben Horin, Yochai

    2016-04-01

    The infrasound monitoring network of the CTBT consists of 60 stations. These stations are capable of detecting atmospheric events, and may provide approximate location within time scale of a few hours. However, the nature of these events cannot be deduced from the infrasound signal. More than two decades ago it was proposed to use the electromagnetic pulse (EMP) as a means of discriminating nuclear explosion from other atmospheric events. An EMP is a unique signature of nuclear explosion and is not detected from chemical ones. Nevertheless, it was decided to exclude the EMP technology from the official CTBT verification regime, mainly because of the risk of high false alarm rate, due to lightning electromagnetic pulses [1]. Here we present a method of integrating the information retrieved from the infrasound system with the EMP signal which enables us to discriminate between lightning discharges and nuclear explosions. Furthermore, we show how spectral and other characteristics of the electromagnetic signal emitted from a nuclear explosion are distinguished from those of lightning discharge. We estimate the false alarm probability of detecting a lightning discharge from a given area of the infrasound event, and identifying it as a signature of a nuclear explosion. We show that this probability is very low and conclude that the combination of infrasound monitoring and EMP spectral analysis may produce a reliable method for identifying nuclear explosions. [1] R. Johnson, Unfinished Business: The Negotiation of the CTBT and the End of Nuclear Testing, United Nations Institute for Disarmament Research, 2009.

  14. Monitoring volcanic activity using correlation patterns between infrasound and ground motion

    NASA Astrophysics Data System (ADS)

    Ichihara, M.; Takeo, M.; Yokoo, A.; Oikawa, J.; Ohminato, T.

    2012-02-01

    This paper presents a simple method to distinguish infrasonic signals from wind noise using a cross-correlation function of signals from a microphone and a collocated seismometer. The method makes use of a particular feature of the cross-correlation function of vertical ground motion generated by infrasound, and the infrasound itself. Contribution of wind noise to the correlation function is effectively suppressed by separating the microphone and the seismometer by several meters because the correlation length of wind noise is much shorter than wavelengths of infrasound. The method is applied to data from two recent eruptions of Asama and Shinmoe-dake volcanoes, Japan, and demonstrates that the method effectively detects not only the main eruptions, but also minor activity generating weak infrasound hardly visible in the wave traces. In addition, the correlation function gives more information about volcanic activity than infrasound alone, because it reflects both features of incident infrasonic and seismic waves. Therefore, a graphical presentation of temporal variation in the cross-correlation function enables one to see qualitative changes of eruptive activity at a glance. This method is particularly useful when available sensors are limited, and will extend the utility of a single microphone and seismometer in monitoring volcanic activity.

  15. Detection of Gravity Waves and Infrasound Signals at the USArray

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine; Hedlin, Michael

    2015-04-01

    The USArray Transportable Array (TA) is a 400-station network that has been deployed in the continental United States since 2004. The network, which at its height spanned 2,000,000 km2, has gradually moved east across the country via station re-deployments. Although originally conceived as a seismic-only network, a suite of atmospheric pressure sensors added to each station starting in early 2010 allows for enhanced observations of pressure variations at the Earth's surface associated with infrasound and other atmospheric phenomena. We present novel techniques that make use of the close spacing of stations within the TA to detect and track the progress of pressure disturbances across the network. The method has been applied to the detection of both atmospheric gravity waves having periods from 40 minutes to 8 hours, and 1-3 Hz infrasound energy generated by meteoroids. The TA is sufficiently dense that gravity waves with wavelengths from tens to hundreds of kilometers are coherent between neighboring stations, but is too large for coherence across the entire network. To examine the characteristics of gravity waves propagating across the network, the TA is divided into a large number of elemental, triangular, sub-arrays consisting of three neighboring stations. Coherent analysis of the data at each triad provides a robust estimate of the signal's direction and speed. The results from all triads are combined to follow the progress of a gravity wave as it propagates across the TA. This method allows for observation of fine-scale variations in the speed, direction and amplitude of long period signals across the TA, as well as the statistics of these waves. The method has been applied to TA data collected over the eastern half of the continental United States over a 5-year timespan beginning on January 1, 2010. The network has detected particularly large and long-lived gravity waves such as from a tornadic storm system in the American south in April, 2011. In addition

  16. Infrasound Generated by Strombolian Eruptions - Insights from Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Dabrowa, A.; Phillips, J. C.; Rust, A.; Green, D. N.

    2010-12-01

    In recent years infrasonic monitoring at volcanoes has become an increasingly common tool. Much of the current work on interpreting volcano infrasound has concentrated on Strombolian eruptions, and several mechanisms have been suggested for the sound produced at these eruptions. However, the precise mechanisms at the vent need to be identified and understood if infrasound recorded in the field is to be used to infer conditions in the volcanic system. In this work, laboratory experiments using audio recordings coupled with high speed video footage have been conducted to gain a deeper understanding of these sounds. A simplified analogue model is used as an analogy for a Strombolian eruption: an air bubble rises through a tank containing a viscous Newtonian liquid (golden syrup) and bursts at the surface. Although the experimental set-up is simple and idealized, it allows control of physical properties and measurement of the processes observed far more accurately than would be possible in the field. Physical parameters which may control the form of the acoustic wave produced, such as liquid viscosity (achieved by dilution of pure golden syrup with water) and bubble volume are investigated. Initial results show that the onset of the main part of the acoustic waveform occurs concurrently with the onset of bubble rupture. Trends in the amplitude and frequency of the acoustic waveform, as well as bubble rupture speed are seen as the liquid viscosity varied. A number of candidate mechanisms for the production of sound during the experiments have been investigated, and synthetic waveforms compared to experimental data. These include the flow of gas through a growing hole from a pressurised reservoir (the bubble), and the mass flux due to the collapse of the bubble film. Importantly it has been shown that even in this very simple case - the sound produced by the bursting of a hemispherical bubble formed at the surface of a viscous liquid - is not as simple as some theories

  17. Integrated Verification Experiment data collected as part of the Los Alamos National Laboratory`s Source Region Program. Appendix C, Infrasonic measurements of IVE events: Los Alamos Source Region Program

    SciTech Connect

    Whitaker, R.W.; Noel, S.D.

    1992-12-01

    The summary report by Tom Weaver gives the overall background for the series of IVE (Integrated Verification Experiment) experiments including information on the full set of measurements made. This appendix presents details of the infrasound data for the and discusses certain aspects of a few special experiments. Prior to FY90, the emphasis of the Infrasound Program was on underground nuclear test (UGT) detection and yield estimation. During this time the Infrasound Program was a separate program at Los Alamos, and it was suggested to DOE/OAC that a regional infrasound network be established around NTS. The IVE experiments took place in a time frame that allowed simultaneous testing of possible network sites and examination of propagation in different directions. Whenever possible, infrasound stations were combined with seismic stations so that a large number could be efficiently fielded. The regional infrasound network was not pursued by DOE, as world events began to change the direction of verification toward non-proliferation. Starting in FY90 the infrasound activity became part of the Source Region Program which has a goal of understanding how energy is transported from the UGT to a variety of measurement locations.

  18. The 2013 Russian fireball largest ever detected by CTBTO infrasound sensors

    NASA Astrophysics Data System (ADS)

    Le Pichon, Alexis; Ceranna, Lars; Pilger, Christoph; Mialle, Pierrick; Brown, David; Herry, Pascal; Brachet, Nicolas

    2013-07-01

    15 February 2013, a large Earth-impacting fireball disintegrated over the Ural Mountains. This extraordinary event is, together with the 1908 Tunguska fireball, among the most energetic events ever instrumentally recorded. It generated infrasound returns, after circling the globe, at distances up to ~85,000 km, and was detected at 20 infrasonic stations of the global International Monitoring System (IMS). For the first time since the establishment of the IMS infrasound network, multiple arrivals involving waves that traveled twice round the globe have been clearly identified. A preliminary estimate of the explosive energy using empirical period-yield scaling relations gives a value of 460 kt of TNT equivalent. In the context of the future verification of the Comprehensive Nuclear-Test-Ban Treaty, this event provides a prominent milestone for studying in detail infrasound propagation around the globe for almost 3 days as well as for calibrating the performance of the IMS network.

  19. Test report for the infrasound prototype: For a CTBT IMS station

    SciTech Connect

    Breding, D.R.; Kromer, R.P.; Whitaker, R.W.; Sandoval, T.

    1997-11-01

    This document describes the results of the Comprehensive Test Ban Treaty (CTBT) Infrasound Prototype Development Test and Evaluation (DT&E). During DT&E the infrasound prototype was evaluated against requirements listed in the System Requirements Document (SRD) based on the Conference on Disarmament/Ad Hoc Committee on a Nuclear Test Ban/Working Papers 224 and 283 and the Preparatory Commission specifications as defined in CTBT/PC/II/1/Add.2, Appendix X, Table 5. The evaluation was conducted during a two-day period, August 6-7, 18997. The System Test Plan (STP) defined the plan and methods to test the infrasound prototype. Specific tests that were performed are detailed in the Test Procedures (TP).

  20. The correction of infrasound signals for upper atmospheric winds

    NASA Technical Reports Server (NTRS)

    Mutschlecner, J. Paul; Whitaker, Rodney W.

    1990-01-01

    Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. A figure illustrates this phenomenon with results from a ray trace model. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. Another figure illustrates the considerable ray differences for rays moving in the wind direction (to the right) and in the counter direction (to the left). It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. A third figure illustrates this with average statistics on the observed zonal wind in the region of 50 plus or minus 5 kilometers in altitude. The results are based upon a survey by Webb; Webb terms this parameterization the Stratospheric Circulation Index (SCI). The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. The purpose here is to obtain a method for the correction of this effect.

  1. Design of infrasound-detection system via adaptive LMSTDE algorithm

    NASA Technical Reports Server (NTRS)

    Khalaf, C. S.; Stoughton, J. W.

    1984-01-01

    A proposed solution to an aviation safety problem is based on passive detection of turbulent weather phenomena through their infrasonic emission. This thesis describes a system design that is adequate for detection and bearing evaluation of infrasounds. An array of four sensors, with the appropriate hardware, is used for the detection part. Bearing evaluation is based on estimates of time delays between sensor outputs. The generalized cross correlation (GCC), as the conventional time-delay estimation (TDE) method, is first reviewed. An adaptive TDE approach, using the least mean square (LMS) algorithm, is then discussed. A comparison between the two techniques is made and the advantages of the adaptive approach are listed. The behavior of the GCC, as a Roth processor, is examined for the anticipated signals. It is shown that the Roth processor has the desired effect of sharpening the peak of the correlation function. It is also shown that the LMSTDE technique is an equivalent implementation of the Roth processor in the time domain. A LMSTDE lead-lag model, with a variable stability coefficient and a convergence criterion, is designed.

  2. The role of infrasounds in maintaining whale herds

    NASA Astrophysics Data System (ADS)

    Payne, Roger S.

    2001-05-01

    For whales and dolphins a basic social unit is the herd. In several species, herds have been observed to maintain the same speed, direction, and membership overnight, and while swimming in waters of near-zero visibility-evidence that individuals can stay together using nonvisual cues. The most likely such cue is sound. If whale herds are held together with sound, yet we define herds as groups of whales seen moving together, then we are using visual criteria to judge what is an acoustic phenomenon, and our conclusions about a most basic unit of cetacean social structure, the herd, are at least incomplete, and, quite possibly, worthless. By calling herds, heards, we remind ourselves that sound controls herd size. We then consider that some whale infrasound can propagate across deep water at useful intensities (even in today's ship-noise-polluted ocean) for thousands of kilometers. The distance to which blue and fin whale sounds propagate before falling below background noise is given, and the possible advantages these whales obtain from such sounds is explored. The conclusion is that by sharing information on food finds infrasonically, fin and blue whales may have developed a way to divide up the food resources of an entire ocean.

  3. Infrasound observation of seismic events occurring in North Korea

    NASA Astrophysics Data System (ADS)

    Park, Y.; Che, I.; Nam, S.; Kim, Y.; Lee, J.

    2012-12-01

    Seismic events of North Korea were analyzed by using data set from the regional network including 31 seismic stations and 5 seismo-acoustic arrays of Korea Institute of Geoscience and Mineral Resources(KIGAM) and 7 Korea-China joint seismic stations in China. Infrasonic data were analysed using the PMCC method, to detect blast-associated infrasonic signals. Phase velocity and back-azimuth of infrasound signals varied between 250 to 400 m/s and ±10° respectively. Seismo-acoustic analysis was conducted to discriminate 375 events which are 38.1 percent of the total seismic events. More than 60 percent of seismo-acoustic events occurred around the Pyeongyang and Wonsan area of North Korea. In the case of the events occurred in the southeastern part of North Korea, the percentage was relatively small. The seismo-acoustic location were improved by using grid-search method. This method was based the observed travel times and azimuths of infrasonic signals and seismic parameter.

  4. Remote and Ground Truth Spectral Measurement Comparisons of FORMOSAT III

    NASA Technical Reports Server (NTRS)

    Abercromby, Kira Jorgensen; Hamada, Kris; Guyote, Michael; Okada, Jennifer; Barker, Edwin

    2007-01-01

    FORMOSAT III are a set of six research satellites from Taiwan that were launched in April 2006. The satellites are in 800 km, 71 degree inclination orbits and separated by 24 degrees in ascending node. Laboratory spectral measurements were taken of outer surface materials on FORMOSAT III. From those measurements, a computer model was built to predict the spectral reflectance accounting for both solar phase angle and orientation of the spacecraft relative to the observer. However, materials exposed to the space environment have exhibited spectral changes including a darkening and a "reddening" of the spectra. This "reddening" is characterized by an increase in slope of the reflectance as the wavelength increases. Therefore, the model of pre-flight materials was augmented to include the presumed causative agent: space weathering effects. Remote data were collected on two of the six FORMOSAT satellites using the 1.6 meter telescope at the AMOS (Air Force Maui Optical and Supercomputing) site with the Spica spectrometer. Due to the separation in ascending node, observations were acquired of whichever one of the six satellites was visible on that specific night. Three nights of data were collected using the red (6000 - 9500 angstroms) filter and five nights of data were collected using the blue (3200 - 6600 angstroms) filter. A comparison of the data showed a good match to the pre-flight models for the blue filter region. The absorption feature near 5500 angstroms due to the copper colored Kapton multi-layer insulation (MLI) was very apparent in the remote samples and a good fit to the data was seen in all satellites observed. The features in the red filter regime agreed with the pre-flight model up through 7000 angstroms where the reddening begins and the slope of the remote sample increases. A comparison of the satellites showed similar features in the red and blue filter regions, i.e. the satellite surfaces were aging at the same rate. A comparison of the pre-flight model to the first month of remote measurements showed the amount by which the satellite had reddened. The second month of data observed a satellite at a higher altitude and was therefore, not compared to the first month. A third month of data was collected but of satellites at the lower altitude regime and can only be compared to the first month. One cause of the reddening that was ruled out in early papers was a possible calibration issue.

  5. GUIDE TO PRESELECTION OF TRAINING SAMPLES AND GROUND TRUTH COLLECTION

    EPA Science Inventory

    This report was prepared to provide the novice data processing analyst and field personnel with the tools and basic concepts used in the processing of multispectral scanner data via an interactive or conventional processing system. Included in the guide is an explanation of the n...

  6. Ground-truthing AVIRIS mineral mapping at Cuprite, Nevada

    NASA Technical Reports Server (NTRS)

    Swayze, Gregg; Clark, Roger N.; Kruse, Fred; Sutley, Steve; Gallagher, Andrea

    1992-01-01

    Mineral abundance maps of 18 minerals were made of the Cuprite Mining District using 1990 AVIRIS data and the Multiple Spectral Feature Mapping Algorithm (MSFMA) as discussed in Clark et al. This technique uses least-squares fitting between a scaled laboratory reference spectrum and ground calibrated AVIRIS data for each pixel. Multiple spectral features can be fitted for each mineral and an unlimited number of minerals can be mapped simultaneously. Quality of fit and depth from continuum numbers for each mineral are calculated for each pixel and the results displayed as a multicolor image.

  7. LRO Diviner Soil Composition Measurements - Lunar Sample Ground Truth

    NASA Technical Reports Server (NTRS)

    Allen, Carlton C.; Greenhagen, Benjamin T.; Paige, David A.

    2010-01-01

    The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter [1,2] includes three thermal infrared channels spanning the wavelength ranges 7.55-8.05 microns 8.10-8.40 microns, and 8.38-8.68 microns. These "8 micron" bands were specifically selected to measure the "Christiansen feature". The wavelength location of this feature, referred to herein as CF, is particularly sensitive to silicate minerals including plagioclase, pyroxene, and olivine the major crystalline components of lunar rocks and soil. The general trend is that lower CF values are correlated with higher silica content and higher CF values are correlated with lower silica content. In a companion abstract, Greenhagen et al. [3] discuss the details of lunar mineral identification using Diviner data.

  8. Crowd-sourced annotation of ecg signals using contextual information.

    PubMed

    Zhu, Tingting; Johnson, Alistair E W; Behar, Joachim; Clifford, Gari D

    2014-04-01

    For medical applications, the ground truth is ascertained through manual labels by clinical experts. However, significant inter-observer variability and various human biases limit accuracy. A probabilistic framework addresses these issues by comparing aggregated human and automated labels to provide a reliable ground truth, with no prior knowledge of the individual performance. As an alternative to median or mean voting strategies, novel contextual features (signal quality and physiology) were introduced to allow the Probabilistic Label Aggregator (PLA) to weight an algorithm or human based on its performance. As a proof of concept, the PLA was applied to QT interval (pro-arrhythmic indicator) estimation from the electrocardiogram using labels from 20 humans and 48 algorithms crowd-sourced from the 2006 PhysioNet/Computing in Cardiology Challenge database. For automatic annotations, the root mean square error of the PLA was 13.97 ± 0.46 ms, significantly outperforming the best Challenge entry (16.36 ms) as well as mean and median voting strategies (17.67 ± 0.56 ms and 14.44 ± 0.52 ms respectively with p < 0.05). When selecting three annotators, the PLA improved the annotation accuracy over median aggregation by 10.7% for human annotators and 14.4% for automated algorithms. The PLA could therefore provide an improved "gold standard" for medical annotation tasks even when ground truth is not available. PMID:24368593

  9. The assessment and evaluation of low-frequency noise near the region of infrasound.

    PubMed

    Ziaran, Stanislav

    2014-01-01

    The main aim of this paper is to present recent knowledge about the assessment and evaluation of low-frequency sounds (noise) and infrasound, close to the threshold of hearing, and identify their potential effect on human health and annoyance. Low-frequency noise generated by air flowing over a moving car with an open window was chosen as a typical scenario which can be subjectively assessed by people traveling by automobile. The principle of noise generated within the interior of the car and its effects on the comfort of the driver and passengers are analyzed at different velocities. An open window of a car at high velocity behaves as a source of specifically strong tonal low-frequency noise which is generally perceived as annoying. The interior noise generated by an open window of a passenger car was measured under different conditions: Driving on a highway and driving on a typical roadway. First, an octave-band analysis was used to assess the noise level and its impact on the driver's comfort. Second, a fast Fourier transform (FFT) analysis and one-third octave-band analysis were used for the detection of tonal low-frequency noise. Comparison between two different car makers was also done. Finally, the paper suggests some possibilities for scientifically assessing and evaluating low-frequency sounds in general, and some recommendations are introduced for scientific discussion, since sounds with strong low-frequency content (but not only strong) engender greater annoyance than is predicted by an A-weighted sound pressure level. PMID:24583675

  10. Evaluation of infrasound signals from the shuttle Atlantis using a large seismic network.

    PubMed

    de Groot-Hedlin, Catherine D; Hedlin, Michael A H; Walker, Kristoffer T; Drob, Douglas P; Zumberge, Mark A

    2008-09-01

    Inclement weather in Florida forced the space shuttle "Atlantis" to land at Edwards Air Force Base in southern California on June 22, 2007, passing near three infrasound stations and several hundred seismic stations in northern Mexico, southern California, and Nevada. The high signal-to-noise ratio, broad receiver coverage, and Atlantis' positional information allow for the testing of infrasound propagation modeling capabilities through the atmosphere to regional distances. Shadow zones and arrival times are predicted by tracing rays that are launched at right angles to the conical shock front surrounding the shuttle through a standard climatological model as well as a global ground to space model. The predictions and observations compare favorably over much of the study area for both atmospheric specifications. To the east of the shuttle trajectory, there were no detections beyond the primary acoustic carpet. Infrasound energy was detected hundreds of kilometers to the west and northwest (NW) of the shuttle trajectory, consistent with the predictions of ducting due to the westward summer-time stratospheric jet. Both atmospheric models predict alternating regions of high and low ensonifications to the NW. However, infrasound energy was detected tens of kilometers beyond the predicted zones of ensonification, possibly due to uncertainties in stratospheric wind speeds. PMID:19045636

  11. A Framework for Real-Time Collection, Analysis, and Classification of Ubiquitous Infrasound Data

    NASA Astrophysics Data System (ADS)

    Christe, A.; Garces, M. A.; Magana-Zook, S. A.; Schnurr, J. M.

    2015-12-01

    Traditional infrasound arrays are generally expensive to install and maintain. There are ~10^3 infrasound channels on Earth today. The amount of data currently provided by legacy architectures can be processed on a modest server. However, the growing availability of low-cost, ubiquitous, and dense infrasonic sensor networks presents a substantial increase in the volume, velocity, and variety of data flow. Initial data from a prototype ubiquitous global infrasound network is already pushing the boundaries of traditional research server and communication systems, in particular when serving data products over heterogeneous, international network topologies. We present a scalable, cloud-based approach for capturing and analyzing large amounts of dense infrasonic data (>10^6 channels). We utilize Akka actors with WebSockets to maintain data connections with infrasound sensors. Apache Spark provides streaming, batch, machine learning, and graph processing libraries which will permit signature classification, cross-correlation, and other analytics in near real time. This new framework and approach provide significant advantages in scalability and cost.

  12. Infrasound radiated by the Gerdec and Chelopechene explosions: propagation along unexpected paths

    NASA Astrophysics Data System (ADS)

    Green, David N.; Vergoz, Julien; Gibson, Robert; Le Pichon, Alexis; Ceranna, Lars

    2011-05-01

    Infrasound propagation paths through the atmosphere are controlled by the temporally and spatially varying sound speed and wind speed amplitudes. Because of the complexity of atmospheric acoustic propagation it is often difficult to reconcile observed infrasonic arrivals with the sound speed profiles predicted by meteorological specifications. This paper provides analyses of unexpected arrivals recorded in Europe and north Africa from two series of accidental munitions dump explosions, recorded at ranges greater than 1000 km: two explosions at Gerdec, Albania, on 2008 March 15 and four explosions at Chelopechene, Bulgaria, on 2008 July 3. The recorded signal characteristics include multiple pulsed arrivals, celerities between 0.24 and 0.34 km s-1 and some signal frequency content above 1 Hz. Often such characteristics are associated with waves that have propagated within a ground-to-stratosphere waveguide, although the observed celerities extend both above and below the conventional range for stratospheric arrivals. However, state-of-the-art meteorological specifications indicate that either weak, or no, ground-to-stratosphere waveguides are present along the source-to-receiver paths. By incorporating realistic gravity-wave induced horizontal velocity fluctuations into time-domain Parabolic Equation models the pulsed nature of the signals is simulated, and arrival times are predicted to within 30 s of the observed values (<1 per cent of the source-to-receiver transit time). Modelling amplitudes is highly dependent upon estimates of the unknown acoustic source strength (or equivalent chemical explosive yield). Current empirical explosive yield relationships, derived from infrasonic amplitude measurements from point-source chemical explosions, suggest that the equivalent chemical yield of the largest Gerdec explosion was of the order of 1 kt and the largest Chelopechene explosion was of the order of 100 t. When incorporating these assumed yields, the Parabolic

  13. Group Behavioural Responses of Atlantic Salmon (Salmo salar L.) to Light, Infrasound and Sound Stimuli

    PubMed Central

    Bui, Samantha; Oppedal, Frode; Korsøen, Øyvind J.; Sonny, Damien; Dempster, Tim

    2013-01-01

    Understanding species-specific flight behaviours is essential in developing methods of guiding fish spatially, and requires knowledge on how groups of fish respond to aversive stimuli. By harnessing their natural behaviours, the use of physical manipulation or other potentially harmful procedures can be minimised. We examined the reactions of sea-caged groups of 50 salmon (1331±364 g) to short-term exposure to visual or acoustic stimuli. In light experiments, fish were exposed to one of three intensities of blue LED light (high, medium and low) or no light (control). Sound experiments included exposure to infrasound (12 Hz), a surface disturbance event, the combination of infrasound and surface disturbance, or no stimuli. Groups that experienced light, infrasound, and the combination of infrasound and surface disturbance treatments, elicited a marked change in vertical distribution, where fish dived to the bottom of the sea-cage for the duration of the stimulus. Light treatments, but not sound, also reduced the total echo-signal strength (indicative of swim bladder volume) after exposure to light, compared to pre-stimulus levels. Groups in infrasound and combination treatments showed increased swimming activity during stimulus application, with swimming speeds tripled compared to that of controls. In all light and sound treatments, fish returned to their pre-stimulus swimming depths and speeds once exposure had ceased. This work establishes consistent, short-term avoidance responses to these stimuli, and provides a basis for methods to guide fish for aquaculture applications, or create avoidance barriers for conservation purposes. In doing so, we can achieve the manipulation of group position with minimal welfare impacts, to create more sustainable practices. PMID:23691087

  14. Group behavioural responses of Atlantic salmon (Salmo salar L.) to light, infrasound and sound stimuli.

    PubMed

    Bui, Samantha; Oppedal, Frode; Korsøen, Øyvind J; Sonny, Damien; Dempster, Tim

    2013-01-01

    Understanding species-specific flight behaviours is essential in developing methods of guiding fish spatially, and requires knowledge on how groups of fish respond to aversive stimuli. By harnessing their natural behaviours, the use of physical manipulation or other potentially harmful procedures can be minimised. We examined the reactions of sea-caged groups of 50 salmon (1331 ± 364 g) to short-term exposure to visual or acoustic stimuli. In light experiments, fish were exposed to one of three intensities of blue LED light (high, medium and low) or no light (control). Sound experiments included exposure to infrasound (12 Hz), a surface disturbance event, the combination of infrasound and surface disturbance, or no stimuli. Groups that experienced light, infrasound, and the combination of infrasound and surface disturbance treatments, elicited a marked change in vertical distribution, where fish dived to the bottom of the sea-cage for the duration of the stimulus. Light treatments, but not sound, also reduced the total echo-signal strength (indicative of swim bladder volume) after exposure to light, compared to pre-stimulus levels. Groups in infrasound and combination treatments showed increased swimming activity during stimulus application, with swimming speeds tripled compared to that of controls. In all light and sound treatments, fish returned to their pre-stimulus swimming depths and speeds once exposure had ceased. This work establishes consistent, short-term avoidance responses to these stimuli, and provides a basis for methods to guide fish for aquaculture applications, or create avoidance barriers for conservation purposes. In doing so, we can achieve the manipulation of group position with minimal welfare impacts, to create more sustainable practices. PMID:23691087

  15. Infrasound increases intracellular calcium concentration and induces apoptosis in hippocampi of adult rats.

    PubMed

    Liu, Zhaohui; Gong, Li; Li, Xiaofang; Ye, Lin; Wang, Bin; Liu, Jing; Qiu, Jianyong; Jiao, Huiduo; Zhang, Wendong; Chen, Jingzao; Wang, Jiuping

    2012-01-01

    In the present study, we determined the effect of infrasonic exposure on apoptosis and intracellular free Ca²⁺ ([Ca²⁺]i) levels in the hippocampus of adult rats. Adult rats were randomly divided into the control and infrasound exposure groups. For infrasound treatment, animals received infrasonic exposure at 90 (8 Hz) or 130 dB (8 Hz) for 2 h per day. Hippocampi were dissected, and isolated hippocampal neurons were cultured. The [Ca²⁺]i levels in hippocampal neurons from adult rat brains were determined by Fluo-3/AM staining with a confocal microscope system on days 1, 7, 14, 21 and 28 following infrasonic exposure. Apoptosis was evaluated by Annexin V-FITC and propidium iodide double staining. Positive cells were sorted and analyzed by flow cytometry. Elevated [Ca²⁺]i levels were observed on days 14 and 21 after rats received daily treatment with 90 or 130 dB sound pressure level (SPL) infrasonic exposure (p<0.01 vs. control). The highest levels of [Ca²⁺]i were detected in the 130 dB SPL infrasonic exposure group. Meanwhile, apoptosis in hippocampal neurons was found to increase on day 7 following 90 dB SPL infrasound exposure, and significantly increased on day 14. Upon 130 dB infrasound treatment, apoptosis was first observed on day 14, whereas the number of apoptotic cells gradually decreased thereafter. Additionally, a marked correlation between cell apoptosis and [Ca²⁺]i levels was found on day 14 and 21 following daily treatment with 90 and 130 dB SPL, respectively. These results demonstrate that a period of infrasonic exposure induced apoptosis and upregulated [Ca²⁺]i levels in hippocampal neurons, suggesting that infrasound may cause damage to the central nervous system (CNS) through the Ca²⁺‑mediated apoptotic pathway in hippocampal neurons. PMID:21946944

  16. Post-installation activities in the Comprehensive Nuclear Test Ban Treaty (CTBT) International Monitoring System (IMS) infrasound network

    NASA Astrophysics Data System (ADS)

    Vivas Veloso, J. A.; Christie, D. R.; Hoffmann, T. L.; Campus, P.; Bell, M.; Langlois, A.; Martysevich, P.; Demirovik, E.; Carvalho, J.; Kramer, A.; Wu, Sean F.

    2002-11-01

    The provisional operation and maintenance of IMS infrasound stations after installation and subsequent certification has the objective to prepare the infrasound network for entry into force of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The goal is to maintain and fine tune the technical capabilities of the network, to repair faulty equipment, and to ensure that stations continue to meet the minimum specifications through evaluation of data quality and station recalibration. Due to the globally dispersed nature of the network, this program constitutes a significant undertaking that requires careful consideration of possible logistic approaches and their financial implications. Currently, 11 of the 60 IMS infrasound stations are transmitting data in the post-installation Testing & Evaluation mode. Another 5 stations are under provisional operation and are maintained in post-certification mode. It is expected that 20% of the infrasound network will be certified by the end of 2002. This presentation will focus on the different phases of post-installation activities of the IMS infrasound program and the logistical challenges to be tackled to ensure a cost-efficient management of the network. Specific topics will include Testing & Evaluation and Certification of Infrasound Stations, as well as Configuration Management and Network Sustainment.

  17. Infrasound network implementation in Iceland - examples of volcano monitoring in an extreme environment

    NASA Astrophysics Data System (ADS)

    Jónsdóttir, Kristín; Ripepe, Maurizio; Barsotti, Sara; Björnsson, Halldór; Del Donne, Dario; Vogfjörð, Kristín

    2015-04-01

    The installation of a network of infrasound arrays for volcano monitoring has been initiated in Iceland. In collaboration with the University of Florence (UNIFI), The Icelandic Meteorological Office (IMO) has been operating infrasound arrays since the Eyjafjallajökull eruption in 2010. An important support came through the 26 partner FP7 FUTUREVOLC project which runs from 2012 - 2016. This project which is relevant to the EU "Supersite concept" for long term monitoring in geologically active regions of Europe, is led by the University of Iceland together with IMO which leads long-term monitoring of geohazards in Iceland and is responsible for maintaining instrument networks for this purpose. As a part of the ground based FUTUREVOLC network, infrasound arrays, are used to monitor volcanic eruptive activity. The arrays are composed of 4 elements with a triangular geometry and an aperture of 120 m where each element has a differential pressure transducer with a sensitivity of 25 mV/Pa in the frequency band 0.001-50 Hz and a noise level of 10-2 Pa. Infrasound is recorded on site at 100 Hz and 24 bits and transmitted via Internet link both to the IMO and UNIFI. Three arrays are installed in South Iceland, one in Gunnarsholt, one in Þjórsárdalur and one in Kirkjubæjarklaustur. These places were chosen with the aim to optimize wind noice reduction (onsite bushes and trees) and close proximity to volcanoes such as Hekla, Katla, Torfajökull, Eyjafjallajökull, Vestmannaeyjar and the Vatnajökull ice cap which covers four central volcanoes known for explosive eruptions. In September 2014, the fourth array was installed a few km north of Vatnajökull glacier, just north of the large effusive eruption in Holuhraun which started on 29 August 2014 and is still ongoing in January 2015. The eruption is associated with the ongoing Bárðarbunga volcanic unrest and caldera collapse which is being monitored closely by the IMO and FUTUREVOLC partners. The new array has the

  18. Synthesis of a Novel Nitronyl Nitroxide Radical and Determination of its Protective Effects Against Infrasound-Induced Injury.

    PubMed

    Wang, Haibo; Wang, Jin; Yang, Qi; Zhang, Xinwei; Gao, Peng; Xu, Shenglong; Sun, XiaoLi; Wang, YuKun

    2015-07-01

    Infrasound causes functional disorders and structural injury to the central nervous system. However, few anti-infrasound drugs exist, and they are inefficient. Nitronyl nitroxide radicals have been reported to be good antioxidants that act as superoxide dismutase mimics and directly react with reactive oxygen species, such as ·OH, H2O2, and O 2 (∙) -. Our previous research showed that the nitronyl nitroxide radical L-NNNBP has good protective effects against β-amyloid deposition and memory deficits in an AD rat model of APP/PS1. The objective of the present study was to find a new group of anti-infrasound drugs and determine the underlying pharmacological actions of nitronyl nitroxide radicals against infrasound-induced neuronal impairment in vivo. We synthesized a new stable nitronyl nitroxide radical, NRbt, and characterized its crystal structure. The results of the anti-oxidative damage effects of NRbt and the positive control drug tempol showed that they could significantly increase the SOD activity, CAT activity and GSH level and decrease the MDA level in rat hippocampi compared with infrasound exposure without pretreatment. Moreover, the ability of NRbt to regulate the activity or level of these biochemical markers was better than that of tempol. Our results showed that both NRbt and tempol significantly protected against the learning and memory impairments induced by infrasound exposure in a Morris water maze, but there were no significant differences in the path length or escape latency between the rats in the tempol group and the three NRbt groups (P > 0.05). In addition, the infrasound-induced neuronal apoptosis in rat hippocampi was significantly suppressed by NRbt and tempol. The results demonstrated that compared with the infrasound exposure group, the expression of Bcl-2 was up-regulated and the expressions of Bax and caspase-3 were down-regulated in rats pretreated with NRbt (40 mg/kg) or tempol (40 mg/kg). These results showed that the newly

  19. Nanotube Aerogel Sheet Flutter for Actuation, Power Generation, and Infrasound Detection

    PubMed Central

    Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E.; Baughman, Ray H.; Lee, Hong H.; Kim, Yong Hyup

    2014-01-01

    Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect infrasound at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for infrasound frequencies. PMID:25130708

  20. On the infrasound detected from the 2013 and 2016 DPRK's underground nuclear tests

    NASA Astrophysics Data System (ADS)

    Assink, J. D.; Averbuch, G.; Smets, P. S. M.; Evers, L. G.

    2016-04-01

    The underground nuclear tests by the Democratic People's Republic of Korea (DPRK) generated atmospheric infrasound both in 2013 and 2016. Clear detections were made in the Russian Federation (I45RU) and Japan (I30JP) in 2013 at stations from the International Monitoring System. Both tropospheric and stratospheric refractions arrived at the stations. In 2016, only a weak return was potentially observed at I45RU. Data analysis and propagation modeling show that the noise level at the stations and the stratospheric circumpolar vortex were different in 2016 compared to 2013. As the seismic magnitude of the 2013 and 2016 nuclear test explosions was comparable, we hypothesize that the 2016 test occurred at least 1.5 times deeper. In such a case, less seismic energy would couple through the lithosphere-atmosphere interface, leading to less observable infrasound. Since explosion depth is difficult to estimate from seismic data alone, this motivates a synergy between seismics and infrasonics.

  1. Nanotube aerogel sheet flutter for actuation, power generation, and infrasound detection.

    PubMed

    Kang, Tae June; Kim, Taewoo; Jang, Eui Yun; Im, Hyeongwook; Lepro-Chavez, Xavier; Ovalle-Robles, Raquel; Oh, Jiyoung; Kozlov, Mikhail E; Baughman, Ray H; Lee, Hong H; Kim, Yong Hyup

    2014-01-01

    Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect infrasound at inaudible frequencies below 20 Hz. Using conformal deposition of 100 nm thick aluminum coatings on the nanotubes in the sheets, mechanical actuation can be obtained by applying millivolts, as compared with the thousand volts needed to achieve giant-stroke electrostatic actuation of carbon nanotube aerogel sheets. Device simplicity and performance suggest possible applications as an energy harvester of low energy air fluctuations and as a sensor for infrasound frequencies. PMID:25130708

  2. Development of a robust and automated infrasound event catalogue using the International Monitoring System

    NASA Astrophysics Data System (ADS)

    Arrowsmith, Stephen; Euler, Garrett; Marcillo, Omar; Blom, Philip; Whitaker, Rod; Randall, George

    2015-03-01

    Methods for detecting, associating and locating infrasound events recorded on the global International Monitoring System (IMS) infrasound network are presented. By using likelihood arguments, and reducing the use of empirically determined parameters, our techniques enable us to formally quantify the false alarm rate at both station and network levels, and to calculate confidence areas for event localization. We outline a new association technique that uses graph theory for associating arrivals at multiple spatially separated stations, and perform Monte Carlo simulations to quantify the performance of the scheme under different scenarios. The detection, association and location techniques are applied to 10 large events in the Reviewed Event Bulletin of the Comprehensive Nuclear Test Ban Treaty Organization. Out of 10 events, a total of seven were automatically detected and associated. By analysing the three missed events, we identify improvements that might be made to improve the algorithms.

  3. Lahar infrasound associated with Volcán Villarrica's 3 March 2015 eruption

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Palma, Jose L.

    2015-08-01

    The paroxysmal 2015 eruption of Volcán Villarrica (Chile) produced a 2.5 h long lahar, which descended more than 20 km within the Rio Correntoso/Turbio drainage and destroyed two small bridges. A three-element infrasound array 10 km from the summit, and 4 km from the lahar's closest approach, was used to study the flow's progression. Array processing using cross-correlation lag times and semblance places constraints on the lahar's dynamics, including detection of an initial flow pulse that traveled from 2 to 12 km at an average speed of 38 m/s. Subsequently, the lahar signal evolved to a relatively stationary infrasonic tremor located 10 to 12 km from the vent and adjacent to a topographic notch, through which sound may have preferentially diffracted toward the recording site. This study demonstrates the powerful capabilities of infrasound arrays for lahar study and suggests their potential application for future hazard monitoring.

  4. Atmospheric infrasound propagation modelling using the reflectivity method with a direct formulation of the wind effect

    NASA Astrophysics Data System (ADS)

    Maupin, Valerie; Näsholm, Sven Peter; Schweitzer, Johannes; Gibbons, Steven J.

    2016-04-01

    We recently advocated using the reflectivity method, also known as the wavenumber integration method or fast-field program, to model atmospheric infrasound propagation at regional distances. The advantage of the reflectivity method is its ability to model the full wavefield, including diffractive effects with head waves and shadow zone arrivals, in a broad frequency range but still at a relatively low computational cost. Attenuation can easily be included, giving the possibility to analyse relative amplitudes and frequency content of the different arrivals. It has clear advantages compared with ray theory in terms of predicting phases considering the particular frequent occurrence of shadow zone arrivals in infrasound observations. Its main limitation, at least in the traditional form of the method, lies in the fact that it can only handle range-independent models. We presented earlier some reflectivity method simulations of an observed accidental explosion in Norway. Wind intensity and direction are non-negligible parameters for infrasound propagation and these are appropriately taken into account in most infrasound ray-tracing codes. On the other hand, in the previous reflectivity simulations wind was taken into account only through the effective sound speed approximation where the horizontal projection of the wind field is added to the adiabatic sound speed profiles. This approximation is appropriate for dominantly horizontal propagation but can give incorrect arrival times and shadow zone locations for waves which have a significant portion of their propagation path at more vertical incidence, like thermospheric arrivals. We present here how we have modified the original reflectivity algorithm in order to take the wind into account in a more correct fashion, and how this improvement influences the synthetics.

  5. [Clinical and functional evaluation of health status of workers exposed to infrasound, noise and general vibration].

    PubMed

    Balunov, V D; Barsukov, A F; Artamonova, V G

    1998-01-01

    The article covers complex evaluation of health state in building industry workers engaged into ferro-concrete production in St. Petersburg. The health state was considered under combined action of infrasound, noise and general vibration. Clinical and functional evaluation included medical examination by doctors, blood biochemistry and CBC, ECG, computer integral rheography, voice audiometry. Data for 62 moulders helped to assess acoustic environment at workplace and to reveal the morbidity structure. PMID:9662931

  6. Infrasound/seismic observation of the Hayabusa reentry: Observations and preliminary results

    NASA Astrophysics Data System (ADS)

    Ishihara, Yoshiaki; Hiramatsu, Yoshihiro; Yamamoto, Masa-yuki; Furumoto, Muneyoshi; Fujita, Kazuhisa

    2012-07-01

    The Hayabusa, the world's first sample-return minor body explorer, returned to the Earth, and reentered the Earth's atmosphere on June 13, 2010. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area (WPA), Australia. The ground observations were configured with optical imaging with still and video recordings, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations, we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations. The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa Sample Return Capsule (H-SRC) and the disrupted fragments of the Hayabusa Spacecraft (H-S/C) itself. Positive overpressure values of shockwaves (corresponding to the H-SRC) recorded at the three main stations were 1.3 Pa, 1.0 Pa, and 0.7 Pa with slant distances of 36.9 km, 54.9 km, and 67.8 km, respectively. Incident vectors of the shockwave from the H-SRC at all three arrays are estimated by an F-K spectrum and agree well with those predicted. Particle motions of ground motions excited by the shockwave show characteristics of a typical Rayleigh wave.

  7. Computationally robust and noise resistant numerical detector for the detection of atmospheric infrasound.

    PubMed

    Lee, Dong-Chang; Olson, John V; Szuberla, Curt A L

    2013-07-01

    This work reports on a performance study of two numerical detectors that are particularly useful for infrasound arrays operating under windy conditions. The sum of squares of variance ratios (SSVR1)-proposed for detecting signals with frequency ranging from 1 to 10 Hz-is computed by taking the ratio of the squared sum of eigenvalues to the square of largest eigenvalue of the covariance matrix of the power spectrum. For signals with lower frequency between 0.015 and 0.1 Hz, SSVR2 is developed to reduce the detector's sensitivity to noise. The detectors' performances are graphically compared against the current method, the mean of cross correlation maxima (MCCM), using the receiver operating characteristics curves and three types of atmospheric infrasound, corrupted by Gaussian and Pink noise. The MCCM and SSVR2 detectors were also used to detect microbaroms from the 24 h-long infrasound data. It was found that the two detectors outperform the MCCM detector in both sensitivity and computational efficiency. For mine blasts corrupted by Pink noise (signal-to-noise ratio = -7 dB), the MCCM and SSVR1 detectors yield 62 and 88 % true positives when accepting 20% false positives. For an eight-sensor array, the speed gain is approximately eleven-fold for a 50 s long signal. PMID:23862892

  8. Detection of regional infrasound signals using array data: Testing, tuning, and physical interpretation.

    PubMed

    Park, Junghyun; Stump, Brian W; Hayward, Chris; Arrowsmith, Stephen J; Che, Il-Young; Drob, Douglas P

    2016-07-01

    This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU). Arrays located on an island and near the coast have higher noise power, consistent with both higher wind speeds and seasonably variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in infrasound detections including daily time of occurrence, detection numbers, and phase velocity/azimuth estimates are documented. These time-dependent effects are strongly correlated with atmospheric winds and temperatures and are predicted by available atmospheric specifications. This suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time. PMID:27475150

  9. Finite-difference time-domain synthesis of infrasound propagation through an absorbing atmosphere.

    PubMed

    de Groot-Hedlin, C

    2008-09-01

    Equations applicable to finite-difference time-domain (FDTD) computation of infrasound propagation through an absorbing atmosphere are derived and examined in this paper. It is shown that over altitudes up to 160 km, and at frequencies relevant to global infrasound propagation, i.e., 0.02-5 Hz, the acoustic absorption in dB/m varies approximately as the square of the propagation frequency plus a small constant term. A second-order differential equation is presented for an atmosphere modeled as a compressible Newtonian fluid with low shear viscosity, acted on by a small external damping force. It is shown that the solution to this equation represents pressure fluctuations with the attenuation indicated above. Increased dispersion is predicted at altitudes over 100 km at infrasound frequencies. The governing propagation equation is separated into two partial differential equations that are first order in time for FDTD implementation. A numerical analysis of errors inherent to this FDTD method shows that the attenuation term imposes additional stability constraints on the FDTD algorithm. Comparison of FDTD results for models with and without attenuation shows that the predicted transmission losses for the attenuating media agree with those computed from synthesized waveforms. PMID:19045635

  10. Dust devil signatures in infrasound records of the International Monitoring System

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Christie, Douglas

    2015-03-01

    We explore whether dust devils have a recognizable signature in infrasound array records, since several Comprehensive Nuclear-Test-Ban Treaty verification stations conducting continuous measurements with microbarometers are in desert areas which see dust devils. The passage of dust devils (and other boundary layer vortices, whether dust laden or not) causes a local temporary drop in pressure: the high-pass time domain filtering in microbarometers results in a "heartbeat" signature, which we observe at the Warramunga station in Australia. We also observe a ~50 min pseudoperiodicity in the occurrence of these signatures and some higher-frequency infrasound. Dust devils do not significantly degrade the treaty verification capability. The pipe arrays for spatial averaging used in infrasound monitoring degrade the detection efficiency of small devils, but the long observation time may allow a useful census of large vortices, and thus, the high-sensitivity infrasonic array data from the monitoring network can be useful in studying columnar vortices in the lower atmosphere.

  11. Using the international monitoring system of seismic, infrasound, and hydroacoustic sensors for global airburst detection

    NASA Astrophysics Data System (ADS)

    Brown, P.

    2014-07-01

    The impact of meter-sized objects with the Earth occurs every few weeks [1,2]. Most of these collisions result in airbursts, here defined as impacts where the meteoroid's initial kinetic energy is of order a small nuclear weapon (> 0.1 kilotons of TNT equivalent = 4.185×10^{11} J) and where this energy is fully deposited at high altitude in the atmosphere. Historically, the majority of these airbursts go undetected over oceans or remote land areas as dedicated fireball camera networks (eg.[ 3]) cover less than 1 % of the globe. Airbursts often produce meteorite falls and hence airburst data may yield pre-atmospheric orbits and physical properties for the impacting NEO providing context for recovered meteorite samples [4]. With the advent of more capable telescopic survey systems, pre-atmospheric detection of NEO-producing airbursts has become possible as evidenced by the impacts of 2014 AA and 2008 TC_3 [5]. Detection of ''terminal plungers'' is expected to become more common as projects such as ATLAS [6] become operational. This increases the need for instrumental data of the corresponding airburst, particularly its location and energy. Beginning in the late 1990s, a global network of seismic, infrasound, and hydroacoustic sensors has been deployed globally to provide treaty verification for a nuclear test ban. This network is the International Monitoring System (IMS) overseen by Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) [7]. The IMS is a unique global resource for detection of explosions worldwide and in recent years shock waves from many airbursts [8] have been detected by the system. Data from the IMS permits airburst location, origin time and energy to be measured. In rare cases, source heights, trajectories, and details of fragmentation may be obtained. Here the current capabilities of the IMS will be presented in the context of airburst detection and characterization. Empirical characteristics of the long-range sound produced by airbursts

  12. Comparing near-regional and local measurements of infrasound from Mount Erebus, Antarctica: Implications for monitoring

    NASA Astrophysics Data System (ADS)

    Dabrowa, A. L.; Green, D. N.; Johnson, J. B.; Phillips, J. C.; Rust, A. C.

    2014-11-01

    Local (100 s of metres from vent) monitoring of volcanic infrasound is a common tool at volcanoes characterized by frequent low-magnitude eruptions, but it is generally not safe or practical to have sensors so close to the vent during more intense eruptions. To investigate the potential and limitations of monitoring at near-regional ranges (10 s of km) we studied infrasound detection and propagation at Mount Erebus, Antarctica. This site has both a good local monitoring network and an additional International Monitoring System infrasound array, IS55, located 25 km away. We compared data recorded at IS55 with a set of 117 known Strombolian events that were recorded with the local network in January 2006. 75% of these events were identified at IS55 by an analyst looking for a pressure transient coincident with an F-statistic detection, which identifies coherent infrasound signals. With the data from January 2006, we developed and calibrated an automated signal-detection algorithm based on threshold values of both the F-statistic and the correlation coefficient. Application of the algorithm across IS55 data for all of 2006 identified infrasonic signals expected to be Strombolian explosions, and proved reliable for indicating trends in eruption frequency. However, detectability at IS55 of known Strombolian events depended strongly on the local signal amplitude: 90% of events with local amplitudes > 25 Pa were identified at IS55, compared to only 26% of events with local amplitudes < 25 Pa. Event detection was also affected by considerable variation in amplitude decay rates between the local and near-regional sensors. Amplitudes recorded at IS55 varied between 3% and 180% of the amplitude expected assuming hemispherical spreading, indicating that amplitudes recorded at near-regional ranges to Erebus are unreliable indicators of event magnitude. Comparing amplitude decay rates with locally collected radiosonde data indicates a close relationship between recorded

  13. Infrasound and Seismic Recordings of a US Airstrike on an ISIS Car Bomb Factory on June 3, 2015

    NASA Astrophysics Data System (ADS)

    Aleqabi, G. I.; Ghalib, H. A. A.; Wysession, M. E.

    2015-12-01

    Concurrent infrasound and seismic records of a jet airstrike in Iraq are presented. Media reports stated that US jets carried out a large airstrike on June 3, 2015, just after midnight local time, that targeted and destroyed an ISIS car bomb factory in Hawija, Iraq, just south of the city of Kirkuk, Iraq. The resulting explosion was felt within Kirkuk and at other locations as far as 34 km away from the Hawija factory. Seismic broadband stations located in northern Iraq, at a distance of about 160 km, show clear simultaneous signals of infrasound waves on the seismometers as well as on collocated infrasound equipment. From an analysis of the body waves, the Pg to Lg time difference is nearly ~20 sec, with a back azimuth of 250o to 260o, which is consistent with explosion location. The time difference between the Pg and infrasound signals is just over 7 minutes, consistent with sound speed in the atmosphere. No clear Rg wave was observed. As was demonstrated by Aleqabi, Wysession, and Ghalib [2015, BSSA, in press], broadband seismic recordings are able to identify and distinguish between several different kinds of MOUT (military operations in urban terrain) and even determine the magnitudes of ordinance used in certain blasts. The addition of collocated infrasound equipment provides additional constraints that can be used in the analysis of the size and form of the MOUT.

  14. In situ calibration of atmospheric-infrasound sensors including the effects of wind-noise-reduction pipe systems.

    PubMed

    Gabrielson, Thomas B

    2011-09-01

    A worldwide network of more than 40 infrasound monitoring stations has been established as part of the effort to ensure compliance with the Comprehensive Nuclear Test Ban Treaty. Each station has four to eight individual infrasound elements in a kilometer-scale array for detection and bearing determination of acoustic events. The frequency range of interest covers a three-decade range-roughly from 0.01 to 10 Hz. A typical infrasound array element consists of a receiving transducer connected to a multiple-inlet pipe network to average spatially over the short-wavelength turbulence-associated "wind noise." Although the frequency response of the transducer itself may be known, the wind-noise reduction system modifies that response. In order to understand the system's impact on detection and identification of acoustical events, the overall frequency response must be determined. This paper describes a technique for measuring the absolute magnitude and phase of the frequency response of an infrasound element including the wind-noise-reduction piping by comparison calibration using ambient noise and a reference-microphone system. Measured coherence between the reference and the infrasound element and the consistency between the magnitude and the phase provide quality checks on the process. PMID:21895058

  15. The first second of volcanic eruptions from the Erebus volcano lava lake, Antarctica—Energies, pressures, seismology, and infrasound

    NASA Astrophysics Data System (ADS)

    Gerst, A.; Hort, M.; Aster, R. C.; Johnson, J. B.; Kyle, P. R.

    2013-07-01

    We describe a multiparameter experiment at Erebus volcano, Antarctica, employing Doppler radar, video, acoustic, and seismic observations to estimate the detailed energy budget of large (up to 40 m-diameter) bubble bursts from a persistent phonolite lava lake. These explosions are readily studied from the crater rim at ranges of less than 500 m and present an ideal opportunity to constrain the dynamics and mechanism of magmatic bubble bursts that can drive Strombolian and Hawaiian eruptions. We estimate the energy budget of the first second of a typical Erebus explosion as a function of time and energy type. We constrain gas pressures and forces using an analytic model for the expansion of a gas bubble above a conduit that incorporates conduit geometry and magma and gas parameters. The model, consistent with video and radar observations, invokes a spherical bulging surface with a base diameter equal to that of the lava lake. The model has no ad hoc free parameters, and geometrical calculations predict zenith height, velocity, and acceleration during shell expansion. During explosions, the energy contained in hot overpressured gas bubbles is freed and partitioned into other energy types, where by far the greatest nonthermal energy component is the kinetic and gravitational potential energy of the accelerated magma shell (>109 J). Seismic source energy created by explosions is estimated from radar measurements and is consistent with source energy determined from seismic observations. For the generation of the infrasonic signal, a dual mechanism incorporating a terminally disrupted slug is proposed, which clarifies previous models and provides good fits to observed infrasonic pressures. A new and straightforward method is presented for determining gas volumes from slug explosions at volcanoes from remote infrasound recordings.

  16. Complex monitoring and alert network for electromagnetic, infrasound, acoustic seismotectonic phenomena

    NASA Astrophysics Data System (ADS)

    -Emilian Toader, Victorin; Moldovan, Iren-Adelina; Constantin, Ionescu

    2014-05-01

    The Romanian seismicity recorded in 2013 three important events: the largest seismic "silence", the shortest sequence of two earthquakes greater than 4.8R in less than 14 days after the "Romanian National Institute for Earth Physics" (NIEP) developed a digital network, and a very high crustal activity in Galati area. We analyze the variations of the telluric currents and local magnetic field, variations of the atmospheric electrostatic field, infrasound, temperature, humidity, wind speed and direction, atmospheric pressure, variations in the earth crust with inclinometers and animal behavior. The general effect is the first high seismic energy discontinuity that could be a precursor factor. Since 1977 Romania did not register any important earthquake that would generate a sense of fear among the population. In parallel with the seismic network NIEP developed a magneto-telluric, bioseismic, VLF and acoustic network. A large frequency spectrum is covered for mechanical vibration, magnetic and electric field with ground and air sensors. Special software was designed for acquisition, analysis and real time alert using internet direct connection, web page, email and SMS. Many examples show the sensitivity of telluric current, infrasound, acoustic records (from air-ground), and the effect of tectonic stress on the magnetic field or ground deformation. The next update of the multidisciplinary monitoring network will include measurement of ionization, radon emission, sky color, solar radiation and extension of infrasound and VL/LF equipment. NOAA Space Weather satellites transmit solar activity magnetic field data, X ray flux, electron, and proton flux information useful for complex analysis.

  17. Brief communication "Modeling tornado dynamics and the generation of infrasound, electric and magnetic fields"

    NASA Astrophysics Data System (ADS)

    Schmitter, E. D.

    2010-02-01

    Recent observations endorse earlier measurements of time varying electric and magnetic fields generated by tornadoes and dust devils. These signals may provide a means for early warning but together with a proper modeling approach can also provide insight into geometry and dynamics of the vortices. Our model calculations show the existence of pressure resonances characterized as acoustic duct modes with well defined frequencies. These resonances not only generate infrasound but also modulate the charge density and the velocity field and in this way lead to electric and magnetic field oscillations in the 0.5-20-Hz range that can be monitored from a distance of several kilometers.

  18. Analysis and modeling of infrasound from a four-stage rocket launch.

    PubMed

    Blom, Philip; Marcillo, Omar; Arrowsmith, Stephen

    2016-06-01

    Infrasound from a four-stage sounding rocket was recorded by several arrays within 100 km of the launch pad. Propagation modeling methods have been applied to the known trajectory to predict infrasonic signals at the ground in order to identify what information might be obtained from such observations. There is good agreement between modeled and observed back azimuths, and predicted arrival times for motor ignition signals match those observed. The signal due to the high-altitude stage ignition is found to be low amplitude, despite predictions of weak attenuation. This lack of signal is possibly due to inefficient aeroacoustic coupling in the rarefied upper atmosphere. PMID:27369137

  19. On the use of infrasound sensors for low frequency atmospheric studies

    NASA Astrophysics Data System (ADS)

    Ponceau, Damien; Marty, Julien; Koenig, Jean-Marc; Denis, Stéphane; Ulziibat, Munkhuu

    2010-05-01

    Most of infrasonic stations from International Monitoring System (IMS) of the Comprehensive Nuclear Test Organization (CTBTO) use absolute infrasound sensors associated with acquisition units dedicated to geophysics. These sensors measure ambient atmospheric pressure over a frequency bandwidth from DC to tens of Hz, including the entire infrasound frequency range. The reference cavity vacuum gives them an intrinsic thermal sensitivity much lower than that of differential infrasound sensors such as microphones. Experience shows that this is especially interesting when low frequency pressure measurements are needed. Direct digitizing of such signals requires a dynamic range better than 145 dB over the frequency bandwidth of interest. Microbarometers were equipped with an additional output attenuating the very low frequencies with a simple first order high pass filter with a cutoff frequency of 0.01 Hz and a gain over its bandwidth of 20. This output has a dynamic range of about 108 dB easier to digitize. It is made from electronic components selected for their accuracy, their stability and insensitivity to environment. This is the "filtered output" which is generally used on the IMS. More and more scientific studies for civilian applications focus on low frequency signals affected by this filtering. This presentation discusses how the use of this filtered output affects data quality in this frequency range and how it is possible to exploit them. Microbarometer output stage has been modeled to estimate the noise induced by filtering and its influence on the infrasonic signals of interest. This presentation discusses how it is possible to compensate filter's influence to recover the "true" signals of interest. It explains how the operating principle of these sensors can minimize errors. Three stations consisting in four sensors were set up in Mongolia in order to record pressure variations produced by the total solar eclipse of the 1 August 2008. For each sensor, the

  20. Effect of infrasound on cochlear damage from exposure to a 4-kHz octave band of noise

    PubMed Central

    Harding, Gary W.; Bohne, Barbara A.; Lee, Steve C.; Salt, Alec N.

    2008-01-01

    Infrasound (i.e., < 20 Hz for humans; < 100 Hz for chinchillas) is not audible, but exposure to high levels of infrasound will produce large movements of cochlear fluids. We speculated that high-level infrasound might bias the basilar membrane and perhaps be able to minimize noise-induced hearing loss. Chinchillas were simultaneously exposed to a 30 Hz tone at 100 dB SPL and a 4-kHz OBN at either 108 dB SPL for 1.75 h or 86 dB SPL for 24 h. For each animal, the tympanic membrane (TM) in one ear was perforated (~1 mm2) prior to exposure to attenuate infrasound transmission to that cochlea by about 50 dB SPL. Controls included animals that were exposed to the infrasound only or the 4-kHz OBN only. ABR threshold shifts (TSs) and DPOAE level shifts (LSs) were determined pre- and post-TM-perforation and immediately post-exposure, just before cochlear fixation. The cochleae were dehydrated, embedded in plastic, and dissected into flat preparations of the organ of Corti (OC). Each dissected segment was evaluated for losses of inner hair cells (IHCs) and outer hair cells (OHCs). For each chinchilla, the magnitude and pattern of functional and hair cell losses were compared between their right and left cochleae. The TM perforation produced no ABR TS across frequency but did produce a 10–21 dB DPOAE LS from 0.6–2 kHz. The infrasound exposure alone resulted in a 10–20 dB ABR TS at and below 2 kHz, no DPOAE LS and no IHC or OHC losses. Exposure to the 4-kHz OBN alone at 108 dB produced a 10–50 dB ABR TS for 0.5–12 kHz, a 10–60 dB DPOAE LS for 0.6–16 kHz and severe OHC loss in the middle of the first turn. When infrasound was present during exposure to the 4-kHz OBN at 108 dB, the functional losses and OHC losses extended much further toward the apical and basal tips of the OC than in cochleae exposed to the 4-kHz OBN alone. Exposure to only the 4-kHz OBN at 86 dB produces a 10–40 dB ABR TS for 3–12 kHz and 10–30 dB DPOAE LS for 3–8 kHz but little or no

  1. Reconstruction of the signal produced by a directional sound source from remote multi-microphone recordings.

    PubMed

    Guarato, Francesco; Hallam, John; Matsuo, Ikuo

    2011-09-01

    A mathematical method for reconstructing the signal produced by a directional sound source from knowledge of the same signal in the far field, i.e., microphone recordings, is developed. The key idea is to compute inverse filters that compensate for the directional filtering of the signal by the sound source directivity, using a least-square error optimization strategy. Previous work pointed out how the method strongly depends on arrival times of signal in the microphone recordings. Two strategies are used in this paper for calculating the time shifts that are afterward taken as inputs, together with source directivity, for the reconstruction. The method has been tested in a laboratory environment, where ground truth was available, with a Polaroid transducer as source. The reconstructions are similar with both strategies. The performance of the method also depends on source orientation. PMID:21895106

  2. Intense monotonic infrasound at Volcan Villarrica: Insights from an Integrated Seismo-acousto-optico-thermo-UV imager field approach

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Anderson, J.; Sanderson, R. W.; McIntosh, W. C.; Goto, A.; Waite, G. P.; Palma, J.; Richardson, J. P.

    2011-12-01

    Toward understanding the origin of the intense (>50 Pa RMS at crater rim) monotone tremor at Volcan Villarrica (Chile), we have deployed instrumentation, including cameras, suspended above the basaltic lava lake. In 2010 we observed a 65-m diameter spatter roof perforated by a 10 m-diameter vent (or skylight) providing a view into a 25 m-tall cavity and roiling lava lake beneath. Conjoint visual observations and infrasound modeling suggest that the 0.77 Hz infrasonic signal is a Helmholtz resonance phenomenon similar to that previously postulated for Kilauea and Shishaldin. A February-March 2011 field campaign was aimed at understanding the relation between surface activity and degassing and thermal flux by deploying a dense linear array of broadband seismo-acoustic sensors on the upper slopes of the volcano and within the upper crater. We also lowered time-synchronized cameras, pressure sensors, and thermocouples down into the vent. Against the background of intense infrasonic tremor we observed discrete strombolian eruptions and spattering events, which generate a preponderance of 5-10 Hz infrasound. A stable peaked infrasound monotone ranging from 0.65-0.8 Hz has been reported by our group and others at Villarrica in 2002, 2008, 2009, 2010, 2011. We propose that the conduit/vent geometry largely control the frequency content of the infrasound whereas the amplitude of the oscillation is controlled by gas emission rates, which we were able to quantify for SO2 in 2011 using UV absorption imagery.

  3. Detection of Regional Infrasound Signals Using Array Data - Testing, Tuning, and Physical Interpretation

    NASA Astrophysics Data System (ADS)

    Park, J.; Stump, B. W.; Hayward, C.; Arrowsmith, S.; Che, I. Y.; Drob, D. P.

    2015-12-01

    In order to understand the impact environmental conditions have on infrasound detection, an automated detector that accounts for both correlated and uncorrelated noise is run on data from a number of infrasonic arrays, all in a regional context. Data from six seismo-acoustic arrays in South Korea (BRDAR, CHNAR, KMPAR, KSGAR, TJIAR, and YPDAR), which are cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU), were used. An adaptive F-detector (AFD) (Arrowsmith et al., 2009) is applied that utilizes the F-statistic (Blandford, 1974) with an adaptive procedure that assesses variations in coherent noise in order to reduce false alarms. The adaptive procedure is characterized by the time dependent C-value that is found to depend on the weather conditions and local site effects. Arrays located on islands or near the coast produce noise power densities that are higher, consistent with both higher wind speeds as well as ocean wave contributions that vary seasonally. These results suggest that optimal detection processing requires careful characterization of background noise level and its relationship to enviornmental measures at individual arrays. This study also documents significant seasonal variations in infrasound detections including daily time of occurrence, total number of detections, and phase velocity/azimuth estimates. These time-dependent effects in most part explained by atmospheric models across the Korean peninsula as described by Drob et al. (2003).

  4. A low-order reduced model for the long range propagation of infrasounds in the atmosphere.

    PubMed

    Bertin, Michael; Millet, Christophe; Bouche, Daniel

    2014-07-01

    This paper considers a class of low-order, range-dependent propagation models obtained from the normal mode decomposition of infrasounds in complex atmospheres. The classical normal mode method requires calculating eigenvalues for large matrices making the computation expensive even though some modes have little influence on the numerically obtained results. By decomposing atmospheric perturbations into a wavelet basis, it is shown that the most sensitive eigenvalues provide the best reduced model for infrasound propagation. These eigenvalues lie on specific curves in the complex plane that can be directly deduced from atmospheric data through a WKB approach. The computation cost can be reduced by computing the invariant subspace associated with the most sensitive eigenvalues. The reduction method is illustrated in the case of the Fukushima explosion (12 March 2011). The implicitly restarted Arnoldi algorithm is used to compute the three most sensitive modes, and the correct tropospheric arrival is found with a cost of 2% of the total run time. The cost can be further reduced by using a stationary phase technique. Finally, it is shown that adding uncertainties triggers a stratospheric arrival even though the classical criteria, based on the ratio of stratospheric sound speed to that at ground level, is not satisfied. PMID:24993194

  5. Health effects from low-frequency noise and infrasound in the general population: Is it time to listen? A systematic review of observational studies.

    PubMed

    Baliatsas, Christos; van Kamp, Irene; van Poll, Ric; Yzermans, Joris

    2016-07-01

    A systematic review of observational studies was conducted to assess the association between everyday life low-frequency noise (LFN) components, including infrasound and health effects in the general population. Literature databases Pubmed, Embase and PsycInfo and additional bibliographic sources such as reference sections of key publications and journal databases were searched for peer-reviewed studies published from 2000 to 2015. Seven studies met the inclusion criteria. Most of them examined subjective annoyance as primary outcome. The adequacy of provided information in the included papers and methodological quality of studies was also addressed. Moreover, studies were screened for meta-analysis eligibility. Some associations were observed between exposure to LFN and annoyance, sleep-related problems, concentration difficulties and headache in the adult population living in the vicinity of a range of LFN sources. However, evidence, especially in relation to chronic medical conditions, was very limited. The estimated pooled prevalence of high subjective annoyance attributed to LFN was about 10%. Epidemiological research on LFN and health effects is scarce and suffers from methodological shortcomings. Low frequency noise in the everyday environment constitutes an issue that requires more research attention, particularly for people living in the vicinity of relevant sources. PMID:26994804

  6. On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

    NASA Astrophysics Data System (ADS)

    Caudron, Corentin; Taisne, Benoít; Garcés, Milton; Alexis, Le Pichon; Mialle, Pierrick

    2015-08-01

    The February 2014 eruption of Kelud volcano (Indonesia) destroyed most of the instruments near it. We use remote seismic and infrasound sensors to reconstruct the eruptive sequence. The first explosions were relatively weak seismic and infrasound events. A major stratospheric ash injection occurred a few minutes later and produced long-lasting atmospheric and ground-coupled acoustic waves that were detected as far as 11,000 km by infrasound sensors and up to 2300 km away on seismometers. A seismic event followed ˜12 minutes later and was recorded 7000 km away by seismometers. We estimate a volcanic intensity around 10.9, placing the 2014 Kelud eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. We demonstrate how remote infrasound and seismic sensors are critical for the early detection of volcanic explosions, and how they can help to constrain and understand eruptive sequences.

  7. Parallel Grid approach to solve Feature Selection problem in volcanic infrasound signals classification

    NASA Astrophysics Data System (ADS)

    Reitano, Danilo; Pistagna, Fabrizio; Russo, Gaetano; Valenti, Vincenzo

    2010-05-01

    The continuous monitoring of an active volcano, such as Mt. Etna (Sicily, Italy), represents one of the main tasks for the Italian National Institute of Geophysics and Volcanology (INGV), Catania Branch. Around the volcano summit area, four infrasound sensors have been installed during the last recent years, which allow to acquire, real time waveforms that are subsequently stored on a server, located inside the INGV Control Room. A new method here introduced, based on Genetic Algorithms (GA), has been used to analyze the data coming from the remote infrasound sensors stations. In particular, the acquired signals have been processed by a custom modular software: the first module allows the visual manipulation, filtering and, in order to optimize performances, resampling the data to better elaborate them. The second module, using an alghorithm (G. Russo, 2009 ) based on two different thresholds (upper and lower) and the standard deviation, is able to recognize and collect infrasound events (IE) from the stored data. In the third step, the Green & Nueberg algorithm (2006) is used to correlate different families of IE and define the clusters nodes. Once a minimum number of families are characterized, they define the main features inside each cluster. Feature extraction process is a very complex algorithm due to the large number of requested correlations. In order to speed up the time needed to carry out so many simulations, the code has been deployed and executed on the Sicilian Grid infrastructure owned and managed by the Consorzio Cometa, a not-for-profit organisation including INGV among its members. The infrastructure, distributed across the Sicilian territory, is composed of 7 sites for a total of about 2000 CPU cores and more than 250 TB of storage. All the sites of the infrastructure are equipped with low latency Infiniband networks and are installed with MPI libraries. A complete workflow has been created from scratch to execute the various phases of the

  8. Improvements of wind noise reduction systems in the International Monitoring System infrasound network

    NASA Astrophysics Data System (ADS)

    Kramer, Alfred Christian; Marty, Julien

    2015-04-01

    The objective of this poster is to present the efforts made by the PTS over the last four years to assess and improve the robustness and efficiency of wind noise reduction systems. This work includes the improvement of the design of the pipe arrays by modelling the frequency response of the different types of filtering systems used within the IMS (International Monitoring System) infrasound network. It also includes the investigation and testing of new acoustic filtering system materials / components to improve the robustness of the pipe arrays. Efforts were also put into the improvement of pipe array design in order to enhance their flexibility to adapt to the station environmental conditions. Finally wind noise reduction system design was also enhanced to reduce maintenance activities and costs, as well as to extend their life cycle.

  9. Optical Fiber Infrasound Sensor Arrays: Signal Detection and Characterization Capabilities in Light Wind Environments

    NASA Astrophysics Data System (ADS)

    Walker, K.; Zumberge, M.; Berger, J.; Matoza, R.; Hedlin, M.; Shearer, P.

    2006-12-01

    Optical fiber infrasound sensors (OFIS) are long compliant tubes wrapped with two optical fibers that measure pressure variation with laser interferometry. Initial work suggested that this sensor has, in low-wind conditions, a lower noise floor above 1 Hz than a traditional microbarometer sensor with a pipe-array wind filter. More recent progress has been made in two other practical areas. First, we have increased reliability and the recorded signal fidelity. Noise caused by ambient temperature changes has been reduced by burial of the OFIS beneath a foot of coarse gravel and by employing a polarization diversity detector. We are currently experimenting with a thermally-controlled OFIS that would eliminate the need for burial of an OFIS. Second, we have been developing OFIS configurations, techniques, and software for signal phase velocity determination. Because the pressure variation is integrated along the length of the tube, the instrument response is a function of the orientation of the OFIS relative to that of the signal wavefront. We show with synthetic data and real data recorded at Pinion Flat Observatory in southern California how to exploit this spectral property to determine the phase velocity of infrasound signals. This type of analysis allows us to use an array that has a smaller surface area than typical microbarometer arrays with wind filters. For signals with very low signal to noise ratios, using circular OFIS in a traditional triangular array geometry works better. We also present preliminary evidence that the response of linear and circular OFIS to light wind is less pronounced than that of traditional sensors connected to a circular porous-hose wind filter.

  10. Characterization of moderate ash-and-gas explosions at Santiaguito volcano, Guatemala, from infrasound waveform inversion and thermal infrared measurements

    NASA Astrophysics Data System (ADS)

    Angelis, S. De; Lamb, O. D.; Lamur, A.; Hornby, A. J.; Aulock, F. W.; Chigna, G.; Lavallée, Y.; Rietbrock, A.

    2016-06-01

    The rapid discharge of gas and rock fragments during volcanic eruptions generates acoustic infrasound. Here we present results from the inversion of infrasound signals associated with small and moderate gas-and-ash explosions at Santiaguito volcano, Guatemala, to retrieve the time history of mass eruption rate at the vent. Acoustic waveform inversion is complemented by analyses of thermal infrared imagery to constrain the volume and rise dynamics of the eruption plume. Finally, we combine results from the two methods in order to assess the bulk density of the erupted mixture, constrain the timing of the transition from a momentum-driven jet to a buoyant plume, and to evaluate the relative volume fractions of ash and gas during the initial thrust phase. Our results demonstrate that eruptive plumes associated with small-to-moderate size explosions at Santiaguito only carry minor fractions of ash, suggesting that these events may not involve extensive magma fragmentation in the conduit.

  11. Characteristic Surface Processes Between Atmosphere, Cryosphere and Oceanic Environment Inferred from Infrasound Array Observations in Lützow-Holm Bay, East Antarctica

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Kanao, M.; Yamamoto, M. Y.; Kakinami, Y.; Murayama, T.; Okada, K.; Toda, S.; Matsushima, T.

    2014-12-01

    Infrasound is sub-audible sound whose frequency range is about 3 mHz to 20 Hz. Because this frequency is common between atmospheric, oceanic and solid earth vibrations, those waves are interacting with each other and interaction itself generates infrasound. At polar region, cryosphere also play an important role for generation and propagation of infrasound. The Japanese Antarctic infrasound observation started at April 2008. A sensor was installed at Syowa Station (SYO) in Lützow-Holm Bay (LHB) of East Antarctica, as a part of the International Polar Year. Characteristic infrasound waves observed at SYO demonstrate physical interaction involving environmental changes in the Antarctic region. Continuous recordings of infrasound clearly indicate existence of the hums generated by ocean-atmosphere interaction (microbaroms) with peaks of 0.1 to 0.25 Hz. Because larger amount of sea-ice extending around the LHB near SYO suppress ocean wave, the microbaroms become weak during austral winter. Following success of pilot observation, in austral summer in 2013, we extended one-sensor observation at SYO to 3-sensor arrayed observations, and installed a few field stations along the coast of the LHB. Newly established SYO array clearly detected the propagating directions and frequency contents of the microbaroms from Southern Ocean. In addition, we found harmonic signals around lowermost human audible band, however, currently unclear how and what generating hamonic signals. Those signals are recorded under windy condition. Since our system has no mechanical resonance at those frequency ranges, we speculate that the characteristic harmonic signals are probably related to local surficial phenomena such as ice sheet vibration generated by katabatic winds. Infrasound measurement at Antarctica could be a new proxy for monitoring a regional environmental change in high southern latitude. In such point of view, we will continue and improve the observations at and around SYO

  12. Effect of time-varying tropospheric models on near-regional and regional infrasound propagation as constrained by observational data

    NASA Astrophysics Data System (ADS)

    McKenna, Mihan H.; Stump, Brian W.; Hayward, Chris

    2008-06-01

    The Chulwon Seismo-Acoustic Array (CHNAR) is a regional seismo-acoustic array with co-located seismometers and infrasound microphones on the Korean peninsula. Data from forty-two days over the course of a year between October 1999 and August 2000 were analyzed; 2052 infrasound-only arrivals and 23 seismo-acoustic arrivals were observed over the six week study period. A majority of the signals occur during local working hours, hour 0 to hour 9 UT and appear to be the result of cultural activity located within a 250 km radius. Atmospheric modeling is presented for four sample days during the study period, one in each of November, February, April, and August. Local meteorological data sampled at six hour intervals is needed to accurately model the observed arrivals and this data produced highly temporally variable thermal ducts that propagated infrasound signals within 250 km, matching the temporal variation in the observed arrivals. These ducts change dramatically on the order of hours, and meteorological data from the appropriate sampled time frame was necessary to interpret the observed arrivals.

  13. A low-order model for long-range infrasound propagation in random atmospheric waveguides

    NASA Astrophysics Data System (ADS)

    Millet, C.; Lott, F.

    2014-12-01

    In numerical modeling of long-range infrasound propagation in the atmosphere, the wind and temperature profiles are usually obtained as a result of matching atmospheric models to empirical data. The atmospheric models are classically obtained from operational numerical weather prediction centers (NOAA Global Forecast System or ECMWF Integrated Forecast system) as well as atmospheric climate reanalysis activities and thus, do not explicitly resolve atmospheric gravity waves (GWs). The GWs are generally too small to be represented in Global Circulation Models, and their effects on the resolved scales need to be parameterized in order to account for fine-scale atmospheric inhomogeneities (for length scales less than 100 km). In the present approach, the sound speed profiles are considered as random functions, obtained by superimposing a stochastic GW field on the ECMWF reanalysis ERA-Interim. The spectral domain is binned by a large number of monochromatic GWs, and the breaking of each GW is treated independently from the others. The wave equation is solved using a reduced-order model, starting from the classical normal mode technique. We focus on the asymptotic behavior of the transmitted waves in the weakly heterogeneous regime (for which the coupling between the wave and the medium is weak), with a fixed number of propagating modes that can be obtained by rearranging the eigenvalues by decreasing Sobol indices. The most important feature of the stochastic approach lies in the fact that the model order (i.e. the number of relevant eigenvalues) can be computed to satisfy a given statistical accuracy whatever the frequency. As the low-order model preserves the overall structure of waveforms under sufficiently small perturbations of the profile, it can be applied to sensitivity analysis and uncertainty quantification. The gain in CPU cost provided by the low-order model is essential for extracting statistical information from simulations. The statistics of a

  14. A study of volcanic eruption characteristics using infrasound data recorded on the global IMS network

    NASA Astrophysics Data System (ADS)

    Dabrowa, Amy; Green, David; Phillips, Jeremy; Rust, Alison

    2010-05-01

    Explosive volcanic eruptions have the capability to generate sound waves with infrasonic frequencies (<20Hz). As such waves can propagate over distances of thousands of kilometres within the atmosphere, they present an opportunity to remotely monitor volcanic eruptions and potentially constrain eruptive characteristics. Though most volcanoes in sensitive areas of the world are monitored individually, many volcanoes in remote locations are not monitored directly but can still pose a threat, especially to aviation. The growing International Monitoring System (IMS) network of infrasound stations provides an opportunity to monitor these remote volcanoes. Currently comprising of 43 arrays, the network is designed to achieve global coverage for surface explosions equivalent to a few hundred tonnes of chemical explosive. In recent years work has been published on the detection of specific volcanic eruptions at IMS stations, primarily at regional ranges (< 1000 km from volcano to receiver). In contrast, work presented here looks to create a catalogue of volcanic eruptions that have been detected at IMS stations, with the aim of assessing the capability of the IMS network for use in global volcano monitoring. At this time 40 eruptive events at 19 volcanoes have been investigated from the period 2004 - 2009; however the work is on-going and it is planned to extend this catalogue. In total we document 61 individual detections that have been made on the IMS network. These range from Strombolian activity at Mount Erebus (Antarctica) recorded at a range of 25 km distance, to the Plinian eruption of Manam Volcano (Papua New Guinea) recorded at ranges of over 10,000 km distance. The observed signal frequencies for different eruptions range from less than 0.01 Hz to greater than 5 Hz, and in general, lower frequencies are generated by the larger eruptions. We provide examples of analyses for eruptions recorded at multiple stations (e.g., Manam, October 2004; Kasatochi, August 2008

  15. Exploring the "what if?" in geology through a RESTful open-source framework for cloud-based simulation and analysis

    NASA Astrophysics Data System (ADS)

    Klump, Jens; Robertson, Jess

    2016-04-01

    The spatial and temporal extent of geological phenomena makes experiments in geology difficult to conduct, if not entirely impossible and collection of data is laborious and expensive - so expensive that most of the time we cannot test a hypothesis. The aim, in many cases, is to gather enough data to build a predictive geological model. Even in a mine, where data are abundant, a model remains incomplete because the information at the level of a blasting block is two orders of magnitude larger than the sample from a drill core, and we have to take measurement errors into account. So, what confidence can we have in a model based on sparse data, uncertainties and measurement error? Our framework consist of two layers: (a) a ground-truth layer that contains geological models, which can be statistically based on historical operations data, and (b) a network of RESTful synthetic sensor microservices which can query the ground-truth for underlying properties and produce a simulated measurement to a control layer, which could be a database or LIMS, a machine learner or a companies' existing data infrastructure. Ground truth data are generated by an implicit geological model which serves as a host for nested models of geological processes as smaller scales. Our two layers are implemented using Flask and Gunicorn, which are open source Python web application framework and server, the PyData stack (numpy, scipy etc) and Rabbit MQ (an open-source queuing library). Sensor data is encoded using a JSON-LD version of the SensorML and Observations and Measurements standards. Containerisation of the synthetic sensors using Docker and CoreOS allows rapid and scalable deployment of large numbers of sensors, as well as sensor discovery to form a self-organized dynamic network of sensors. Real-time simulation of data sources can be used to investigate crucial questions such as the potential information gain from future sensing capabilities, or from new sampling strategies, or the

  16. Transfer function for vital infrasound pressures between the carotid artery and the tympanic membrane.

    PubMed

    Furihata, Kenji; Yamashita, Masato

    2013-02-01

    While occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration, the complex mechanisms causing such injuries are not yet fully understood. The relationship between the infrasound pressures of the tympanic membrane [ear canal pressure (ECP)], detected using an earplug embedded with a low-frequency microphone, and the carotid artery [carotid artery pressure (CAP)], detected using a stethoscope fitted with the same microphone, can be quantitatively characterized using systems analysis. The transfer functions of 40 normal workers (19 to 57 years old) were characterized, involving the analysis of 446 data points. The ECP waveform exhibits a pulsatile character with a slow respiratory component, which is superimposed on a biphasic recording that is synchronous with the cardiac cycle. The respiratory ECP waveform correlates with the instantaneous heart rate. The results also revealed that various fatigue-related risk factors may affect the mean magnitudes of the measured pressures and the delay transfer functions between CAP and ECP in the study population; these factors include systolic blood pressure, salivary amylase activity, age, sleep duration, postural changes, chronic fatigue, and pulse rate. PMID:23363133

  17. Infrasound-array-element frequency response: in-situ measurement and modeling

    NASA Astrophysics Data System (ADS)

    Gabrielson, T.

    2011-12-01

    Most array elements at the infrasound stations of the International Monitoring System use some variant of a multiple-inlet pipe system for wind-noise suppression. These pipe systems have a significant impact on the overall frequency response of the element. The spatial distribution of acoustic inlets introduces a response dependence that is a function of frequency and of vertical and horizontal arrival angle; the system of inlets, pipes, and summing junctions further shapes that response as the signal is ducted to the transducer. In-situ measurements, using a co-located reference microphone, can determine the overall frequency response and diagnose problems with the system. As of July 2011, the in-situ frequency responses for 25 individual elements at 6 operational stations (I10, I53, I55, I56, I57, and I99) have been measured. In support of these measurements, a fully thermo-viscous model for the acoustics of these multiple-inlet pipe systems has been developed. In addition to measurements at operational stations, comparative analyses have been done on experimental systems: a multiple-inlet radial-pipe system with varying inlet hole size; a one-quarter scale model of a 70-meter rosette system; and vertical directionality of a small rosette system using aircraft flyovers. [Funded by the US Army Space and Missile Defense Command

  18. An Offline-Online Android Application for Hazard Event Mapping Using WebGIS Open Source Technologies

    NASA Astrophysics Data System (ADS)

    Olyazadeh, Roya; Jaboyedoff, Michel; Sudmeier-Rieux, Karen; Derron, Marc-Henri; Devkota, Sanjaya

    2016-04-01

    Nowadays, Free and Open Source Software (FOSS) plays an important role in better understanding and managing disaster risk reduction around the world. National and local government, NGOs and other stakeholders are increasingly seeking and producing data on hazards. Most of the hazard event inventories and land use mapping are based on remote sensing data, with little ground truthing, creating difficulties depending on the terrain and accessibility. Open Source WebGIS tools offer an opportunity for quicker and easier ground truthing of critical areas in order to analyse hazard patterns and triggering factors. This study presents a secure mobile-map application for hazard event mapping using Open Source WebGIS technologies such as Postgres database, Postgis, Leaflet, Cordova and Phonegap. The objectives of this prototype are: 1. An Offline-Online android mobile application with advanced Geospatial visualisation; 2. Easy Collection and storage of events information applied services; 3. Centralized data storage with accessibility by all the service (smartphone, standard web browser); 4. Improving data management by using active participation in hazard event mapping and storage. This application has been implemented as a low-cost, rapid and participatory method for recording impacts from hazard events and includes geolocation (GPS data and Internet), visualizing maps with overlay of satellite images, viewing uploaded images and events as cluster points, drawing and adding event information. The data can be recorded in offline (Android device) or online version (all browsers) and consequently uploaded through the server whenever internet is available. All the events and records can be visualized by an administrator and made public after approval. Different user levels can be defined to access the data for communicating the information. This application was tested for landslides in post-earthquake Nepal but can be used for any other type of hazards such as flood, avalanche

  19. Spatial rainfall data in open source environment

    NASA Astrophysics Data System (ADS)

    Schuurmans, Hanneke; Maarten Verbree, Jan; Leijnse, Hidde; van Heeringen, Klaas-Jan; Uijlenhoet, Remko; Bierkens, Marc; van de Giesen, Nick; Gooijer, Jan; van den Houten, Gert

    2013-04-01

    Since January 2013 The Netherlands have access to innovative high-quality rainfall data that is used for watermanagers. This product is innovative because of the following reasons. (i) The product is developed in a 'golden triangle' construction - corporation between government, business and research. (ii) Second the rainfall products are developed according to the open-source GPL license. The initiative comes from a group of water boards in the Netherlands that joined their forces to fund the development of a new rainfall product. Not only data from Dutch radar stations (as is currently done by the Dutch meteorological organization KNMI) is used but also data from radars in Germany and Belgium. After a radarcomposite is made, it is adjusted according to data from raingauges (ground truth). This results in 9 different rainfall products that give for each moment the best rainfall data. Specific knowledge is necessary to develop these kind of data. Therefore a pool of experts (KNMI, Deltares and 3 universities) participated in the development. The philosophy of the developers (being corporations) is that products like this should be developed in open source. This way knowledge is shared and the whole community is able to make suggestions for improvement. In our opinion this is the only way to make real progress in product development. Furthermore the financial resources of government organizations are optimized. More info (in Dutch): www.nationaleregenradar.nl

  20. Using Citizen Science and Crowdsourcing via Aurorasaurus as a Near Real Time Data Source for Space Weather Applications

    NASA Astrophysics Data System (ADS)

    MacDonald, E.; Heavner, M.; Hall, M.; Tapia, A.; Lalone, N.; Clayon, J.; Case, N.

    2014-12-01

    Aurorasaurus is on the cutting edge of space science, citizen science, and computer science simultaneously with the broad goals to develop a real-time citizen science network, educate the general public about the northern lights, and revolutionize real-time space weather nowcasting of the aurora for the public. We are currently in the first solar maximum with social media, which enables the technological roots to connect users, citizen scientists, and professionals around a shared global, rare interest. We will introduce the project which has been in a prototype mode since 2012 and recently relaunched with a new mobile and web presence and active campaigns. We will showcase the interdisciplinary advancements which include a more educated public, disaster warning system applications, and improved real-time ground truth data including photographs and observations of the Northern Lights. We will preview new data which validates the proof of concept for significant improvements in real-time space weather nowcasting. Our aim is to provide better real-time notifications of the visibility of the Northern Lights to the interested public via the combination of noisy crowd-sourced ground truth with noisy satellite-based predictions. The latter data are available now but are often delivered with significant jargon and uncertainty, thus reliable, timely interpretation of such forecasts by the public are problematic. The former data show real-time characteristic significant rises (in tweets for instance) that correlate with other non-real-time indices of auroral activity (like the Kp index). We will discuss the source of 'noise' in each data source. Using citizen science as a platform to provide a basis for deeper understanding is one goal; secondly we want to improve understanding of and appreciation for the dynamics and beauty of the Northern Lights by the public and scientists alike.

  1. Estimating the detection capability of the International Monitoring System infrasound network

    NASA Astrophysics Data System (ADS)

    Green, D. N.; Bowers, D.

    2010-09-01

    A 59 station infrasound network is being established as part of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty. We present a probabilistic model for predicting the network detection threshold (defined as the chemical explosive yield at which two stations will detect signals with 90% probability). We incorporate the influence of stratospheric wind and detection bandwidth while accounting for estimates of noise amplitude and propagation uncertainties. Inclusion of the stratospheric wind, using a state-of-the-art climatological model, tends to reduce the detection threshold. For 66%/88% of Earth's surface area the detection threshold is lower than that expected for the windless case for all/≥90% of the time. However, preferential downwind detection makes location of explosions with yields close to the threshold more difficult due to the restricted azimuthal coverage. Completing the IMS network is also important: the detection threshold for the 39 station network operating in October 2008 is approximately 45% higher than that predicted for the full 59 station network. Moreover, the absolute detection threshold values are highly sensitive to the frequency band in which the noise is evaluated. A detector simulation comprising overlapping two-octave frequency bands indicates that, when accounting for low noise at frequencies above 0.2 Hz, detection capability at low yields (<0.5 kt) may be considerably better than previously estimated. Our simulations, using a two-octave bandwidth detector and incorporating stratospheric winds from a climatological model, predict that explosions of >210 t chemical explosive (>420 t nuclear equivalent yield) will be detected over ≥95% of Earth's surface at any time of year (with a 90% probability).

  2. Brief bursts of infrasound may improve cognitive function--an fMRI study.

    PubMed

    Weichenberger, Markus; Kühler, Robert; Bauer, Martin; Hensel, Johannes; Brühl, Rüdiger; Ihlenfeld, Albrecht; Ittermann, Bernd; Gallinat, Jürgen; Koch, Christian; Sander, Tilmann; Kühn, Simone

    2015-10-01

    At present, infrasound (sound frequency < 20 Hz; IS) is being controversially discussed as a potential mediator of several adverse bodily as well as psychological effects. However, it remains unclear, if and in what way IS influences cognition. Here, we conducted an fMRI experiment, in which 13 healthy participants were exposed to IS, while cognitive performance was assessed in an n-back working memory paradigm. During the task, short sinusoidal tone bursts of 12 Hz were administered monaurally with sound pressure levels that had been determined individually in a categorical loudness scaling session prior to the fMRI experiment. We found that task execution was associated with a significant activation of the prefrontal and the parietal cortex, as well as the striatum and the cerebellum, indicating the recruitment of a cognitive control network. Reverse contrast analysis (n-back with tone vs. n-back without tone) revealed a significant activation of the bilateral primary auditory cortex (Brodmann areas 41, 42). Surprisingly, we also found a strong, yet non-significant trend for an improvement of task performance during IS exposure. There was no correlation between performance and brain activity measures in tone and no-tone condition with sum scores of depression-, anxiety-, and personality factor assessment scales (BDI, STAIX1/X2, BFI-S). Although exerting a pronounced effect on cortical brain activity, we obtained no evidence for an impairment of cognition due to brief bursts of IS. On the contrary, potential improvement of working memory function introduces an entirely new aspect to the debate on IS-related effects. PMID:26260309

  3. The foodscape: classification and field validation of secondary data sources across urban/rural and socio-economic classifications in England

    PubMed Central

    2012-01-01

    Background In recent years, alongside the exponential increase in the prevalence of overweight and obesity, there has been a change in the food environment (foodscape). This research focuses on methods used to measure and classify the foodscape. This paper describes the foodscape across urban/rural and socio-economic divides. It examines the validity of a database of food outlets obtained from Local Authority sources (secondary level & desk based), across urban/rural and socio-economic divides by conducting fieldwork (ground-truthing). Additionally this paper tests the efficacy of using a desk based classification system to describe food outlets, compared with ground-truthing. Methods Six geographically defined study areas were purposively selected within North East England consisting of two Lower Super Output Areas (LSOAs; a small administrative geography) each. Lists of food outlets were obtained from relevant Local Authorities (secondary level & desk based) and fieldwork (ground-truthing) was conducted. Food outlets were classified using an existing tool. Positive predictive values (PPVs) and sensitivity analysis was conducted to explore validation of secondary data sources. Agreement between 'desk' and 'field' based classifications of food outlets were assessed. Results There were 438 food outlets within all study areas; the urban low socio-economic status (SES) area had the highest number of total outlets (n = 210) and the rural high SES area had the least (n = 19). Differences in the types of outlets across areas were observed. Comparing the Local Authority list to fieldwork across the geographical areas resulted in a range of PPV values obtained; with the highest in urban low SES areas (87%) and the lowest in Rural mixed SES (79%). While sensitivity ranged from 95% in the rural mixed SES area to 60% in the rural low SES area. There were no significant associations between field/desk percentage agreements across any of the divides. Conclusion Despite the

  4. Vehicular sources in acoustic propagation experiments

    NASA Technical Reports Server (NTRS)

    Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

    1990-01-01

    One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

  5. Characterization of volcanic activity using observations of infrasound, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Lopez, T.; Fee, D.; Prata, F.

    2012-04-01

    Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, with activity ranging from vigorous degassing, frequent ash emissions, and apparent vent sealing, all punctuated by daily to weekly explosive magmatic eruptions. Recent studies have highlighted the strengths in using complementary infrasound measurements and remote volcanic emission measurements to characterize volcanic activity, with the potential to discriminate emission-type, approximate ash-cloud height, and estimate SO2 emission mass. Here we use coincident measurements of infrasound, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only infrasound data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1 - 5 minutes that either jet or roil out of the vent, by plumes from 500 - 1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1 - 3 minutes, and by plumes from 300 - 1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude infrasound and occasionally visible shock

  6. Frequency and Size of Strombolian Eruptions from the Phonolitic Lava Lake at Erebus Volcano, Antarctica: Insights from Infrasound and Seismic Observations on Bubble Formation and Ascent

    NASA Astrophysics Data System (ADS)

    Rotman, H. M. M.; Kyle, P. R.; Fee, D.; Curtis, A.

    2015-12-01

    Erebus, an active intraplate volcano on Ross Island, commonly produces bubble burst Strombolian explosions from a long-lived, convecting phonolitic lava lake. Persistent lava lakes are rare, and provide direct insights into their underlying magmatic system. Erebus phonolite is H2O-poor and contains ~30% anorthoclase megacrysts. At shallow depths lab measurements suggest the magma has viscosities of ~107 Pa s. This has implications for magma and bubble ascent rates through the conduit and into the lava lake. The bulk composition and matrix glass of Erebus ejecta has remained uniform for many thousands of years, but eruptive activity varies on decadal and shorter time scales. Over the last 15 years, increased activity took place in 2005-2007, and more recently in the 2013 austral summer. In the 2014 austral summer, new infrasound sensors were installed ~700 m from the summit crater hosting the lava lake. These sensors, supplemented by the Erebus network seismic stations, recorded >1000 eruptions between 1 January and 7 April 2015, with an average infrasound daily uptime of 9.6 hours. Over the same time period, the CTBT infrasound station IS55, ~25 km from Erebus, detected ~115 of the >1000 locally observed eruptions with amplitude decreases of >100x. An additional ~200 eruptions were recorded during local infrasound downtime. This represents an unusually high level of activity from the Erebus lava lake, and while instrument noise influences the minimum observable amplitude each day, the eruption infrasound amplitudes may vary by ~3 orders of magnitude over the scale of minutes to hours. We use this heightened period of variable activity and associated seismic and acoustic waveforms to examine mechanisms for bubble formation and ascent, such as rise speed dependence and collapsing foam; repose times for the larger eruptions; and possible eruption connections to lava lake cyclicity.

  7. Ground truth data for test sites (SL-3). [solar radiation and thermal radiation brightness temperature measurements

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Field measurements performed simultaneously with Skylab overpasses in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. The solar radiation region from 400 to 1300 nanometers and the thermal radiation region from 8 to 14 micrometer region were investigated. The measurements of direct solar radiation were analyzed for atmospheric optical depth; the total and reflected solar radiation were analyzed for target reflectivity. These analyses were used in conjunction with a radiative transfer computer program in order to calculate the amount and spectral distribution of solar radiation at the apertures of the EREP sensors. The instrumentation and techniques employed, calibrations and analyses performed, and results obtained are discussed.

  8. Ground truth methods as a part of space mapping of inland water phytopigment dynamics

    NASA Astrophysics Data System (ADS)

    Shevyrnogov, A. P.; Sid'Ko, A. F.

    Spectral radiance and reflectance of the Krasnoyarsk reservoir water surface were studied from 1974 until 1989. Spectral brightness coefficient (SBC) curves have been found to record chlorophyll absorption band in the red part of the spectrum lambda = 680 nm and spectral indices of ``yellow matter'' absorption in the short-wave part lambda = 400-500 nm. Blue-green algae SBC curves record phycocyanine absorption peak at lambda_max = 630 mm. The peak is inherent in this type of algae only.

  9. Eltanin: Ground Truth for Kilometer-Sized Deep-Ocean Impacts (Invited)

    NASA Astrophysics Data System (ADS)

    Kyte, F. T.; Gersonde, R.; Kuhn, G.

    2009-12-01

    Deposits of the late Pliocene (2.5 Ma) Eltanin impact are unique in the known geological record. The only known example of a km-sized asteroid to impact a deep-ocean (5 km) basin, is the most meterorite-rich locality known on Earth. This was discovered as an Ir anomaly in sediments from three cores collected in the SE Pacific in 1965 by the USNS Eltanin. Subsequently, two expeditions of the R/V Polarstern in 1995 and 2001 have conducted geological and geophysical investigations in the impact region. An area of ~80,000 km2 has been mapped in some detail, and deposits from the impact are found in 23 cores spanning a region extending 660 (E-W) by 250 km (N-S). We find a central region 50 to 100 km across, near the Freeden Seamounts (57.3S, 90.5W), where sediments as old as Eocene have been ripped up (perhaps to basement) and redeposited by the impact into a chaotic mix of pebble to boulder-sized fragments. This is overlain by a fining upward sequence of sediments with laminations and some cross-bedding consistent with deposition in a high-energy flow regime. Near the top of this impact deposit, sub mm- to cm-sized meteoritic ejecta is mixed into the disturbed sediment. This ejecta is composed of 90% shock-melted asteroid and 10% unmelted meteorite fragments from the lo-metal mesosiderite asteroid. The amount of meteoritic ejecta in 13 cores from the central region record deposition of 3 to 50 kg of asteroid material per square meter. Km-sized impacts are fairly common on geological timescales, occurring a few times per m.y., so one or two other similar-sized, and several smaller projectiles likely hit the Pacific basin since the Late Pliocene. Undoubtedly, this is not the only such impact collected in deep-sea cores; it is unique only in that it has been recognized. Eltanin thus serves as type section for identifying ocean-impact deposits at other localities. Projectiles of this size cannot penetrate to the ocean floor and indeed there is no chemical evidence in the ejecta of mixing between asteroidal and terrestrial silicates. However, severe disturbance of of seafloor sediments over a wide region attest to the energy of this event. We have found no evidence of a physical “crater,” but it is conceivable that the water cavity formed by the impact extended to the bottom and could have even briefly exposed large areas of the seafloor. If deep-ocean impacts represent a significant hazard due to climate change or wave propagation, Eltanin could be a good test case if it’s effects can just be discerned outside the immediate impact region. The late Pliocene was a time of rapid climate change, but we have been unsuccessful at detecting Eltanin ejecta in high-resolution cores from the S. Atlantic. Unfortunately, the poor time-resolution in the Polarstern piston cores is insufficient to tie the impact to the O-isotope-based climate record. Perhaps the best chance would be to search for tsunami deposits. Models projecting the propagation of Eltanin-sized impact waves would be useful in evaluating the effects of this impact across the Pacific and other ocean basins.

  10. Design of the primary and secondary Pre-TRMM and TRMM ground truth sites

    NASA Technical Reports Server (NTRS)

    Garstang, Michael; Austin, Geoffrey; Cosgrove, Claire

    1991-01-01

    Results generated over six months are covered in five manuscripts: (1) estimates of rain volume over the Peninsula of Florida during the summer season based upon the Manually Digitized Radar data; (2) the diurnal characteristics of rainfall over Florida and over the near shore waters; (3) convective rainfall as measured over the east coast of central Florida; (4) the spatial and temporal variability of rainfall over Florida; and (5) comparisons between the land based radar and an optical raingage onboard an anchored buoy 50 km offshore.

  11. Experimental impact cratering provides ground truth data for understanding planetary-scale collision processes

    NASA Astrophysics Data System (ADS)

    Poelchau, Michael H.; Deutsch, Alex; Kenkmann, Thomas

    2013-04-01

    Impact cratering is generally accepted as one of the primary processes that shape planetary surfaces in the solar system. While post-impact analysis of craters by remote sensing or field work gives many insights into this process, impact cratering experiments have several advantages for impact research: 1) excavation and ejection processes can be directly observed, 2) physical parameters of the experiment are defined and can be varied, and 3) cratered target material can be analyzed post-impact in an unaltered, uneroded state. The main goal of the MEMIN project is to comprehensively quantify impact processes by conducting a stringently controlled experimental impact cratering campaign on the meso-scale with a multidisciplinary analytical approach. As a unique feature we use two-stage light gas guns capable of producing impact craters in the decimeter size-range in solid rocks that, in turn, allow detailed spatial analysis of petrophysical, structural, and geochemical changes in target rocks and ejecta. In total, we have carried out 24 experiments at the facilities of the Fraunhofer EMI, Freiburg - Germany. Steel, aluminum, and iron meteorite projectiles ranging in diameter from 2.5 to 12 mm were accelerated to velocities ranging from 2.5 to 7.8 km/s. Targets were solid rocks, namely sandstone, quartzite and tuff that were either dry or saturated with water. In the experimental setup, high speed framing cameras monitored the impact process, ultrasound sensors were attached to the target to record the passage of the shock wave, and special particle catchers were positioned opposite of the target surface to capture the ejected target and projectile material. In addition to the cratering experiments, planar shock recovery experiments were performed on the target material, and numerical models of the cratering process were developed. The experiments resulted in craters with diameters up to 40 cm, which is unique in laboratory cratering research. Target porosity exponentially reduces crater volumes and cratering efficiency relative to non-porous rocks, and also yields less steep ejecta angles. Microstructural analysis of the subsurface shows a zone of pervasive grain crushing and pore space reduction. This is in good agreement with new mesoscale numerical models, which are able to quantify localized shock pressure behavior in the target's pore space. Planar shock recovery experiments confirm these local pressure excursions, based on microanalysis of shock metamorphic features in quartz. Saturation of porous target rocks with water counteracts many of the effects of porosity. Post-impact analysis of projectile remnants shows that during mixing of projectile and target melts, the Fe of the projectile is preferentially partitioned into target melt to a greater degree than Ni and Co. We plan to continue evaluating the experimental results in combination with numerical models. These models help to quantify and evaluate cratering processes, while experimental data serve as benchmarks to validate the improved numerical models, thus helping to "bridge the gap" between experiments and nature. The results confirm and expand current crater scaling laws, and make an application to craters on planetary surfaces possible.

  12. Optimal spatial sampling techniques for ground truth data in microwave remote sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Rao, R. G. S.; Ulaby, F. T.

    1977-01-01

    The paper examines optimal sampling techniques for obtaining accurate spatial averages of soil moisture, at various depths and for cell sizes in the range 2.5-40 acres, with a minimum number of samples. Both simple random sampling and stratified sampling procedures are used to reach a set of recommended sample sizes for each depth and for each cell size. Major conclusions from statistical sampling test results are that (1) the number of samples required decreases with increasing depth; (2) when the total number of samples cannot be prespecified or the moisture in only one single layer is of interest, then a simple random sample procedure should be used which is based on the observed mean and SD for data from a single field; (3) when the total number of samples can be prespecified and the objective is to measure the soil moisture profile with depth, then stratified random sampling based on optimal allocation should be used; and (4) decreasing the sensor resolution cell size leads to fairly large decreases in samples sizes with stratified sampling procedures, whereas only a moderate decrease is obtained in simple random sampling procedures.

  13. Ground-Truthing Seismic Refraction Tomography for Sinkhole Detection in Florida

    NASA Astrophysics Data System (ADS)

    Hiltunen, D. R.; Hudyma, N.; Quigley, T. P.; Samakur, C.

    2007-12-01

    In order to provide effective return of storm water runoff to the subsurface aquifer, the Florida Department of Transportation (FDOT) constructs detention basins adjacent to its transportation facilities. These basins serve as a collection point for runoff within a local drainage area, and the overburden soil above the aquifer provides a natural filter for contaminants in the surface runoff water. However, the geologic setting for many of these basins in Florida is karst, limestone bedrock at shallow depth, and the concentration of water flow in these basins leads to frequent development of sinkholes. These sinkholes are an environmental hazard, as they provide a direct, open conduit for contaminant-laden runoff water to return to the aquifer rather than percolate through the overburden soil. Consequently, FDOT is keenly interested in all aspects of sinkholes, including factors leading to formation, methods of early detection, and effective methods for rapid repair. Recently, FDOT has engaged in a research effort to evaluate the capabilities of a wide range of geophysical investigation tools with regard to detection of sinkhole-prone areas within sites being considered for construction of detention ponds. The geophysical techniques evaluated have included ground penetrating radar (GPR), multi- electrode electrical resistivity (MER), seismic MASW, and seismic refraction tomography. In addition to geophysical testing at the research sites, extensive traditional geotechnical site characterization has been conducted, including boring and sampling of soil and rock, standard penetration tests (SPT), and cone penetration tests (CPT). The proposed paper will evaluate the capabilities of seismic refraction tomography. Comparisons between refraction tomograms and borehole logs, SPT soundings, and CPT soundings suggest that the refraction method can map the laterally-variable top of bedrock surface typical of karst terrane. During a recent ground proving exercise at the University of North Florida/University of Florida karstic limestone geophysical/ground proving test site in central Florida, the limestone bedrock surface was mapped along several survey lines using both intrusive and geophysical techniques. Analyses of site data revealed a highly erratic limestone bedrock surface. Analysis of seismic refraction data demonstrated that the refraction tomography software system was able to reveal the undulating bedrock surface. However, the tomography data revealed marked differences in the compression wave velocities at the top of the bedrock surface at various locations along one of the survey lines. Compression wave velocities were highest within slots or valleys and lowest at the tops of blocks or pinnacles. Ground proving via cone penetration tests and geotechnical borings appears to corroborate this finding, and demonstrates the importance of measuring multiple material parameters during site characterization activities in complex terrane. Finally, two sinkholes formed in the detention pond directly over two valley/bowl features after refraction testing was completed, demonstrating that refraction tomography has potential in identifying areas at risk for sinkhole development.

  14. Field experiment provides ground truth for surface nuclear magnetic resonance measurement

    USGS Publications Warehouse

    Knight, R.; Grunewald, E.; Irons, T.; Dlubac, K.; Song, Y.; Bachman, H.N.; Grau, B.; Walsh, D.; Abraham, J.D.; Cannia, J.

    2012-01-01

    The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governing the non-invasive Surface NMR (SNMR) technology. We acquired both SNMR data and logging NMR data at a field site, along with lithology information from drill cuttings. This allowed us to directly compare the NMR relaxation parameter measured during logging, T 2, to the relaxation parameter T 2 * measured using the SNMR method. The latter can be affected by inhomogeneity in the magnetic field, thus obscuring the link between the NMR relaxation parameter and the hydraulic conductivity of the geologic material. When the logging T 2 data were transformed to pseudo-T 2 * data, by accounting for inhomogeneity in the magnetic field and instrument dead time, we found good agreement with T 2 * obtained from the SNMR measurement. These results, combined with the additional information about lithology at the site, allowed us to delineate the physical mechanisms governing the SNMR measurement. Such understanding is a critical step in developing SNMR as a reliable geophysical method for the assessment of groundwater resources. Copyright 2012 by the American Geophysical Union.

  15. Intrepid: Lunar Roving Prospector — Providing Ground Truth and Enabling Future Exporation

    NASA Astrophysics Data System (ADS)

    Robinson, M. S.; Lawrence, S. J.; Speyerer, E. J.; Stopar, J. D.

    2014-10-01

    We propose a long range lunar roving prospector, Intrepid, to collect essential measurements to address key questions and demonstrate technologies required for future robotic and human exploration of the Moon, Mars, and other terrestrial bodies.

  16. Liberal or Conservative: Evaluation and Classification with Distribution as Ground Truth

    ERIC Educational Resources Information Center

    Zhou, Daniel Xiaodan

    2013-01-01

    The ability to classify the political leaning of a large number of articles and items is valuable to both academic research and practical applications. The challenge, though, is not only about developing innovative classification algorithms, which constitutes a "classifier" theme in this thesis, but also about how to define the…

  17. Skylab program earth resources experiment package: Ground truth data for test sites (SL-2)

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Field measurements were performed at selected ground sites in order to provide comparative calibration measurements of sensors for the Earth Resources Experiment Package. Specifically, the solar radiation (400 to 1300 namometers) and thermal radiation (8-14 micrometers) were measured. Sites employed for the thermal measurements consisted of warm and cold water lakes. The thermal brightness temperature of the lake water, the temperature and humidity profile above the lake, and near surface meteorology (wind speed, pressure, etc.) were measured near the time of overpass. Sites employed for the solar radiation measurements were two desert type sites. Ground measurements consisted of: (1) direct solar radiation - optical depth; (2) diffuse solar radiation; (3) total solar radiation, (4) target directional (normal) reflectance; (5) target hemispherical reflectance; and (6) near surface meteorology.

  18. Ground-truthing evoked potential measurements against behavioral conditioning in the goldfish, Carassius auratus

    NASA Astrophysics Data System (ADS)

    Hill, Randy J.; Mann, David A.

    2005-04-01

    Auditory evoked potentials (AEPs) have become commonly used to measure hearing thresholds in fish. However, it is uncertain how well AEP thresholds match behavioral hearing thresholds and what effect variability in electrode placement has on AEPs. In the first experiment, the effect of electrode placement on AEPs was determined by simultaneously recording AEPs from four locations on each of 12 goldfish, Carassius auratus. In the second experiment, the hearing sensitivity of 12 goldfish was measured using both classical conditioning and AEP's in the same setup. For behavioral conditioning, the fish were trained to reduce their respiration rate in response to a 5 s sound presentation paired with a brief shock. A modified staircase method was used in which 20 reversals were completed for each frequency, and threshold levels were determined by averaging the last 12 reversals. Once the behavioral audiogram was completed, the AEP measurements were made without moving the fish. The recording electrode was located subdermally over the medulla, and was inserted prior to classical conditioning to minimize handling of animal. The same sound stimuli (pulsed tones) were presented and the resultant evoked potentials were recorded for 1000-6000 averages. AEP input-output functions were then compared to the behavioral audiogram to compare techniques for estimating behavioral thresholds from AEP data.

  19. Techniques of ground-truth measurements of desert-scrub structure

    NASA Technical Reports Server (NTRS)

    Ottermann, J.; Deering, D.; Eck, T.; Ringrose, S.

    1987-01-01

    Inversion of remote sensing data taken over a desert scrub surface in Texas with a multidirectionally viewing field radiometer, PARABOLA, yields the value of 0.12 for the protrusion parameter, s, (the projection on a vertical plane of plants per unit area) if isotropy (Lambert law) is assumed for the underlying soil. However, a significantly higher value of s, in the range 0.15 to 0.20, can be inferred if the soil is assumed anisotropic. It is concluded that in remote sensing of sparse vegetation, it is important to know the reflectance characteristics of the underlying soil. Other techniques that can be used to infer desert scrub vegetation structure include various photographic techniques, and measurements of reflected radiance from zenith for a range of solar elevation angles on a clear day.

  20. Gulf stream ground truth project - Results of the NRL airborne sensors

    NASA Technical Reports Server (NTRS)

    Mcclain, C. R.; Chen, D. T.; Hammond, D. L.

    1980-01-01

    Results of an airborne study of the waves in the Gulf Stream are presented. These results show that the active microwave sensors (high-flight radar and wind-wave radar) provide consistent and accurate estimates of significant wave height and surface wind speed, respectively. The correlation between the wave height measurements of the high-flight radar and a laser profilometer is excellent.

  1. AN ASSESSMENT OF GROUND TRUTH VARIABILITY USING A "VIRTUAL FIELD REFERENCE DATABASE"

    EPA Science Inventory



    A "Virtual Field Reference Database (VFRDB)" was developed from field measurment data that included location and time, physical attributes, flora inventory, and digital imagery (camera) documentation foy 1,01I sites in the Neuse River basin, North Carolina. The sampling f...

  2. The Dawn exploration of (4) Vesta as the `ground truth' to interpret asteroid polarimetry

    NASA Astrophysics Data System (ADS)

    Cellino, A.; Ammannito, E.; Magni, G.; Gil-Hutton, R.; Tedesco, E. F.; Belskaya, I. N.; De Sanctis, M. C.; Schröder, S.; Preusker, F.; Manara, A.

    2016-02-01

    The results of the in situ exploration of the asteroid (4) Vesta by the Dawn spacecraft open new perspectives in the field of interpretation of remote-sensing polarimetric measurements of asteroids. (4) Vesta has long been known to be the only asteroid exhibiting a cyclic variation of the degree of linear polarization of the sunlight scattered by its surface, with a period which is synchronous with the object's rotation. This variation must be the consequence of some heterogeneity of the asteroid's surface, including regions characterized by different albedo, or composition, or regolith properties, or a combination of the above features. For a long time, this kind of conclusion has remained essentially qualitative. Now, after the extensive exploration of Vesta's surface by Dawn, it is possible to interpret the data set of polarimetric measurements of Vesta, including some unpublished data presented here for the first time, in terms of a correspondence between the degree of linear polarization and the variation of local properties of the surface visible to ground-based observers during Vesta's rotation, as seen at different epochs and under different illumination conditions. This makes it possible to refine our knowledge of the empirical relation between polarization properties and albedo, which is commonly used to derive the albedo from remote-sensing measurements of linear polarization of atmosphereless Solar system bodies.

  3. Soils maps supplement to soil moisture ground truth, Lafayette, Indiana, site St. Charles, Missouri, site

    NASA Technical Reports Server (NTRS)

    Jones, E. B.; Olt, S. E.

    1975-01-01

    A compilation of soils information obtained as the result of a library search of data on the Lafayette, Indiana, site and St. Charles, Missouri, site is presented. Soils data for the Lafayette, Indiana, site are shown in Plates 1 and 2; and soils data for the St. Charles, Missouri, site are shown in Plates 3 and 4.

  4. Ground Truthing the ‘Conventional Wisdom’ of Lead Corrosion Control Using Mineralogical Analysis

    EPA Science Inventory

    For drinking water distribution systems (DWDS) with lead-bearing plumbing materials some form of corrosion control is typically necessary, with the goal of mitigating lead release by forming adherent, stable corrosion scales composed of low-solubility mineral phases. Conventional...

  5. Ground Truthing the 'Conventional Wisdom' of Lead Corrosion Control Using Mineralogical Analysis

    EPA Science Inventory

    For drinking water distribution systems (DWDS) with lead-bearing plumbing materials some form of corrosion control is typically necessary, with the goal of mitigating lead release by forming adherent, stable corrosion scales composed of low-solubility mineral phases. Conventional...

  6. Completing a Ground Truth View of the Global Heliosphere: What Does IMAP Tell Us?

    NASA Astrophysics Data System (ADS)

    Matthaeus, W. H.

    2014-12-01

    Recent and planned advances in heliospheric research promise to provide for the first time a fairly complete picture of the processes that shape the Geospace environment and the Heliospheric envelope that defines the magnetic and plasma neighborhood of the Sun. The upcoming Solar Orbiter and Solar probe Plus missions will vastly extend our knowledge of the inner heliospheric drivers that impact the entire system. However to develop understanding of energy and particle transport that controls the Geospace plasma and radiation envirionment, it is necessary to maintain an accurate monitoring of the plasma and electromagnetic properties of the solar wind near 1 AU. To complete understanding of the Heliosphere we must also extend understanding of energy and plasma transport to regions beyond 1 AU and throughout the Heliosphere. This understanding will complete the connection between the the corona, the 1AU environment and the outer boundaries recently explored by the Voyagers and IBEX. This talk will focus on the linkages between inner heliosphere, the Geospace environment and the outer heliosphere, with an emphasis on what an L1 monitor such as IMAP can provde for the next decade of great discoveries in space physics.

  7. Objective evaluation of reconstruction methods for quantitative SPECT imaging in the absence of ground truth

    PubMed Central

    Jha, Abhinav K.; Song, Na; Caffo, Brian; Frey, Eric C.

    2015-01-01

    Quantitative single-photon emission computed tomography (SPECT) imaging is emerging as an important tool in clinical studies and biomedical research. There is thus a need for optimization and evaluation of systems and algorithms that are being developed for quantitative SPECT imaging. An appropriate objective method to evaluate these systems is by comparing their performance in the end task that is required in quantitative SPECT imaging, such as estimating the mean activity concentration in a volume of interest (VOI) in a patient image. This objective evaluation can be performed if the true value of the estimated parameter is known, i.e. we have a gold standard. However, very rarely is this gold standard known in human studies. Thus, no-gold-standard techniques to optimize and evaluate systems and algorithms in the absence of gold standard are required. In this work, we developed a no-gold-standard technique to objectively evaluate reconstruction methods used in quantitative SPECT when the parameter to be estimated is the mean activity concentration in a VOI. We studied the performance of the technique with realistic simulated image data generated from an object database consisting of five phantom anatomies with all possible combinations of five sets of organ uptakes, where each anatomy consisted of eight different organ VOIs. Results indicate that the method provided accurate ranking of the reconstruction methods. We also demonstrated the application of consistency checks to test the no-gold-standard output. PMID:26430292

  8. Grid-Search Location Methods for Ground-Truth Collection From Local and Regional Seismic Networks

    SciTech Connect

    William Rodi; Craig A. Schultz; Gardar Johannesson; Stephen C. Myers

    2005-05-13

    This project investigated new techniques for improving seismic event locations derived from regional and local networks. The technqiues include a new approach to empirical travel-time calibration that simultaneously fits data from multiple stations and events, using a generalization of the kriging method, and predicts travel-time corrections for arbitrary event-station paths. We combined this calibration approach with grid-search event location to produce a prototype new multiple-event location method that allows the use of spatially well-distributed events and takes into account correlations between the travel-time corrections from proximate event-station paths. Preliminary tests with a high quality data set from Nevada Test Site explosions indicated that our new calibration/location method offers improvement over the conventional multiple-event location methods now in common use, and is applicable to more general event-station geometries than the conventional methods. The tests were limited, however, and further research is needed to fully evaluate, and improve, the approach. Our project also demonstrated the importance of using a realistic model for observational errors in an event location procedure. We took the initial steps in developing a new error model based on mixture-of-Gaussians probability distributions, which possess the properties necessary to characterize the complex arrival time error processes that can occur when picking low signal-to-noise arrivals. We investigated various inference methods for fitting these distributions to observed travel-time residuals, including a Markov Chain Monte Carlo technique for computing Bayesian estimates of the distribution parameters.

  9. WFST-based ground truth alignment for difficult historical documents with text modification and layout variations

    NASA Astrophysics Data System (ADS)

    Al Azawi, Mayce; Liwicki, Marcus; Breuel, Thomas M.

    2013-01-01

    This work proposes several approaches that can be used for generating correspondences between real scanned books and their transcriptions which might have different modifications and layout variations, also taking OCR errors into account. Our approaches for the alignment between the manuscript and the transcription are based on weighted finite state transducers (WFST). In particular, we propose adapted WFSTs to represent the transcription to be aligned with the OCR lattices. The character-level alignment has edit rules to allow edit operations (insertion, deletion, substitution). Those edit operations allow the transcription model to deal with OCR segmentation and recognition errors, and also with the task of aligning with different text editions. We implemented an alignment model with a hyphenation model, so it can adapt the non-hyphenated transcription. Our models also work with Fraktur ligatures, which are typically found in historical Fraktur documents. We evaluated our approach on Fraktur documents from Wanderungen durch die Mark Brandenburg" volumes (1862-1889) and observed the performance of those models under OCR errors. We compare the performance of our model for three different scenarios: having no information about the correspondence at the word (i), line (ii), sentence (iii) or page (iv) level.

  10. Inter-Vehicular Ad Hoc Networks: From the Ground Truth to Algorithm Design and Testbed Architecture

    ERIC Educational Resources Information Center

    Giordano, Eugenio

    2011-01-01

    Many of the devices we interact with on a daily basis are currently equipped with wireless connectivity. Soon this will be extended to the vehicles we drive/ride every day. Wirelessly connected vehicles will form a new kind of network that will enable a wide set of innovative applications ranging from enhanced safety to entertainment. To…

  11. Ground truth spectrometry and imagery of eruption clouds to maximize utility of satellite imagery

    NASA Technical Reports Server (NTRS)

    Rose, William I.

    1993-01-01

    Field experiments with thermal imaging infrared radiometers were performed and a laboratory system was designed for controlled study of simulated ash clouds. Using AVHRR (Advanced Very High Resolution Radiometer) thermal infrared bands 4 and 5, a radiative transfer method was developed to retrieve particle sizes, optical depth and particle mass involcanic clouds. A model was developed for measuring the same parameters using TIMS (Thermal Infrared Multispectral Scanner), MODIS (Moderate Resolution Imaging Spectrometer), and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). Related publications are attached.

  12. Airborne multi-spectral remote sensing with ground truth for areawide pest management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scientists and researchers have been developing, integrating, and evaluating multiple strategies and technologies into a systems approach for management of field crop insect pests. Remote sensing along with Global Positioning Systems, Geographic Information Systems, and variable rate technology are...

  13. Airborne multispectral remote sensing with ground truth for areawide pest management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Scientists and engineers in areawide pest management programs have been developing, integrating, and evaluating multiple strategies and technologies into a systems approach for management of field crop insect pests. Remote sensing along with global positioning systems, geographic information system...

  14. Ground truth report 1975 Phoenix microwave experiment. [Joint Soil Moisture Experiment

    NASA Technical Reports Server (NTRS)

    Blanchard, B. J.

    1975-01-01

    Direct measurements of soil moisture obtained in conjunction with aircraft data flights near Phoenix, Arizona in March, 1975 are summarized. The data were collected for the Joint Soil Moisture Experiment.

  15. Objective evaluation of reconstruction methods for quantitative SPECT imaging in the absence of ground truth

    NASA Astrophysics Data System (ADS)

    Jha, Abhinav K.; Song, Na; Caffo, Brian; Frey, Eric C.

    2015-03-01

    Quantitative single-photon emission computed tomography (SPECT) imaging is emerging as an important tool in clinical studies and biomedical research. There is thus a need for optimization and evaluation of systems and algorithms that are being developed for quantitative SPECT imaging. An appropriate objective method to evaluate these systems is by comparing their performance in the end task that is required in quantitative SPECT imaging, such as estimating the mean activity concentration in a volume of interest (VOI) in a patient image. This objective evaluation can be performed if the true value of the estimated parameter is known, i.e. we have a gold standard. However, very rarely is this gold standard known in human studies. Thus, no-gold-standard techniques to optimize and evaluate systems and algorithms in the absence of gold standard are required. In this work, we developed a no-gold-standard technique to objectively evaluate reconstruction methods used in quantitative SPECT when the parameter to be estimated is the mean activity concentration in a VOI. We studied the performance of the technique with realistic simulated image data generated from an object database consisting of five phantom anatomies with all possible combinations of five sets of organ uptakes, where each anatomy consisted of eight different organ VOIs. Results indicate that the method pro- vided accurate ranking of the reconstruction methods. We also demonstrated the application of consistency checks to test the no-gold-standard output.

  16. Ground truth data for test sites (SL-4). [thermal radiation brightness temperature and solar radiation measurments

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Field measurements performed simultaneous with Skylab overpass in order to provide comparative calibration and performance evaluation measurements for the EREP sensors are presented. Wavelength region covered include: solar radiation (400 to 1300 nanometer), and thermal radiation (8 to 14 micrometer). Measurements consisted of general conditions and near surface meteorology, atmospheric temperature and humidity vs altitude, the thermal brightness temperature, total and diffuse solar radiation, direct solar radiation (subsequently analyzed for optical depth/transmittance), and target reflectivity/radiance. The particular instruments used are discussed along with analyses performed. Detailed instrument operation, calibrations, techniques, and errors are given.

  17. Man and the Biosphere: Ground Truthing Coral Reefs for the St. John Island Biosphere Reserve.

    ERIC Educational Resources Information Center

    Brody, Michael J.; And Others

    Research on the coral species composition of St. John's reefs in the Virgin Islands was conducted through the School for Field Studies (SFS) Coral Reef Ecology course (winter 1984). A cooperative study program based on the United Nations Educational, Scientific, and Cultural Organization's (Unesco) program, Man and the Biosphere, was undertaken by…

  18. Operation of an array of field-change detectors to provide ground truth for FORTE data

    SciTech Connect

    Massey, R.S.; Eack, K.B.; Eberle, M.H.; Shao, X.M.; Smith, D.A.; Wiens, K.C.

    1999-06-01

    The authors have deployed an array of fast electric-field-change sensors around the state of New Mexico to help identify the lightning processes responsible for the VHF RF signals detected by the FORTE satellite`s wide-band transient radio emission receivers. The array provides them with locations and electric-field waveforms for events within New Mexico and into surrounding states, and operates continuously. They are particularly interested in events for which there are coincident FORTE observations. For these events, they can correct both the array and FORTE waveforms for time of flight, and can plot the two waveforms on a common time axis. Most of the coincident events are from cloud-go-ground discharges, but the most powerful are from a little-studied class of events variously called narrow bipolar events and compact intra-cloud discharges. They have therefore focused their attention on these events whether or not FORTE was in position to observe them.

  19. SU-E-J-42: Customized Deformable Image Registration Using Open-Source Software SlicerRT

    SciTech Connect

    Gaitan, J Cifuentes; Chin, L; Pignol, J; Kirby, N; Pouliot, J; Lasso, A; Pinter, C; Fichtinger, G

    2014-06-01

    Purpose: SlicerRT is a flexible platform that allows the user to incorporate the necessary images registration and processing tools to improve clinical workflow. This work validates the accuracy and the versatility of the deformable image registration algorithm of the free open-source software SlicerRT using a deformable physical pelvic phantom versus available commercial image fusion algorithms. Methods: Optical camera images of nonradiopaque markers implanted in an anatomical pelvic phantom were used to measure the ground-truth deformation and evaluate the theoretical deformations for several DIR algorithms. To perform the registration, full and empty bladder computed tomography (CT) images of the phantom were obtained and used as fixed and moving images, respectively. The DIR module, found in SlicerRT, used a B-spline deformable image registration with multiple optimization parameters that allowed customization of the registration including a regularization term that controlled the amount of local voxel displacement. The virtual deformation field at the center of the phantom was obtained and compared to the experimental ground-truth values. The parameters of SlicerRT were then varied to improve spatial accuracy. To quantify image similarity, the mean absolute difference (MAD) parameter using Hounsfield units was calculated. In addition, the Dice coefficient of the contoured rectum was evaluated to validate the strength of the algorithm to transfer anatomical contours. Results: Overall, SlicerRT achieved one of the lowest MAD values across the algorithm spectrum, but slightly smaller mean spatial errors in comparison to MIM software (MIM). On the other hand, SlicerRT created higher mean spatial errors than Velocity Medical Solutions (VEL), although obtaining an improvement on the DICE to 0.91. The large spatial errors were attributed to the poor contrast in the prostate bladder interface of the phantom. Conclusion: Based phantom validation, SlicerRT is capable of

  20. Finding, characterizing and classifying variable sources in multi-epoch sky surveys: QSOs and RR Lyraes in PS1 3Pi

    NASA Astrophysics Data System (ADS)

    Hernitschek, N.; Schlafly, E. F.; Sesar, B.; Rix, H.-W.; Hogg, D. W.; Ivezic, Z.; Grebel, E. K.

    2016-05-01

    We develop a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light-curve structure functions. Using PS1 data on SDSS Stripe 82 as "ground truth", a Random Forest Classifier identifies QSOs and RR Lyrae stars based on their variability and mean PS1 and WISE colors. We find that, aside from the Galactic plane, QSO and RR Lyrae samples of purity 75% and completeness 92% can be selected. On this completeness and purity basis we have identified a QSO candidate sample of a million objects, including many at low latitudes. We have assembled an unprecedentedly large and deep sample of 150 000 likely RR Lyrae candidates, with distances from 10 kpc to 120 kpc. We provide a catalog of 2.6 x 107 likely variable point sources. This work illustrates the power of time- domain surveys to identify variable objects and opens up enormous follow-up possibilities.

  1. Infrasound and Seismic Observation of the Hayabusa Reentry: Burst Signals and Air-to-Ground Coupling Process

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Hiramatsu, Y.; Yamamoto, M.; Furumoto, M.; Fujita, K.

    2012-12-01

    The Hayabusa, the world's first sample-return minor body explorer, reentered the Earth's atmosphere on June 13, 2010. This was the third direct reentry event from the interplanetary transfer orbit to the Earth at a velocity of over 11.2 km/s, and was the world's first case of a direct reentry of the spacecraft itself from the interplanetary transfer orbit. This was the very good and rare opportunity to study bolide class meteor phenomena by various aspects. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area, Australia (Fujita et al., 2011). The observations were configured with optical imaging, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations (GOS2, GOS2A, and GOS2B), we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations (GOS2B-sub1, to GOS2B-sub3) (Yamamoto et al., 2011; Ishihara et al., 2012). The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa sample return capsule (Ishihara et al., 2012). In addition, following capsule signal, lots of signals that probably correspond shockwave from disrupted fragments of spacecraft and energetic bursts of the spacecraft were also recorded (Yamamoto et al., 2011). In this study, we analyze signals generated by hypersonic motion of the disrupted fragments and energetic burst of the spacecraft. In addition, we examine the air-to-ground coupling process by comparing the waveforms computed by finite difference scheme with the actual ones. At all three arrayed main stations, after the capsule's shockwave arrival, we detect multiple shockwave signals by both infrasound and seismic sensors. For some of these signals arrive within 10 seconds after capsule's signal, we can identify one to one correspondence with optically tracked disrupted fragments of the spacecraft. Far after the capsule's signal, we also detect some arrivals of wave

  2. On the development and testing of a database-centric pipeline for the analysis of a regional infrasound network

    NASA Astrophysics Data System (ADS)

    Marcillo, O. E.; Blom, P. S.; Euler, G. G.; MacCarthy, J.; Park, J.; Stump, B. W.; Hayward, C.; Dannemann, F. K.

    2015-12-01

    We are developing a database-centric pipeline for the analysis of data from a regional network of infrasound arrays. The pipeline includes analysis at station and network levels (using beam-forming and clustering techniques, respectively) for the detection, association and location of events. The pipeline relies on the interaction of the algorithms with a relational database structure to organize and store waveform data, the parameters for the analysis, and results of both levels of analysis. Our implementation can interact seamlessly with traditional (e.g.: Oracle) and serverless (e.g.: SQLite) relational databases. Data from nine infrasonic arrays co-located with University of Utah Seismograph Stations, three additional arrays in Nevada, operated by Southern Methodist University, and IMS arrays at IS56 in Washington State and IS57 in California are used to test the operation of the pipeline, the algorithms, and the sensitivity of the results to the parameters of the analysis

  3. The fall of the Grimsby meteorite—I: Fireball dynamics and orbit from radar, video, and infrasound records

    NASA Astrophysics Data System (ADS)

    Brown, P.; McCausland, P. J. A.; Fries, M.; Silber, E.; Edwards, W. N.; Wong, D. K.; Weryk, R. J.; Fries, J.; Krzeminski, Z.

    2011-03-01

    The Grimsby meteorite (H4-06) fell on September 25, 2009. As of mid-2010, 13 fragments totaling 215 g have been recovered. Records of the accompanying fireball from the Southern Ontario Meteor Network, including six all-sky video cameras, a large format CCD, infrasound and radar records, have been used to characterize the trajectory, speed, orbit, and initial mass of the meteoroid. From the four highest quality all-sky video records, the initial entry velocity was 20.91 ± 0.19 km s-1 while the derived radiant has a local azimuth of 309.40° ± 0.19° and entry angle of 55.20° ± 0.13°. Three major fragmentation episodes are identified at 39, 33, and 30 km height, with corresponding uncertainties of approximately 2 km. Evidence for early fragmentation at heights of approximately 70 km is found in radar data; dynamic pressure of this earliest fragmentation is near 0.1 MPa while the main flare at 39 km occurred under ram pressures of 1.5 MPa. The fireball was luminous to at least 19.7 km altitude and the dynamic mass estimate of the largest remaining fragment at this height is approximately several kilograms. The initial mass is constrained to be <100 kg from infrasound data and ablation modeling, with a most probable mass of 20-050 kg. The preatmospheric orbit is typical of an Apollo asteroid with a likely immediate origin in either the 3:1 or ν6 resonances.

  4. Classifying the Infrasonic Fingerprints of a Dynamic Volcanic System: A Quantitative Comparison of Optical and Infrasound Records at Villarrica Volcano, Chile.

    NASA Astrophysics Data System (ADS)

    Miller, A. J. C.; Palma, J.; Keller, W.; Johnson, J. B.

    2015-12-01

    On March 3, 2015 Villarrica Volcano underwent an abrupt change in volcanic behavior that culminated in a large fire fountaining event lasting 30 minutes that prompted the evacuation of residents within 9 km from the vent. This paroxysm was the first in 30 years and changed summit morphology by temporarily capping the previously stable lava lake with volcanic material. After March 3, Villarrica exhibited a period of quiescence before reactivating with various levels of ash venting associated with strombolian style activity. Ten infrasound arrays, each comprising three pressure transducers, were deployed in January and February that recorded until mid June and serendipitously chronicled the awakening, paroxysm, and recovery to a more open vent system typical to Villarrica. Coincidentally, several optical datasets were gathered. Time lapse photography, provided by Proyecto Observacion Villarrica Internet (POVI), recorded vent activity at an interval of ~15 seconds with a 240 mm zoom lens at 16 km from the vent, starting December 2014 until March 12, 2015. Additionally, video footage of the vent was recorded at 30 frames per second (fps) with a 50 mm lensed surveillance camera between March 4 and June of 2015 at a distance of 16 km from the vent. The combined infrasound and image processing approach offers novel insight into the various acoustic signatures of a dynamic and violent volcanic system. Video parameters, including plume color, ascent rate, and duration of venting are synthesized as time series. These video metrics of vent activity are then quantitatively compared to the corresponding infrasound waveform. The result is the classification of several different infrasound modes of activity during the diverse eruptive sequence of Villarrica between January and June of 2015.

  5. Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground source.

    NASA Astrophysics Data System (ADS)

    Averbuch, Gil; Price, Colin

    2015-04-01

    Lithosphere-Atmosphere coupling: Spectral element modeling of the evolution of acoustic waves in the atmosphere from an underground source. G. Averbuch, C. Price Department of Geosciences, Tel Aviv University, Israel Infrasound is one of the four Comprehensive Nuclear-Test Ban Treaty technologies for monitoring nuclear explosions. This technology measures the acoustic waves generated by the explosions followed by their propagation through the atmosphere. There are also natural phenomena that can act as an infrasound sources like sprites, volcanic eruptions and earthquakes. The infrasound waves generated from theses phenomena can also be detected by the infrasound arrays. In order to study the behavior of these waves, i.e. the physics of wave propagation in the atmosphere, their evolution and their trajectories, numerical methods are required. This presentation will deal with the evolution of acoustic waves generated by underground sources (earthquakes and underground explosions). A 2D Spectral elements formulation for lithosphere-atmosphere coupling will be presented. The formulation includes the elastic wave equation for the seismic waves and the momentum, mass and state equations for the acoustic waves in a moving stratified atmosphere. The coupling of the two media is made by boundary conditions that ensures the continuity of traction and velocity (displacement) in the normal component to the interface. This work has several objectives. The first is to study the evolution of acoustic waves in the atmosphere from an underground source. The second is to derive transmission coefficients for the energy flux with respect to the seismic magnitude and earth density. The third will be the generation of seismic waves from acoustic waves in the atmosphere. Is it possible?

  6. Seismoacoustic Signatures from Chelyabinsk Meteor Observed by the Kazakhstan Nuclear Explosion Monitoring Network (Invited)

    NASA Astrophysics Data System (ADS)

    Smirnov, A.; Mikhailova, N.; Garces, M. A.

    2013-12-01

    Infrasound and seismic stations of the Kazakhstan Nuclear Explosion Monitoring network recorded high-fidelity seismoacoustic signatures from the Chelyabinsk meteor. Infrasound array I31KZ in Aktyubinsk was the closest IMS infrasound station to the source. This station is in the Northwest Kazakhstan, approximately 520 km southward from the bolide blast. The propitious station position relative to the entry trajectory, coupled with calm weather during the event, permitted a detailed, broadband record of the bolide explosion. All eight I31KZ infrasound array channels show an extremely strong broadband signal at 03:48 UTC and a duration of ~20 minutes. Array processing of the signal with PMCC4 shows that signal contains unprecedented detail on the source characteristics. Another Kazakhstani infrasound array in Kurchatov, Northeast Kazakhstan, also recorded the explosion signals. This is third closest infrasound array to the source. The second one is Russian array I43RU, Dubna. Epicentral distances are 1090 km for Dubna and 1300 km for Kurchatov. Traveltimes are 26 minutes for I31KZ Aktyubinsk and 66 minutes for the Kurchatov array. In addition to infrasound arrays, Kazakhstani seismic arrays belonging to Institute of Geophysical Research also recorded the signals generated by the bolide. The epicentral seismic source location corresponds to the pressure shock wave ground impact, and is under the meteor hypercenter. The seismic signal was recorded by Akbulak, Borovoe, Karatau and Makanchy arrays and other Kazakhstani seismic stations. Akbulak was the station nearest to epicenter, at a range of 630 km southward. The estimated origin time of the seismic event following the bolide explosion is 03:21:59.64 GMT. The difference between ground truth time 3:20:33 GMT provided by NASA and the seismic origin time is in reasonable agreement with the reported hypercenter altitude range of 25-30 km asl. The seismic event had a body wave magnitude of Mb 3.5, with energy class K 8

  7. Methods to assess atmospheric emissions of persistent organic pollutants from point sources

    SciTech Connect

    Pacyna, J.M.; Thomas, D.; Horejs, J.

    1995-12-31

    A set of guidelines for estimating POP emissions from various sources is presented together with procedures for verification of emission data. The guidelines include a compilation of emission factors for various POPs together with information on the physical, chemical, technological, and meteorological conditions under which these factors were elaborated. The above information is presented for PCBs, PCP, HCB, selected dibenzodioxins and dibenzofurans and selected PAHs. An assessment of uncertainty in the estimation of emission factors is enclosed with classification based on the frequency and accuracy of emission measurements. Ground Truth verification procedure has been elaborated which involves techniques that make direct comparisons between emission estimates and some other known quantity which is related either directly to the emission source or indirectly to the underlying process that results in the emissions. POP profiles are presented for major source categories. Combustion of coal generates higher emissions of most of the studied POPs than the combustion of oil, gas, and fuel wood. This particularly applies to the emissions of PCBs and PCDDs/Fs during combustion of hard coal. In the emissions from the burning of fossil fuels there is a considerable content of PCDDs/Fs in comparison with their emissions from other sources. There is also a higher proportion of phenanthrene compared with other PAHs. During the combustion of industrial wastes, phenanthrene, fluoranthene, and pyrene are characteristically, significantly higher in the flue gas.

  8. Analysis of the acoustic conversion efficiency for infrasound from atmospheric entry of NEO`s

    SciTech Connect

    Whitaker, R.W.; ReVelle, D.O.

    1996-02-01

    ReVelle (1995) has recently presented a summary of available infrasonic signals from near earth objects (NEO`s) that entered the earth`s atmosphere between 1960-1980. We will analyze these signals using a formalism developed by Cox (1958) to calculate the energy of explosive sources in the atmosphere. For each source we will calculate the acoustic conversion efficiency for each source, i.e., the fraction of the original source energy that is available to couple into an acoustic wave. Based on results in Cox with conventional explosions, this quantity is expected to depend weakly on the range from the source. Since this quantity is difficult to estimate using fundamental blast wave theories, we instead use well-known, and independently calibrated, semi-empirical source energy-wave period (at maximum amplitude) scaling relations developed in the 1960-1975 period by the U.S. Air Force to determine the source energy, E{sub s}, from observations. Using E{sub s} and range to the source along with various observed signal and atmospheric properties, the efficiency can be computed, similar calculations have been done for other relevant atmospheric phenomena for low altitude sources. For example, thunder observations at relatively close range have been used by Few and co-workers to determine an acoustic conversion efficiency of about 0.4%. The only previous estimation for meteors was made by Astapovich (1946) who determined the acoustic efficiency to be less than 0.01%. By computing this efficiency factor we hope to predict the expected detection rate of large NEO`s for the proposed CTBT global scale infrasonic array systems, and to establish the rate of false alarms due to natural atmospheric explosions.

  9. Simultaneous localization of multiple broadband non-impulsive acoustic sources in an ocean waveguide using the array invariant.

    PubMed

    Gong, Zheng; Ratilal, Purnima; Makris, Nicholas C

    2015-11-01

    The array invariant method, previously derived for instantaneous range and bearing estimation of a single broadband impulsive source in a horizontally stratified ocean waveguide, can be generalized to simultaneously localize multiple uncorrelated broadband noise sources that are not necessarily impulsive in the time domain by introducing temporal pulse compression and an image processing technique similar to the Radon transform. This can be done by estimating the range and bearing of broadband non-impulsive sources from measured beam-time migration lines of modal arrivals along a horizontal array arising from differences in modal group velocity and modal polar angle for each propagating mode. The generalized array invariant approach is used to estimate the range of a vertical source array and vocalizing humpback whales over wide areas from measurements made by a towed horizontal receiver array during the Gulf of Maine 2006 Experiment. The localization results are shown to have roughly 12% root-mean-squared errors from Global Positioning System measured ground truth positions for controlled source transmissions and less than 10% discrepancy from those obtained independently via moving array triangulation for vocalizing humpbacks, respectively. PMID:26627743

  10. Tropical deep convection and density current signature in surface pressure: comparison between WRF model simulations and infrasound measurements

    NASA Astrophysics Data System (ADS)

    Costantino, L.; Heinrich, P.

    2013-06-01

    Deep convection is a major atmospheric transport process in the tropics, affecting the global weather and the climate system. In the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project, we combine model simulations of tropical deep convection with in-situ ground measurements, from a IMS (International Monitoring System) infrasound station in Ivory Coast, to analyse the effects of density current propagation. The WRF (Weather Research and Forecasting) model is firstly run in a simplified (referred to as "idealized case") and highly resolved configuration, to explicitly account for convective dynamics. Then, a coarser threedimensional simulation (referred to as "real") is nudged towards meteorological re-analysis data, to compare the real case with the idealized model and in-situ observations. In the 2-D run, the evolution of a deep convective cloud generates a density current, that moves outward up to 30 km away from storm center. The increase in surface density (up to 18 g m-3 larger than surrounding air) is mostly due to the sudden temperature decrease (down to -2 °C, with respect to domain averaged value), from diabatic cooling by rain evaporation near ground level. It is accompanied by a dramatic decrease in relative humidity (down to -50%), buoyancy (down to -0.08 m s-2), equivalent potential temperature (25 °C lower than the PBL) and the rapid enhancement of horizontal wind speed (up to 15 m s-2). If temperature and density changes are strong enough, surface pressure gets largely affected and high frequency disturbances (up to several tens of Pa) can be detected, at the leading edges of density current. The moister and warmer air of subcloud layer is lifted up and replaced by a more stable flow. The resulting thermodynamical instabilities are shown to play a key role in triggering new convection. If the initial environment is sufficiently unstable, they can give rise to continuous updrafts that may lead to the transition

  11. Tropical deep convection and density current signature in surface pressure: comparison between WRF model simulations and infrasound measurements

    NASA Astrophysics Data System (ADS)

    Costantino, L.; Heinrich, P.

    2014-03-01

    Deep convection is a major atmospheric transport process in the tropics, affecting the global weather and the climate system. In the framework of the ARISE (Atmospheric dynamics Research InfraStructure in Europe) project, we combine model simulations of tropical deep convection with in situ ground measurements from an IMS (International Monitoring System) infrasound station in the Ivory Coast to analyze the effects of density current propagation. The WRF (Weather Research and Forecasting) model is firstly run in a simplified (referred to as "idealized case") and highly resolved configuration to explicitly account for convective dynamics. Then, a coarser three-dimensional simulation (referred to as "real") is nudged towards meteorological reanalysis data in order to compare the real case with the idealized model and in situ observations. In the 2-D run, the evolution of a deep convective cloud generates a density current that moves outward up to 30 km away from storm center. The increase in surface density (up to 18 g m-3 larger than surrounding air) is mostly due to the sudden temperature decrease (down to -2 °C, with respect to the domain-averaged value) from diabatic cooling by rain evaporation near ground level. It is accompanied by a dramatic decrease in relative humidity (down to -50%), buoyancy (down to -0.08 m s-2), equivalent potential temperature (25 °C lower than the planetary boundary layer (PBL)) and the rapid enhancement of horizontal wind speed (up to 15 m s-2). If temperature and density changes are strong enough, surface pressure becomes largely affected and high-frequency disturbances (up to several tens of Pa) can be detected at the leading edges of density current. The moister and warmer air of subcloud layer is lifted up and replaced by a more stable flow. The resulting thermodynamical instabilities are shown to play a key role in triggering new convection. If the initial environment is sufficiently unstable, they can give rise to continuous

  12. Health-based audible noise guidelines account for infrasound and low-frequency noise produced by wind turbines.

    PubMed

    Berger, Robert G; Ashtiani, Payam; Ollson, Christopher A; Whitfield Aslund, Melissa; McCallum, Lindsay C; Leventhall, Geoff; Knopper, Loren D

    2015-01-01

    Setbacks for wind turbines have been established in many jurisdictions to address potential health concerns associated with audible noise. However, in recent years, it has been suggested that infrasound (IS) and low-frequency noise (LFN) could be responsible for the onset of adverse health effects self-reported by some individuals living in proximity to wind turbines, even when audible noise limits are met. The purpose of this paper was to investigate whether current audible noise-based guidelines for wind turbines account for the protection of human health, given the levels of IS and LFN typically produced by wind turbines. New field measurements of indoor IS and outdoor LFN at locations between 400 and 900 m from the nearest turbine, which were previously underrepresented in the scientific literature, are reported and put into context with existing published works. Our analysis showed that indoor IS levels were below auditory threshold levels while LFN levels at distances >500 m were similar to background LFN levels. A clear contribution to LFN due to wind turbine operation (i.e., measured with turbines on in comparison to with turbines off) was noted at a distance of 480 m. However, this corresponded to an increase in overall audible sound measures as reported in dB(A), supporting the hypothesis that controlling audible sound produced by normally operating wind turbines will also control for LFN. Overall, the available data from this and other studies suggest that health-based audible noise wind turbine siting guidelines provide an effective means to evaluate, monitor, and protect potential receptors from audible noise as well as IS and LFN. PMID:25759808

  13. Atmospheric pressure fluctuations in the far infrasound range and emergency transport events coded as circulatory system diseases

    NASA Astrophysics Data System (ADS)

    Didyk, L. A.; Gorgo, Yu. P.; Dirckx, J. J. J.; Bogdanov, V. B.; Buytaert, J. A. N.; Lysenko, V. A.; Didyk, N. P.; Vershygora, A. V.; Erygina, V. T.

    2008-09-01

    This study examines whether a relation exists between rapid atmospheric pressure fluctuations, attributed to the far infrasound frequency range (APF), and a number of emergency transport events coded as circulatory system diseases (EEC). Over an entire year, the average integral amplitudes of APF in the range of periods from 3 s to 120 s over each hour (HA) were measured. Daily dynamics of HA averaged over the year revealed a wave shape with smooth increase from night to day followed by decrease from day to night. The total daily number of EEC within the city of Kiev, Ukraine, was related to the daily mean of HA (DHA) and to the ratio of HA averaged over the day time to HA averaged over the night time (Rdn), and was checked for confounding effects of classical meteorological variables through non-parametric regression algorithms. The number of EEC were significantly higher on days with high DHA (3.72 11.07 Pa, n = 87) compared to the low DHA (0.7 3.62 Pa, n = 260, p = 0.01), as well at days with low Rdn (0.21 1.64, n = 229) compared to the high Rdn (1.65 7.2, n = 118, p = 0.03). A difference between DHA and Rdn effects on the emergency events related to different categories of circulatory diseases points to a higher sensitivity of rheumatic and cerebro-vascular diseases to DHA, and ischaemic and hypertensive diseases to Rdn. Results suggest that APF could be considered as a meteorotropic factor capable of influencing circulatory system diseases.

  14. Health-Based Audible Noise Guidelines Account for Infrasound and Low-Frequency Noise Produced by Wind Turbines

    PubMed Central

    Berger, Robert G.; Ashtiani, Payam; Ollson, Christopher A.; Whitfield Aslund, Melissa; McCallum, Lindsay C.; Leventhall, Geoff; Knopper, Loren D.

    2015-01-01

    Setbacks for wind turbines have been established in many jurisdictions to address potential health concerns associated with audible noise. However, in recent years, it has been suggested that infrasound (IS) and low-frequency noise (LFN) could be responsible for the onset of adverse health effects self-reported by some individuals living in proximity to wind turbines, even when audible noise limits are met. The purpose of this paper was to investigate whether current audible noise-based guidelines for wind turbines account for the protection of human health, given the levels of IS and LFN typically produced by wind turbines. New field measurements of indoor IS and outdoor LFN at locations between 400 and 900 m from the nearest turbine, which were previously underrepresented in the scientific literature, are reported and put into context with existing published works. Our analysis showed that indoor IS levels were below auditory threshold levels while LFN levels at distances >500 m were similar to background LFN levels. A clear contribution to LFN due to wind turbine operation (i.e., measured with turbines on in comparison to with turbines off) was noted at a distance of 480 m. However, this corresponded to an increase in overall audible sound measures as reported in dB(A), supporting the hypothesis that controlling audible sound produced by normally operating wind turbines will also control for LFN. Overall, the available data from this and other studies suggest that health-based audible noise wind turbine siting guidelines provide an effective means to evaluate, monitor, and protect potential receptors from audible noise as well as IS and LFN. PMID:25759808

  15. An open source multivariate framework for n-tissue segmentation with evaluation on public data.

    PubMed

    Avants, Brian B; Tustison, Nicholas J; Wu, Jue; Cook, Philip A; Gee, James C

    2011-12-01

    We introduce Atropos, an ITK-based multivariate n-class open source segmentation algorithm distributed with ANTs ( http://www.picsl.upenn.edu/ANTs). The Bayesian formulation of the segmentation problem is solved using the Expectation Maximization (EM) algorithm with the modeling of the class intensities based on either parametric or non-parametric finite mixtures. Atropos is capable of incorporating spatial prior probability maps (sparse), prior label maps and/or Markov Random Field (MRF) modeling. Atropos has also been efficiently implemented to handle large quantities of possible labelings (in the experimental section, we use up to 69 classes) with a minimal memory footprint. This work describes the technical and implementation aspects of Atropos and evaluates its performance on two different ground-truth datasets. First, we use the BrainWeb dataset from Montreal Neurological Institute to evaluate three-tissue segmentation performance via (1) K-means segmentation without use of template data; (2) MRF segmentation with initialization by prior probability maps derived from a group template; (3) Prior-based segmentation with use of spatial prior probability maps derived from a group template. We also evaluate Atropos performance by using spatial priors to drive a 69-class EM segmentation problem derived from the Hammers atlas from University College London. These evaluation studies, combined with illustrative examples that exercise Atropos options, demonstrate both performance and wide applicability of this new platform-independent open source segmentation tool. PMID:21373993

  16. Improvement of dem Generation from Aster Images Using Satellite Jitter Estimation and Open Source Implementation

    NASA Astrophysics Data System (ADS)

    Girod, L.; Nuth, C.; Kääb, A.

    2015-12-01

    The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) system embarked on the Terra (EOS AM-1) satellite has been a source of stereoscopic images covering the whole globe at a 15m resolution at a consistent quality for over 15 years. The potential of this data in terms of geomorphological analysis and change detection in three dimensions is unrivaled and needs to be exploited. However, the quality of the DEMs and ortho-images currently delivered by NASA (ASTER DMO products) is often of insufficient quality for a number of applications such as mountain glacier mass balance. For this study, the use of Ground Control Points (GCPs) or of other ground truth was rejected due to the global "big data" type of processing that we hope to perform on the ASTER archive. We have therefore developed a tool to compute Rational Polynomial Coefficient (RPC) models from the ASTER metadata and a method improving the quality of the matching by identifying and correcting jitter induced cross-track parallax errors. Our method outputs more accurate DEMs with less unmatched areas and reduced overall noise. The algorithms were implemented in the open source photogrammetric library and software suite MicMac.

  17. Ionospheric signatures of the April 25, 2015 Nepal earthquake and the relative role of compression and advection for Doppler sounding of infrasound in the ionosphere

    NASA Astrophysics Data System (ADS)

    Chum, Jaroslav; Liu, Jann-Yenq; Laštovička, Jan; Fišer, Jiří; Mošna, Zbyšek; Baše, Jiří; Sun, Yang-Yi

    2016-02-01

    Ionospheric signatures possibly induced by the Nepal earthquake are investigated far outside the epicentral region in Taiwan (~3700 km distance from the epicenter) and in the Czech Republic (~6300 km distance from the epicenter). It is shown that the ionospheric disturbances were caused by long period, ~20 s, infrasound waves that were excited locally by vertical component of the ground surface motion and propagated nearly vertically to the ionosphere. The infrasound waves are heavily damped at the heights of F layer at around 200 km, so their amplitude strongly depends on the altitude of observation. In addition, in the case of continuous Doppler sounding, the value of the Doppler shift depends not only on the advection (up and down motion) of the reflecting layer but also on the compression/rarefaction of the electron gas and hence on the electron density gradient. Consequently, under significant differences of reflection height of sounding radio waves and partly also under large differences in plasma density gradients, the observed ionospheric response at larger distances from the epicenter can be comparable with the ionospheric response observed at shorter distances, although the amplitudes of causative seismic motions differ by more than one order of magnitude.

  18. Ionosonde tracking of infrasound wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel

    2016-03-01

    Ionospheric disturbances associated with the M8.8 Chile earthquake (35.91°S, 72.73°W) on 27 February 2010 were observed at Kazan, Russia (55.85°N, 48.81°E). Rapid-run ionograms at 1 min intervals exhibited multiple-cusp signatures (MCSs) for more than 30 min, which have been observed several times after large earthquakes. The ionospheric disturbances were caused by infrasound propagating upward in the atmosphere, which modified the electron density distribution through ion-neutral collisions. The anomaly of the vertical electron density distribution responsible for the MCSs was analyzed by converting the ionogram traces into real height profiles. The density profiles at 1 min intervals allowed the tracking of the vertical propagation of infrasound and provided information on parameters of acoustic waves, which was not possible from the previous measurements such as standard ionograms at 5-15 min intervals, HF Doppler soundings, and total electron content using satellite beacon signals. The speed of acoustic waves in the thermosphere was evaluated from the consecutive ionograms with MCSs, and it was found that the thermospheric temperature was slightly higher than that calculated using the Mass Spectrometer and Incoherent Scatter Radar empirical model (NRLMSISE-00).

  19. Sources of Uncertainty in Rainfall Maps from Cellular Communication Networks

    NASA Astrophysics Data System (ADS)

    Rios Gaona, Manuel Felipe; Overeem, Aart; Leijnse, Hidde; Uijlenhoet, Remko

    2015-04-01

    Accurate measurements of rainfall are important in many hydrological applications, for instance, flash-flood early-warning systems, hydraulic structures design, agriculture, weather forecasting, and climate modelling. Rainfall intensities can be retrieved from (commercial) microwave link networks. Whenever possible, link networks measure and store the decrease in power of the electromagnetic signal at regular intervals. The decrease in power is largely due to the attenuation by raindrops along the link paths. Such an alternative technique fulfills the continuous strive for measurements of rainfall in time and space at higher resolutions, especially in places where traditional rain gauge networks are scarce or poorly maintained. Rainfall maps from microwave link networks have recently been introduced at country-wide scales. Despite their potential in rainfall estimation at high spatiotemporal resolutions, the uncertainties present in rainfall maps from link networks are not yet fully comprehended. The aim of this work is to identify and quantify the sources of uncertainty present in interpolated rainfall maps from link rainfall depths. In order to disentangle these sources of uncertainty, we classified them into two categories: (1) those associated with the individual microwave link measurements, i.e., the physics involved in the measurements such as wet antenna attenuation, sampling interval of measurements, wet/dry period classification, drop size distribution (DSD), and multi-path propagation; (2) those associated with mapping, i.e., the combined effect of the interpolation methodology, the spatial density of the network, and the availability of link measurements. We computed ~ 3500 rainfall maps from real and simulated link rainfall depths for 12 days for the land surface of The Netherlands. These rainfall maps were compared against quality-controlled gauge-adjusted radar rainfall fields (assumed to be the ground truth). Thus, we were able to not only identify

  20. A numerical study of nonlinear infrasound propagation in a windy atmosphere.

    PubMed

    Sabatini, R; Marsden, O; Bailly, C; Bogey, C

    2016-07-01

    Direct numerical simulations of the two-dimensional unsteady compressible Navier-Stokes equations are performed to study the acoustic field generated by an infrasonic source in a realistic atmosphere. Some of the main phenomena affecting the propagation of infrasonic waves at large distances from the source are investigated. The effects of thermal and wind-related refraction on the signals recorded at ground level are highlighted, with particular emphasis on the phase shift induced by the presence of caustics in the acoustic field. Nonlinear waveform steepening associated with harmonic generation, and period lengthening, both of which are typical of large source amplitudes, are illustrated, and the importance of thermoviscous absorption in the upper atmosphere is clearly demonstrated. The role of diffraction in the shadow zone, around caustics and at stratospheric altitudes is also pointed out. The Navier-Stokes equations are solved using high-order finite-differences and a Runge-Kutta time integration method both originally developed for aeroacoustic applications, along with an adaptive shock-capturing algorithm which allows high-intensity acoustic fields to be examined. An improvement to the shock detection procedure is also proposed in order to meet the specificities of nonlinear propagation at long range. The modeling as well as the numerical results are reported in detail and discussed. PMID:27475186

  1. Acoustic source characterization of impulsive Strombolian eruptions from the Mount Erebus lava lake

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey; Aster, Richard; Jones, Kyle R.; Kyle, Philip; McIntosh, Bill

    2008-11-01

    We invert for acoustic source volume outflux and momentum imparted to the atmosphere using an infrasonic network distributed about the erupting lava lake at Mount Erebus, Ross Island, Antarctica. By modeling these relatively simple eruptions as monopole point sources we estimate explosively ejected gas volumes that range from 1,000 m 3 to 24,000 m 3 for 312 lava lake eruptions recorded between January 6 and April 13, 2006. Though these volumes are compatible with bubble volumes at rupture (as estimated from explosion video records), departures from isotropic radiation are evident in the recorded acoustic wavefield for many eruptions. A point-source acoustic dipole component with arbitrary axis orientation and strength provides precise fit to the recorded infrasound. This dipole source axis, corresponding to the axis of inferred short-duration material jetting, varies significantly between events. Physical interpretation of dipole orientation as being indicative of eruptive directivity is corroborated by directional emissions of ejecta observed in Erebus eruption video footage. Although three azimuthally distributed stations are insufficient to fully characterize the eruptive acoustic source we speculate that a monopole with a minor amount of oriented dipole radiation may reasonably model the primary features of the recorded infrasound for these eruptio