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.

Development of mine explosion ground truth smart sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Steven R.; Harben, Phillip E.; Jarpe, Steve

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 themore » 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

Characterization of infrasound from lightning

NASA Astrophysics Data System (ADS)

Assink, J. D.; Evers, L. G.; Holleman, I.; Paulssen, H.

2008-08-01

During thunderstorm activity in the Netherlands, electromagnetic and infrasonic signals are emitted due to the process of lightning and thunder. It is shown that correlating infrasound detections with results from a electromagnetic lightning detection network is successful up to distances of 50 km from the infrasound array. Infrasound recordings clearly show blastwave characteristics which can be related to cloud-ground discharges, with a dominant frequency between 1-5 Hz. Amplitude measurements of CG discharges can partly be explained by the beam pattern of a line source with a dominant frequency of 3.9 Hz, up to a distance of 20 km. The ability to measure lightning activity with infrasound arrays has both positive and negative implications for CTBT verification purposes. As a scientific application, lightning studies can benefit from the worldwide infrasound verification system.

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.

Overview of IMS infrasound station and engineering projects

NASA Astrophysics Data System (ADS)

Marty, J.; Doury, B.; Kramer, A.; Martysevich, P.

2015-12-01

The Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBTO) has a continuous interest in enhancing its capability in acoustic source detection, localization and characterization. The infrasound component of the International Monitoring System (IMS) constitutes the only worldwide ground-based infrasound network. It consists of sixty stations, among which forty-eight are already certified and continuously transmit data to the International Data Centre (IDC) in Vienna, Austria. Each infrasound station is composed of an array of infrasound sensors capable of measuring micro-pressure changes produced at ground level by infrasonic waves. The characteristics of infrasonic waves are computed in near real-time by IDC automatic detection software and are used as an input to IDC source categorization and localization algorithms. The PTS is continuously working towards the completion and sustainment of the IMS infrasound network. The objective of this presentation is to review the main activities performed in the IMS infrasound network over the last five years. This includes construction, installation, certification, major upgrade and revalidation activities. Major technology development projects to improve the reliability and robustness of IMS infrasound stations as well as their compliance with IMS Operational Manual requirements will also be presented. This includes advances in array geometry, wind noise reduction, system calibration, meteorological data as well as power and communication infrastructures. Finally the impact of all these changes on the overall detection capability of the IMS infrasound network will be highlighted.

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

Near-source and Regional Experiments to Quantify Coupling and Propagation Effects of Seismic and Infrasound Signals from Mining Explosions

NASA Astrophysics Data System (ADS)

Stump, B. W.; Hayward, C.; Zhou, R.; House, S. M.

2001-12-01

Mining explosions designed to fragment rock are known to be regular sources of seismic waves as exemplified by the routine identification of these events in the USGS Mining Seismicity Report. Near-surface explosions can also generate low frequency acoustic waves or infrasound that can propagate through the atmosphere to regional distances. An understanding of source contributions to the size and character of waves initiated in the solid earth and atmosphere can be used to interpret propagation path effects as well as provide a physical understanding of characteristics that can be used for identifying the source type from the regional observations. The porphyry copper district of the SW United States was chosen for the study of these effects because of the existence of mining explosions that are routinely included in the USGS Mining Seismicity Report and an abundance of high quality regional seismic stations. A regional network of infrasound arrays was installed in order to quantify the accompanying low-frequency acoustic signals. In-mine seismic and acoustic measurements were made to quantify the source. These observations were supplemented with GPS locked video and in-mine documentation of the explosion design parameters. This comprehensive data set has been used to estimate source parameters that can be used to interpret the regional signals. Infrasound signals observed over a one-year time period indicate that the direction of atmospheric winds controls the amplitude and thus detection of these signals. Regional seismic observations are strongly affected by the style of blasting. The largest of the ground truth events (~250,000 kg explosive) are detonated in relatively long blasting sequences (~2 seconds) and produce some of the smallest regional signals. Smaller blasts (~25,000 to 50,000 kg) are detonated over relatively shorter time periods (`~0.2 to 0.4 seconds) and produce the largest regional signals. This source time function signature in the regional

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.

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.

Ground-truth collections at the MTI core sites

NASA Astrophysics Data System (ADS)

Garrett, Alfred J.; Kurzeja, Robert J.; Parker, Matthew J.; O'Steen, Byron L.; Pendergast, Malcolm M.; Villa-Aleman, Eliel

2001-08-01

The Savannah River Technology Center (SRTC) selected 13 sites across the continental US and one site in the western Pacific to serve as the primary or core site for collection of ground truth data for validation of MTI science algorithms. Imagery and ground truth data from several of these sites are presented in this paper. These sites are the Comanche Peak, Pilgrim and Turkey Point power plants, Ivanpah playas, Crater Lake, Stennis Space Center and the Tropical Western Pacific ARM site on the island of Nauru. Ground truth data includes water temperatures (bulk and skin), radiometric data, meteorological data and plant operating data. The organizations that manage these sites assist SRTC with its ground truth data collections and also give the MTI project a variety of ground truth measurements that they make for their own purposes. Collectively, the ground truth data from the 14 core sites constitute a comprehensive database for science algorithm validation.

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.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 Whitakermore » (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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 wavefrontsmore » 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

Seismoacoustic Coupled Signals From Earthquakes in Central Italy: Epicentral and Secondary Sources of Infrasound

NASA Astrophysics Data System (ADS)

Shani-Kadmiel, Shahar; Assink, Jelle D.; Smets, Pieter S. M.; Evers, Läslo G.

2018-01-01

In this study we analyze infrasound signals from three earthquakes in central Italy. The Mw 6.0 Amatrice, Mw 5.9 Visso, and Mw 6.5 Norcia earthquakes generated significant epicentral ground motions that couple to the atmosphere and produce infrasonic waves. Epicentral seismic and infrasonic signals are detected at I26DE; however, a third type of signal, which arrives after the seismic wave train and before the epicentral infrasound signal, is also detected. This peculiar signal propagates across the array at acoustic wave speeds, but the celerity associated with it is 3 times the speed of sound. Atmosphere-independent backprojections and full 3-D ray tracing using atmospheric conditions of the European Centre for Medium-Range Weather Forecasts are used to demonstrate that this apparently fast-arriving infrasound signal originates from ground motions more than 400 km away from the epicenter. The location of the secondary infrasound patch coincides with the closest bounce point to I26DE as depicted by ray tracing backprojections.

Infrasound from ground to space

NASA Astrophysics Data System (ADS)

Bowman, Daniel Charles

Acoustic detector networks are usually located on the Earth's surface. However, these networks suffer from shortcomings such as poor detection range and pervasive wind noise. An alternative is to deploy acoustic sensors on high altitude balloons. In theory, such platforms can resolve signals arriving from great distances, acquire others that never reach the surface at all, and avoid wind noise entirely. This dissertation focuses on scientific advances, instrumentation, and analytical techniques resulting from the development of such sensor arrays. Results from infrasound microphones deployed on balloon flights in the middle stratosphere are described, and acoustic sources such as the ocean microbarom and building ventilation systems are discussed. Electromagnetic noise originating from the balloon, flight system, and other payloads is shown to be a pervasive issue. An experiment investigating acoustic sensor calibration at low pressures is presented, and implications for high altitude recording are considered. Outstanding challenges and opportunities in sound measurement using sensors embedded in the free atmosphere are outlined. Acoustic signals from field scale explosions designed to emulate volcanic eruptions are described, and their generation mechanisms modeled. Wave forms recorded on sensors suspended from tethered helium balloons are compared with those detected on ground stations during the experiment. Finally, the Hilbert-Huang transform, a high time resolution spectral analysis method for nonstationary and nonlinear time series, is presented.

Non-traditional Infrasound Deployment

NASA Astrophysics Data System (ADS)

McKenna, M. H.; McComas, S.; Simpson, C. P.; Diaz-Alvarez, H.; Costley, R. D.; Hayward, C.; Golden, P.; Endress, A.

2017-12-01

Historically, infrasound arrays have been deployed in rural environments where anthropological noise sources are limited. As interest in monitoring low energy sources at local distances grows in the infrasound community, it will be vital to understand how to monitor infrasound sources in an urban environment. Arrays deployed in urban centers have to overcome the decreased signal-to-noise ratio and reduced amount of real estate available to deploy an array. To advance the understanding of monitoring infrasound sources in urban environments, local and regional infrasound arrays were deployed on building rooftops on the campus at Southern Methodist University (SMU), and data were collected for one seasonal cycle. The data were evaluated for structural source signals (continuous-wave packets), and when a signal was identified, the back azimuth to the source was determined through frequency-wavenumber analysis. This information was used to identify hypothesized structural sources; these sources were verified through direct measurement and dynamic structural analysis modeling. In addition to the rooftop arrays, a camouflaged infrasound sensor was installed on the SMU campus and evaluated to determine its effectiveness for wind noise reduction. Permission to publish was granted by Director, Geotechnical and Structures Laboratory.

Magnetic infrasound sensor

DOEpatents

Mueller, Fred M [Los Alamos, NM; Bronisz, Lawrence [Los Alamos, NM; Grube, Holger [Los Alamos, NM; Nelson, David C [Santa Fe, NM; Mace, Jonathan L [Los Alamos, NM

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.

Relating ground truth collection to model sensitivity

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

Infrasound from thunder: A natural seismic source

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2007-07-01

A small array consisting of five three-component short-period surface seismometers, a three-component borehole seismometer, and five infrasound microphones was built to investigate thunder-induced ground motions. Data from two thunder events with similar N-wave waveforms but different horizontal slownesses are chosen as examples of data collected by the array. These impulsive acoustic waves excited P and S reverberations in the near surface that depend on both the incident wave horizontal slowness and the velocity structure in the upper 30 meters at the site. Although the depth of the borehole is relatively shallow compared to a seismic wave wavelength, velocity amplitude in the radial component decays as much as 63 percent with depth but vertical component amplitudes are unaffected consistent with air-coupled Rayleigh wave excitation. Naturally occurring thunder appears to be a useful seismic source to empirically determine site resonance characteristics for hazards assessments.

Infrasound Observations from Lightning

NASA Astrophysics Data System (ADS)

Arechiga, R. O.; Johnson, J. B.; Edens, H. E.; Thomas, R. J.; Jones, K. R.

2008-12-01

To provide additional insight into the nature of lightning, we have investigated its infrasound manifestations. An array of three stations in a triangular configuration, with three sensors each, was deployed during the Summer of 2008 (July 24 to July 28) in the Magdalena mountains of New Mexico, to monitor infrasound (below 20 Hz) sources due to lightning. Hyperbolic formulations of time of arrival (TOA) measurements and interferometric techniques were used to locate lightning sources occurring over and outside the network. A comparative analysis of simultaneous Lightning Mapping Array (LMA) data and infrasound measurements operating in the same area was made. The LMA locates the sources of impulsive RF radiation produced by lightning flashes in three spatial dimensions and time, operating in the 60 - 66 MHz television band. The comparison showed strong evidence that lightning does produce infrasound. This work is a continuation of the study of the frequency spectrum of thunder conducted by Holmes et al., who reported measurements of infrasound frequencies. The integration of infrasound measurements with RF source localization by the LMA shows great potential for improved understanding of lightning processes.

Infrasound associated with 2004-2005 large Sumatra earthquakes and tsunami

NASA Astrophysics Data System (ADS)

Le Pichon, A.; Herry, P.; Mialle, P.; Vergoz, J.; Brachet, N.; Garcés, M.; Drob, D.; Ceranna, L.

2005-10-01

Large earthquakes that occurred in the Sumatra region in 2004 and 2005 generated acoustic waves recorded by the Diego Garcia infrasound array. The Progressive Multi-Channel Correlation (PMCC) analysis is performed to detect the seismic and infrasound signals associated with these events. The study is completed by an inverse location procedure that permitted reconstruction of the source location of the infrasonic waves. The results show that ground motion near the epicenter and vibrations of nearby land masses efficiently produced infrasound. The analysis also reveals unique evidence of long period pressure waves from the tsunami earthquake (M9.0) of December 26, 2004.

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

What is infrasound?

PubMed

Leventhall, Geoff

2007-01-01

Definitions of infrasound and low-frequency noise are discussed and the fuzzy boundary between them described. Infrasound, in its popular definition as sound below a frequency of 20 Hz, is clearly audible, the hearing threshold having been measured down to 1.5 Hz. The popular concept that sound below 20 Hz is inaudible is not correct. Sources of infrasound are in the range from very low-frequency atmospheric fluctuations up into the lower audio frequencies. These sources include natural occurrences, industrial installations, low-speed machinery, etc. Investigations of complaints of low-frequency noise often fail to measure any significant noise. This has led some complainants to conjecture that their perception arises from non-acoustic sources, such as electromagnetic radiation. Over the past 40 years, infrasound and low-frequency noise have attracted a great deal of adverse publicity on their effects on health, based mainly on media exaggerations and misunderstandings. A result of this has been that the public takes a one-dimensional view of infrasound, concerned only by its presence, whilst ignoring its low levels.

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

A portable infrasound generator.

PubMed

Park, Joseph; Robertson, James

2009-04-01

The rotary subwoofer is a novel low frequency transducer capable of efficiently generating infrasound from a compact source. A field-deployable version of this device may find application as a calibration source for infrasound arrays of the International Monitoring System (IMS) [(2001). The Global Verification Regime and the International Monitoring System (CTBTO Preparatory Commission Vienna International Centre, Vienna, Austria)]. A prototype tested at the IMS infrasound array I59US demonstrated the ability to insonify all elements of the array from a standoff distance of 3.8 km. Signal-to-noise ratios of continuous wave signals ranged from 5 to 15 dB, indicating the utility of this source to transmit controllable infrasound signals over distances of 5 km.

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.

Time-space variations in infrasound sources related to environmental dynamics around Lützow-Holm Bay, east Antarctica

NASA Astrophysics Data System (ADS)

Murayama, Takahiko; Kanao, Masaki; Yamamoto, Masa-Yuki; Ishihara, Yoshiaki; Matsushima, Takeshi; Kakinami, Yoshihiro; Okada, Kazumi; Miyamachi, Hiroki; Nakamoto, Manami; Takeuchi, Yukari; Toda, Shigeru

2017-12-01

Characteristic features of infrasound waves observed in the Antarctic reflect the physical interaction between the surface environment along the continental margin and the surrounding Southern Ocean. The temporal-spatial variability of the source locations for infrasound excitation during the eight-month period between January and August 2015 was investigated using recordings made by two infrasound arrays deployed along a section of the coast of Lützow-Holm Bay (LHB), Antarctica. The infrasound arrays clearly detected temporal variations in frequency content and propagation direction during this period. A number of infrasound sources were identified, many located north of the arrays. Many of the events had a predominant frequency content of a few Hz, higher than microbaroms from the ocean. A comparison of the results with MODIS satellite images indicated that these infrasound sources were ice-quakes associated with the calving of glaciers, the breaking off of sea ice, and collisions between this sea ice and icebergs around the LHB. Continuous measurements of infrasound in the Antarctic may serve as a proxy for monitoring the regional surface environment in terms of climate change at high southern latitudes.

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.

Infrasound Observations from the Source Physics Experiment (Tests 1 and 2) at the Nevada National Security Site

DTIC Science & Technology

2012-09-01

series of explosions, we have the unique and rare opportunity to study infrasound generated by a well-characterized source from the same borehole ...opportunity to study infrasound generated by a well-characterized source from the same borehole . This reduces the number of variables that must be...experiment is to study the seismic waves generated from explosions in both damaged and undamaged rock and that the observed infrasound is a

Infrasound wave propagation over near-regional and tele-infrasonic distances

NASA Astrophysics Data System (ADS)

McKenna, Sara Mihan House

2005-11-01

Infrasound research is experiencing a renaissance due to advances in acoustic propagation calculations and a deeper understanding of the atmosphere. Uniquely combining observed data and propagation modeling, the three papers presented here quantify the effects of the atmosphere on propagation from a variety of sources at distances from less than 100 km (near-regional distances) to nearly 600 km (tele-infrasonic distances) for sources on the surface and at altitude (63 km). Paper one analyzes infrasound signals recorded at the CHNAR seismo-acoustic array. These sources are predominantly on the surface, result from human activity and occur closer than 250 km away. Propagation for these near-regional distances depends on tropospheric weather patterns and temporally varying, low-altitude ducts. To predict the observed arrivals local meteorological data is necessary; MSIS/HWM (Mass Spectrometer Incoherent Scatter/Horizontal Wind Model) and NRL-G2S (Naval Research Laboratory Ground To Space) did not predict the observed arrivals. Paper two is the first time a waveform from an explosion at height has ever been reproduced; the recorded waveform was from the break-up of the space shuttle Columbia. For the tele-infrasonic normal mode modeling, MSIS/HWM and NRL-G2S yielded identical waveform results. Paper three looks at the tele-infrasonic path between an iron mine in Minnesota and an infrasound array in Manitoba, Canada. Over a four month period, the IS-10 infrasound array provided infrasound data to compare to archived blast statistics. NRL-G2S better reproduced the observed arrival travel times than MSIS/HWM; whether or not arrivals were observed depended on the noise field at the infrasound array. For any distance range or source height, accurate atmospheric parameters from the corresponding propagation paths are necessary to predict observed infrasound.

Infrasound as a Depth Discriminant

DTIC Science & Technology

2011-09-01

INFRASOUND AS A DEPTH DISCRIMINANT Stephen J. Arrowsmith, Rod W. Whitaker, and Richard J. Stead Los Alamos National Laboratory Sponsored by the... infrasound from earthquakes, in conjunction with modeling, to better constrain our understanding of the generation of infrasound from earthquakes, in...particular the effect of source depth. Here, we first outline a systematic search for infrasound from earthquakes from a range of magnitudes. Based

Experimental characterization of seasonal variations in infrasonic traveltimes on the Korean Peninsula with implications for infrasound event location

NASA Astrophysics Data System (ADS)

Che, Il-Young; Stump, Brian W.; Lee, Hee-Il

2011-04-01

The dependence of infrasound propagation on the season and path environment was quantified by the analysis of more than 1000 repetitive infrasonic ground-truth events at an active, open-pit mine over two years. Blast-associated infrasonic signals were analysed from two infrasound arrays (CHNAR and ULDAR) located at similar distances of 181 and 169 km, respectively, from the source but in different azimuthal directions and with different path environments. The CHNAR array is located to the NW of the source area with primarily a continental path, whereas the ULDAR is located East of the source with a path dominated by open ocean. As a result, CHNAR observations were dominated by stratospheric phases with characteristic celerities of 260-289 m s-1 and large seasonal variations in the traveltime, whereas data from ULDAR consisted primarily of tropospheric phases with larger celerities from 322 to 361 m s-1 and larger daily than seasonal variation in the traveltime. The interpretation of these observations is verified by ray tracing using atmospheric models incorporating daily weather balloon data that characterizes the shallow atmosphere for the two years of the study. Finally, experimental celerity models that included seasonal path effects were constructed from the long-term data set. These experimental celerity models were used to constrain traveltime variations in infrasonic location algorithms providing improved location estimates as illustrated with the empirical data set.

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.

Infrasound in the middle stratosphere measured with a free-flying acoustic array

NASA Astrophysics Data System (ADS)

Bowman, Daniel C.; Lees, Jonathan M.

2015-11-01

Infrasound recorded in the middle stratosphere suggests that the acoustic wavefield above the Earth's surface differs dramatically from the wavefield near the ground. In contrast to nearby surface stations, the balloon-borne infrasound array detected signals from turbulence, nonlinear ocean wave interactions, building ventilation systems, and other sources that have not been identified yet. Infrasound power spectra also bore little resemblance to spectra recorded on the ground at the same time. Thus, sensors on the Earth's surface likely capture a fraction of the true diversity of acoustic waves in the atmosphere. Future studies building upon this experiment may quantify the acoustic energy flux from the surface to the upper atmosphere, extend the capability of the International Monitoring System to detect nuclear explosions, and lay the observational groundwork for a recently proposed mission to detect earthquakes on Venus using free-flying microphones.

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.

Modelling infrasound signal generation from two underground explosions at the Source Physics Experiment using the Rayleigh integral

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Kyle R.; Whitaker, Rodney W.; Arrowsmith, Stephen J.

2014-12-11

For this study, we use the Rayleigh integral (RI) as an approximation to the Helmholtz–Kirchoff integral to model infrasound generation and propagation from underground chemical explosions at distances of 250 m out to 5 km as part of the Source Physics Experiment (SPE). Using a sparse network of surface accelerometers installed above ground zero, we are able to accurately create synthetic acoustic waveforms and compare them to the observed data. Although the underground explosive sources were designed to be symmetric, the resulting seismic wave at the surface shows an asymmetric propagation pattern that is stronger to the northeast of themore » borehole. This asymmetric bias may be attributed to the subsurface geology and faulting of the area and is observed in the acoustic waveforms. We compare observed and modelled results from two of the underground SPE tests with a sensitivity study to evaluate the asymmetry observed in the data. This work shows that it is possible to model infrasound signals from underground explosive sources using the RI and that asymmetries observed in the data can be modelled with this technique.« less

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.

Infrasound in the ionosphere from earthquakes and typhoons

NASA Astrophysics Data System (ADS)

Chum, J.; Liu, J.-Y.; Podolská, K.; Šindelářová, T.

2018-06-01

Infrasound waves are observed in the ionosphere relatively rarely, in contrast to atmospheric gravity waves. Infrasound waves excited by two distinguished sources as seismic waves from strong earthquakes (M > 7) and severe tropospheric weather systems (typhoons) are discussed and analyzed. Examples of observation by an international network of continuous Doppler sounders are presented. It is documented that the co-seismic infrasound is generated by vertical movement of the ground surface caused by seismic waves propagating at supersonic speeds. The coseismic infrasound propagates nearly vertically and has usually periods of several tens of seconds far away from the epicenter. However, in the vicinity of the epicenter (up to distance about 1000-1500 km), the large amplitudes might lead to nonlinear formation of N-shaped pulse in the upper atmosphere with much longer dominant period, e.g. around 2 min. The experimental observation is in good agreement with numerical modeling. The spectral content can also be nonlinearly changed at intermediate distances (around 3000-4000 km), though the N-shaped pulse is not obvious. Infrasound waves associated with seven typhoons that passed over Taiwan in 2014-2016 were investigated. The infrasound waves were observed at heights approximately from 200 to 300 km. Their spectra differed during the individual events and event from event and covered roughly the spectral range 3.5-20 mHz. The peak of spectral density was usually around 5 mHz. The observed spectra exhibited fine structures that likely resulted from modal resonances. The infrasound was recorded during several hours for strong events, especially for two typhoons in September 2016.

Community annotation experiment for ground truth generation for the i2b2 medication challenge

PubMed Central

Solti, Imre; Xia, Fei; Cadag, Eithon

2010-01-01

Objective Within the context of the Third i2b2 Workshop on Natural Language Processing Challenges for Clinical Records, the authors (also referred to as ‘the i2b2 medication challenge team’ or ‘the i2b2 team’ for short) organized a community annotation experiment. Design For this experiment, the authors released annotation guidelines and a small set of annotated discharge summaries. They asked the participants of the Third i2b2 Workshop to annotate 10 discharge summaries per person; each discharge summary was annotated by two annotators from two different teams, and a third annotator from a third team resolved disagreements. Measurements In order to evaluate the reliability of the annotations thus produced, the authors measured community inter-annotator agreement and compared it with the inter-annotator agreement of expert annotators when both the community and the expert annotators generated ground truth based on pooled system outputs. For this purpose, the pool consisted of the three most densely populated automatic annotations of each record. The authors also compared the community inter-annotator agreement with expert inter-annotator agreement when the experts annotated raw records without using the pool. Finally, they measured the quality of the community ground truth by comparing it with the expert ground truth. Results and conclusions The authors found that the community annotators achieved comparable inter-annotator agreement to expert annotators, regardless of whether the experts annotated from the pool. Furthermore, the ground truth generated by the community obtained F-measures above 0.90 against the ground truth of the experts, indicating the value of the community as a source of high-quality ground truth even on intricate and domain-specific annotation tasks. PMID:20819855

Infrasound detection of meteors

NASA Astrophysics Data System (ADS)

ElGabry, M. N.; Korrat, I. M.; Hussein, H. M.; Hamama, I. H.

2017-06-01

Meteorites that penetrate the atmosphere generate infrasound waves of very low frequency content. These waves can be detected even at large distances. In this study, we analyzed the infrasound waves produced by three meteors. The October 7, 2008 TC3 meteor fell over the north Sudan Nubian Desert, the February 15, 2013 Russian fireball, and the February 6, 2016 Atlantic meteor near to the Brazil coast. The signals of these three meteors were detected by the infrasound sensors of the International Monitoring System (IMS) of the Comprehensive Test Ban Treaty Organization (CTBTO). The progressive Multi Channel Technique is applied to the signals in order to locate these infrasound sources. Correlation of the recorded signals in the collocated elements of each array enables to calculate the delays at the different array element relative to a reference one as a way to estimate the azimuth and velocity of the coming infrasound signals. The meteorite infrasound signals show a sudden change in pressure with azimuth due to its track variation at different heights in the atmosphere. Due to movement of the source, a change in azimuth with time occurs. Our deduced locations correlate well with those obtained from the catalogues of the IDC of the CTBTO.

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

, the Heroy Building Rooftop Array, is a two-element 30m line on a single rooftop. Large-scale fireworks displays in Dallas on 4 July 2012 provided an opportunity to identify and characterize known signals in an urban setting. The identified events were associated with one of these fireworks displays about 2 km from the arrays. Signals from these sources were used to tune processing parameters for an automatic coherent detection process, Progressive Multichannel Correlation Method (PMCC). PMCC was then used to scan the data for all possible firework sources in the urban environment and determine temporal, back azimuth, apparent velocity, and frequency information about the sources. The signal frequencies seen were 10-80 Hz and documented the details of the nearly 30 minute firework show. The resulting PMCC analysis showed potential to effectively identify other, lower frequency sources in the urban environment. These data were also is used to characterize the noise environment. Significant roof-to-roof noise differences may be related to the building configurations and mechanical equipment, as well as the interactions of the winds with the structures. During the evening of July 4th , additional ground deployed infrasound gauges provided a comparison of free surface and rooftop measurements. Permission to publish was granted by Director, Geotechnical and Structures Laboratory.

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.

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.

Infrasound Signal Characteristics from Small Earthquakes

DTIC Science & Technology

2010-09-01

INFRASOUND SIGNAL CHARACTERISTICS FROM SMALL EARTHQUAKES J. Mark Hale1, Stephen J. Arrowsmith2, Chris Hayward3, Relu Burlacu1, Kristine L. Pankow1...ABSTRACT Understanding the source properties responsible for infrasound generation is critical to developing a seismo-acoustic data discriminant...mining in the Utah region create a unique setting for the study of near-field infrasound . The Utah network has been operating three permanent infrasound

Infrasound array observation at Sakurajima volcano

NASA Astrophysics Data System (ADS)

Yokoo, A.; Suzuki, Y. J.; Iguchi, M.

2012-12-01

Showa crater at the southeastern flank of the Sakurajima volcano has erupted since 2006, accompanying intermittent Vulcanian eruptions with small scale ash emissions. We conducted an array observation in the last half of 2011 in order to locate infrasound source generated by the eruptions. The array located 3.5 km apart from the crater was composed of 5 microphones (1kHz sampling) aligned in the radial direction from the crater with 100-m-intervals, and additional 4 microphones (200Hz sampling) in tangential direction to the first line in December 2011. Two peaks, around 2Hz and 0.5Hz, in power spectrum of the infrasound were identified; the former peak would be related to the eigen frequency of the vent of Showa crater, but the latter would be related to ejection of eruption clouds. They should be checked by experimental studies. The first 10 s infrasound signal was made by explosion directly and the following small amplitude infrasound tremors for about 2 min were mostly composed of diffraction and reflection waves from the topography around the volcano, mainly the wall of the Aira Caldera. It shows propagation direction of infrasound tremor after the explosion signals should be carefully examined. Clear change in the height of the infrasound source was not identified while volcanic cloud grew up. Strong eddies of the growing volcanic cloud would not be main sources of such weak infrasound signals, thus, infrasound waves are emitted mainly from (or through) the vent itself.

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.

New Ground Truth Capability from InSAR Time Series Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buckley, S; Vincent, P; Yang, D

2005-07-13

We demonstrate that next-generation interferometric synthetic aperture radar (InSAR) processing techniques applied to existing data provide rich InSAR ground truth content for exploitation in seismic source identification. InSAR time series analyses utilize tens of interferograms and can be implemented in different ways. In one such approach, conventional InSAR displacement maps are inverted in a final post-processing step. Alternatively, computationally intensive data reduction can be performed with specialized InSAR processing algorithms. The typical final result of these approaches is a synthesized set of cumulative displacement maps. Examples from our recent work demonstrate that these InSAR processing techniques can provide appealing newmore » ground truth capabilities. We construct movies showing the areal and temporal evolution of deformation associated with previous nuclear tests. In other analyses, we extract time histories of centimeter-scale surface displacement associated with tunneling. The potential exists to identify millimeter per year surface movements when sufficient data exists for InSAR techniques to isolate and remove phase signatures associated with digital elevation model errors and the atmosphere.« less

Infrasound Waveform Inversion and Mass Flux Validation from Sakurajima Volcano, Japan

NASA Astrophysics Data System (ADS)

Fee, D.; Kim, K.; Yokoo, A.; Izbekov, P. E.; Lopez, T. M.; Prata, F.; Ahonen, P.; Kazahaya, R.; Nakamichi, H.; Iguchi, M.

2015-12-01

Recent advances in numerical wave propagation modeling and station coverage have permitted robust inversion of infrasound data from volcanic explosions. Complex topography and crater morphology have been shown to substantially affect the infrasound waveform, suggesting that homogeneous acoustic propagation assumptions are invalid. Infrasound waveform inversion provides an exciting tool to accurately characterize emission volume and mass flux from both volcanic and non-volcanic explosions. Mass flux, arguably the most sought-after parameter from a volcanic eruption, can be determined from the volume flux using infrasound waveform inversion if the volcanic flow is well-characterized. Thus far, infrasound-based volume and mass flux estimates have yet to be validated. In February 2015 we deployed six infrasound stations around the explosive Sakurajima Volcano, Japan for 8 days. Here we present our full waveform inversion method and volume and mass flux estimates of numerous high amplitude explosions using a high resolution DEM and 3-D Finite Difference Time Domain modeling. Application of this technique to volcanic eruptions may produce realistic estimates of mass flux and plume height necessary for volcanic hazard mitigation. Several ground-based instruments and methods are used to independently determine the volume, composition, and mass flux of individual volcanic explosions. Specifically, we use ground-based ash sampling, multispectral infrared imagery, UV spectrometry, and multigas data to estimate the plume composition and flux. Unique tiltmeter data from underground tunnels at Sakurajima also provides a way to estimate the volume and mass of each explosion. In this presentation we compare the volume and mass flux estimates derived from the different methods and discuss sources of error and future improvements.

Balloon-Borne Infrasound Detection of Energetic Bolide Events

NASA Astrophysics Data System (ADS)

Young, Eliot F.; Ballard, Courtney; Klein, Viliam; Bowman, Daniel; Boslough, Mark

2016-10-01

Infrasound is usually defined as sound waves below 20 Hz, the nominal limit of human hearing. Infrasound waves propagate over vast distances through the Earth's atmosphere: the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization) has 48 installed infrasound-sensing stations around the world to detect nuclear detonations and other disturbances. In February 2013, several CTBTO infrasound stations detected infrasound signals from a large bolide that exploded over Chelyabinsk, Russia. Some stations recorded signals that had circumnavigated the Earth, over a day after the original event. The goal of this project is to improve upon the sensitivity of the CTBTO network by putting microphones on small, long-duration super-pressure balloons, with the overarching goal of studying the small end of the NEO population by using the Earth's atmosphere as a witness plate.A balloon-borne infrasound sensor is expected to have two advantages over ground-based stations: a lack of wind noise and a concentration of infrasound energy in the "stratospheric duct" between roughly 5 - 50 km altitude. To test these advantages, we have built a small balloon payload with five calibrated microphones. We plan to fly this payload on a NASA high-altitude balloon from Ft Sumner, NM in August 2016. We have arranged for three large explosions to take place in Socorro, NM while the balloon is aloft to assess the sensitivity of balloon-borne vs. ground-based infrasound sensors. We will report on the results from this test flight and the prospects for detecting/characterizing small bolides in the stratosphere.

Characteristics of infrasound from lightning and sprites near thunderstorm areas

NASA Astrophysics Data System (ADS)

Farges, Thomas; Blanc, Elisabeth

2010-06-01

Research about thunder was mainly performed 20-30 years ago but has been renewed in recent years due to new interest about infrasound in the framework of the verification of the compliance of the Comprehensive Nuclear-Test-Ban Treaty. During the Eurosprite 2005 campaign, an infrasound miniarray has been set up in France to measure the characteristics of infrasound from lightning and sprites when these kinds of sources were close to the sensors (that is, for lightning distances lower than 100 km and sprite distances lower than 300 km). For two large thunderstorms which passed over the station, detection conditions of infrasound from lightning are detailed, and some characteristics are thoroughly described (e.g., amplitude variation with distance and spectrum of an individual event in the frequency range from 0.01 to 10 Hz). The locations of infrasound sources are determined using a 3-D inversion. Infrasound signals from sprites have also been detected, and the 3-D inversion method used for lightning infrasound has been adapted to locate the sources of infrasound from sprites. Four different sprite infrasound events are analyzed in this way. The infrasound source corresponds well to the sprite spatial characteristics deduced from camera observations. Questions about generation mechanisms of infrasound from lightning and sprites still remain. These new results should help us to understand the sound generation processes.

Infrasound from the 2009 and 2017 DPRK rocket launches

NASA Astrophysics Data System (ADS)

Evers, L. G.; Assink, J. D.; Smets, P. SM

2018-06-01

Supersonic rockets generate low-frequency acoustic waves, that is, infrasound, during the launch and re-entry. Infrasound is routinely observed at infrasound arrays from the International Monitoring System, in place for the verification of the Comprehensive Nuclear-Test-Ban Treaty. Association and source identification are key elements of the verification system. The moving nature of a rocket is a defining criterion in order to distinguish it from an isolated explosion. Here, it is shown how infrasound recordings can be associated, which leads to identification of the rocket. Propagation modelling is included to further constrain the source identification. Four rocket launches by the Democratic People's Republic of Korea in 2009 and 2017 are analysed in which multiple arrays detected the infrasound. Source identification in this region is important for verification purposes. It is concluded that with a passive monitoring technique such as infrasound, characteristics can be remotely obtained on sources of interest, that is, infrasonic intelligence, over 4500+ km.

Detection of atmospheric infrasound with a ring laser interferometer

NASA Astrophysics Data System (ADS)

Dunn, Robert W.; Meredith, John A.; Lamb, Angela B.; Kessler, Elijah G.

2016-09-01

In this paper, the results from using a large active ring laser interferometer as an infrasound detector are presented. On April 27, 2014, an EF4 tornado struck Central Arkansas and passed within 21 km of the ring laser interferometer. The tornado resulted in 16 fatalities and millions of dollars in damage. Using the ring laser to study the tornado infrasound produced results that qualitatively agree with several findings from a long-term study of weather generated infrasound by the National Oceanic and Atmospheric Administration. A Fast Fourier Transform of the ring laser output revealed a coherent frequency of approximately 0.94 Hz that lasted during the life of the storm. The 0.94 Hz frequency was initially observed 30 min before the funnel was reported on the ground. Infrasound signatures from four separate tornadoes are presented. In each case, coherent infrasound was detected at least 30 min before the tornado was reported on the ground. Examples of the detection of distant coherent acoustic-gravity waves from volcanoes and typhoons are also presented. In addition, buoyancy waves were recorded.

Local Infrasound Variability Related to In Situ Atmospheric Observation

NASA Astrophysics Data System (ADS)

Kim, Keehoon; Rodgers, Arthur; Seastrand, Douglas

2018-04-01

Local infrasound is widely used to constrain source parameters of near-surface events (e.g., chemical explosions and volcanic eruptions). While atmospheric conditions are critical to infrasound propagation and source parameter inversion, local atmospheric variability is often ignored by assuming homogeneous atmospheres, and their impact on the source inversion uncertainty has never been accounted for due to the lack of quantitative understanding of infrasound variability. We investigate atmospheric impacts on local infrasound propagation by repeated explosion experiments with a dense acoustic network and in situ atmospheric measurement. We perform full 3-D waveform simulations with local atmospheric data and numerical weather forecast model to quantify atmosphere-dependent infrasound variability and address the advantage and restriction of local weather data/numerical weather model for sound propagation simulation. Numerical simulations with stochastic atmosphere models also showed nonnegligible influence of atmospheric heterogeneity on infrasound amplitude, suggesting an important role of local turbulence.

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

A Framework for Estimating Stratospheric Wind Speeds from Infrasound Noise

NASA Astrophysics Data System (ADS)

Arrowsmith, S.; Marcillo, O. E.

2012-12-01

We present a methodology for infrasonic remote sensing of winds in the stratosphere that does not require discrete ground-truth events. Our method uses measured time delays between arrays of sensors to provide group velocities and then minimizes the difference between observed and predicted group velocities. Because we focus on inter-array propagation effects, it is not necessary to simulate the full propagation path from source to receiver. This feature allows us to use a relatively simple forward model that is applicable over short-regional distances. By focusing on stratospheric returns, we show that our nonlinear inversion scheme converges much better if the starting model contains a strong stratospheric duct. Using the HWM/MSISE model, we demonstrate that the inversion scheme is robust to large uncertainties in backazimuth, but that uncertainties in the measured trace velocity and group velocity should be controlled through the addition of adjoint constraints. Using realistic estimates of measurement error, our results show that the inversion scheme will nevertheless improve upon a starting model under most scenarios for the 9-array Utah infrasound network. Future research should investigate the effects of model error associated with these measurements.

Ground truth and benchmarks for performance evaluation

NASA Astrophysics Data System (ADS)

Takeuchi, Ayako; Shneier, Michael; Hong, Tsai Hong; Chang, Tommy; Scrapper, Christopher; Cheok, Geraldine S.

2003-09-01

Progress in algorithm development and transfer of results to practical applications such as military robotics requires the setup of standard tasks, of standard qualitative and quantitative measurements for performance evaluation and validation. Although the evaluation and validation of algorithms have been discussed for over a decade, the research community still faces a lack of well-defined and standardized methodology. The range of fundamental problems include a lack of quantifiable measures of performance, a lack of data from state-of-the-art sensors in calibrated real-world environments, and a lack of facilities for conducting realistic experiments. In this research, we propose three methods for creating ground truth databases and benchmarks using multiple sensors. The databases and benchmarks will provide researchers with high quality data from suites of sensors operating in complex environments representing real problems of great relevance to the development of autonomous driving systems. At NIST, we have prototyped a High Mobility Multi-purpose Wheeled Vehicle (HMMWV) system with a suite of sensors including a Riegl ladar, GDRS ladar, stereo CCD, several color cameras, Global Position System (GPS), Inertial Navigation System (INS), pan/tilt encoders, and odometry . All sensors are calibrated with respect to each other in space and time. This allows a database of features and terrain elevation to be built. Ground truth for each sensor can then be extracted from the database. The main goal of this research is to provide ground truth databases for researchers and engineers to evaluate algorithms for effectiveness, efficiency, reliability, and robustness, thus advancing the development of algorithms.

Infrasound Signal Characteristics from Small Earthquakes

DTIC Science & Technology

2011-09-01

INFRASOUND SIGNAL CHARACTERISTICS FROM SMALL EARTHQUAKES Stephen J. Arrowsmith1, J. Mark Hale2, Relu Burlacu2, Kristine L. Pankow2, Brian W. Stump3...ABSTRACT Physical insight into source properties that contribute to the generation of infrasound signals is critical to understanding the...m, with one element being co-located with a seismic station. One of the goals of this project is the recording of infrasound from earthquakes of

The Temporal Morphology of Infrasound Propagation

DTIC Science & Technology

2010-01-01

that incorpo- ration of hybrid ground-to-space (G2S) enviromental specifications in numerical calculations of infrasound signal travel time and...Ban Treaty Organization. Numerous studies have demonstrated that incorporation of hybrid ground-to-space (G2S) enviromental specifications in numerical

Improving Infrasound Signal Detection and Event Location in the Western US Using Atmospheric Modeling

NASA Astrophysics Data System (ADS)

Dannemann, F. K.; Park, J.; Marcillo, O. E.; Blom, P. S.; Stump, B. W.; Hayward, C.

2016-12-01

Data from five infrasound arrays in the western US jointly operated by University of Utah Seismograph Station and Southern Methodist University are used to test a database-centric processing pipeline, InfraPy, for automated event detection, association and location. Infrasonic array data from a one-year time period (January 1 2012 to December 31 2012) are used. This study focuses on the identification and location of 53 ground-truth verified events produced from near surface military explosions at the Utah Test and Training Range (UTTR). Signals are detected using an adaptive F-detector, which accounts for correlated and uncorrelated time-varying noise in order to reduce false detections due to the presence of coherent noise. Variations in detection azimuth and correlation are found to be consistent with seasonal changes in atmospheric winds. The Bayesian infrasonic source location (BISL) method is used to produce source location and time credibility contours based on posterior probability density functions. Updates to the previous BISL methodology include the application of celerity range and azimuth deviation distributions in order to accurately account for the spatial and temporal variability of infrasound propagation through the atmosphere. These priors are estimated by ray tracing through Ground-to-Space (G2S) atmospheric models as a function of season and time of day using historic atmospheric characterizations from 2007 to 2013. Out of the 53 events, 31 are successfully located using the InfraPy pipeline. Confidence contour areas for maximum a posteriori event locations produce error estimates which are reduced a maximum of 98% and an average of 25% from location estimates utilizing a simple time independent uniform atmosphere. We compare real-time ray tracing results with the statistical atmospheric priors used in this study to examine large time differences between known origin times and estimated origin times that might be due to the misidentification of

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.

Seismic and Infrasound Location

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arrowsmith, Stephen J.; Begnaud, Michael L.

2014-03-19

This presentation includes slides on Signal Propagation Through the Earth/Atmosphere Varies at Different Scales; 3D Seismic Models: RSTT; Ray Coverage (Pn); Source-Specific Station Corrections (SSSCs); RSTT Conclusions; SALSA3D (SAndia LoS Alamos) Global 3D Earth Model for Travel Time; Comparison of IDC SSSCs to RSTT Predictions; SALSA3D; Validation and Model Comparison; DSS Lines in the Siberian Platform; DSS Line CRA-4 Comparison; Travel Time Δak135; Travel Time Prediction Uncertainty; SALSA3D Conclusions; Infrasound Data Processing: An example event; Infrasound Data Processing: An example event; Infrasound Location; How does BISL work?; BISL: Application to the 2013 DPRK Test; and BISL: Ongoing Research.

Assessing the detection capability of a dense infrasound network in the southern Korean Peninsula

NASA Astrophysics Data System (ADS)

Che, Il-Young; Le Pichon, Alexis; Kim, Kwangsu; Shin, In-Cheol

2017-08-01

The Korea Infrasound Network (KIN) is a dense seismoacoustic array network consisting of eight small-aperture arrays with an average interarray spacing of ∼100 km. The processing of the KIN historical recordings over 10 yr in the 0.05-5 Hz frequency band shows that the dominant sources of signals are microbaroms and human activities. The number of detections correlates well with the seasonal and daily variability of the stratospheric wind dynamics. The quantification of the spatiotemporal variability of the KIN detection performance is simulated using a frequency-dependent semi-empirical propagation modelling technique. The average detection thresholds predicted for the region of interest by using both the KIN arrays and the International Monitoring System (IMS) infrasound station network at a given frequency of 1.6 Hz are estimated to be 5.6 and 10.0 Pa for two- and three-station coverage, respectively, which was about three times lower than the thresholds predicted by using only the IMS stations. The network performance is significantly enhanced from May to August, with detection thresholds being one order of magnitude lower than the rest of the year due to prevailing steady stratospheric winds. To validate the simulations, the amplitudes of ground-truth repeated surface mining explosions at an open-pit limestone mine were measured over a 19-month period. Focusing on the spatiotemporal variability of the stratospheric winds which control to first order where infrasound signals are expected to be detected, the predicted detectable signal amplitude at the mine and the detection capability at one KIN array located at a distance of 175 km are found to be in good agreement with the observations from the measurement campaign. The detection threshold in summer is ∼2 Pa and increases up to ∼300 Pa in winter. Compared with the low and stable thresholds in summer, the high temporal variability of the KIN performance is well predicted throughout the year. Simulations

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…

Sayarim Infrasound Calibration Explosion: Near-Source and Local Observations and Yield Estimation

DTIC Science & Technology

2010-09-01

Institute of Israel (GII) at Sayarim Military Range (SMR), Negev Desert, Israel, on 26 August 2009. Near-source high-pressure values, measured...possible an upward directivity effect and asymmetric energy radiation to the atmosphere. Clear infrasound signals were well observed at distances up to...of Israel (GII) at Sayarim Military Range (SMR), Negev Desert, Israel, on 26 August 2009. Near-source high-pressure values, measured in the range 200

Prospects for infrasound bolide detections from balloon-borne platforms

NASA Astrophysics Data System (ADS)

Young, Eliot; Bowman, Daniel; Arrowsmith, Stephen; Boslough, Marc; Klein, Viliam; Ballard, Courtney; Lees, Jonathan

2017-04-01

We report on an experiment to assess whether balloon-borne instruments can improve sensitivities to bolides exploding in the Earth's atmosphere (essentially using the atmosphere as a witness plate to characterize the small end of the NEO (Near Earth Object) population). The CTBTO's infrasound network regularly detects infrasound disturbances caused by bolides, including the 15-FEB-2013 Chelybinsk impact. Balloon-borne infrasound sensors should have two important advantages over ground-based infrasound stations: there should be virtually no wind noise on a free-floating platform, and a sensor in the stratosphere should benefit from its location within the stratospheric duct. Balloon-borne sensors also have the disadvantage that the amplitude of infrasound waves will decrease as they ascend with altitude. To test the performance of balloon-borne sensors, we conducted an experiment on a NASA high altitude (35 km) balloon launched from Ft Sumner, NM on 28-SEP-2016. We were able to put two independent infrasound payloads on this flight. We arranged for three 3000-lb ANFO explosions to be detonated from Socorro, NM at 12:00, 14:00 and 16:29:59 MST. The first two explosions were detected from the NASA balloon, with the first explosion showing three separate waveforms arriving within a 25-s span. The peak-to-peak amplitude of the waveforms was about 0.06 Pa, and the cleanest microphone channel detected this waveform with an SNR greater than 20. A second balloon at 15 km altitude also detected the second explosion. We have signals from a dozen ground stations at various positions from Socorro to Ft Sumner. We will report on wave propagation models and how they compare with observations from the two balloons and the various ground-stations.

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

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).

Capturing the Acoustic Radiation Pattern of Strombolian Eruptions using Infrasound Sensors Aboard a Tethered Aerostat, Yasur Volcano, Vanuatu

NASA Astrophysics Data System (ADS)

Jolly, Arthur D.; Matoza, Robin S.; Fee, David; Kennedy, Ben M.; Iezzi, Alexandra M.; Fitzgerald, Rebecca H.; Austin, Allison C.; Johnson, Richard

2017-10-01

We obtained an unprecedented view of the acoustic radiation from persistent strombolian volcanic explosions at Yasur volcano, Vanuatu, from the deployment of infrasound sensors attached to a tethered aerostat. While traditional ground-based infrasound arrays may sample only a small portion of the eruption pressure wavefield, we were able to densely sample angular ranges of 200° in azimuth and 50° in takeoff angle by placing the aerostat at 38 tethered loiter positions around the active vent. The airborne data joined contemporaneously collected ground-based infrasound and video recordings over the period 29 July to 1 August 2016. We observe a persistent variation in the acoustic radiation pattern with average eastward directed root-mean-square pressures more than 2 times larger than in other directions. The observed radiation pattern may be related to both path effects from the crater walls, and source directionality.

On Evaluating Brain Tissue Classifiers without a Ground Truth

PubMed Central

Martin-Fernandez, Marcos; Ungar, Lida; Nakamura, Motoaki; Koo, Min-Seong; McCarley, Robert W.; Shenton, Martha E.

2009-01-01

In this paper, we present a set of techniques for the evaluation of brain tissue classifiers on a large data set of MR images of the head. Due to the difficulty of establishing a gold standard for this type of data, we focus our attention on methods which do not require a ground truth, but instead rely on a common agreement principle. Three different techniques are presented: the Williams’ index, a measure of common agreement; STAPLE, an Expectation Maximization algorithm which simultaneously estimates performance parameters and constructs an estimated reference standard; and Multidimensional Scaling, a visualization technique to explore similarity data. We apply these different evaluation methodologies to a set eleven different segmentation algorithms on forty MR images. We then validate our evaluation pipeline by building a ground truth based on human expert tracings. The evaluations with and without a ground truth are compared. Our findings show that comparing classifiers without a gold standard can provide a lot of interesting information. In particular, outliers can be easily detected, strongly consistent or highly variable techniques can be readily discriminated, and the overall similarity between different techniques can be assessed. On the other hand, we also find that some information present in the expert segmentations is not captured by the automatic classifiers, suggesting that common agreement alone may not be sufficient for a precise performance evaluation of brain tissue classifiers. PMID:17532646

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

Ground Truth Creation for Complex Clinical NLP Tasks - an Iterative Vetting Approach and Lessons Learned.

PubMed

Liang, Jennifer J; Tsou, Ching-Huei; Devarakonda, Murthy V

2017-01-01

Natural language processing (NLP) holds the promise of effectively analyzing patient record data to reduce cognitive load on physicians and clinicians in patient care, clinical research, and hospital operations management. A critical need in developing such methods is the "ground truth" dataset needed for training and testing the algorithms. Beyond localizable, relatively simple tasks, ground truth creation is a significant challenge because medical experts, just as physicians in patient care, have to assimilate vast amounts of data in EHR systems. To mitigate potential inaccuracies of the cognitive challenges, we present an iterative vetting approach for creating the ground truth for complex NLP tasks. In this paper, we present the methodology, and report on its use for an automated problem list generation task, its effect on the ground truth quality and system accuracy, and lessons learned from the effort.

Nuclear Explosion and Infrasound Event Resources of the SMDC Monitoring Research Program

DTIC Science & Technology

2008-09-01

2008 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies 928 Figure 7. Dozens of detected infrasound signals from...investigate alternative detection schemes at the two infrasound arrays based on frequency-wavenumber (fk) processing and the F-statistic. The results of... infrasound signal - detection processing schemes. REFERENCES Bahavar, M., B. Barker, J. Bennett, R. Bowman, H. Israelsson, B. Kohl, Y-L. Kung, J. Murphy

Infrasound and seismic array analysis of snow avalanches: results from the 2015-2017 experiment in Dischma valley above Davos, Switzerland

NASA Astrophysics Data System (ADS)

Marchetti, Emanuele; van Herwijnen, Alec; Ripepe, Maurizio

2017-04-01

While flowing downhill a snow avalanche radiates seismic and infrasonic waves being coupled both with the ground and the atmosphere. Infrasound waves are mostly generated by the powder cloud of the avalanche, while seismic waves are mostly generated by the dense flowing snow mass on the ground, resulting in different energy partitioning between seismic and infrasound for different kinds of avalanches. This results into a general uncertainty on the efficiency of seismic and infrasound monitoring, in terms of the size and source-to-receiver distance of detectable events. Nevertheless, both seismic and infrasound have been used as monitoring systems for the remote detection of snow avalanches, being the reliable detection of snow avalanches of crucial importance to better understand triggering mechanisms, identify possible precursors, or improve avalanche forecasting. We present infrasonic and seismic array data collected during the winters of 2015- 2016 and 2016-2017 in the Dischma valley above Davos, Switzerland, where a five element infrasound array and a 7 element seismic array had been deployed at short distance from each other and with several avalanche paths nearby. Avalanche observation in the area is performed through automatic cameras providing additional information on the location, type (dry or wet), size and occurrence time of the avalanches released. The use of arrays instead of single sensors allows increasing the signal-to-noise ratio and identifying events in terms of back-azimuth and apparent velocity of the wave-field, thus providing indication on the source position of the recorded signal. For selected snow avalanches captured with automatic cameras, we therefore perform seismic and infrasound array processing to constrain the avalanche path and dynamics and investigate the partitioning of seismic and infrasound energy for the different portions of the avalanche path. Moreover we compare results of seismic and infrasound array processing for the

Near- and far-field infrasound monitoring in the Mediterranean area

NASA Astrophysics Data System (ADS)

Campus, Paola; Marchetti, Emanuele; Le Pichon, Alexis; Wallenstein, Nicolau; Ripepe, Maurizio; Kallel, Mohamed; Mialle, Pierrick

2013-04-01

The Mediterranean area is characterized by a number of very interesting sources of infrasound signals and offers a promising playground for the development of a deeper understanding of such sources and of the associated propagation models. The progress in the construction and certification of infrasound arrays belonging to the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in the vicinity of this area has been complemented, in the last decade, by the construction of infrasound arrays established by several European research groups. The University of Florence (UniFi) plays a crucial role for the detection of infrasound signals in the Mediterranean area, having deployed since several years two infrasound arrays on Stromboli and Etna volcanoes, and, more recently, three infrasound arrays in the Alpine area of NW Italy and one infrasound array on the Apennines (Mount Amiata), designed and established in the framework of the ARISE Project. The IMS infrasound arrays IS42 (Graciosa, Azores, Portugal) and IS48 (Kesra, Tunisia) recorded, since the time of their certification, a number of far-field events which can be correlated with some near-field records of the infrasound arrays belonging to UniFi. An analysis of the results and potentialities of infrasound source's detections in near and far-field realized by IS42, IS48 and UniFi arrays in the Mediterranean area, with special focus on volcanic events is presented. The combined results deriving from the analysis of data recorded by the Unifi arrays and by the IS42 and IS48 arrays, in collaboration with the Department of Analyse et Surveillance (CEA/DASE), will generate a synergy which will certainly contribute to the progress of the ARISE Project.

Infrasound and SO2 Observations of the 2011 Explosive Eruption of Nabro Volcano, Eritrea

NASA Astrophysics Data System (ADS)

Fee, D.; Carn, S. A.; Prata, F.

2011-12-01

Nabro volcano, Eritrea erupted explosively on 12 June 2011 and produced near continuous emissions and infrasound until mid-July. The eruption disrupted air traffic and severely affected communities in the region. Although the eruption was relatively ash-poor, it produced significant SO2 emissions, including: 1) the highest SO2 column ever retrieved from space (3700 DU), 2) >1.3 Tg SO2 mass on 13 June, and 3) >2 Tg of SO2 for the entire eruption, one of the largest eruptive SO2 masses produced since the 1991 eruption of Mt. Pinatubo. Peak emissions reached well into the stratosphere (~19 km). Although the 12 June eruption was preceded by significant seismicity and clearly detected by satellite sensors, Nabro volcano is an understudied volcano that lies in a remote region with little ground-based monitoring. The Nabro eruption also produced significant infrasound signals that were recorded by two infrasound arrays: I19DJ (Djibouti, 264 km) and I32KE (Kenya, 1708 km). The I19DJ infrasound array detected the eruption with high signal-noise and provides the most detailed eruption chronology available, including eruption onset, duration, changes in intensity, etc. As seen in numerous other studies, sustained low frequency infrasound from Nabro is coincident with high-altitude emissions. Unexpectedly, the eruption also produced hundreds of short-duration, impulsive explosion signals, in addition to the sustained infrasonic jetting signals more typical of subplinian-plinian eruptions. These explosions are variable in amplitude, duration, and often cluster in groups. Here we present: 1) additional analyses, classification, and source estimation of the explosions, 2) infrasound propagation modeling to determine acoustic travel times and propagation paths, 3) detection and characterization of the SO2 emissions using the Ozone Monitoring Instrument (OMI) and Spin Enhanced Visible and Infra-Red Instrument (SEVIRI), and 4) a comparison between the relative infrasound energy and

Improved Bayesian Infrasonic Source Localization for regional infrasound

DOE PAGES

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

2015-10-20

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

Recent Infrasound Calibration Activity at Los Alamos

NASA Astrophysics Data System (ADS)

Whitaker, R. W.; Marcillo, O. E.

2014-12-01

Absolute infrasound sensor calibration is necessary for estimating source sizes from measured waveforms. This can be an important function in treaty monitoring. The Los Alamos infrasound calibration chamber is capable of absolute calibration. Early in 2014 the Los Alamos infrasound calibration chamber resumed operations in its new location after an unplanned move two years earlier. The chamber has two sources of calibration signals. The first is the original mechanical piston, and the second is a CLD Dynamics Model 316 electro-mechanical unit that can be digitally controlled and provide a richer set of calibration options. During 2008-2010 a number of upgrades were incorporated for improved operation and recording. In this poster we give an overview of recent chamber work on sensor calibrations, calibration with the CLD unit, some measurements with different porous hoses and work with impulse sources.

Infrasound signal detection and characterization using ground-coupled airwaves on a single seismo-acoustic sensor pair

NASA Astrophysics Data System (ADS)

McKee, K. F.; Fee, D.; Haney, M. M.; Lyons, J. J.; Matoza, R. S.

2016-12-01

A ground-coupled airwave (GCA) occurs when an incident atmospheric pressure wave encounters the Earth's surface and part of the energy of the wave is transferred to the ground (i.e. coupled to the ground) as a seismic wave. This seismic wave propagates as a surface Rayleigh wave evidenced by the retrograde particle motion detected on a three-component seismometer. Acoustic waves recorded on a collocated microphone and seismometer can be coherent and have a 90-degree phase difference, predicted by theory and in agreement with observations. If the sensors are separated relative to the frequencies of interest, usually 10s to 100s of meters, then recorded wind noise becomes incoherent and an additional phase shift is present due to the separation distance. These characteristics of GCAs have been used to distinguish wind noise from other sources as well as to determine the acoustic contribution to seismic recordings. Here we aim to develop a minimalist infrasound signal detection and characterization technique requiring just one microphone and one three-component seismometer. Based on GCA theory, determining a source azimuth should be possible using a single seismo-acoustic sensor pair by utilizing the phase difference and exploiting the characteristic particle motion. We will use synthetic seismo-acoustic data generated by a coupled Earth-atmosphere 3D finite difference code to test and tune the detection and characterization method. The method will then be further tested using various well-constrained sources (e.g. Chelyabinsk meteor, Pagan Volcano, Cleveland Volcano). Such a technique would be advantageous in situations where resources are limited and large sensor networks are not feasible.

Frequency-Wavenumber (F-K) Processing for Infrasound Distributed Arrays

DTIC Science & Technology

2012-10-01

UNCLASSIFIED Approved for public release; distribution is unlimited (U) Frequency-Wavenumber (F-K) Processing for Infrasound Distributed...have conventionally been used to detect infrasound . Pipe arrays, used in conjunction with microbarometers, provide noise reduction by averaging wind...signals. This is especially true for infrasound and low-frequency acoustic sources of tactical interest in the 1 to 100 Hz range. The work described

High Altitude Infrasound Measurements using Balloon-Borne Arrays

NASA Astrophysics Data System (ADS)

Bowman, D. C.; Johnson, C. S.; Gupta, R. A.; Anderson, J.; Lees, J. M.; Drob, D. P.; Phillips, D.

2015-12-01

For the last fifty years, almost all infrasound sensors have been located on the Earth's surface. A few experiments consisting of microphones on poles and tethered aerostats comprise the remainder. Such surface and near-surface arrays likely do not capture the full diversity of acoustic signals in the atmosphere. Here, we describe results from a balloon mounted infrasound array that reached altitudes of up to 38 km (the middle stratosphere). The balloon drifted at the ambient wind speed, resulting in a near total reduction in wind noise. Signals consistent with tropospheric turbulence were detected. A spectral peak in the ocean microbarom range (0.12 - 0.35 Hz) was present on balloon-mounted sensors but not on static infrasound stations near the flight path. A strong 18 Hz signal, possibly related to building ventilation systems, was observed in the stratosphere. A wide variety of other narrow band acoustic signals of uncertain provenance were present throughout the flight, but were absent in simultaneous recordings from nearby ground stations. Similar phenomena were present in spectrograms from the last balloon infrasound campaign in the 1960s. Our results suggest that the infrasonic wave field in the stratosphere is very different from that which is readily detectable on surface stations. This has implications for modeling acoustic energy transfer between the lower and upper atmosphere as well as the detection of novel acoustic signals that never reach the ground. Our work provides valuable constraints on a proposed mission to detect earthquakes on Venus using balloon-borne infrasound sensors.

AMS Ground Truth Measurements: Calibrations and Test Lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasiolek, Piotr T.

2015-12-01

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 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 data, expressed in counts per second (cps), need to be converted to a terrestrial component ofmore » the exposure rate at 1 meter (m) above ground, or surface activity of the 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, because production of a single, consistent map product depicting the ground contamination is the primary goal, it is critical to establish a common calibration line very early into the event. Such a line should be flown periodically in order to normalize data collected from different aerial acquisition systems and that are 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.« less

AMS Ground Truth Measurements: Calibration and Test Lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 tomore » 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.« less

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.

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

Atmospheric Infrasound during a Large Wildfire

NASA Astrophysics Data System (ADS)

Vance, Alexis; Elbing, Brian

2017-11-01

Numerous natural and manmade sources generate infrasound, including tornado producing storms, human heart, hurricanes, and volcanoes. Infrasound is currently being studied as part of Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUD MAP), which is a multi-university collaboration focused on development and implementation of unmanned aircraft systems (UAS) and integration with sensors for atmospheric measurements. To support this effort a fixed infrasonic microphone located in Stillwater, Oklahoma has been monitoring atmospheric emissions since September of 2016. While severe storm systems is the primary focus of this work, the system also captures a wide range of infrasonic sources from distances in excess of 300 miles due to an acoustic ceiling and weak atmospheric absorption. The current presentation will focus on atmospheric infrasound observations during a large wildfire on the Kansas-Oklahoma border that occurred between March 6-22, 2017. This work was supported by NSF Grant 1539070.

Volcanic eruptions, lightning, and a waterfall: Differentiating the menagerie of infrasound in the Ecuadorian jungle

NASA Astrophysics Data System (ADS)

Johnson, Jeffrey B.; Lees, Jonathan M.; Yepes, Hugo

2006-03-01

In northeastern Ecuador, near Reventador Volcano, the airwaves are filled with infrasound. Here we identify the locations and characterize three distinct sources of local infrasound, including two types of infrasonic sources, which are not commonly discussed in the literature. The first of these novel sources is an intense and continuous radiator with a fixed location corresponding to San Rafael Waterfall. The signal from the river exhibits a tremor-like envelope that is well correlated across the 3-element infrasound network. Beyond the river, we also observe and map spatially variable sources corresponding to thunder. These transient signals have impulsive onsets, but are not well correlated across the network and are attributable to spatially-distributed source regions. Finally, we identify plentiful infrasound corresponding to Reventador's volcanic vent that is associated with unrest. This study demonstrates the utility of dispersed infrasound networks for distinguishing variable sources and improving interpretation of mechanisms of infrasound radiators.

Modified ground-truthing: an accurate and cost-effective food environment validation method for town and rural areas.

PubMed

Caspi, Caitlin Eicher; Friebur, Robin

2016-03-17

A major concern in food environment research is the lack of accuracy in commercial business listings of food stores, which are convenient and commonly used. Accuracy concerns may be particularly pronounced in rural areas. Ground-truthing or on-site verification has been deemed the necessary standard to validate business listings, but researchers perceive this process to be costly and time-consuming. This study calculated the accuracy and cost of ground-truthing three town/rural areas in Minnesota, USA (an area of 564 miles, or 908 km), and simulated a modified validation process to increase efficiency without comprising accuracy. For traditional ground-truthing, all streets in the study area were driven, while the route and geographic coordinates of food stores were recorded. The process required 1510 miles (2430 km) of driving and 114 staff hours. The ground-truthed list of stores was compared with commercial business listings, which had an average positive predictive value (PPV) of 0.57 and sensitivity of 0.62 across the three sites. Using observations from the field, a modified process was proposed in which only the streets located within central commercial clusters (the 1/8 mile or 200 m buffer around any cluster of 2 stores) would be validated. Modified ground-truthing would have yielded an estimated PPV of 1.00 and sensitivity of 0.95, and would have resulted in a reduction in approximately 88 % of the mileage costs. We conclude that ground-truthing is necessary in town/rural settings. The modified ground-truthing process, with excellent accuracy at a fraction of the costs, suggests a new standard and warrants further evaluation.

Satellite markers: a simple method for ground truth car pose on stereo video

NASA Astrophysics Data System (ADS)

Gil, Gustavo; Savino, Giovanni; Piantini, Simone; Pierini, Marco

2018-04-01

Artificial prediction of future location of other cars in the context of advanced safety systems is a must. The remote estimation of car pose and particularly its heading angle is key to predict its future location. Stereo vision systems allow to get the 3D information of a scene. Ground truth in this specific context is associated with referential information about the depth, shape and orientation of the objects present in the traffic scene. Creating 3D ground truth is a measurement and data fusion task associated with the combination of different kinds of sensors. The novelty of this paper is the method to generate ground truth car pose only from video data. When the method is applied to stereo video, it also provides the extrinsic camera parameters for each camera at frame level which are key to quantify the performance of a stereo vision system when it is moving because the system is subjected to undesired vibrations and/or leaning. We developed a video post-processing technique which employs a common camera calibration tool for the 3D ground truth generation. In our case study, we focus in accurate car heading angle estimation of a moving car under realistic imagery. As outcomes, our satellite marker method provides accurate car pose at frame level, and the instantaneous spatial orientation for each camera at frame level.

Distinct Crater and Conduit Infrasound Reveal an Open Vent Volcano Running Out of Gas

NASA Astrophysics Data System (ADS)

Lyons, J. J.; Fee, D.; Haney, M. M.; Diefenbach, A. K.; Carn, S. A.

2017-12-01

Open-vent degassing dominated activity at Mount Pagan, Mariana Islands dating back to at least 2013, when ground-based sensors were installed, to mid-2015 when degassing fell below detection limits. Gas sampling indicated shallow magma was the source, and an analysis of LP seismicity showed that repeated pressurization and venting of a shallow crack controlled degassing. Open-vent degassing also produced abundant infrasound, recorded on two 6-element arrays. Two main infrasound features are the focus of this study: 1) a 0.3 Hz iVLP and 2) a 1.7 Hz iLP. Tens of thousands of iVLPs and iLPs were recorded over the 22-month study period, and correlation and cluster analyses show little change in both waveform and frequency content, suggesting a non-destructive, repeating source. An interesting upper conduit-crater geometry was discovered in helicopter overflights of the summit crater, and to test the effects of the crater and conduit shape and size on the infrasound signals, a high-resolution (<1 meter) DEM of the crater was produced by structure-from-motion using video captured during helicopter orbits. We perform full-waveform inversion of the infrasound data using the 3D topography, and show that a synthetic monopole source induces distinct resonance in the crater and upper conduit that mostly reproduces the iVLP and iLP signals, respectively. Further investigation of the infrasound catalogue shows that while the frequency content and waveforms remained stable through time, the amplitude of the iVLP events began decreasing months prior to cessation of degassing. Initially, the iLP amplitudes remained unaffected while the iVLP amplitudes dropped, but in the final months before degassing ended iLP amplitudes also began decreasing. We interpret this pattern as a progressive decline in the gas overpressure, initially resulting in a decreased ability to trigger resonance in the large crater volume, but eventually affecting the ability of the monopole source to induce

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. © 2012 Acoustical Society of America.

Modeling multiple time series annotations as noisy distortions of the ground truth: An Expectation-Maximization approach.

PubMed

Gupta, Rahul; Audhkhasi, Kartik; Jacokes, Zach; Rozga, Agata; Narayanan, Shrikanth

2018-01-01

Studies of time-continuous human behavioral phenomena often rely on ratings from multiple annotators. Since the ground truth of the target construct is often latent, the standard practice is to use ad-hoc metrics (such as averaging annotator ratings). Despite being easy to compute, such metrics may not provide accurate representations of the underlying construct. In this paper, we present a novel method for modeling multiple time series annotations over a continuous variable that computes the ground truth by modeling annotator specific distortions. We condition the ground truth on a set of features extracted from the data and further assume that the annotators provide their ratings as modification of the ground truth, with each annotator having specific distortion tendencies. We train the model using an Expectation-Maximization based algorithm and evaluate it on a study involving natural interaction between a child and a psychologist, to predict confidence ratings of the children's smiles. We compare and analyze the model against two baselines where: (i) the ground truth in considered to be framewise mean of ratings from various annotators and, (ii) each annotator is assumed to bear a distinct time delay in annotation and their annotations are aligned before computing the framewise mean.

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

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.

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

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

Multidirectional seismo-acoustic wavefield of strombolian explosions at Yasur, Vanuatu using a broadband seismo-acoustic network, infrasound arrays, and infrasonic sensors on tethered balloons

NASA Astrophysics Data System (ADS)

Matoza, R. S.; Jolly, A. D.; Fee, D.; Johnson, R.; Kilgour, G.; Christenson, B. W.; Garaebiti, E.; Iezzi, A. M.; Austin, A.; Kennedy, B.; Fitzgerald, R.; Key, N.

2016-12-01

Seismo-acoustic wavefields at volcanoes contain rich information on shallow magma transport and subaerial eruption processes. Acoustic wavefields from eruptions are predicted to be directional, but sampling this wavefield directivity is challenging because infrasound sensors are usually deployed on the ground surface. We attempt to overcome this observational limitation using a novel deployment of infrasound sensors on tethered balloons in tandem with a suite of dense ground-based seismo-acoustic, geochemical, and eruption imaging instrumentation. We present preliminary results from a field experiment at Yasur Volcano, Vanuatu from July 26th to August 4th 2016. Our observations include data from a temporary network of 11 broadband seismometers, 6 single infrasonic microphones, 7 small-aperture 3-element infrasound arrays, 2 infrasound sensor packages on tethered balloons, an FTIR, a FLIR, 2 scanning Flyspecs, and various visual imaging data. An introduction to the dataset and preliminary analysis of the 3D seismo-acoustic wavefield and source process will be presented. This unprecedented dataset should provide a unique window into processes operating in the shallow magma plumbing system and their relation to subaerial eruption dynamics.

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.

Sea Ice Thickness Measurement by Ground Penetrating Radar for Ground Truth of Microwave Remote Sensing Data

NASA Astrophysics Data System (ADS)

Matsumoto, M.; Yoshimura, M.; Naoki, K.; Cho, K.; Wakabayashi, H.

2018-04-01

Observation of sea ice thickness is one of key issues to understand regional effect of global warming. One of approaches to monitor sea ice in large area is microwave remote sensing data analysis. However, ground truth must be necessary to discuss the effectivity of this kind of approach. The conventional method to acquire ground truth of ice thickness is drilling ice layer and directly measuring the thickness by a ruler. However, this method is destructive, time-consuming and limited spatial resolution. Although there are several methods to acquire ice thickness in non-destructive way, ground penetrating radar (GPR) can be effective solution because it can discriminate snow-ice and ice-sea water interface. In this paper, we carried out GPR measurement in Lake Saroma for relatively large area (200 m by 300 m, approximately) aiming to obtain grand truth for remote sensing data. GPR survey was conducted at 5 locations in the area. The direct measurement was also conducted simultaneously in order to calibrate GPR data for thickness estimation and to validate the result. Although GPR Bscan image obtained from 600MHz contains the reflection which may come from a structure under snow, the origin of the reflection is not obvious. Therefore, further analysis and interpretation of the GPR image, such as numerical simulation, additional signal processing and use of 200 MHz antenna, are required to move on thickness estimation.

Eruption mass estimation using infrasound waveform inversion and ash and gas measurements: Evaluation at Sakurajima Volcano, Japan

NASA Astrophysics Data System (ADS)

Fee, David; Izbekov, Pavel; Kim, Keehoon; Yokoo, Akihiko; Lopez, Taryn; Prata, Fred; Kazahaya, Ryunosuke; Nakamichi, Haruhisa; Iguchi, Masato

2017-12-01

Eruption mass and mass flow rate are critical parameters for determining the aerial extent and hazard of volcanic emissions. Infrasound waveform inversion is a promising technique to quantify volcanic emissions. Although topography may substantially alter the infrasound waveform as it propagates, advances in wave propagation modeling and station coverage permit robust inversion of infrasound data from volcanic explosions. The inversion can estimate eruption mass flow rate and total eruption mass if the flow density is known. However, infrasound-based eruption flow rates and mass estimates have yet to be validated against independent measurements, and numerical modeling has only recently been applied to the inversion technique. Here we present a robust full-waveform acoustic inversion method, and use it to calculate eruption flow rates and masses from 49 explosions from Sakurajima Volcano, Japan. Six infrasound stations deployed from 12-20 February 2015 recorded the explosions. We compute numerical Green's functions using 3-D Finite Difference Time Domain modeling and a high-resolution digital elevation model. The inversion, assuming a simple acoustic monopole source, provides realistic eruption masses and excellent fit to the data for the majority of the explosions. The inversion results are compared to independent eruption masses derived from ground-based ash collection and volcanic gas measurements. Assuming realistic flow densities, our infrasound-derived eruption masses for ash-rich eruptions compare favorably to the ground-based estimates, with agreement ranging from within a factor of two to one order of magnitude. Uncertainties in the time-dependent flow density and acoustic propagation likely contribute to the mismatch between the methods. Our results suggest that realistic and accurate infrasound-based eruption mass and mass flow rate estimates can be computed using the method employed here. If accurate volcanic flow parameters are known, application of

Integration of video and infrasound to understand source locations and vent geometry at Erebus Volcano, Antarctica

NASA Astrophysics Data System (ADS)

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

2007-05-01

Infrasound monitoring at Erebus volcano has enabled us to quantify eruption energetics and precisely determine the source location of Strombolian eruptions. Since January 2006 we have operated a three-element network of identical infrasound pressure transducers, to track explosive eruptions, triangulate source locations of the eruptions, and distinguish activity from several vents with diverse activities. In December 2006 the network was expanded to six identical pressure transducers with improved azimuthal distribution sited ~300 m to 700 m from the erupting vents. These sensors have a dynamic range of +/-125 Pa and are able to record non-distorted waveforms for almost all eruptive events. Since January 2006, eruptions have been identified from locations within the ~40 m diameter phonolitic lava lake, an adjacent smaller "active vent", and a vent ~80 m distant from the lava lake known as "Werner's". Since late 2005 until the end of 2006, activity was considerably elevated at the "lava lake", from which frequent (up to six per day) explosions were noted. These events entailed gas bubble bursts, some of which were capable of ejecting bombs more than 1 km distant and producing infrasonic transients in excess of 100 Pa at a distance of 700 m. Activity from "Werner's" vent was much more subdued in terms of eruptive frequency and the radiated acoustic energy, with all signals less than about 5 Pa at 700 m. Activity from the "active vent" was also observed, though notably, these acoustic transients were extended in duration in terms of time (> 5 s to more than 30 s), which reflects extended duration ash-venting source mechanisms, corroborated by video records. The updated infrasound network has operated through a relative lull in eruptive intensity (November - December 2006 - January 2007). Since January 2007 more frequent and larger explosions from the lava lake have been observed and recorded with infrasound and video. We quantify this recent upsurge in lava lake

Investigation of the infrasound produced by geophysical events such as volcanoes, thunder, and avalanches: the case for local infrasound monitoring (Invited)

NASA Astrophysics Data System (ADS)

Johnson, J. B.; Marcillo, O. E.; Arechiga, R. O.; Johnson, R.; Edens, H. E.; Marshall, H.; Havens, S.; Waite, G. P.

2010-12-01

Volcanoes, lightning, and mass wasting events generate substantial infrasonic energy that propagates for long distances through the atmosphere with generally low intrinsic attenuation. Although such sources are often studied with regional infrasound arrays that provide important records of their occurrence, position, and relative magnitudes these signals recorded at tens to hundreds of kilometers are often significantly affected by propagation effects. Complex atmospheric structure, due to heterogeneous winds and temperatures, and intervening topography can be responsible for multi-pathing, signal attenuation, and focusing or, alternatively, information loss (i.e., a shadow zone). At far offsets, geometric spreading diminishes signal amplitude requiring low noise recording sites and high fidelity microphones. In contrast recorded excess pressures at local distances are much higher in amplitude and waveforms are more representative of source phenomena. We report on recent studies of volcanoes, thunder, and avalanches made with networks and arrays of infrasound sensors deployed local (within a few km) to the source. At Kilauea Volcano (Hawaii) we deployed a network of ~50 infrasound sensitive sensors (flat from 50 s to 50 Hz) to track the coherence of persistent infrasonic tremor signals in the near-field (out to a few tens of kilometers). During periods of high winds (> 5-10 m/s) we found significant atmospheric influence for signals recorded at stations only a few kilometers from the source. Such observations have encouraged us to conduct a range of volcano, thunder, and snow avalanche studies with networks of small infrasound arrays (~30 m aperture) deployed close to the source region. We present results from local microphone deployments (12 sensors) at Santiaguito Volcano (Guatemala) where we are able to precisely (~10 m resolution) locate acoustic sources from explosions and rock falls. We also present results from our thunder mapping acoustic arrays (15 sensors

The ground truth about metadata and community detection in networks

PubMed Central

Peel, Leto; Larremore, Daniel B.; Clauset, Aaron

2017-01-01

Across many scientific domains, there is a common need to automatically extract a simplified view or coarse-graining of how a complex system’s components interact. This general task is called community detection in networks and is analogous to searching for clusters in independent vector data. It is common to evaluate the performance of community detection algorithms by their ability to find so-called ground truth communities. This works well in synthetic networks with planted communities because these networks’ links are formed explicitly based on those known communities. However, there are no planted communities in real-world networks. Instead, it is standard practice to treat some observed discrete-valued node attributes, or metadata, as ground truth. We show that metadata are not the same as ground truth and that treating them as such induces severe theoretical and practical problems. We prove that no algorithm can uniquely solve community detection, and we prove a general No Free Lunch theorem for community detection, which implies that there can be no algorithm that is optimal for all possible community detection tasks. However, community detection remains a powerful tool and node metadata still have value, so a careful exploration of their relationship with network structure can yield insights of genuine worth. We illustrate this point by introducing two statistical techniques that can quantify the relationship between metadata and community structure for a broad class of models. We demonstrate these techniques using both synthetic and real-world networks, and for multiple types of metadata and community structures. PMID:28508065

The ground truth about metadata and community detection in networks.

PubMed

Peel, Leto; Larremore, Daniel B; Clauset, Aaron

2017-05-01

Across many scientific domains, there is a common need to automatically extract a simplified view or coarse-graining of how a complex system's components interact. This general task is called community detection in networks and is analogous to searching for clusters in independent vector data. It is common to evaluate the performance of community detection algorithms by their ability to find so-called ground truth communities. This works well in synthetic networks with planted communities because these networks' links are formed explicitly based on those known communities. However, there are no planted communities in real-world networks. Instead, it is standard practice to treat some observed discrete-valued node attributes, or metadata, as ground truth. We show that metadata are not the same as ground truth and that treating them as such induces severe theoretical and practical problems. We prove that no algorithm can uniquely solve community detection, and we prove a general No Free Lunch theorem for community detection, which implies that there can be no algorithm that is optimal for all possible community detection tasks. However, community detection remains a powerful tool and node metadata still have value, so a careful exploration of their relationship with network structure can yield insights of genuine worth. We illustrate this point by introducing two statistical techniques that can quantify the relationship between metadata and community structure for a broad class of models. We demonstrate these techniques using both synthetic and real-world networks, and for multiple types of metadata and community structures.

Microwave radiometric studies and ground truth measurements of the NASA/USGS Southern California test site

NASA Technical Reports Server (NTRS)

Edgerton, A. T.; Trexler, D. T.; Sakamoto, S.; Jenkins, J. E.

1969-01-01

The field measurement program conducted at the NASA/USGS Southern California Test Site is discussed. Ground truth data and multifrequency microwave brightness data were acquired by a mobile field laboratory operating in conjunction with airborne instruments. The ground based investigations were performed at a number of locales representing a variety of terrains including open desert, cultivated fields, barren fields, portions of the San Andreas Fault Zone, and the Salton Sea. The measurements acquired ground truth data and microwave brightness data at wavelengths of 0.8 cm, 2.2 cm, and 21 cm.

Retina lesion and microaneurysm segmentation using morphological reconstruction methods with ground-truth data.

PubMed

Karnowski, Thomas P; Govindasamy, V; Tobin, Kenneth W; 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.

Implications from Meteoric and Volcanic Infrasound Measured in the Netherlands

NASA Astrophysics Data System (ADS)

Evers, L.

2003-12-01

Infrasound observations started in the Netherlands in 1986. Since then, several array configurations and instruments have been developed, tested and made operational. Currently, three infrasound arrays are continuously measuring infrasound with in-house developed microbarometers. The array apertures vary from 30 to 1500 meters and the number of instruments from 6 to 16 microbarometers. The inter-array distance ranges from 50 up to 150 km. This dense network of infrasound arrays is used to distinguish between earthquakes and sources in the atmosphere. Sonic booms, for example, can be experienced in the same manner as small (gas induced) earthquakes. Furthermore, Comprehensive Nuclear-Test-Ban Treaty (CTBT) related research is done. Meteors are one of the few natural impulsive sources generating energy in kT TNT equivalent range. Therefore, the study of meteors is essential to the CTBT where infrasound is applied as monitoring technique. Studies of meteors in the Netherlands have shown the capability of infrasound to trace a meteor through the stratosphere. The propagation of infrasound is in first order dependent on the wind and temperature structure of the atmosphere. The meteor's path could be reconstructed by using ECMWF atmospheric models for wind and temperature. The results were compared to visual observations, confirming the location, direction and reported origin time. The accuracy of the localization mainly depends on the applied atmospheric model and array resolution. Successfully applying infrasound depends on the array configuration that should be based on the -frequency depend- spatial coherence of the signals of interest. The array aperture and inter-element distance will play a decisive role in detecting low signal-to-noise ratios. This is shown by results from studies on volcanic infrasound from Mt. Etna (Italy) detected in the Netherlands. Sub-array processing on the 16 element array revealed an increased detectability of infrasound for small

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.

Infrasound analysis of I18DK, northwest Greenland

NASA Astrophysics Data System (ADS)

Evers, L. G.; Weemstra, C.

2010-12-01

Within the scope of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), four methods are used to verify the treaty. One of these methods is based on the detection of infrasound waves generated by a nuclear explosion. Seismological, hydroacoustical and radionuclide measurements are also applied. The International Monitoring System (IMS) will consist of 60 infrasound stations of which 35 stations are currently operational. Data obtained from an infrasound station situated on the northwestern shoreline of Greenland is analyzed. This station is operated by Denmark and labeled as I18DK. I18DK is situated in an area which receives an ever increasing attention from a geophysical perspective. I18DK has continuously been operational from April 2003 and onwards. The IMS station is an infrasound array with an aperture of about 1200 meters, where air-pressure fluctuations are recorded by eight microbarometers at a sample-rate of 20 Hz. The infrasonic recordings are filtered between 0.1 & 1.0 and 1.0 & 6.0 Hz. The slowness grid is searched for two different configurations in the higher frequency band. Once using all 8 stations and once only taking into account the 5 center stations. Several different source types are known to generate infrasound, for example, calving of icebergs and glaciers, explosions, earthquakes, oceanic wave-wave interaction, volcanic eruptions and aurora. The challenge is to distinguish between these different source types and use the outcome of the array analysis to better understand these phenomena. The rate of occurrence of icequakes, the calving of glaciers and the variation in extent of the sea ice in this area is of interest in relation to global warming. The processing results of the 1 to 6 Hz band seem to show dominating back-azimuths related to these sources. The glaciers south of I18DK produce significant infrasound during summer time. As well, a direct link can be found between the number of warm days in a year and the number of infrasound

Sensitivity of the International Monitoring System infrasound network to elevated sources: a western Eurasia case study

NASA Astrophysics Data System (ADS)

Nippress, Alexandra; Green, David N.

2017-11-01

For the past 5 years (2010-2015) infrasound arrivals have been included in International Data Centre analyst-reviewed bulletins of events detected across the International Monitoring System (IMS). In western Eurasia, there are clusters of up to 268 events that consist of only infrasound arrivals (no associated seismic phases). These clusters are of unknown origin, although one in the North Sea region is associated with sonic booms from supersonic aircraft activity. IMS data for 17 North Sea events are analysed and compared with data from the Large Aperture Infrasound Array in the Netherlands to support the existence of these events and to determine common characteristics. Three other large clusters in western Eurasia are also identified and studied and show similar characteristics to the North Sea events, indicative of supersonic aircraft activity. The IMS infrasound network is shown to be particularly sensitive to sonic booms because the elevated source height reduces the anisotropy of infrasonic propagation within a stratospheric duct and allows for episodic upwind propagation. This episodic upwind propagation in addition to the prevailing downwind propagation, leads to clusters of Reviewed Event Bulletin events with constrained locations in western Eurasia region during the summer months. In the winter months, the recorded arrivals suggest that episodic upwind propagation is not as prevalent. Propagation modelling indicates that the subsequent unidirectional propagation, combined with the sparseness of the IMS network, leads to elongated lines of estimated event locations.

Investigation and Characterization of Acoustic Emissions of Tornadoes Using Arrays of Infrasound Sensors

NASA Astrophysics Data System (ADS)

Frazier, W. G.; Talmadge, C. L.; Waxler, R.; Knupp, K. R.; Goudeau, B.; Hetzer, C. H.

2017-12-01

Working in co-ordination with the NOAA Vortex Southeast (Vortex SE) research program, 9 infrasound sensor arrays were deployed at fixed sites across North Alabama, South-central Tennessee, and Northwest Georgia during March and April of 2017, to investigate the emission and characterization of infrasonic acoustic energy from tornadoes and related phenomena. Each array consisted of seven broadband acoustic sensors with calibrated frequency response from 0.02 Hz to 200 Hz. The arrays were configured in a pattern such that accurate bearings to acoustic sources could be obtained over a broad range of frequencies (nominally from 1 Hz to 100 Hz). Data were collected synchronously at a rate of 1000 samples per second. On 22 April 2017 a line of strong storms passed directly through the area being monitored producing at least three verified tornadoes. Two of these were rated at EF0 and the other an EF1. Subsequent processing of the data from several of the arrays revealed acoustic emissions from the tornadic storms ranging in frequencies below 1 Hz to frequencies greater than 10 Hz. Accurate bearings to the storms have been calculated from distances greater than 60 km. Preliminary analysis has revealed that continuous emissions occurred prior to the estimated touchdown times, while the storms were on the ground, and for short periods after the tornadoes lifted; however, the strongest emissions appeared to occur while the storms were on the ground. One of the storms passed near two arrays simultaneously, and therefore accurate an accurate track of the storm as it moved has been obtained only using the infrasound measurements. Initial results from the analysis of the infrasound data will be presented. Under Vortex SE meteorological data was collected on a large suite of sensors. Correlations between the infrasound data and the meteorological data will be investigated and discussed.

Balloon Borne Infrasound Platforms for Remote Monitoring of Natural Hazards

NASA Astrophysics Data System (ADS)

Lees, J. M.; Bowman, D. C.

2016-12-01

In the last three years several NASA supported balloon launches were instrumented with infrasound sensors to monitor acoustic wavefields in the stratosphere. Such high altitude platforms may detect geoacoustic phenomena at much greater ranges than equivalent ground stations, and perhaps record sound waves that rarely reach the Earth's surface. Since acoustic waves are a key diagnostic for several natural hazards (volcanic eruptions, severe storms, and tsunamis, for example), the increased range and spatial coverage of balloon borne arrays promise greater quantification and perhaps early warning of such events. Before this can be accomplished, the performance of stratospheric arrays must be compared to tthat of those on the ground. Here, we show evidence for 0.2 Hz infrasound associated with oceanic oscillations recorded during night time hours of the flights, consistent with concurrent ground recordings on the east and west coasts of North America. We also report numerous narrow band acoustic signals (5-30 Hz) that resemble recordings made in in the 1960's, the last time microphones were lofted into the stratosphere. Theoretical and ground based observational data from Rind(1977) indicate loss of acoustic energy in the thermosphere, where heating of the upper atmosphere is predicted to be on the order of 30-40 degrees Kelvin per day. We propose testing these ideas by using extensive ground arrays recently deployed in North America in conjunction with airborne platforms installed in the mid-stratosphere. New experiments scheduled for 2016 include circumnavigation of Antarctica (collected in June) as well as two proposed flights in New Mexico in September. The flights are designed to both capture known acoustic sources as well as events of opportunity.

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.

Ground-Truthing a Next Generation Snow Radar

NASA Astrophysics Data System (ADS)

Yan, S.; Brozena, J. M.; Gogineni, P. S.; Abelev, A.; Gardner, J. M.; Ball, D.; Liang, R.; Newman, T.

2016-12-01

During the early spring of 2016 the Naval Research Laboratory (NRL) performed a test of a next generation airborne snow radar over ground truth data collected on several areas of fast ice near Barrow, AK. The radar was developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, and includes several improvements compared to their previous snow radar. The new unit combines the earlier Ku-band and snow radars into a single unit with an operating frequency spanning the entire 2-18 GHz, an enormous bandwidth which provides the possibility of snow depth measurements with 1.5 cm range resolution. Additionally, the radar transmits on dual polarizations (H and V), and receives the signal through two orthogonally polarized Vivaldi arrays, each with 128 phase centers. The 8 sets of along-track phase centers are combined in hardware to improve SNR and narrow the beamwidth in the along-track, resulting in 8 cross-track effective phase centers which are separately digitized to allow for beam sharpening and forming in post-processing. Tilting the receive arrays 30 degrees from the horizontal also allows the formation of SAR images and the potential for estimating snow-water equivalent (SWE). Ground truth data (snow depth, density, salinity and SWE) were collected over several 60 m wide swaths that were subsequently overflown with the snow radar mounted on a Twin Otter. The radar could be operated in nadir (by beam steering the receive antennas to point beneath the aircraft) or side-looking modes. Results from the comparisons will be shown.

Narrow infrasound pulses from lightning; are they of electrostatic or thermal origin?

NASA Astrophysics Data System (ADS)

CHUM, Jaroslav; Diendorfer, Gerhard; Šindelářová, Tereza; Baše, Jiří; Hruška, František

2014-05-01

Narrow (~1-2 s) infrasound pulses that followed, with ~11 to ~50 s delays, rapid changes of electrostatic field were observed by a microbarometer array in the Czech Republic during thunderstorm activity. The angles of arrival (azimuth and elevation) were analyzed for selected distinct events. Comparisons of distances and azimuths of infrasound sources from the center of microbarometer array with lightning locations determined by EUCLID lightning detection network show that most of the selected events are most likely associated with intra-cloud (IC) discharges. Preceding rapid changes of electrostatic field, potential association of infrasound pulses with IC discharges, and high elevation angles of arrival for near infrasound sources indicate that an electrostatic mechanism is probably responsible for their generation. It is discussed that distinguishing of the relative role of thermal and electrostatic mechanism is difficult, and that none of published models of electrostatic production of infrasound thunder can explain the presented observations precisely. A modification of the current models, based on consideration of at least two charged layers is suggested. Further theoretical and experimental investigations are however needed to get a better description of the generation mechanism of those infrasound pulses.

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.

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

Ground Truth Collections for Explosions in Northern Fennoscandia and Russia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, D B; Ringdal, F; Kremenetskaya, E

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 frommore » 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

The importance of ground truth data in remote sensing

NASA Technical Reports Server (NTRS)

Hoffer, R. M.

1972-01-01

Surface observation data is discussed as an essential part of remote sensing research. One of the most important aspects of ground truth is the collection of measurements and observations about the type, size, condition and other physical or chemical properties of importance concerning the materials on the earth's surface that are being sensed remotely. The use of a variety of sensor systems in combination at different altitudes is emphasized.

Evaluating segmentation error without ground truth.

PubMed

Kohlberger, Timo; Singh, Vivek; Alvino, Chris; Bahlmann, Claus; Grady, Leo

2012-01-01

The automatic delineation of the boundaries of organs and other anatomical structures is a key component of many medical image processing systems. In this paper we present a generic learning approach based on a novel space of segmentation features, which can be trained to predict the overlap error and Dice coefficient of an arbitrary organ segmentation without knowing the ground truth delineation. We show the regressor to be much stronger a predictor of these error metrics than the responses of probabilistic boosting classifiers trained on the segmentation boundary. The presented approach not only allows us to build reliable confidence measures and fidelity checks, but also to rank several segmentation hypotheses against each other during online usage of the segmentation algorithm in clinical practice.

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.

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

A dataset of stereoscopic images and ground-truth disparity mimicking human fixations in peripersonal space

PubMed Central

Canessa, Andrea; Gibaldi, Agostino; Chessa, Manuela; Fato, Marco; Solari, Fabio; Sabatini, Silvio P.

2017-01-01

Binocular stereopsis is the ability of a visual system, belonging to a live being or a machine, to interpret the different visual information deriving from two eyes/cameras for depth perception. From this perspective, the ground-truth information about three-dimensional visual space, which is hardly available, is an ideal tool both for evaluating human performance and for benchmarking machine vision algorithms. In the present work, we implemented a rendering methodology in which the camera pose mimics realistic eye pose for a fixating observer, thus including convergent eye geometry and cyclotorsion. The virtual environment we developed relies on highly accurate 3D virtual models, and its full controllability allows us to obtain the stereoscopic pairs together with the ground-truth depth and camera pose information. We thus created a stereoscopic dataset: GENUA PESTO—GENoa hUman Active fixation database: PEripersonal space STereoscopic images and grOund truth disparity. The dataset aims to provide a unified framework useful for a number of problems relevant to human and computer vision, from scene exploration and eye movement studies to 3D scene reconstruction. PMID:28350382

Infrasound data inversion for atmospheric sounding

NASA Astrophysics Data System (ADS)

Lalande, J.-M.; Sèbe, O.; Landès, M.; Blanc-Benon, Ph.; Matoza, R. S.; Le Pichon, A.; Blanc, E.

2012-07-01

The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) continuously records acoustic waves in the 0.01-10 Hz frequency band, known as infrasound. These waves propagate through the layered structure of the atmosphere. Coherent infrasonic waves are produced by a variety of anthropogenic and natural sources and their propagation is controlled by spatiotemporal variations of temperature and wind velocity. Natural stratification of atmospheric properties (e.g. temperature, density and winds) forms waveguides, allowing long-range propagation of infrasound waves. However, atmospheric specifications used in infrasound propagation modelling suffer from lack and sparsity of available data above an altitude of 50 km. As infrasound can propagate in the upper atmosphere up to 120 km, we assume that infrasonic data could be used for sounding the atmosphere, analogous to the use of seismic data to infer solid Earth structure and the use of hydroacoustic data to infer oceanic structure. We therefore develop an inversion scheme for vertical atmospheric wind profiles in the framework of an iterative linear inversion. The forward problem is treated in the high-frequency approximation using a Hamiltonian formulation and complete first-order ray perturbation theory is developed to construct the Fréchet derivatives matrix. We introduce a specific parametrization for the unknown model parameters based on Principal Component Analysis. Finally, our algorithm is tested on synthetic data cases spanning different seasonal periods and network configurations. The results show that our approach is suitable for infrasound atmospheric sounding on a regional scale.

BBN technical memorandum W1291 infrasound model feasibility study

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 studymore » 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

Infrasound Sensor and Porous-Hose Filter Characterization Results

NASA Astrophysics Data System (ADS)

Hart, D. M.; Harris, J. M.

2008-12-01

The Ground-Based Nuclear Explosion Monitoring Research and Development (GNEM R&D) program at Sandia National Laboratories (SNL) is regarded as the primary center for unbiased expertise in testing and evaluation of geophysical sensors and instrumentation for nuclear explosion monitoring. Over the past year much of our work has focused in the area of infrasound sensor characterization through the continuing development of an infrasound sensor characterization test-bed. Our main areas of focus have been in new sensor characterization and understanding the effects of porous-hose filters for reducing acoustic background signals. Three infrasound sensors were evaluated for characteristics of instrument response, linearity and self-noise. The sensors tested were Chaparral Physics model 2.5 low-gain, New Mexico Tech All-Sensor and the Inter-Mountain Labs model SS avalanche sensor. For the infrasound sensors tested, the test results allow us to conclude that two of the three sensors had sufficiently quiet noise floor to be at or below the Acoustic low-noise model from 0.1 to 7 Hz, which make those sensors suitable to explosion monitoring. The other area of focus has been to understand the characteristics of porous-hose filters used at some monitoring sites. For this, an experiment was designed in which two infrasound sensors were co- located. One sensor was connected to a typical porous-hose spatial filter consisting of eight individual hoses covering a 30m aperture and the second sensor was left open to unimpeded acoustic input. Data were collected for several days, power spectrum computed for two-hour windows and the relative gain of the porous-hose filters were estimated by dividing the power spectrum. The porous-hose filter appears to attenuate less than 3 dB (rel 1 Pa**2/Hz) below 0.1 Hz and as much as 25 dB at 1 Hz and between 20 to 10 dB above 10 Hz. Several more experiments will be designed to address the effects of different characteristics of the individual porous

Assessment of atmospheric models for tele-infrasonic propagation

NASA Astrophysics Data System (ADS)

McKenna, Mihan; Hayek, Sylvia

2005-04-01

Iron mines in Minnesota are ideally located to assess the accuracy of available atmospheric profiles used in infrasound modeling. These mines are located approximately 400 km away to the southeast (142) of the Lac-Du-Bonnet infrasound station, IS-10. Infrasound data from June 1999 to March 2004 was analyzed to assess the effects of explosion size and atmospheric conditions on observations. IS-10 recorded a suite of events from this time period resulting in well constrained ground truth. This ground truth allows for the comparison of ray trace and PE (Parabolic Equation) modeling to the observed arrivals. The tele-infrasonic distance (greater than 250 km) produces ray paths that turn in the upper atmosphere, the thermosphere, at approximately 120 km to 140 km. Modeling based upon MSIS/HWM (Mass Spectrometer Incoherent Scatter/Horizontal Wind Model) and the NOGAPS (Navy Operational Global Atmospheric Prediction System) and NRL-GS2 (Naval Research Laboratory Ground to Space) augmented profiles are used to interpret the observed arrivals.

Application of a New Infrasound Sensor Technology in a Long Range Infrasound Propagation Experiment

NASA Astrophysics Data System (ADS)

Talmadge, C. L.; Waxler, R.; Hetzer, C. H.; Kleniert, D. E., Jr.; Dillion, K.; Assink, J.; Aydin, A.

2009-12-01

A low-cost ruggedized infrasound sensor has been developed at the NCPA laboratory of the University of Mississippi for outdoor infrasound measurements. This sensor has similar performance characteristics to other "standard" infrasound sensors, such as the Chaparral 50. A total of 50 sensors were constructed for this experiment, of which 42 were deployed on the Nevada and Utah desert for a period of four months. A long-range infrasound propagation experiment using these sensors was performed during the summer and fall of 2009. Source sizes varied in size from 4, 20 and 80 equivalent tons of TNT. The blasts were carried out typically on the Monday of each week in the afternoon, and were part of a scheduled demolition of first, second and third stages of trident missiles. In addition to a source capture location 23-km south of the site of the blasts, a series of 8 5-element arrays are located to the west of the blast location, at approximate ranges of 180 through 250 km in 10-km steps. Each array consisted of elements at -150-m, -50-m, 0-m, 50-m and 150-m relative to the center of the array along an east-west direction, and all microphones were equipped with 4 50-ft porous hoses connected to the microphone manifold for wind noise suppression. The signals from the microphones were digitized using GPS-synchronized, 24-bit DAQ systems. A Westerly direction for the deployment of the microphones was motivated by the presence of a strong stratospheric duct that persists through the summer months in the northern hemisphere at these latitudes. In this paper, we will discuss feasibility issues related the design of the NCPA microphone that makes possible deployments on these on large scales. Signal to noise issues related to temperature and wind fluctuations will also be discussed. Future plans include a larger scale deployment of several hundred microphones during 2010. We will discuss how the lessons learned from this series of measurements impacts that future deployment.

Uncertainties associated with parameter estimation in atmospheric infrasound arrays.

PubMed

Szuberla, Curt A L; Olson, John V

2004-01-01

This study describes a method for determining the statistical confidence in estimates of direction-of-arrival and trace velocity stemming from signals present in atmospheric infrasound data. It is assumed that the signal source is far enough removed from the infrasound sensor array that a plane-wave approximation holds, and that multipath and multiple source effects are not present. Propagation path and medium inhomogeneities are assumed not to be known at the time of signal detection, but the ensemble of time delays of signal arrivals between array sensor pairs is estimable and corrupted by uncorrelated Gaussian noise. The method results in a set of practical uncertainties that lend themselves to a geometric interpretation. Although quite general, this method is intended for use by analysts interpreting data from atmospheric acoustic arrays, or those interested in designing and deploying them. The method is applied to infrasound arrays typical of those deployed as a part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization.

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; Le Pichon, Alexis

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.

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

NASA Astrophysics Data System (ADS)

Trabant, Chad; Thurber, Clifford; Leith, William

2002-07-01

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 km 2 (90% CE: 5.1 km 2), 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 km 2 (90% CE: 438 km 2), and the other two covering 1730 and 8869 km 2 (90% CE: 1331 and 6822 km 2). 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 km 2 for all events having more than three observations.

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.

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.

On the use of infrasound for constraining global climate models

NASA Astrophysics Data System (ADS)

Millet, Christophe; Ribstein, Bruno; Lott, Francois; Cugnet, David

2017-11-01

Numerical prediction of infrasound is a complex issue due to constantly changing atmospheric conditions and to the random nature of small-scale flows. Although part of the upward propagating wave is refracted at stratospheric levels, where gravity waves significantly affect the temperature and the wind, yet the process by which the gravity wave field changes the infrasound arrivals remains poorly understood. In the present work, we use a stochastic parameterization to represent the subgrid scale gravity wave field from the atmospheric specifications provided by the European Centre for Medium-Range Weather Forecasts. It is shown that regardless of whether the gravity wave field possesses relatively small or large features, the sensitivity of acoustic waveforms to atmospheric disturbances can be extremely different. Using infrasound signals recorded during campaigns of ammunition destruction explosions, a new set of tunable parameters is proposed which more accurately predicts the small-scale content of gravity wave fields in the middle atmosphere. Climate simulations are performed using the updated parameterization. Numerical results demonstrate that a network of ground-based infrasound stations is a promising technology for dynamically tuning the gravity wave parameterization.

Hyperion 5113/A Infrasound Sensor Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

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).

Machine processing of ERTS and ground truth data

NASA Technical Reports Server (NTRS)

Rogers, R. H. (Principal Investigator); Peacock, K.

1973-01-01

The author has identified the following significant results. Results achieved by ERTS-Atmospheric Experiment PR303, whose objective is to establish a radiometric calibration technique, are reported. This technique, which determines and removes solar and atmospheric parameters that degrade the radiometric fidelity of ERTS-1 data, transforms the ERTS-1 sensor radiance measurements to absolute target reflectance signatures. A radiant power measuring instrument and its use in determining atmospheric parameters needed for ground truth are discussed. The procedures used and results achieved in machine processing ERTS-1 computer -compatible tapes and atmospheric parameters to obtain target reflectance are reviewed.

Volcanic eruption volume flux estimations from very long period infrasound signals

NASA Astrophysics Data System (ADS)

Yamada, Taishi; Aoyama, Hiroshi; Nishimura, Takeshi; Iguchi, Masato; Hendrasto, Muhamad

2017-01-01

We examine very long period infrasonic signals accompanying volcanic eruptions near active vents at Lokon-Empung volcano in Indonesia, Aso, Kuchinoerabujima, and Kirishima volcanoes in Japan. The excitation of the very long period pulse is associated with an explosion, the emerging of an eruption column, and a pyroclastic density current. We model the excitation of the infrasound pulse, assuming a monopole source, to quantify the volume flux and cumulative volume of erupting material. The infrasound-derived volume flux and cumulative volume can be less than half of the video-derived results. A largely positive correlation can be seen between the infrasound-derived volume flux and the maximum eruption column height. Therefore, our result suggests that the analysis of very long period volcanic infrasound pulses can be helpful in estimating the maximum eruption column height.

Seismic and Infrasound Energy Generation and Propagation at Local and Regional Distances Phase 1 - Divine Strake Experiment

DTIC Science & Technology

2007-10-11

large mine collapse (M=3.9) and shallow earthquake (M=3.9) indicates that there were no signals generated by these events. A new type of infrasound ...provide data to document the propagation of the acoustic signals between the infrasound array sites and allow us to estimate group velocities since...in near-source acoustic and seismic signals . 10 Near-source acoustic and seismic signals recorded at UTTR3 Explosion generated infrasound signals

Reference-free ground truth metric for metal artifact evaluation in CT images.

PubMed

Kratz, Bärbel; Ens, Svitlana; Müller, Jan; Buzug, Thorsten M

2011-07-01

In computed tomography (CT), metal objects in the region of interest introduce data inconsistencies during acquisition. Reconstructing these data results in an image with star shaped artifacts induced by the metal inconsistencies. To enhance image quality, the influence of the metal objects can be reduced by different metal artifact reduction (MAR) strategies. For an adequate evaluation of new MAR approaches a ground truth reference data set is needed. In technical evaluations, where phantoms can be measured with and without metal inserts, ground truth data can easily be obtained by a second reference data acquisition. Obviously, this is not possible for clinical data. Here, an alternative evaluation method is presented without the need of an additionally acquired reference data set. The proposed metric is based on an inherent ground truth for metal artifacts as well as MAR methods comparison, where no reference information in terms of a second acquisition is needed. The method is based on the forward projection of a reconstructed image, which is compared to the actually measured projection data. The new evaluation technique is performed on phantom and on clinical CT data with and without MAR. The metric results are then compared with methods using a reference data set as well as an expert-based classification. It is shown that the new approach is an adequate quantification technique for artifact strength in reconstructed metal or MAR CT images. The presented method works solely on the original projection data itself, which yields some advantages compared to distance measures in image domain using two data sets. Beside this, no parameters have to be manually chosen. The new metric is a useful evaluation alternative when no reference data are available.

Infrasound, Its Sources and Its Effects on Man

DTIC Science & Technology

1976-05-01

modulated by an infra - Annoyance has been broken out as a separate sonic frequency. For instance, the amplified topic because I believe that the greatest...importance is the nigh frequency response of quency sound. In general, infrasound does not the measurement system. Measurement of infra - often occur at levels...esuential for detailed analysis and changes in barometric pressure would be con- from these recordings a narrow band spectral sidered infrasonic . The

The Role of Ground Truth in Improved Identification of Mining Explosion Signals Utilization of Calibration Explosions and Acoustic Signals

DTIC Science & Technology

2000-09-01

and the Porphyry Copper District (PCD) of east central Arizona and south west New Mexico were used in gathering ground truth ranging from mine records...previous studies of large coal cast blasting operations in Wyoming that trigger the IMS (Hedlin et al. 2000), the porphyry copper region of Arizona and...local mines producing the sources. Close cooperation has been developed with the Phelps Dodge mines in Morenci, Arizona and Tyrone, New Mexico where in

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.

[Truth telling to patients--A discussion of Jewish sources (corrected)].

PubMed

Gesundheit, Benjamin; Zlotnick, Eitan; Wygoda, Michael; Rosenzweig, Joshua P; Steinberg, Avraham

2014-10-01

Defining truth and truth-telling to patients are central topics in philosophy, law, and psychology, with many implications in medicine. In the last hundred years, with the transition from paternalistic medicine to a system in which the patient's autonomy is emphasized, the decision on the quantity and quality of medical information to be disclosed to the patient has become more complicated and requires careful consideration and special sensitivity on the part of the doctor. The Israeli Patients' Rights Act (1996] established guidelines for medical staff about telltting the truth to patients with occasional special authority delegated to the doctor to decide for the benefit of the patient at his discretion and with the approval of the institutional ethics committee, but in practice there are difficulties in implementing the Law. This article reviews a selection of sources from Jewish tradition throughout the ages that deal with truthtelling or concealing the truth in medical contexts and other contexts. Sources are drawn from the Bible, Mishna-Talmud, and halachic Literature, from which.conclusions can be drawn regarding this issue. In our opinion, these sources yield messages and values that are also relevant to the modern medical world. This is especially true in a multi-cultural environment such as Israel that requires the physician to consider the patient's background and to communicate information in accordance with his/her will, in an efficient and sensitive manner.

Improving Estimates of Regional Infrasound Propagation by Incorporating Three-Dimensional Weather Modeling

NASA Astrophysics Data System (ADS)

McKenna, M. H.; Alter, R. E.; Swearingen, M. E.; Wilson, D. K.

2017-12-01

Many larger sources, such as volcanic eruptions and nuclear detonations, produce infrasound (acoustic waves with a frequency lower than humans can hear, namely 0.1-20 Hz) that can propagate over global scales. But many smaller infrastructure sources, such as bridges, dams, and buildings, also produce infrasound, though with a lower amplitude that tends to propagate only over regional scales (up to 150 km). In order to accurately calculate regional-scale infrasound propagation, we have incorporated high-resolution, three-dimensional forecasts from the Weather Research and Forecasting (WRF) meteorological model into a signal propagation modeling system called Environmental Awareness for Sensor and Emitter Employment (EASEE), developed at the US Army Engineer Research and Development Center. To quantify the improvement of infrasound propagation predictions with more realistic weather data, we conducted sensitivity studies with different propagation ranges and horizontal resolutions and compared them to default predictions with no weather model data. We describe the process of incorporating WRF output into EASEE for conducting these acoustic propagation simulations and present the results of the aforementioned sensitivity studies.

Infrasound ray tracing models for real events

NASA Astrophysics Data System (ADS)

Averbuch, Gil; Applbaum, David; Price, Colin; Ben Horin, Yochai

2015-04-01

's height or the sprite's most energetic part. Even though atmospheric wind has a strong influence on infrasound wave propagation, our estimation is that for high altitude sources, extreme weather in the troposphere below has low impact on the trajectories of the waves.

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.

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

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

IMS Infrasound Monitoring Test Site at Trafelberg, Austria: Preliminary Results from In-Situ Response Measurements of Infrasound Elements

DTIC Science & Technology

2010-09-01

IMS INFRASOUND MONITORING TEST SITE AT TRAFELBERG, AUSTRIA: PRELIMINARY RESULTS FROM IN-SITU RESPONSE MEASUREMENTS OF INFRASOUND ELEMENTS Thomas...The International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) has a unique infrasound test site...all four infrasound elements at I99 were made from 0.008 Hz to several Hz. For all four elements, from 0.01 to 0.1 Hz, the measured magnitude and

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.

Infrasound as a Depth Discriminant

DTIC Science & Technology

2010-09-01

INFRASOUND AS A DEPTH DISCRIMINANT Stephen J. Arrowsmith1, Hans E. Hartse1, Steven R. Taylor2, Richard J. Stead1, and Rod W. Whitaker1 Los Alamos...LA09-Depth-NDD02 ABSTRACT The identification of a signature relating depth to a remotely recorded infrasound signal requires a dataset of...can generate infrasound via a variety of processes, which have occasionally been confused in past studies due to the complexity of the process; (2

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

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.

Infrasound pulses from lightning and electrostatic field changes: Observation and discussion

NASA Astrophysics Data System (ADS)

Chum, J.; Diendorfer, G.; Å indelářová, T.; Baše, J.; Hruška, F.

2013-10-01

Narrow (~1-2 s) infrasound pulses that followed, with ~11 to ~50 s delays, rapid changes of electrostatic field were observed by a microbarometer array in the Czech Republic during thunderstorm activity. A positive pressure fluctuation (compression phase) always preceded decompression; the compression was usually higher than the decompression. The angles of arrival (azimuth and elevation) were analyzed for selected distinct events. Comparisons of distances and azimuths of infrasound sources from the center of microbarometer array with lightning locations determined by the European Cooperation for Lighting Detection lightning detection network show that most of the selected events can be very likely associated with intracloud (IC) discharges. The preceding rapid changes of electrostatic field, their potential association with IC discharges, and high-elevation angles of arrival for near infrasound sources indicate that an electrostatic mechanism is probably responsible for their generation. It is discussed that distinguishing the relative role of thermal and electrostatic mechanism is difficult and that none of the published models of electrostatic production of infrasound thunder can explain the presented observations precisely. A modification of the current models, based on consideration of at least two charged layers, is suggested. Further theoretical and experimental investigations are however needed to get a better description of the generation mechanism.

Recent development of infrasound monitoring network in Romania

NASA Astrophysics Data System (ADS)

Ghica, Daniela; Popa, Mihaela; Ionescu, Constantin

2017-04-01

The second half of 2016 was marked at National Institute for Earth Physics (NIEP) by a significant development of infrasound monitoring infrastructure in Romania. In addition to IPLOR, the 6-element acoustic array installed at Plostina, in the central part of Romania, since 2009, two other four-element arrays were deployed. The first one, BURARI infrasound research array, was deployed in late July 2016, under a joint effort of AFTAC, USA and NIEP, in the northern part of Romania, in Bucovina region. The sites, placed in vicinity of the central elements of BURAR seismic array (over 1.2 km aperture), are equipped with Chaparral Physics Model 21 microbarometers and Reftek RT 130 data loggers. The data, used mainly for research purposes within the scientific collaboration project between NIEP and AFTAC, are available to scientific community. The second one is a PTS portable infrasound array (I67RO) deployed for one year, starting with the end of September 2016, within a collaboration project between NIEP and PTS of the Preparatory Commission for CTBTO. This array is located in the western part of Romania, at Marisel, Cluj County, covering a 0.9 km aperture and being equipped with CEA/DAM MB2005 microbarometers and Reftek RT 130 data loggers. This joint experiment aims to contribute both to advanced understanding of infrasound sources in Central-Europe and to ARISE design study project, as an expansion of the spatial coverage of the European infrasound network. The data recorded by the three infrasound arrays deployed in Romania, during a same time interval (October - December 2016) were processed into detection arrival bulletins applying CEA/DASE PMCC algorithm embedded in DTK-GPMCC (extended CTBTO NDC-in-a-box) and WinPMCC software applications. The results were plotted and analyzed using DTK-DIVA software (extended CTBTO NDC-in-a-box), in order to assess detectability of each station, as well as the capacity of fusing detections into support of infrasound monitoring

Detecting and Cataloging Global Explosive Volcanism Using the IMS Infrasound Network

NASA Astrophysics Data System (ADS)

Matoza, R. S.; Green, D. N.; LE Pichon, A.; Fee, D.; Shearer, P. M.; Mialle, P.; Ceranna, L.

2015-12-01

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. These eruptions can also inject large volumes of ash into heavily travelled aviation corridors, thus posing a significant societal and economic hazard. Detecting and counting the global occurrence of explosive volcanism helps with progress toward several goals in earth sciences and has direct applications in volcanic hazard mitigation. This project aims to build a quantitative catalog of global explosive volcanic activity using the International Monitoring System (IMS) infrasound network. We are developing methodologies to search systematically through IMS infrasound array detection bulletins to identify signals of volcanic origin. We combine infrasound signal association and source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent infrasound signals in a global grid. When volcanic signals are identified, we extract metrics such as location, origin time, acoustic intensity, signal duration, and frequency content, compiling the results into a catalog. We are testing and validating our method on several well-known case studies, including the 2009 eruption of Sarychev Peak, Kuriles, the 2010 eruption of Eyjafjallajökull, Iceland, and the 2015 eruption of Calbuco, Chile. This work represents a step toward the goal of integrating IMS data products into global volcanic eruption early warning and notification systems. Additionally, a better characterization of volcanic signal detection helps improve understanding of operational event detection, discrimination, and association capabilities of the IMS network.

Using infrasound waves to monitor tropospheric weather and crater morphology changes at Volcán Tungurahua, Ecuador

NASA Astrophysics Data System (ADS)

Ortiz, Hugo D.; Johnson, Jeffrey B.; Ramón, Patricio G.; Ruiz, Mario C.

2018-01-01

We use infrasound waves generated during eruptions of Volcán Tungurahua (Ecuador) to study both, changing atmospheric conditions and volcanic source characteristics. Analyzed infrasound data were recorded for a 32-month period by a five-station network located within 6.5 km from the vent. We use cross-network correlation to quantify the recurrent eruptive behavior of Tungurahua and results are corroborated by reports from the Ecuadorian monitoring agency. Cross-network lag times vary over short time periods (minutes to days) when vent location is stable and attribute these variations to changes in atmospheric structure. Assuming a fixed source location, we invert for average air temperatures and winds in Tungurahua's vicinity (< 6.5 km) and find evidence for diurnal and semidiurnal tropospheric tides. We also use cross-network correlation lag times to compute infrasound source positions with resolutions of 11.6 m, taking into account coarse NOAA atmospheric models for local winds and temperatures. Variable infrasound-derived source locations suggest source migration during the 32 months of analyzed data. Such source position variability is expected following energetic eruptions that destructively altered the crater/vent morphology as confirmed by imagery obtained during regular overflights.

Seismo-acoustic analysis of the near quarry blasts using Plostina small aperture array

NASA Astrophysics Data System (ADS)

Ghica, Daniela; Stancu, Iulian; Ionescu, Constantin

2013-04-01

amplitudes below 5 Pa. Seismic data analysis shows that the frequency range of the signals are above 2 Hz. Surface explosions such as quarry blasts are useful sources for checking detection and location efficiency, when seismic measurements are added. The process is crucial for discrimination purposes and for establishing of a set of ground-truth infrasound events. Ground truth information plays a key role in the interpretation of infrasound signals, by including near-field observations from industrial blasts.

Eruption mass estimation using infrasound waveform inversion and ash and gas measurements: Evaluation at Sakurajima Volcano, Japan [Comparison of eruption masses at Sakurajima Volcano, Japan calculated by infrasound waveform inversion and ground-based sampling

DOE PAGES

Fee, David; Izbekov, Pavel; Kim, Keehoon; ...

2017-10-09

Eruption mass and mass flow rate are critical parameters for determining the aerial extent and hazard of volcanic emissions. Infrasound waveform inversion is a promising technique to quantify volcanic emissions. Although topography may substantially alter the infrasound waveform as it propagates, advances in wave propagation modeling and station coverage permit robust inversion of infrasound data from volcanic explosions. The inversion can estimate eruption mass flow rate and total eruption mass if the flow density is known. However, infrasound-based eruption flow rates and mass estimates have yet to be validated against independent measurements, and numerical modeling has only recently been appliedmore » to the inversion technique. Furthermore we present a robust full-waveform acoustic inversion method, and use it to calculate eruption flow rates and masses from 49 explosions from Sakurajima Volcano, Japan.« less

Eruption mass estimation using infrasound waveform inversion and ash and gas measurements: Evaluation at Sakurajima Volcano, Japan [Comparison of eruption masses at Sakurajima Volcano, Japan calculated by infrasound waveform inversion and ground-based sampling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fee, David; Izbekov, Pavel; Kim, Keehoon

Eruption mass and mass flow rate are critical parameters for determining the aerial extent and hazard of volcanic emissions. Infrasound waveform inversion is a promising technique to quantify volcanic emissions. Although topography may substantially alter the infrasound waveform as it propagates, advances in wave propagation modeling and station coverage permit robust inversion of infrasound data from volcanic explosions. The inversion can estimate eruption mass flow rate and total eruption mass if the flow density is known. However, infrasound-based eruption flow rates and mass estimates have yet to be validated against independent measurements, and numerical modeling has only recently been appliedmore » to the inversion technique. Furthermore we present a robust full-waveform acoustic inversion method, and use it to calculate eruption flow rates and masses from 49 explosions from Sakurajima Volcano, Japan.« less

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

Improved Infrasound Event Location

DTIC Science & Technology

2007-09-01

Bolide (20) —— 1 signal —— 5-8 signals Mine Explosion (112) Volcano (20) —— 2 signals —— >8 signals Rocket Motor Test (1) Landslide (1) —— 3-4...significant bookkeeping, since the ray-tracing programs must be executed separately for each source-receiver-model scenario, each producing multiple...Infrasound monitoring of volcanoes to probe high-altitude winds, J. Geophys. Res. 110, D13106, doi: 10.1029/2004JD005587. Le Pichon, A., K

MB3a Infrasound Sensor Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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).

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.

Sound Is Sound: Film Sound Techniques and Infrasound Data Array Processing

NASA Astrophysics Data System (ADS)

Perttu, A. B.; Williams, R.; Taisne, B.; Tailpied, D.

2017-12-01

A multidisciplinary collaboration between earth scientists and a sound designer/composer was established to explore the possibilities of audification analysis of infrasound array data. Through the process of audification of the infrasound we began to experiment with techniques and processes borrowed from cinema to manipulate the noise content of the signal. The results of this posed the question: "Would the accuracy of infrasound data array processing be enhanced by employing these techniques?". So a new area of research was born from this collaboration and highlights the value of these interactions and the unintended paths that can occur from them. Using a reference event database, infrasound data were processed using these new techniques and the results were compared with existing techniques to asses if there was any improvement to detection capability for the array. With just under one thousand volcanoes, and a high probability of eruption, Southeast Asia offers a unique opportunity to develop and test techniques for regional monitoring of volcanoes with different technologies. While these volcanoes are monitored locally (e.g. seismometer, infrasound, geodetic and geochemistry networks) and remotely (e.g. satellite and infrasound), there are challenges and limitations to the current monitoring capability. Not only is there a high fraction of cloud cover in the region, making plume observation more difficult via satellite, there have been examples of local monitoring networks and telemetry being destroyed early in the eruptive sequence. The success of local infrasound studies to identify explosions at volcanoes, and calculate plume heights from these signals, has led to an interest in retrieving source parameters for the purpose of ash modeling with a regional network independent of cloud cover.

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.

Wind Noise Suppression for Infrasound Sensors

DTIC Science & Technology

2014-03-01

Wind Noise Suppression for Infrasound Sensors by John M. Noble, W.C. Kirkpatrick Alberts, II, Sandra L. Collier, Richard Raspet, and Mark A...Laboratory Adelphi, MD 20783-1197 ARL-TR-6873 March 2014 Wind Noise Suppression for Infrasound Sensors John M. Noble, Sandra L. Collier, and...DATES COVERED (From - To) October 2012 to September 2013 4. TITLE AND SUBTITLE Wind Noise Suppression for Infrasound Sensors 5a. CONTRACT NUMBER 5b

Hyperion 5113/GP Infrasound Sensor Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

First- and third-party ground truth for key frame extraction from consumer video clips

NASA Astrophysics Data System (ADS)

Costello, Kathleen; Luo, Jiebo

2007-02-01

Extracting key frames (KF) from video is of great interest in many applications, such as video summary, video organization, video compression, and prints from video. KF extraction is not a new problem. However, current literature has been focused mainly on sports or news video. In the consumer video space, the biggest challenges for key frame selection from consumer videos are the unconstrained content and lack of any preimposed structure. In this study, we conduct ground truth collection of key frames from video clips taken by digital cameras (as opposed to camcorders) using both first- and third-party judges. The goals of this study are: (1) to create a reference database of video clips reasonably representative of the consumer video space; (2) to identify associated key frames by which automated algorithms can be compared and judged for effectiveness; and (3) to uncover the criteria used by both first- and thirdparty human judges so these criteria can influence algorithm design. The findings from these ground truths will be discussed.

Infrasound's capability to detect and characterise volcanic events, from local to regional scale.

NASA Astrophysics Data System (ADS)

Taisne, Benoit; Perttu, Anna

2017-04-01

Local infrasound and seismic networks have been successfully used for identification and quantification of explosions at single volcanoes. However the February, 2014 eruption of Kelud volcano, Indonesia, destroyed most of the local monitoring network. The use of remote seismic and infrasound sensors proved to be essential in the reconstruction of the eruptive sequence. The first recorded explosive event, with relatively weak seismic and infrasonic signature, was followed by a 2 hour sustained signal detected as far away as 11,000 km by infrasound sensors and up to 2,300 km away by seismometers. The volcanic intensity derived from these observations places the 2014 Kelud eruption between the intensity of the 1980 Mount St. Helens and the 1991 Pinatubo eruptions. The use of remote seismic stations and infrasound arrays in deriving valuable information about the onset, evolution, and intensity of volcanic eruptions is clear from the Kelud example. After this eruption the Singapore Infrasound Array became operational. This array, along with the other regional infrasound arrays which are part of the International Monitoring System, have recorded events from fireballs and regional volcanoes. The detection capability of this network for any specific volcanic event is not only dependent on the amplitude of the source, but also the propagation effects, noise level at each station, and characteristics of the regional persistent noise sources (like the microbarum). Combining the spatial and seasonal characteristics of this noise, within the same frequency band as significant eruptive events, with the probability of such events to occur, gives us a comprehensive understanding of detection capability for any of the 750 active or potentially active volcanoes in Southeast Asia.

Infrasound and Seismic Recordings of Rocket Launches from Kennedy Space Center, 2016-2017

NASA Astrophysics Data System (ADS)

McNutt, S. R.; Thompson, G.; Brown, R. G.; Braunmiller, J.; Farrell, A. K.; Mehta, C.

2017-12-01

We installed a temporary 3-station seismic-infrasound network at Kennedy Space Center (KSC) in February 2016 to test sensor calibrations and train students in field deployment and data acquisitions techniques. Each station featured a single broadband 3-component seismometer and a 3-element infrasound array. In May 2016 the network was scaled back to a single station due to other projects competing for equipment. To date 8 rocket launches have been recorded by the infrasound array, as well as 2 static tests, 1 aborted launch and 1 rocket explosion (see next abstract). Of the rocket launches recorded 4 were SpaceX Falcon-9, 2 were ULA Atlas-5 and 2 were ULA Delta-IV. A question we attempt to answer is whether the rocket engine type and launch trajectory can be estimated with appropriate travel-time, amplitude-ratio and spectral techniques. For example, there is a clear Doppler shift in seismic and infrasound spectrograms from all launches, with lower frequencies occurring later in the recorded signal as the rocket accelerates away from the array. Another question of interest is whether there are relationships between jet noise frequency, thrust and/or nozzle velocity. Infrasound data may help answer these questions. We are now in the process of deploying a permanent seismic and infrasound array at the Astronaut Beach House. 10 more rocket launches are schedule before AGU. NASA is also conducting a series of 33 sonic booms over KSC beginning on Aug 21st. Launches and other events at KSC have provided rich sources of signals that are useful to characterize and gain insight into physical processes and wave generation from man-made sources.

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

Characterization of Atmospheric Infrasound for Improved Weather Monitoring

NASA Astrophysics Data System (ADS)

Threatt, Arnesha; Elbing, Brian

2016-11-01

Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics (CLOUD MAP) is a multi-university collaboration focused on development and implementation of unmanned aircraft systems (UAS) and integration with sensors for atmospheric measurements. A primary objective for this project is to create and demonstrate UAS capabilities needed to support UAS operating in extreme conditions, such as a tornado producing storm system. These storm systems emit infrasound (acoustic signals below human hearing, <20 Hz) up to 2 hours before tornadogenesis. Due to an acoustic ceiling and weak atmospheric absorption, infrasound can be detected from distances in excess of 300 miles. Thus infrasound could be used for long-range, passive monitoring and detection of tornadogenesis as well as directing UAS resources to high-decision-value-information. To achieve this the infrasonic signals with and without severe storms must be understood. This presentation will report findings from the first CLOUD MAP field demonstration, which acquired infrasonic signals while simultaneously sampling the atmosphere with UAS. Infrasonic spectra will be shown from a typical calm day, a continuous source (pulsed gas-combustion torch), singular events, and UAS flights as well as localization results from a controlled source and multiple microphones. This work was supported by NSF Grant 1539070: CLOUD MAP - Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics.

Infrasound workshop for CTBT monitoring: Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 PrepCommore » 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.« less

Validation of neural spike sorting algorithms without ground-truth information.

PubMed

Barnett, Alex H; Magland, Jeremy F; Greengard, Leslie F

2016-05-01

The throughput of electrophysiological recording is growing rapidly, allowing thousands of simultaneous channels, and there is a growing variety of spike sorting algorithms designed to extract neural firing events from such data. This creates an urgent need for standardized, automatic evaluation of the quality of neural units output by such algorithms. We introduce a suite of validation metrics that assess the credibility of a given automatic spike sorting algorithm applied to a given dataset. By rerunning the spike sorter two or more times, the metrics measure stability under various perturbations consistent with variations in the data itself, making no assumptions about the internal workings of the algorithm, and minimal assumptions about the noise. We illustrate the new metrics on standard sorting algorithms applied to both in vivo and ex vivo recordings, including a time series with overlapping spikes. We compare the metrics to existing quality measures, and to ground-truth accuracy in simulated time series. We provide a software implementation. Metrics have until now relied on ground-truth, simulated data, internal algorithm variables (e.g. cluster separation), or refractory violations. By contrast, by standardizing the interface, our metrics assess the reliability of any automatic algorithm without reference to internal variables (e.g. feature space) or physiological criteria. Stability is a prerequisite for reproducibility of results. Such metrics could reduce the significant human labor currently spent on validation, and should form an essential part of large-scale automated spike sorting and systematic benchmarking of algorithms. Copyright © 2016 Elsevier B.V. All rights reserved.

Chaparral Model 60 Infrasound Sensor Evaluation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slad, George William; Merchant, Bion J.

2016-03-01

Sandia National Laboratories has tested and evaluated an infrasound sensor, the Model 60 manufactured by Chaparral Physics, a Division of Geophysical Institute of the University of Alaska, Fairbanks. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, and seismic sensitivity. The Model 60 infrasound sensor is a new sensor developed by Chaparral Physics intended to be a small, rugged sensor used in more flexible application conditions.

Effects of infrasound on vestibular function

NASA Astrophysics Data System (ADS)

Takigawa, H.; Sakamoto, H.; Murata, M.

1991-12-01

The present study was undertaken to elucidate subjective symptoms reported by some individuals exposed to various sounds, including infrasound. Narrow band infrasound of 5 Hz at center frequency and wide octave band audible noise were separately applied at an intensity of 95 dB. Parameters such as involuntary eye movement with the eyes visually fixed, body sway and pulse-wave were investigated. The total amount and power percentage in the low-frequency band of involuntary eye movement was significantly increased upon exposure to infrasound. Furthermore, confusion in postural control at the time of transition from opening to closing of the subject's eyes was inhibited by this exposure. Conversely, pulse-wave height decrement was observed upon exposure to both sounds, although this was smaller in the case of infrasound as compared with that of noise. These findings are taken to indicate that the effects taking place via the two different pathways were mixed in the subjective symptoms, and that functional changes caused by infrasound exposure were unrelated to an emotion stimulated by acoustical sensation.

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.

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.

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

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

Detection of Nuclear Explosions Using Infrasound Techniques

DTIC Science & Technology

2007-12-01

signal correlation between array elements in these arrays can seriously limit the reliable detection of infrasound generated ...goals of this investigation are to identify problems with the detection of explosion- generated infrasonic signals at stations in the global infrasound ...restricted to a thermospheric waveguide. The second part is focused on the limitations imposed on array detection of explosion- generated infrasound

Imaging the atmosphere using volcanic infrasound recorded on a dense local sensor network

NASA Astrophysics Data System (ADS)

Marcillo, O. E.; Johnson, J. B.; Johnson, R.

2010-12-01

. The furthest sensors were located at ~24 km and ~10 km from the vent respectively. Numerical analysis indicates that these two configurations will be able to probe the atmospheric conditions up to 2 km above the ground. The third topology featured most of the sensors on the summit crater at similar radial distances (2-4 km) and different azimuths. The data collected with the third topology is expected to provide detailed information of the very-local infrasonic field. Each configuration was on the ground and operational for around 84 hours. This full dataset will provide an opportunity to investigate source phenomenology and/or propagation effects of the infrasonic field. Tomographic studies of the atmosphere are expected to provide meteorological data that will be of value for ash and gas propagation models.

A multivariate analytical method to characterize sediment attributes from high-frequency acoustic backscatter and ground-truthing data (Jade Bay, German North Sea coast)

NASA Astrophysics Data System (ADS)

Biondo, Manuela; Bartholomä, Alexander

2017-04-01

One of the burning issues on the topic of acoustic seabed classification is the lack of solid, repeatable, statistical procedures that can support the verification of acoustic variability in relation to seabed properties. Acoustic sediment classification schemes often lead to biased and subjective interpretation, as they ultimately aim at an oversimplified categorization of the seabed based on conventionally defined sediment types. However, grain size variability alone cannot be accounted for acoustic diversity, which will be ultimately affected by multiple physical processes, scale of heterogeneity, instrument settings, data quality, image processing and segmentation performances. Understanding and assessing the weight of all of these factors on backscatter is a difficult task, due to the spatially limited and fragmentary knowledge of the seabed from of direct observations (e.g. grab samples, cores, videos). In particular, large-scale mapping requires an enormous availability of ground-truthing data that is often obtained from heterogeneous and multidisciplinary sources, resulting into a further chance of misclassification. Independently from all of these limitations, acoustic segments still contain signals for seabed changes that, if appropriate procedures are established, can be translated into meaningful knowledge. In this study we design a simple, repeatable method, based on multivariate procedures, with the scope to classify a 100 km2, high-frequency (450 kHz) sidescan sonar mosaic acquired in the year 2012 in the shallow upper-mesotidal inlet of the Jade Bay (German North Sea coast). The tool used for the automated classification of the backscatter mosaic is the QTC SWATHVIEWTMsoftware. The ground-truthing database included grab sample data from multiple sources (2009-2011). The method was designed to extrapolate quantitative descriptors for acoustic backscatter and model their spatial changes in relation to grain size distribution and morphology. The

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.

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.

Modal expansions for infrasound propagation and their implications for ground-to-ground propagation.

PubMed

Waxler, Roger; Assink, Jelle; Velea, Doru

2017-02-01

The use of expansions in vertical eigenmodes for long range infrasound propagation modeling in the effective sound speed approximation is investigated. The question of convergence of such expansions is related to the maximum elevation angles that are required. Including atmospheric attenuation leads to a non-self-adjoint vertical eigenvalue problem. The use of leading order perturbation theory for the modal attenuation is compared to the results of numerical solutions to the non-self-adjoint eigenvalue problem and conditions under which the perturbative result is expected to be valid are obtained. Modal expansions are obtained in the frequency domain; broadband signals must be modeled through Fourier reconstruction. Such broadband signal reconstruction is investigated and the relation between bandwidth, wavetrain duration, and frequency sampling is discussed.

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.

Seismic generated infrasounds on Telluric Planets: Modeling and comparisons between Earth, Venus and Mars

NASA Astrophysics Data System (ADS)

Lognonne, P. H.; Rolland, L.; Karakostas, F. G.; Garcia, R.; Mimoun, D.; Banerdt, W. B.; Smrekar, S. E.

2015-12-01

Earth, Venus and Mars are all planets in which infrasounds can propagate and interact with the solid surface. This leads to infrasound generation for internal sources (e.g. quakes) and to seismic waves generations for atmospheric sources (e.g. meteor, impactor explosions, boundary layer turbulences). Both the atmospheric profile, surface density, atmospheric wind and viscous/attenuation processes are however greatly different, including major differences between Mars/Venus and Earth due to the CO2 molecular relaxation. We present modeling results and compare the seismic/acoustic coupling strength for Earth, Mars and Venus. This modeling is made through normal modes modelling for models integrating the interior, atmosphere, both with realistic attenuation (intrinsic Q for solid part, viscosity and molecular relaxation for the atmosphere). We complete these modeling, made for spherical structure, by integration of wind, assuming the later to be homogeneous at the scale of the infrasound wavelength. This allows us to compute either the Seismic normal modes (e.g. Rayleigh surface waves), or the acoustic or the atmospheric gravity modes. Comparisons are done, for either a seismic source or an atmospheric source, on the amplitude of expected signals as a function of distance and frequency. Effects of local time are integrated in the modeling. We illustrate the Rayleigh waves modelling by Earth data (for large quakes and volcanoes eruptions). For Venus, very large coupling can occur at resonance frequencies between the solid part and atmospheric part of the planet through infrasounds/Rayleigh waves coupling. If the atmosphere reduced the Q (quality coefficient) of Rayleigh waves in general, the atmosphere at these resonance soffers better propagation than Venus crust and increases their Q. For Mars, Rayleigh waves excitations by atmospheric burst is shown and discussed for the typical yield of impacts. The new data of the Nasa INSIGHT mission which carry both seismic and

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.

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).

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.

Evaluation of multiple precipitation products across Mainland China using the triple collocation method without ground truth

NASA Astrophysics Data System (ADS)

Tang, G.; Li, C.; Hong, Y.; Long, D.

2017-12-01

Proliferation of satellite and reanalysis precipitation products underscores the need to evaluate their reliability, particularly over ungauged or poorly gauged regions. However, it is really challenging to perform such evaluations over regions lacking ground truth data. Here, using the triple collocation (TC) method that is capable of evaluating relative uncertainties in different products without ground truth, we evaluate five satellite-based precipitation products and comparatively assess uncertainties in three types of independent precipitation products, e.g., satellite-based, ground-observed, and model reanalysis over Mainland China, including a ground-based precipitation dataset (the gauge based daily precipitation analysis, CGDPA), the latest version of the European reanalysis agency reanalysis (ERA-interim) product, and five satellite-based products (i.e., 3B42V7, 3B42RT of TMPA, IMERG, CMORPH-CRT, PERSIANN-CDR) on a regular 0.25° grid at the daily timescale from 2013 to 2015. First, the effectiveness of the TC method is evaluated by comparison with traditional methods based on ground observations in a densely gauged region. Results show that the TC method is reliable because the correlation coefficient (CC) and root mean square error (RMSE) are close to those based on the traditional method with a maximum difference only up to 0.08 and 0.71 (mm/day) for CC and RMSE, respectively. Then, the TC method is applied to Mainland China and the Tibetan Plateau (TP). Results indicate that: (1) the overall performance of IMERG is better than the other satellite products over Mainland China; (2) over grid cells without rain gauges in the TP, IMERG and ERA show better performance than CGDPA, indicating the potential of remote sensing and reanalysis data over these regions and the inherent uncertainty of CGDPA due to interpolation using sparsely gauged data; (3) both TMPA-3B42 and CMORPH-CRT have some unexpected CC values over certain grid cells that contain water

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.

Regional discrimination studies: Phase III. Scientific report No. 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonner, J.; Herrin, E.; Sorrells, G.G.

1997-03-01

This report consists of three parts. Part 1, `Construction of Regional Ground Truth Data Bases Using Seismic And Infrasound Data` is by Gordon Sorrells, Eugene Herrin, and Jessie Bonner with contributions from Jack Swanson, Sarah Deering and Angela Maddox. Part 2, `Seismic And Infrasound Data Observations At TXAR` is by Jessie Bonner, Sarah Deering, Tao Liu, Jack Swanson and Ileana Tibuleac. Part 3, consists of the Acknowledgments called for by the contract.

USGS VDP Infrasound Sensor Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slad, George William; Merchant, Bion J.

2016-10-01

Sandia National Laboratories has tested and evaluated two infrasound sensors, the model VDP100 and VDP250, built in-house at the USGS Cascades Volcano Observatory. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, self-noise, dynamic range and nominal transfer function. Notable features of the VDP sensors include novel and durable construction and compact size.

Can expectations produce symptoms from infrasound associated with wind turbines?

PubMed

Crichton, Fiona; Dodd, George; Schmid, Gian; Gamble, Greg; Petrie, Keith J

2014-04-01

The development of new wind farms in many parts of the world has been thwarted by public concern that subaudible sound (infrasound) generated by wind turbines causes adverse health effects. Although the scientific evidence does not support a direct pathophysiological link between infrasound and health complaints, there is a body of lay information suggesting a link between infrasound exposure and health effects. This study tested the potential for such information to create symptom expectations, thereby providing a possible pathway for symptom reporting. A sham-controlled double-blind provocation study, in which participants were exposed to 10 min of infrasound and 10 min of sham infrasound, was conducted. Fifty-four participants were randomized to high- or low-expectancy groups and presented audiovisual information, integrating material from the Internet, designed to invoke either high or low expectations that exposure to infrasound causes specified symptoms. High-expectancy participants reported significant increases, from preexposure assessment, in the number and intensity of symptoms experienced during exposure to both infrasound and sham infrasound. There were no symptomatic changes in the low-expectancy group. Healthy volunteers, when given information about the expected physiological effect of infrasound, reported symptoms that aligned with that information, during exposure to both infrasound and sham infrasound. Symptom expectations were created by viewing information readily available on the Internet, indicating the potential for symptom expectations to be created outside of the laboratory, in real world settings. Results suggest psychological expectations could explain the link between wind turbine exposure and health complaints.

On the Discovery of Evolving Truth

PubMed Central

Li, Yaliang; Li, Qi; Gao, Jing; Su, Lu; Zhao, Bo; Fan, Wei; Han, Jiawei

2015-01-01

In the era of big data, information regarding the same objects can be collected from increasingly more sources. Unfortunately, there usually exist conflicts among the information coming from different sources. To tackle this challenge, truth discovery, i.e., to integrate multi-source noisy information by estimating the reliability of each source, has emerged as a hot topic. In many real world applications, however, the information may come sequentially, and as a consequence, the truth of objects as well as the reliability of sources may be dynamically evolving. Existing truth discovery methods, unfortunately, cannot handle such scenarios. To address this problem, we investigate the temporal relations among both object truths and source reliability, and propose an incremental truth discovery framework that can dynamically update object truths and source weights upon the arrival of new data. Theoretical analysis is provided to show that the proposed method is guaranteed to converge at a fast rate. The experiments on three real world applications and a set of synthetic data demonstrate the advantages of the proposed method over state-of-the-art truth discovery methods. PMID:26705502

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.

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.

Hindcasting the paroxysmal eruption of Villarrica using resonant infrasound tones

NASA Astrophysics Data System (ADS)

Johnson, J. B.; Watson, L. M.; Dunham, E. M.; Anderson, J.; Franco, L.; Cardona, C., Sr.; Palma, J.

2017-12-01

Volcanoes radiate their most intense sounds in the infrasound band (below 20 Hz), which can be well recorded many kilometers from a vent. Open-vent volcanic systems, with active degassing, are particularly effective at producing infrasound, and they characteristically produce resonant tones controlled by the geometry of their crater. Changes in infrasound resonant tones, and their damping coefficient, thus provide a means to infer crater geometry, including crater volume, depth, and profile. This study analyzes the rapidly varying infrasound tone and quality factor of infrasound at Volcan Villarrica (Chile) leading up to its paroxysmal eruption on 3 March 2015. The changes in infrasound reflected a rise in the lava lake surface starting 100 hours prior to the violent and sudden eruption. We suggest that infrasound surveillance of open-vent resonance is a powerful tool with application for forecasting volcanic unrest at open vent volcanoes.

Assessing the intrinsic precision of 3D/3D rigid image registration results for patient setup in the absence of a ground truth.

PubMed

Wu, Jian; Murphy, Martin J

2010-06-01

To assess the precision and robustness of patient setup corrections computed from 3D/3D rigid registration methods using image intensity, when no ground truth validation is possible. Fifteen pairs of male pelvic CTs were rigidly registered using four different in-house registration methods. Registration results were compared for different resolutions and image content by varying the image down-sampling ratio and by thresholding out soft tissue to isolate bony landmarks. Intrinsic registration precision was investigated by comparing the different methods and by reversing the source and the target roles of the two images being registered. The translational reversibility errors for successful registrations ranged from 0.0 to 1.69 mm. Rotations were less than 1 degrees. Mutual information failed in most registrations that used only bony landmarks. The magnitude of the reversibility error was strongly correlated with the success/ failure of each algorithm to find the global minimum. Rigid image registrations have an intrinsic uncertainty and robustness that depends on the imaging modality, the registration algorithm, the image resolution, and the image content. In the absence of an absolute ground truth, the variation in the shifts calculated by several different methods provides a useful estimate of that uncertainty. The difference observed by reversing the source and target images can be used as an indication of robust convergence.

Progresses with Net-VISA on Global Infrasound Association

NASA Astrophysics Data System (ADS)

Mialle, Pierrick; Arora, Nimar

2017-04-01

Global Infrasound Association algorithms are an important area of active development at the International Data Centre (IDC). These algorithms play an important part of the automatic processing system for verification technologies. A key focus at the IDC is to enhance association and signal characterization methods by incorporating the identification of signals of interest and the optimization of the network detection threshold. The overall objective is to reduce the number of associated infrasound arrivals that are rejected from the automatic bulletins when generating the Reviewed Event Bulletins (REB), and hence reduce IDC analyst workload. Despite good accuracy by the IDC categorization, a number of signal detections due to clutter sources such as microbaroms or surf are built into events. In this work we aim to optimize the association criteria based on knowledge acquired by IDC in the last 6 years, and focus on the specificity of seismo-acoustic events. The resulting work has been incorporated into NETVISA [1], a Bayesian approach to network processing. The model that we propose is a fusion of seismic, hydroacoustic and infrasound processing built on a unified probabilistic framework. References: [1] NETVISA: Network Processing Vertically Integrated Seismic Analysis. N. S. Arora, S. Russell, and E. Sudderth. BSSA 2013

Progresses with Net-VISA on Global Infrasound Association

NASA Astrophysics Data System (ADS)

Mialle, P.; Arora, N. S.

2016-12-01

Global Infrasound Association algorithms are an important area of active development at the International Data Centre (IDC). These algorithms play an important part of the automatic processing system for verification technologies. A key focus at the IDC is to enhance association and signal characterization methods by incorporating the identification of signals of interest and the optimization of the network detection threshold. The overall objective is to reduce the number of associated infrasound arrivals that are rejected from the automatic bulletins when generating the Reviewed Event Bulletins (REB), and hence reduce IDC analyst workload. Despite good accuracy by the IDC categorization, a number of signal detections due to clutter sources such as microbaroms or surf are built into events. In this work we aim to optimize the association criteria based on knowledge acquired by IDC in the last 6 years, and focus on the specificity of seismo-acoustic events. The resulting work has been incorporated into NETVISA [1], a Bayesian approach to network processing. The model that we propose is a fusion of seismic, hydroacoustic and infrasound processing built on a unified probabilistic framework. References: [1] NETVISA: Network Processing Vertically Integrated Seismic Analysis. N. S. Arora, S. Russell, and E. Sudderth. BSSA 2013

Skepticism, truth as coherence, and constructivist epistemology: grounds for resolving the discord between science and religion?

NASA Astrophysics Data System (ADS)

Staver, John R.

2010-03-01

Science and religion exhibit multiple relationships as ways of knowing. These connections have been characterized as cousinly, mutually respectful, non-overlapping, competitive, proximate-ultimate, dominant-subordinate, and opposing-conflicting. Some of these ties create stress, and tension between science and religion represents a significant chapter in humans' cultural heritage before and since the Enlightenment. Truth, knowledge, and their relation are central to science and religion as ways of knowing, as social institutions, and to their interaction. In religion, truth is revealed through God's word. In science, truth is sought after via empirical methods. Discord can be viewed as a competition for social legitimization between two social institutions whose goals are explaining the world and how it works. Under this view, the root of the discord is truth as correspondence. In this concept of truth, knowledge corresponds to the facts of reality, and conflict is inevitable for many because humans want to ask which one—science or religion—gets the facts correct. But, the root paradox, also known as the problem of the criterion, suggests that seeking to know nature as it is represents a fruitless endeavor. The discord can be set on new ground and resolved by taking a moderately skeptical line of thought, one which employs truth as coherence and a moderate form of constructivist epistemology. Quantum mechanics and evolution as scientific theories and scientific research on human consciousness and vision provide support for this line of argument. Within a constructivist perspective, scientists would relinquish only the pursuit of knowing reality as it is. Scientists would retain everything else. Believers who hold that religion explains reality would come to understand that God never revealed His truth of nature; rather, He revealed His truth in how we are to conduct our lives.

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

First stereo video dataset with ground truth for remote car pose estimation using satellite markers

NASA Astrophysics Data System (ADS)

Gil, Gustavo; Savino, Giovanni; Pierini, Marco

2018-04-01

Leading causes of PTW (Powered Two-Wheeler) crashes and near misses in urban areas are on the part of a failure or delayed prediction of the changing trajectories of other vehicles. Regrettably, misperception from both car drivers and motorcycle riders results in fatal or serious consequences for riders. Intelligent vehicles could provide early warning about possible collisions, helping to avoid the crash. There is evidence that stereo cameras can be used for estimating the heading angle of other vehicles, which is key to anticipate their imminent location, but there is limited heading ground truth data available in the public domain. Consequently, we employed a marker-based technique for creating ground truth of car pose and create a dataset∗ for computer vision benchmarking purposes. This dataset of a moving vehicle collected from a static mounted stereo camera is a simplification of a complex and dynamic reality, which serves as a test bed for car pose estimation algorithms. The dataset contains the accurate pose of the moving obstacle, and realistic imagery including texture-less and non-lambertian surfaces (e.g. reflectance and transparency).

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

Source Region Modeling of Explosions 2 and 3 from the Source Physics Experiment Using the Rayleigh Integral Method

NASA Astrophysics Data System (ADS)

Jones, K. R.; Arrowsmith, S.; Whitaker, R. W.

2012-12-01

The overall mission of the National Center for Nuclear Security (NCNS) Source Physics Experiment at the National Nuclear Security Site (SPE-N) near Las Vegas, Nevada is to improve upon and develop new physics based models for underground nuclear explosions using scaled, underground chemical explosions as proxies. To this end, we use the Rayleigh integral as an approximation to the Helmholz-Kirchoff integral, [Whitaker, 2007 and Arrowsmith et al., 2011], to model infrasound generation in the far-field. Infrasound generated by single-point explosive sources above ground can typically be treated as monopole point-sources. While the source is relatively simple, the research needed to model above ground point-sources is complicated by path effects related to the propagation of the acoustic signal and out of the scope of this study. In contrast, for explosions that occur below ground, including the SPE explosions, the source region is more complicated but the observation distances are much closer (< 5 km), thus greatly reducing the complication of path effects. In this case, elastic energy from the explosions radiates upward and spreads out, depending on depth, to a more distributed region at the surface. Due to this broad surface perturbation of the atmosphere we cannot model the source as a simple monopole point-source. Instead, we use the analogy of a piston mounted in a rigid, infinite baffle, where the surface area that moves as a result of the explosion is the piston and the surrounding region is the baffle. The area of the "piston" is determined by the depth and explosive yield of the event. In this study we look at data from SPE-N-2 and SPE-N-3. Both shots had an explosive yield of 1 ton at a depth of 45 m. We collected infrasound data with up to eight stations and 32 sensors within a 5 km radius of ground zero. To determine the area of the surface acceleration, we used data from twelve surface accelerometers installed within 100 m radially about ground zero

Regional measurements of infrasound signals from ARIANE-5 engine tests in Southern Germany

NASA Astrophysics Data System (ADS)

Koch, K.

2012-04-01

A well-controlled source of repetitive infrasound emissions was previously identified and has been related to development and acceptance tests of the European Space Agencies ARIANE-5 main engine. The propulsion testing facility of the German Aerospace Agency (DLR) near Heilbronn, Southern Germany, is a distance of about 320 km away from the International Monitoring System (IMS) station IS26 in east-southeasterly direction. In the past, signals associated with these propulsion tests could normally be detected at IS26 during winter months, but not during summer months, reflecting the changes in atmospheric conditions between winter and summer. Over the last year, DLR has prepared to conduct a series of seven propulsion tests which started in November 2011; with interim times between tests of 3-4 weeks it will last until late March or early April 2012. With mobile infrasound recording equipment available at BGR we planned to record the infrasonic wavefield along the path to IS26 at regular distances starting as close as 20 km from the source. Our aim is to study sound propagation from direct paths mainly involving the tropospheric layer through the "zone of silence" to distances close to IS26, where paths through stratospheric layers are followed. Preliminary results show that during the relevant winter season direct path propagation can be observed to some 40 km from the propulsion test source, even at seismographic stations where the acoustic wave couples into the ground. The tests are also observed at IS26, and waveform duration and f-k-analysis confirm the signals to be associated with the GT-type propulsion tests.

Detection of infrasound and linear acceleration in fishes.

PubMed

Sand, O; Karlsen, H E

2000-09-29

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.

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

Infrasound Studies for Yield Estimation of HE Explosions

DTIC Science & Technology

2011-03-05

AFRL-RV-HA-TR-2011-1022 Infrasound Studies for Yield Estimation of HE Explosions Paul Golden Petru Negraru Southern Methodist...DATES COVERED (From - To) 5 Mar 2010 to 5 Mar 2011 4. TITLE AND SUBTITLE Infrasound Studies for Yield Estimation of HE Explosions 5a. CONTRACT NUMBER...conducting investigations to determine the yield of HE explosions from infrasound signals. In particular SMU is investigating how the period and amplitude

North Korea nuclear test analysis results using KMA seismic and infrasound networks

NASA Astrophysics Data System (ADS)

Jeon, Y. S.; Park, E.; Lee, D.; Min, K.; CHO, S.

2017-12-01

Democratic People's Republic of Korea(DPRK) carried out 6th nuclear test on 3 Sep. 2017 at 03:30 UTC. Seismic and infrasound network operated by Korea Meteorological Administration(KMA) successfully detected signals took place in the DPRK's test site, Punggye-ri. First, we checked that Pg/Lg spectral amplitude ratio greater than 1 in the frequency range from 1.0 to 10.0 Hz is useful to discriminate between DPRK test signals and natural earthquakes. KMA's infrasound stations of Cheorwon(CW) and Yanggu(YG) successfully monitored the azimuth direction of the arrival of the infrasound signals generated from DPRK underground nuclear explosions, including the recent test on September 03, 2017. The azimuthal direction of 210(CW) and 130 (YG) point out Punggye-ri test site. Complete waveforms at stations MDJ, CHC2, YNCB in long period(0.05 to 0.1 HZ) are jointly inverted with local P-wave polarities to generate moment tensor inversion result of the explosive moment 1.20e+24 dyne cm(Mw 5.31) and 65% of ISO. The moment magnitude of 5th, 4th and 3rd are 4.61, 4.69 and 4.46 respectively. Source type moment tensor inversion result of DPRK nuclear tests show that the event is significantly away from the deviatoric line of the Hudson et at. (1989) source-type diagram and identifies as having a significant explosive component. Analysis results using seismic and infrasound network verify that the DPRK's explosion tests classified as nuclear test.

Infrasound Studies for Yield Estimation of HE Explosions

DTIC Science & Technology

2012-06-05

AFRL-RV-PS- AFRL-RV-PS- TR-2012-0084 TR-2012-0084 INFRASOUND STUDIES FOR YIELD ESTIMATION OF HE EXPLOSIONS Paul Golden, et al...05 Mar 2010 to 05 Mar 2012 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER FA9453-10-C-0212 Infrasound Studies for Yield Estimation of HE...report we discuss the capability of estimating the yield of an explosion from infrasound signals generated by low yield chemical explosions. We used

Soil moisture ground truth, Lafayette, Indiana, site; St. Charles Missouri, site; Centralia, Missouri, site

NASA Technical Reports Server (NTRS)

Jones, E. B.

1975-01-01

The soil moisture ground-truth measurements and ground-cover descriptions taken at three soil moisture survey sites located near Lafayette, Indiana; St. Charles, Missouri; and Centralia, Missouri are given. The data were taken on November 10, 1975, in connection with airborne remote sensing missions being flown by the Environmental Research Institute of Michigan under the auspices of the National Aeronautics and Space Administration. Emphasis was placed on the soil moisture in bare fields. Soil moisture was sampled in the top 0 to 1 in. and 0 to 6 in. by means of a soil sampling push tube. These samples were then placed in plastic bags and awaited gravimetric analysis.

Infrasound Observation of the Apparent North Korean Nuclear Test of 25 May 2009

NASA Astrophysics Data System (ADS)

Jeon, J.; Che, I.; Kim, T.; Lee, H.

2009-12-01

On 25 May 2009, a seismic event (mb 4.6) was recorded from a source in northeastern North Korea, close to the location of a previous seismic event on 9 October 2006. Both events have been declared to be nuclear tests. Five seismo-acoustic arrays in South Korea recorded epicentral infrasonic signals for the more recent test following the strong seismic waves from the explosion. This study describes the characteristics of the nuclear test-generated infrasound signals observed at infrasound arrays located from 304 to 528 km from the source. The signals were characterized by stratospheric returns with amplitudes from 0.16 to 0.35 microbar and dominant frequencies between 1.0 and 4.3 Hz. Celerities determined for the arrivals suggest that most of the infrasonic energy travelled as a stratospheric phase. The inferred infrasonic location was offset about 15.7 km from the reference seismic location. On the basis of observed amplitudes of the stratospheric phases and corrections based on prevailing winds, the epicentral infrasonic energy was estimated to be equivalent to that expected from about 2.2 ton surface detonation of conventional explosives. We conclude that this small energy estimate is related to the partitioning of the contained explosive energy resulting from the interaction of strong ground motion at the surface with the atmosphere rather than the direct transfer of explosion energy to the air. This relatively small energy ratio between the infrasonic energy and the seismic energy could be used to distinguish the event from a common surface explosion.

Incorporating atmospheric uncertainties into estimates of the detection capability of the IMS infrasound network

NASA Astrophysics Data System (ADS)

Le Pichon, Alexis; Ceranna, Lars; Taillepied, Doriane

2015-04-01

To monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a dedicated network is being deployed. Multi-year observations recorded by the International Monitoring System (IMS) infrasound network confirm that its detection capability is highly variable in space and time. Today, numerical modeling techniques provide a basis to better understand the role of different factors describing the source and the atmosphere that influence propagation predictions. Previous studies estimated the radiated source energy from remote observations using frequency dependent attenuation relation and state-of-the-art specifications of the stratospheric wind. In order to account for a realistic description of the dynamic structure of the atmosphere, model predictions are further enhanced by wind and temperature error distributions as measured in the framework of the ARISE project (http://arise-project.eu/). In the context of the future verification of the CTBT, these predictions quantify uncertainties in the spatial and temporal variability of the IMS infrasound network performance in higher resolution, and will be helpful for the design and prioritizing maintenance of any arbitrary infrasound monitoring network.

Incorporating atmospheric uncertainties into estimates of the detection capability of the IMS infrasound network

NASA Astrophysics Data System (ADS)

Le Pichon, Alexis; Blanc, Elisabeth; Rüfenacht, Rolf; Kämpfer, Niklaus; Keckhut, Philippe; Hauchecorne, Alain; Ceranna, Lars; Pilger, Christoph; Ross, Ole

2014-05-01

To monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a dedicated network is being deployed. Multi-year observations recorded by the International Monitoring System (IMS) infrasound network confirm that its detection capability is highly variable in space and time. Today, numerical modeling techniques provide a basis to better understand the role of different factors describing the source and the atmosphere that influence propagation predictions. Previous studies estimated the radiated source energy from remote observations using frequency dependent attenuation relation and state-of-the-art specifications of the stratospheric wind. In order to account for a realistic description of the dynamic structure of the atmosphere, model predictions are further enhanced by wind and temperature error distributions as measured in the framework of the ARISE project (http://arise-project.eu/). In the context of the future verification of the CTBT, these predictions quantify uncertainties in the spatial and temporal variability of the IMS infrasound network performance in higher resolution, and will be helpful for the design and prioritizing maintenance of any arbitrary infrasound monitoring network.

Infrasound Detection of Rocket Launches

DTIC Science & Technology

2000-09-01

infrasound pressure, and λ and µ are the Lame and shear modulii. Seismic data was available from the IRIS data center for the seismic station DWPF ...the bandwidth of interest. Figure 4 shows a recording of STS-93 (07/24/99 04:31:00GMT) at DWPF (97 km). The largest seismic amplitudes are consistent...lasts ~400 seconds. The dominant frequency (~4 Hz) at DWPF is consistent with the long-range infrasound signals observed at DLIAR. Figure 3. Seismic

Global scale stratospheric processes as measured by the infrasound IMS network

NASA Astrophysics Data System (ADS)

Le Pichon, A.; Ceranna, L.; Kechut, P.

2012-12-01

IMS infrasound array data are routinely processed at the International Data Center (IDC). The wave parameters of the detected signals are estimated with the Progressive Multi-Channel Correlation method (PMCC). We have processed continuous recordings from 41 certified IMS stations from 2005 to 2010 in the 0.01-5 Hz frequency band using a new implementation of the PMCC algorithm. Microbaroms are the dominant source of signals near-continuously and globally detected. The observed azimuthal seasonal trend correlates well with the variation of the effective sound speed ratio (Veff-ratio) which is a proxy for the combined effects of refraction due to sound speed gradients and advection due to along-path stratospheric wind on infrasound propagation. Systematic correlations between infrasound parameters (e.g. number of detections, amplitude) and Veff-ratio calculated at different ranges of altitudes are performed. Combined with propagation modeling, we show that such an analysis enables a characterization of the wind and temperature structure above the stratosphere and may provide detailed information on upper atmospheric processes (e.g., large-scale planetary waves, stratospheric warming effects) from the seasonal trend to short time scale variability. We discuss the potential benefit of long-term infrasound monitoring to infer stratospheric processes for the first time on a global scale. This study suggests poorly resolved stratospheric wind fluctuations at low latitude regions with strengths of horizontal wind structures underestimated by at least ~10 m/s. It is expected that this correlation between infrasound observations and the state-of-the-art atmospheric specifications will allow to statistically quantify the spatial and temporal resolutions of the wind structures at different ranges of altitudes, latitudes and time scales.

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.

Possible influence of infrasound on glioma cell response to chemotherapy: a pilot study.

PubMed

Yount, Garret; Taft, Ryan; West, Jeremy; Moore, Dan

2004-04-01

To assess the response of cultured human tumor cells to infrasound in combination with conventional anticancer agents using an infrasound-emitting apparatus marketed as a therapeutic device. Two pilot experiments measured proliferation of cultured brain tumor cells exposed to three treatment conditions: infrasound emission alone, infrasound in combination with the chemotherapy 5-fluorouracil (5-FU), and infrasound in combination with ionizing radiation. Results from each experimental condition were compared to those from appropriate control conditions. A standard colony-forming efficiency assay was used to assess tumor cell proliferation. Tumor cell proliferation was not significantly altered by treatment with infrasound alone, nor did infrasound appear to influence cellular response to x-rays. There was a significant interaction between 5-FU and infrasound (P < 0.0001), however, evident in decreased colony formation. Further research is warranted to assess potential synergism between infrasound and 5-FU against tumor cell proliferation, and to investigate the possible therapeutic use of infrasound.

Assessment of eruption intensity using infrasound waveform inversion at Mt. Etna, Italy.

NASA Astrophysics Data System (ADS)

Diaz Moreno, A.; Iezzi, A. M.; Lamb, O. D.; Zuccarello, L.; Fee, D.; De Angelis, S.

2017-12-01

Mt. Etna, Italy, a 3,330 m stratovolcano, is one of the most active volcanoes in the world. It is topped by five craters: Voragine, Bocca Nuova, the North-East, South-East, and New South-East Crater. Its activity during the past decade can be separated into two main types: i) nearly-continuous degassing interspersed by mild-to-vigorous Strombolian activity within the summit craters, and ii) effusive flank eruptions. In June 2017, we deployed a large temporary network of 14 infrasound sensors (Chaparral UHP60) and 12 broadband seismometers (Guralp EX-120s). We also recorded Thermal Infrared (TIR) and Unmanned Aerial Vehicle images of activity at the summit vents. Our primary objective is to quantify the intensity and mechanisms of infrasound sources at Mt. Etna, and use these results to improve models of volcanic plumes. From June 2017 until the time of writing, the infrasound network detected signals associated with nearly-continuous degassing and discrete small-to-moderate explosions originating at two distinct locations within the Voragine Crater and the New South-East Crater, respectively. During periods of increased explosive activity, we recorded 20-30 discrete events/day with infrasonic amplitudes of up to 7.5 Pa at 1 km distance from the active vent. The explosions exhibited sinusoidal acoustic waveforms, often with similar characteristics, durations of 1-3 s, and a 2 Hz peak frequency. Due to the relatively dense station coverage and the azimuthal distribution of the network, our deployment offers an opportunity to characterize, with unprecedented resolution, infrasound sources at Mt. Etna. Here we present preliminary results of 3D acoustic wave-field simulations, using a Finite Difference Time Domain modelling scheme, and a preliminary assessment of volumetric eruption rates through acoustic waveform inversion. We investigate the effects of local topography and atmospheric winds on the propagation of the acoustic wavefield, and discuss the implications for

On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caudron, Corentin; Taisne, Benoit; Garces, Milton

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 Keludmore » eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. As a result, 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.« less

On the use of remote infrasound and seismic stations to constrain the eruptive sequence and intensity for the 2014 Kelud eruption

DOE PAGES

Caudron, Corentin; Taisne, Benoit; Garces, Milton; ...

2015-07-14

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 Keludmore » eruption between the 1980 Mount St. Helens and 1991 Pinatubo eruptions intensities. As a result, 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.« less

Location and analysis of acoustic infrasound pulses in lightning

NASA Astrophysics Data System (ADS)

Arechiga, R.; Stock, M.; Thomas, R.; Erives, H.; Rison, W.; Edens, H.; Lapierre, J.

2014-07-01

Acoustic, VHF, and electrostatic measurements throw new light onto the origin and production mechanism of the thunder infrasound signature (<10 Hz) from lightning. This signature, composed of an initial compression followed by a rarefaction pulse, has been the subject of several unconfirmed theories and models. The observations of two intracloud flashes which each produced multiple infrasound pulses were analyzed for this work. Once the variation of the speed of sound with temperature is taken into account, both the compression and rarefaction portions of the infrasound pulses are found to originate very near lightning channels mapped by the Lightning Mapping Array. We found that none of the currently proposed models can explain infrasound generation by lightning, and thus propose an alternate theory: The infrasound compression pulse is produced by electrostatic interaction of the charge deposited on the channel and in the streamer zone of the lightning channel.

Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network

NASA Astrophysics Data System (ADS)

Matoza, Robin S.; Green, David N.; Le Pichon, Alexis; Shearer, Peter M.; Fee, David; Mialle, Pierrick; Ceranna, Lars

2017-04-01

We experiment with a new method to search systematically through multiyear data from the International Monitoring System (IMS) infrasound network to identify explosive volcanic eruption signals originating anywhere on Earth. Detecting, quantifying, and cataloging the global occurrence of explosive volcanism helps toward several goals in Earth sciences and has direct applications in volcanic hazard mitigation. We combine infrasound signal association across multiple stations with source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent unwanted infrasound signals (clutter) in a global grid, without needing to screen array processing detection lists from individual stations prior to association. We develop the algorithm using case studies of explosive eruptions: 2008 Kasatochi, Alaska; 2009 Sarychev Peak, Kurile Islands; and 2010 Eyjafjallajökull, Iceland. We apply the method to global IMS infrasound data from 2005-2010 to construct a preliminary acoustic catalog that emphasizes sustained explosive volcanic activity (long-duration signals or sequences of impulsive transients lasting hours to days). This work represents a step toward the goal of integrating IMS infrasound data products into global volcanic eruption early warning and notification systems. Additionally, a better understanding of volcanic signal detection and location with the IMS helps improve operational event detection, discrimination, and association capabilities.

Auroral Infrasound Observed at I53US at Fairbanks, Alaska

NASA Astrophysics Data System (ADS)

Wilson, C. R.; Olson, J. V.

2003-12-01

In this presentation we will describe two different types of auroral infrasound recently observed at Fairbanks, Alaska in the pass band from 0.015 to 0.10 Hz. Infrasound signals associated with auroral activity (AIW) have been observed in Fairbanks over the past 30 years with infrasonic microphone arrays. The installation of the new CTBT/IMS infrasonic array, I53US, at Fairbanks has resulted in a greatly increased quality of the infrasonic data with which to study natural sources of infrasound. In the historical data at Fairbanks all the auroral infrasonic waves (AIW) detected were found to be the result of bow waves that are generated by supersonic motion of auroral arcs that contain strong electrojet currents. This infrasound is highly anisotropic, moving in the same direction as that of the auroral arc. AIW bow waves observed in 2003 at I53US will be described. Recently at I53US we have observed many events of very high trace velocity that are comprised of continuous, highly coherent wave trains. These waves occur in the morning hours at times of strong auroral activity. This new type of very high trace velocity AIW appears to be associated with pulsating auroral displays. Pulsating auroras occur predominantly after magnetic midnight (10:00 UT at Fairbanks). They are a usual part of the recovery phase of auroral substorms and are produced by energetic electrons precipitating into the atmosphere. Given proper dark, cloudless sky conditions during the AIW events, bright pulsating auroral forms were sometimes visible overhead.

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

Strategies for cloud-top phase determination: differentiation between thin cirrus clouds and snow in manual (ground truth) analyses

NASA Astrophysics Data System (ADS)

Hutchison, Keith D.; Etherton, Brian J.; Topping, Phillip C.

1996-12-01

Quantitative assessments on the performance of automated cloud analysis algorithms require the creation of highly accurate, manual cloud, no cloud (CNC) images from multispectral meteorological satellite data. In general, the methodology to create ground truth analyses for the evaluation of cloud detection algorithms is relatively straightforward. However, when focus shifts toward quantifying the performance of automated cloud classification algorithms, the task of creating ground truth images becomes much more complicated since these CNC analyses must differentiate between water and ice cloud tops while ensuring that inaccuracies in automated cloud detection are not propagated into the results of the cloud classification algorithm. The process of creating these ground truth CNC analyses may become particularly difficult when little or no spectral signature is evident between a cloud and its background, as appears to be the case when thin cirrus is present over snow-covered surfaces. In this paper, procedures are described that enhance the researcher's ability to manually interpret and differentiate between thin cirrus clouds and snow-covered surfaces in daytime AVHRR imagery. The methodology uses data in up to six AVHRR spectral bands, including an additional band derived from the daytime 3.7 micron channel, which has proven invaluable for the manual discrimination between thin cirrus clouds and snow. It is concluded that while the 1.6 micron channel remains essential to differentiate between thin ice clouds and snow. However, this capability that may be lost if the 3.7 micron data switches to a nighttime-only transmission with the launch of future NOAA satellites.

Snowpack ground truth: Radar test site, Steamboat Springs, Colorado, 8-16 April 1976

NASA Technical Reports Server (NTRS)

Howell, S.; Jones, E. B.; Leaf, C. F.

1976-01-01

Ground-truth data taken at Steamboat Springs, Colorado is presented. Data taken during the period April 8, 1976 - April 16, 1976 included the following: (1) snow depths and densities at selected locations (using a Mount Rose snow tube); (2) snow pits for temperature, density, and liquid water determinations using the freezing calorimetry technique and vertical layer classification; (3) snow walls were also constructed of various cross sections and documented with respect to sizes and snow characteristics; (4) soil moisture at selected locations; and (5) appropriate air temperature and weather data.

How Many Subjects are Needed for a Visual Field Normative Database? A Comparison of Ground Truth and Bootstrapped Statistics.

PubMed

Phu, Jack; Bui, Bang V; Kalloniatis, Michael; Khuu, Sieu K

2018-03-01

The number of subjects needed to establish the normative limits for visual field (VF) testing is not known. Using bootstrap resampling, we determined whether the ground truth mean, distribution limits, and standard deviation (SD) could be approximated using different set size ( x ) levels, in order to provide guidance for the number of healthy subjects required to obtain robust VF normative data. We analyzed the 500 Humphrey Field Analyzer (HFA) SITA-Standard results of 116 healthy subjects and 100 HFA full threshold results of 100 psychophysically experienced healthy subjects. These VFs were resampled (bootstrapped) to determine mean sensitivity, distribution limits (5th and 95th percentiles), and SD for different ' x ' and numbers of resamples. We also used the VF results of 122 glaucoma patients to determine the performance of ground truth and bootstrapped results in identifying and quantifying VF defects. An x of 150 (for SITA-Standard) and 60 (for full threshold) produced bootstrapped descriptive statistics that were no longer different to the original distribution limits and SD. Removing outliers produced similar results. Differences between original and bootstrapped limits in detecting glaucomatous defects were minimized at x = 250. Ground truth statistics of VF sensitivities could be approximated using set sizes that are significantly smaller than the original cohort. Outlier removal facilitates the use of Gaussian statistics and does not significantly affect the distribution limits. We provide guidance for choosing the cohort size for different levels of error when performing normative comparisons with glaucoma patients.

A Method for Assessing Ground-Truth Accuracy of the 5DCT Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Tai H., E-mail: tdou@mednet.ucla.edu; Thomas, David H.; O'Connell, Dylan P.

2015-11-15

Purpose: To develop a technique that assesses the accuracy of the breathing phase-specific volume image generation process by patient-specific breathing motion model using the original free-breathing computed tomographic (CT) scans as ground truths. Methods: Sixteen lung cancer patients underwent a previously published protocol in which 25 free-breathing fast helical CT scans were acquired with a simultaneous breathing surrogate. A patient-specific motion model was constructed based on the tissue displacements determined by a state-of-the-art deformable image registration. The first image was arbitrarily selected as the reference image. The motion model was used, along with the free-breathing phase information of the originalmore » 25 image datasets, to generate a set of deformation vector fields that mapped the reference image to the 24 nonreference images. The high-pitch helically acquired original scans served as ground truths because they captured the instantaneous tissue positions during free breathing. Image similarity between the simulated and the original scans was assessed using deformable registration that evaluated the pointwise discordance throughout the lungs. Results: Qualitative comparisons using image overlays showed excellent agreement between the simulated images and the original images. Even large 2-cm diaphragm displacements were very well modeled, as was sliding motion across the lung–chest wall boundary. The mean error across the patient cohort was 1.15 ± 0.37 mm, and the mean 95th percentile error was 2.47 ± 0.78 mm. Conclusion: The proposed ground truth–based technique provided voxel-by-voxel accuracy analysis that could identify organ-specific or tumor-specific motion modeling errors for treatment planning. Despite a large variety of breathing patterns and lung deformations during the free-breathing scanning session, the 5-dimensionl CT technique was able to accurately reproduce the original helical CT scans, suggesting its

A framework for estimating stratospheric wind speeds from unknown sources and application to the 2010 December 25 bolide

NASA Astrophysics Data System (ADS)

Arrowsmith, Stephen J.; Marcillo, Omar; Drob, Douglas P.

2013-10-01

We present a methodology for infrasonic remote sensing of winds in the stratosphere that does not require discrete ground-truth events. Our method uses measured time delays between arrays of sensors to provide group velocities (referred to here as celerities) and then minimizes the difference between observed and predicted celerities by perturbing an initial atmospheric specification. Because we focus on interarray propagation effects, it is not necessary to simulate the full propagation path from source to receiver. This feature allows us to use a relatively simple forward model that is applicable over short-regional distances. By focusing on stratospheric returns, we show that our non-linear inversion scheme converges much better if the starting model contains a strong stratospheric duct. Using the Horizontal Wind Model (HWM)/Mass Spectrometer Incoherent Scatter (MSISE) empirical climatology as a starting model, we demonstrate that the inversion scheme is robust to large uncertainties in backazimuth, but that uncertainties in the measured trace velocity and celerity require the use of prior constraints to ensure suitable convergence. The inversion of synthetic data, using realistic estimates of measurement error, shows that our scheme will nevertheless improve upon a starting model under most scenarios. The inversion scheme is applied to infrasound data recorded from a large event on 2010 December 25, which is presumed to be a bolide, using data from a nine-element infrasound network in Utah. We show that our recorded data require a stronger zonal wind speed in the stratosphere than is present in the HWM profile, and are more consistent with the Ground-to-Space (G2S) profile.

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.

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.

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

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

Using the IMS infrasound network for the identification of mountain-associated waves and gravity waves hotspots

NASA Astrophysics Data System (ADS)

Hupe, Patrick; Ceranna, Lars; Pilger, Christoph; Le Pichon, Alexis

2017-04-01

The infrasound network of the International Monitoring System (IMS) has been established for monitoring the atmosphere to detect violations of the Comprehensive nuclear-Test-Ban Treaty (CTBT). The IMS comprises 49 certified infrasound stations which are globally distributed. Each station provides data for up to 16 years. Due to the uniform distribution of the stations, the IMS infrasound network can be used to derive global information on atmospheric dynamics' features. This study focuses on mountain-associated waves (MAWs), i.e. acoustic waves in the frequency range between approximately 0.01 Hz and 0.05 Hz. MAWs can be detected in infrasound data by applying the Progressive Multi-Channel Correlation (PMCC) algorithm. As a result of triangulation, global hotspots of MAWs can be identified. Previous studies on gravity waves indicate that global hotspots of gravity waves are similar to those found for MAWs by using the PMCC algorithm. The objective of our study is an enhanced understanding of the excitation sources and of possible interactions between MAWs and gravity waves. Therefore, spatial and temporal correlation analyses will be performed. As a preceding step, we will present (seasonal) hotspots of MAWs as well as hotspots of gravity waves derived by the IMS infrasound network.

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.

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. Copyright © 2014 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Fee, David; Garces, Milton; Orr, Tim; Poland, Mike

2011-03-01

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 'Ō'ō 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.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 rearedmore » 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.« less

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. © 2011 Acoustical Society of America

2013 certified IMS infrasound stations: IS37 (Bardufoss, Norway) and IS58 (Midway, USA)

NASA Astrophysics Data System (ADS)

Haralabus, Georgios; Marty, Julien; Kramer, Alfred; Mialle, Pierrick; Robertson, James

2014-05-01

The Infrasound component of the International Monitoring System (IMS) of the Comprehensive Nuclear?Test?Ban Treaty Organization (CTBTO) includes 60 infrasound stations out of which 47 are currently certified. The latest two additions to this Infrasound network, namely IS58 on Sand Island, Midway Atoll, United States of America (USA), and IS37 in Bardufoss, Norway, are presented here. Both stations were certified in 2013. IS58 is a 4 element infrasound array arranged in a triangular geometry with a central component. The triangular bases vary from 1.1 to 1.8 km. The micropressure sensors deployed at each element were Chaparral 50A microbarometers. Signals from IS58 were processed by the International Data Centre (IDC) and detection associated not only with microbaroms but also with the activity of the Kliuchevskoi volcano in the Russian Peninsula Kamchatka were built. These initial results indicate good detection capability of the IS58 station for low wind conditions. In Norway the topography allowed for a large element array, so IS37 was built with 10-elements that have average spacing of 1 km. This design allows the formation of several triangles with baseline of 1 to 2 km and also a triangular sub array with spacing of approximately 360 m. The sensors utilized in IS37 elements were MB2005 microbarometers. Initial data analysis by IDC identified distant microbarom sources with strong azimuth and frequency content variability as well as strong detections from local sources, namely the Finnfjord ferro-alloy plant in Norway and the Kiruna iron mine in Sweden.

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.

Acquisition and analysis of coastal ground-truth data for correlation with ERTS-1 imagery. [surface radiance data for Santa Monica Bay and Santa Barbara Channel

NASA Technical Reports Server (NTRS)

Anikouchine, W. A. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Radiance profiles drawn along cruise tracks have been examined for use in correlating digital radiance levels with ground truth data. Preliminary examination results are encouraging. Adding weighted levels from the 4 MSS bands appears to enhance specular surface reflections while rendering sensor noise white. Comparing each band signature to the added specular signature ought to enhance non-specular effects caused by ocean turbidity. Preliminary examination of radiance profiles and ground truth turbidity measurements revealed substantial correlation.

Atmospheric propagation of infrasound across mountain ranges

NASA Astrophysics Data System (ADS)

Damiens, Florentin; Millet, Christophe; Lott, Francois

2017-11-01

Linear theory of acoustic propagation is used to analyze trapping of infrasound within the lower tropospheric waveguide during propagation above a mountain range. Atmospheric flow produced by the mountains is predicted by a nonlinear mounatin wave model. For the infrasound component, we solve the wave equation under the effective sound speed approximation using both a spectral collocation method and a WKB approach. It is shown that in realistic configurations, the mountain waves can deeply perturb the low level waveguide, which leads to significant acoustic dispersion. To interpret these results each acoustic mode is tracked separately as the horizontal distance increases. It is shown that during statically stable situations, roughly representative of winter or night situations, the mountain waves induce a Foehn effect downstream which shrinks significantly the waveguide. This yields a new form of infrasound absorption, that can largely outweigh the direct effect the moutain induces on the low-level waveguide. For the opposite case, when the low level flow is less statically stable (summer or day situations), mountain wave dynamics do not produce dramatic responses downstream. Instead, it favors the passage of infrasound, which somehow mitigates the direct effect of the obstacle.

Eddy-Current Non-Inertial Displacement Sensing for Underwater Infrasound Measurements

DTIC Science & Technology

2011-05-01

Eddy-current non-inertial displacement sensing for underwater infrasound measurements Dimitri M. Donskoy Stevens Institute of Technology, 711 Hudson...geophysicists have an ongoing interest in exploring underwater acous- tic processes at infrasound frequencies, for example, for monitoring natural events...underwater infrasound measurements 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f

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.

Volcanic Infrasound - A technical topic communicated in an entertaining way

NASA Astrophysics Data System (ADS)

Kerlow, Isaac

2017-04-01

Volcanic Infrasound is a 9-minute film about using infrasound waves to detect and measure volcanic eruptions as they unfold. The film was made by an interdisciplinary team of filmmakers and scientists for a general audience. The movie explains the basic facts of using infrasound to detect volcanic activity, and it also shows volcano researchers as they install infrasound sensors in a natural reserve in the middle of the city. This is the first in a series of films that seek to address natural hazards of relevance to Singapore, a country shielded from violent hazards. This presentation reviews the science communication techniques and assumptions used to develop and produce this entertaining scientific documentary short. Trailer: https://vimeo.com/192206460

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.

[Effects of infrasound on ultrastructure of testis cell in mice].

PubMed

Wei, Ya-Ning; Liu, Jing; Shu, Qing; Huang, Xiao-Feng; Chen, Jing-Zao

2002-01-01

To investigate the effects of infrasound on ultrastructure of testis in mouse. Twelve male BALB/C mice were randomly divided into three groups according to exposed duration on 1, 7 and 14 day. The mice were separately exposed to infrasound environment under 8 Hz/90 dB, 8 Hz/130 dB, 16 Hz/90 dB, 16 Hz/130 dB 2 hours per day. There was another control group which had three mice were separated into module with no infrasound. All the mice were killed on schedule. Then all the sections of testis were observed under electronic microscope. The alterations of structure and the chromatin were observed. Some acute alteration in one day group was found in testis cell, such as cellular denaturation and necrosis, intercellular edema, mitochondria swelling, liposome hyperplasia. When the infrasound was up to 8 Hz/130 dB, the damage showed seriously. In 7 and 14 day group, the acute alteration was gradually decreased. A plenty of abnormal sperm were found. And other alteration was chromatin condense. The effect of variational frequency was important in ultrastructure. The infrasound markedly effected to testicular cell morphology and secreting function. Infrasound will lead to the alteration of procreation in mouse.

[The effects of infrasound on the blood coagulation function of guinea pigs].

PubMed

Ma, Wen-min; Qi, Peng; Zhang, Jian-zhong; Yi, Yong; Chen, Xing-ming; Zhang, Jun; Han, Rui-gang

2011-03-01

To study the change of the blood coagulation function of guinea pigs exposed to 16 Hz/120 dB, 16 Hz/125 dB infrasound and to explore the mechanism of circulation system damage. Seventy-two guinea pigs were divided into 3 groups: the control group, the group exposed to 16 Hz/120 dB infrasound for 1.5 h a day and the group exposed to 16 Hz/125 dB infrasound for 1.5 h a day. Each exposure group was divided into 4 sub-groups (8 guinea pigs a sub-group) which were exposed to infrasound for 1, 7, 14 and 21 d, respectively. The coagulation function and serum nitric oxide (NO) were measured for control group and all sub-groups after exposure to infrasound. The prothrombin time (PT), international normalized ratio (INR) and serum NO of group exposed to 16 Hz/125 dB infrasound were (31.16 ± 3.05) s, 2.53 ± 1.21 and (88.304 ± 52.601) µmol/L, respectively, which were significantly higher than those [(21.36 ± 0.10) s, 1.65 ± 0.07 and (30.943 ± 26.864) µmol/L] of control group (P < 0.05). PT and INR of sub-groups exposed to 16 Hz/125 dB infrasound for 14 and 21 d were significantly higher than those of control group. NO of sub-groups exposed to 16 Hz/125 dB infrasound for 1 week and 2 weeks were significantly higher than that of control group (P < 0.05), but NO of sub-group exposed to 16 Hz/125 dB infrasound for 3 weeks decreased slightly. The blood coagulation function of guinea pigs exposed to 16 Hz/125 dB infrasound decreased, PT and INR may be used as the indexes to assess of blood coagulation function change induced by the infrasound exposure.

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.

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.

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.

The source of the truth bias: Heuristic processing?

PubMed

Street, Chris N H; Masip, Jaume

2015-06-01

People believe others are telling the truth more often than they actually are; this is called the truth bias. Surprisingly, when a speaker is judged at multiple points across their statement the truth bias declines. Previous claims argue this is evidence of a shift from (biased) heuristic processing to (reasoned) analytical processing. In four experiments we contrast the heuristic-analytic model (HAM) with alternative accounts. In Experiment 1, the decrease in truth responding was not the result of speakers appearing more deceptive, but was instead attributable to the rater's processing style. Yet contrary to HAMs, across three experiments we found the decline in bias was not related to the amount of processing time available (Experiments 1-3) or the communication channel (Experiment 2). In Experiment 4 we found support for a new account: that the bias reflects whether raters perceive the statement to be internally consistent. © 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Evaluating the Capability of High-Altitude Infrasound Platforms to Cover Gaps in Existing Networks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, Daniel

A variety of Earth surface and atmospheric sources generate low frequency sound waves that can travel great distances. Despite a rich history of ground-based sensor studies, very few experiments have investigated the prospects of free floating microphone arrays at high altitudes. However, recent initiatives have shown that such networks have very low background noise and may sample an acoustic wave field that is fundamentally different than that at the Earth's surface. The experiments have been limited to at most two stations at altitude, limiting their utility in acoustic event detection and localization. We describe the deployment of five drifting microphonemore » stations at altitudes between 21 and 24 km above sea level. The stations detected one of two regional ground-based explosions as well as the ocean microbarom while traveling almost 500 km across the American Southwest. The explosion signal consisted of multiple arrivals; signal amplitudes did not correlate with sensor elevation or source range. A sparse network method that employed curved wave front corrections was able to determine the backazimuth from the free flying network to the acoustic source. Episodic broad band signals similar to those seen on previous flights in the same region were noted as well, but their source remains unclear. Background noise levels were commensurate with those on infrasound stations in the International Monitoring System (IMS) below 2 seconds, but sensor self noise appears to dominate at higher frequencies.« less

Seismic &Infrasound Integrated Array "Apatity". Techniques, data processing, first results of observations.

NASA Astrophysics Data System (ADS)

Vinogradov, Y.; Baryshnikov, A.

2003-04-01

Since September 2001 3 infrasound membrane type sensors "K-304 AM" have been installed on the territory seismic array "Apatity" near the lake Imandra. A seismic array comprising 11 short-period sensors (type "Geotech S-500"), disposed on small and large circle (0.4 and 1 km diameter). Infrasound sensors located on small circle near the seismograths. All data are digitized at the array site and transmitted in real time to a processing center in Apatity to the Kola Regional Seismological Centre (KRSC). Common complex we are called - Seismic &Infrasound Integrated Array (SISIA) "Apatity". To support temporary storage the transmitting data in a disk loop and access to the data "NEWNORAC" program was created. This program replaced "NORAC" system developed by Norwegian Institute NORSAR, which was in use in KRSC before. A program package EL (event locator) for display and processing of the data has been modified. Now it includes the following : - quick access to the data stored in the disk loop (last two weeks); - data convertation from disk loop format to CSS 3.0 format; - data filtering using bandpass, highpass, lowpass, adaptive or rejector filters; - calculation of spectra and sonograms (spectral diagrams); - seismic events location with plotting on a map; - calculation of backazimuth and apparent velocity of acoustic wave by similar parts of wave recordings; - loading and processing CSS 3.0 seismic and acoustic data from KRSC archive. To store the acoustic data permanently the program BARCSS was made. It rewrites the data from the disk loop to KRSC archive in CSS 3.0 format. For comparison of acoustic noise level with wind we use data from meteorological station in Kandalaksha city, sampling rate is 3 hours. During the period from October 2001 to October 2002 more than 745 seismic events, which basically connected with mine technical activity of the large mining enterprises at the Kola Peninsula, were registered. The most part of events, caused by ground explosions

Coherent ambient infrasound recorded by the International Monitoring System

NASA Astrophysics Data System (ADS)

Matoza, Robin S.; LandèS, Matthieu; Le Pichon, Alexis; Ceranna, Lars; Brown, David

2013-01-01

The ability of the International Monitoring System (IMS) infrasound network to detect atmospheric nuclear explosions and other signals of interest is strongly dependent on station-specific ambient noise. This ambient noise includes both incoherent wind noise and real coherent infrasonic waves. Previous ambient infrasound noise models have not distinguished between incoherent and coherent components. We present a first attempt at statistically and systematically characterizing coherent infrasound recorded by the IMS. We perform broadband (0.01-5 Hz) array processing with the IMS continuous waveform archive (39 stations from 1 April 2005 to 31 December 2010) using an implementation of the Progressive Multi-Channel Correlation algorithm in log-frequency space. From these results, we estimate multi-year 5th, 50th, and 95th percentiles of the RMS pressure of coherent signals in 15 frequency bands for each station. We compare the resulting coherent infrasound models with raw power spectral density noise models, which inherently include both incoherent and coherent components. Our results indicate that IMS arrays consistently record coherent ambient infrasound across the broad frequency range from 0.01 to 5 Hz when wind noise levels permit. The multi-year averaging emphasizes continuous signals such as oceanic microbaroms, as well as persistent transient signals such as repetitive volcanic, surf, thunder, or anthropogenic activity. Systematic characterization of coherent infrasound detection is important for quantifying a station's recording environment, signal-to-noise ratio as a function of frequency and direction, and overall performance, which all influence the detection probability of specific signals of interest.

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.

Infrasound propagation in tropospheric ducts and acoustic shadow zones.

PubMed

de Groot-Hedlin, Catherine D

2017-10-01

Numerical computations of the Navier-Stokes equations governing acoustic propagation are performed to investigate infrasound propagation in the troposphere and into acoustic shadow zones. An existing nonlinear finite-difference, time-domain (FDTD) solver that constrains input sound speed models to be axisymmetric is expanded to allow for advection and rigid, stair-step topography. The FDTD solver permits realistic computations along a given azimuth. It is applied to several environmental models to examine the effects of nonlinearity, topography, advection, and two-dimensional (2D) variations in wind and sound speeds on the penetration of infrasound into shadow zones. Synthesized waveforms are compared to a recording of a rocket motor fuel elimination event at the Utah Test and Training Range. Results show good agreement in the amplitude, duration, and spectra of synthesized and recorded waveforms for propagation through 2D atmospheric models whether or not topography, advection, or nonlinearity is explicitly included. However, infrasound propagation through a one-dimensional, range-averaged, atmospheric model yields waveforms with lower amplitudes and frequencies, suggesting that small-scale atmospheric variability causes significant scatter within the troposphere, leading to enhanced infrasound penetration into shadow zones. Thus, unresolved fine-scale atmospheric dynamics are not required to explain infrasound propagation into shadow zones.

Object Segmentation and Ground Truth in 3D Embryonic Imaging.

PubMed

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.

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

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.

Statistical analysis of infrasound signatures in airglow observations: Indications for acoustic resonance

NASA Astrophysics Data System (ADS)

Pilger, Christoph; Schmidt, Carsten; Bittner, Michael

2013-02-01

The detection of infrasonic signals in temperature time series of the mesopause altitude region (at about 80-100 km) is performed at the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) using GRIPS instrumentation (GRound-based Infrared P-branch Spectrometers). Mesopause temperature values with a temporal resolution of up to 10 s are derived from the observation of nocturnal airglow emissions and permit the identification of signals within the long-period infrasound range.Spectral intensities of wave signatures with periods between 2.5 and 10 min are estimated applying the wavelet analysis technique to one minute mean temperature values. Selected events as well as the statistical distribution of 40 months of observation are presented and discussed with respect to resonant modes of the atmosphere. The mechanism of acoustic resonance generated by strong infrasonic sources is a potential explanation of distinct features with periods between 3 and 5 min observed in the dataset.

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.

[Analysis on the mechanism of acupuncture infrasound energy in treatment of diseases].

PubMed

Wang, Xi-ming

2009-03-01

Infrasound is a sound wave with vibration frequency of less than 20 Hz, characterized by a longer wavelength, weak attenuating and strong penetration power, etc. Since the inherent frequencies of the human body and the organs are within infrasound vibration range, so infrasound has a stronger effect on the human body. The study found that the process of acupuncture at acupoints could be regarded as one containing a forced vibration with damping, and in the acupuncture, a infrasound of 2-15 Hz could be produced, which can easily has a resonance with the human body and the organs. By calculation of the sound pressure and sound strength in acupuncture, it was found that acupuncture infrasound had four characteristics: small total energy, small amplitude, strong voice, and orientation spreading along the meridian line. Because the meridian lines are the good pathway to spread low-frequency sound, acupuncture infrasound energy can successfully pass the meridian lines to reach the focus, penetrate the morbid tissues and improve the functions of tissues or organs.

Status report on the establishment of the CTBTO IMS infrasound network

NASA Astrophysics Data System (ADS)

Hoffmann, Thomas L.

2005-04-01

Steady progress has been made in the establishment of the CTBTO IMS infrasound monitoring network. To date 86% of the site surveys for 60 infrasound stations in the network have been completed, 50% of the stations are transmitting continuous data to Vienna, and 40% of the stations have been certified. While the global distribution pattern of infrasound stations transmitting data to Vienna is still disperse, regional networks begin to form in North and South America as well as in the Australian and South African regions. This presentation will focus on an overview of recent progress made in the establishment of the global infrasound network, and also present some of the challenges and difficulties encountered in this program.

The Gem Infrasound Logger and Custom-Built Instrumentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Jacob F.; Johnson, Jeffrey B.; Bowman, Daniel C.

Here, we designed, built, and recorded data with a custom infrasound logger (referred to as the Gem) that is inexpensive, portable, and easy to use. We also describe its design process, qualities, and applications in this article. Field instrumentation is a key element of geophysical data collection, and the quantity and quality of data that can be recorded is determined largely by the characteristics of the instruments used. Geophysicists tend to rely on commercially available instruments, which suffice for many important types of fieldwork. However, commercial instrumentation can fall short in certain roles, which motivates the development of custom sensorsmore » and data loggers. Particularly, we found existing data loggers to be expensive and inconvenient for infrasound campaigns, and developed the Gem infrasound logger in response. In this article, we discuss development of this infrasound logger and the various uses found for it, including projects on volcanoes, high-altitude balloons, and rivers. Further, we demonstrate that when needed, scientists can feasibly design and build their own specialized instruments, and that doing so can enable them to record more and better data at a lower cost.« less

The Gem Infrasound Logger and Custom-Built Instrumentation

DOE PAGES

Anderson, Jacob F.; Johnson, Jeffrey B.; Bowman, Daniel C.; ...

2017-11-22

Here, we designed, built, and recorded data with a custom infrasound logger (referred to as the Gem) that is inexpensive, portable, and easy to use. We also describe its design process, qualities, and applications in this article. Field instrumentation is a key element of geophysical data collection, and the quantity and quality of data that can be recorded is determined largely by the characteristics of the instruments used. Geophysicists tend to rely on commercially available instruments, which suffice for many important types of fieldwork. However, commercial instrumentation can fall short in certain roles, which motivates the development of custom sensorsmore » and data loggers. Particularly, we found existing data loggers to be expensive and inconvenient for infrasound campaigns, and developed the Gem infrasound logger in response. In this article, we discuss development of this infrasound logger and the various uses found for it, including projects on volcanoes, high-altitude balloons, and rivers. Further, we demonstrate that when needed, scientists can feasibly design and build their own specialized instruments, and that doing so can enable them to record more and better data at a lower cost.« less

Coherent ambient infrasound recorded by the global IMS network

NASA Astrophysics Data System (ADS)

Matoza, R. S.; Landes, M.; Le Pichon, A.; Ceranna, L.; Brown, D.

2011-12-01

The International Monitoring System (IMS) includes a global network of infrasound arrays, which is designed to detect atmospheric nuclear explosions anywhere on the planet. The infrasound network also has potential application in detection of natural hazards such as large volcanic explosions and severe weather. Ambient noise recorded by the network includes incoherent wind noise and coherent infrasound. We present a statistical analysis of coherent infrasound recorded by the IMS network. We have applied broadband (0.01 to 5 Hz) array processing systematically to the multi-year IMS historical dataset (2005-present) using an implementation of the Progressive Multi-Channel Correlation (PMCC) algorithm in log-frequency space. We show that IMS arrays consistently record coherent ambient infrasound across the broad frequency range from 0.01 to 5 Hz when wind-noise levels permit. Multi-year averaging of PMCC detection bulletins emphasizes continuous signals such as oceanic microbaroms, as well as persistent transient signals such as repetitive volcanic, surf, or anthropogenic activity (e.g., mining or industrial activity). While many of these continuous or repetitive signals are of interest in their own right, they may dominate IMS array detection bulletins and obscure or complicate detection of specific signals of interest. The new PMCC detection bulletins have numerous further applications, including in volcano and microbarom studies, and in IMS data quality assessment.

Using barometric time series of the IMS infrasound network for a global analysis of thermally induced atmospheric tides

NASA Astrophysics Data System (ADS)

Hupe, Patrick; Ceranna, Lars; Pilger, Christoph

2018-04-01

The International Monitoring System (IMS) has been established to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty and comprises four technologies, one of which is infrasound. When fully established, the IMS infrasound network consists of 60 sites uniformly distributed around the globe. Besides its primary purpose of determining explosions in the atmosphere, the recorded data reveal information on other anthropogenic and natural infrasound sources. Furthermore, the almost continuous multi-year recordings of differential and absolute air pressure allow for analysing the atmospheric conditions. In this paper, spectral analysis tools are applied to derive atmospheric dynamics from barometric time series. Based on the solar atmospheric tides, a methodology for performing geographic and temporal variability analyses is presented, which is supposed to serve for upcoming studies related to atmospheric dynamics. The surplus value of using the IMS infrasound network data for such purposes is demonstrated by comparing the findings on the thermal tides with previous studies and the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2), which represents the solar tides well in its surface pressure fields. Absolute air pressure recordings reveal geographical characteristics of atmospheric tides related to the solar day and even to the lunar day. We therefore claim the chosen methodology of using the IMS infrasound network to be applicable for global and temporal studies on specific atmospheric dynamics. Given the accuracy and high temporal resolution of the barometric data from the IMS infrasound network, interactions with gravity waves and planetary waves can be examined in future for refining the knowledge of atmospheric dynamics, e.g. the origin of tidal harmonics up to 9 cycles per day as found in the barometric data sets. Data assimilation in empirical models of solar tides would be a valuable application of the IMS infrasound

Inhibitory Effects of Low Decibel Infrasound on the Cardiac Fibroblasts and the Involved Mechanism

PubMed Central

Jin, Wei; Deng, Qin-Qin; Chen, Bao-Ying; Lu, Zhen-Xing; Li, Qing; Zhao, Hai-Kang; Chang, Pan; Yu, Jun; Pei, Zhao-Hui

2017-01-01

Introduction: Infrasound is a mechanical vibration wave with frequency between 0.0001 and 20 Hz. It has been established that infrasound of 120 dB or stronger is dangerous to humans. However, the biological effects of low decibel infrasound are largely unknown. The purpose of this study was to investigate the effects of low decibel infrasound on the cardiac fibroblasts. Materials and Methods: The cardiac fibroblasts were isolated and cultured from Sprague–Dawley rats. The cultured cells were assigned into the following four groups: control group, angiotensin II (Ang II) group, infrasound group, and Ang II+infrasound group. The cell proliferation and collagen synthesis rates were evaluated by means of [3H]-thymidine and [3H]-proline incorporation, respectively. The levels of TGF-β were determined by enzyme-linked immunosorbent assay. Moreover, RNAi approaches were used for the analysis of the biological functions of miR-29a, and the phosphorylation status of Smad3 was detected using western blotting analysis. Results: The results showed that low decibel infrasound significantly alleviated Ang II-induced enhancement of cell proliferation and collagen synthesis. Discussion: Compared with the control, Ang II markedly decreased the expression of miR-29a levels and increased the secretion of TGF-β and phosphorylation of Smad3, which was partly reversed by the treatment with low decibel infrasound. Importantly, knockdown of miR-29a diminished the effects of infrasound on the cardiac fibroblasts. In conclusion, low decibel infrasound inhibits Ang II-stimulated cardiac fibroblasts via miR-29a targeting TGF-β/Smad3 signaling. PMID:28615545

Inhibitory effects of low decibel infrasound on the cardiac fibroblasts and the involved mechanism.

PubMed

Jin, Wei; Deng, Qin-Qin; Chen, Bao-Ying; Lu, Zhen-Xing; Li, Qing; Zhao, Hai-Kang; Chang, Pan; Yu, Jun; Pei, Zhao-Hui

2017-01-01

Infrasound is a mechanical vibration wave with frequency between 0.0001 and 20 Hz. It has been established that infrasound of 120 dB or stronger is dangerous to humans. However, the biological effects of low decibel infrasound are largely unknown. The purpose of this study was to investigate the effects of low decibel infrasound on the cardiac fibroblasts. The cardiac fibroblasts were isolated and cultured from Sprague-Dawley rats. The cultured cells were assigned into the following four groups: control group, angiotensin II (Ang II) group, infrasound group, and Ang II+infrasound group. The cell proliferation and collagen synthesis rates were evaluated by means of [3H]-thymidine and [3H]-proline incorporation, respectively. The levels of TGF-β were determined by enzyme-linked immunosorbent assay. Moreover, RNAi approaches were used for the analysis of the biological functions of miR-29a, and the phosphorylation status of Smad3 was detected using western blotting analysis. The results showed that low decibel infrasound significantly alleviated Ang II-induced enhancement of cell proliferation and collagen synthesis. Compared with the control, Ang II markedly decreased the expression of miR-29a levels and increased the secretion of TGF-β and phosphorylation of Smad3, which was partly reversed by the treatment with low decibel infrasound. Importantly, knockdown of miR-29a diminished the effects of infrasound on the cardiac fibroblasts. In conclusion, low decibel infrasound inhibits Ang II-stimulated cardiac fibroblasts via miR-29a targeting TGF-β/Smad3 signaling.

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.

Infra-sound cancellation and mitigation in wind turbines

NASA Astrophysics Data System (ADS)

Boretti, Albert; Ordys, Andrew; Al Zubaidy, Sarim

2018-03-01

The infra-sound spectra recorded inside homes located even several kilometres far from wind turbine installations is characterized by large pressure fluctuation in the low frequency range. There is a significant body of literature suggesting inaudible sounds at low frequency are sensed by humans and affect the wellbeing through different mechanisms. These mechanisms include amplitude modulation of heard sounds, stimulating subconscious pathways, causing endolymphatic hydrops, and possibly potentiating noise-induced hearing loss. We suggest the study of infra-sound active cancellation and mitigation to address the low frequency noise issues. Loudspeakers generate pressure wave components of same amplitude and frequency but opposite phase of the recorded infra sound. They also produce pressure wave components within the audible range reducing the perception of the infra-sound to minimize the sensing of the residual infra sound.

Acoustic event location and background noise characterization on a free flying infrasound sensor network in the stratosphere

NASA Astrophysics Data System (ADS)

Bowman, Daniel C.; Albert, Sarah A.

2018-06-01

A variety of Earth surface and atmospheric sources generate low-frequency sound waves that can travel great distances. Despite a rich history of ground-based sensor studies, very few experiments have investigated the prospects of free floating microphone arrays at high altitudes. However, recent initiatives have shown that such networks have very low background noise and may sample an acoustic wave field that is fundamentally different than that at Earth's surface. The experiments have been limited to at most two stations at altitude, making acoustic event detection and localization difficult. We describe the deployment of four drifting microphone stations at altitudes between 21 and 24 km above sea level. The stations detected one of two regional ground-based chemical explosions as well as the ocean microbarom while travelling almost 500 km across the American Southwest. The explosion signal consisted of multiple arrivals; signal amplitudes did not correlate with sensor elevation or source range. The waveforms and propagation patterns suggest interactions with gravity waves at 35-45 km altitude. A sparse network method that employed curved wave front corrections was able to determine the backazimuth from the free flying network to the acoustic source. Episodic signals similar to those seen on previous flights in the same region were noted, but their source remains unclear. Background noise levels were commensurate with those on infrasound stations in the International Monitoring System below 2 s.

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.

Multi-Array Detection, Association and Location of Infrasound and Seismo-Acoustic Events in Utah

DTIC Science & Technology

2008-09-30

techniques for detecting , associating, and locating infrasound signals at single and multiple arrays and then combining the processed results with...was detected and located by both infrasound and seismic instruments (Figure 3). Infrasound signals at all three arrays , from one of the explosions, are...COVERED (From - To) 30-Sep-2008 REPRINT 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER MULTI- ARRAY DETECTION , ASSOCIATION AND LOCATION OF INFRASOUND FA8718

Global scale stratospheric processes as measured by the infrasound IMS network

NASA Astrophysics Data System (ADS)

Le Pichon, A.; Ceranna, L.; Kechut, P.

2012-04-01

IMS infrasound array data are routinely processed at the International Data Center (IDC). The wave parameters of the detected signals are estimated with the Progressive Multi-Channel Correlation method (PMCC). This new implementation of the PMCC algorithm allows the full frequency range of interest (0.01-5 Hz) to be processed efficiently in a single computational run. We have processed continuous recordings from 41 certified IMS stations from 2005 to 2010. We show that microbaroms are the dominant source of signals and are near-continuously globally detected. The observed azimuthal seasonal trend correlates well with the variation of the effective sound speed ratio which is a proxy for the combined effects of refraction due to sound speed gradients and advection due to along-path wind on infrasound propagation. A general trend in signal backazimuth is observed between winter and summer, driven by the seasonal reversal of the stratospheric winds. Combined with propagation modeling, we show that such an analysis enables a characterization of the wind and temperature structure above the stratosphere and may provide detailed information on upper atmospheric processes (e.g., large-scale planetary waves, stratospheric warming effects). We correlate perturbations and deviations from the seasonal trend to short time-scale variability of the atmosphere. We discuss the potential benefit of long-term infrasound monitoring to infer stratospheric processes for the first time on a global scale.

[Observation of the L929 cell membrane after infrasound exposure with atomic force microscope].

PubMed

Wang, Bing-shui; Chen, Jing-zao; Liu, Bin; Li, Ling; Yi, Nan; Liu, Jing; Zhang, Sa

2005-12-01

To observe the changes of L929 cell membrane with atomic force microscope (AFM) after infrasound exposure and to explore the mechanisms of effect of infrasound on cell membrane. After primary culture, the L929 cells were exposed to infrasound with intensity output of 130 dB and frequency of 16 Hz 2 hours each day for 3 days. The subsequent changes in the membrane of the control cells and the cells exposed to the infrasound were determined by nano-scale scanning with AFM. After infrasound exposure, the normal prominence of the membrane became short and the dent became shallow in the 7.5 microm x 7.5 microm and 4.0 microm x 4.0 microm photographs. The prominence appeared as cobblestones. The surface of the membrane became smooth. The membrane structure of the L929 cells can be changed by infrasound exposure with intensity of 130 dB and frequency of 16 Hz. The change might be one of the characteristics of effect of infrasound on cell membrane.

The Development of Methodologies for Determining Non-Linear Effects in Infrasound Sensors

DTIC Science & Technology

2010-09-01

THE DEVELOPMENT OF METHODOLOGIES FOR DETERMINING NON-LINEAR EFFECTS IN INFRASOUND SENSORS Darren M. Hart, Harold V. Parks, and Randy K. Rembold...the past year, four new infrasound sensor designs were evaluated for common performance characteristics, i.e., power consumption, response (amplitude...and phase), noise, full-scale, and dynamic range. In the process of evaluating a fifth infrasound sensor, which is an update of an original design

Visualizing the deep end of sound: plotting multi-parameter results from infrasound data analysis

NASA Astrophysics Data System (ADS)

Perttu, A. B.; Taisne, B.

2016-12-01

Infrasound is sound below the threshold of human hearing: approximately 20 Hz. The field of infrasound research, like other waveform based fields relies on several standard processing methods and data visualizations, including waveform plots and spectrograms. The installation of the International Monitoring System (IMS) global network of infrasound arrays, contributed to the resurgence of infrasound research. Array processing is an important method used in infrasound research, however, this method produces data sets with a large number of parameters, and requires innovative plotting techniques. The goal in designing new figures is to be able to present easily comprehendible, and information-rich plots by careful selection of data density and plotting methods.

An investigation of infrasound propagation over mountain ranges.

PubMed

Damiens, Florentin; Millet, Christophe; Lott, François

2018-01-01

Linear theory is used to analyze trapping of infrasound within the lower tropospheric waveguide during propagation above a mountain range. Atmospheric flow produced by the mountains is predicted by a nonlinear mountain gravity wave model. For the infrasound component, this paper solves the wave equation under the effective sound speed approximation using both a finite difference method and a Wentzel-Kramers-Brillouin approach. It is shown that in realistic configurations, the mountain waves can deeply perturb the low-level waveguide, which leads to significant acoustic dispersion. To interpret these results, each acoustic mode is tracked separately as the horizontal distance increases. It is shown that during statically stable situations, situations that are common during night over land in winter, the mountain waves induce a strong Foehn effect downstream, which shrinks the waveguide significantly. This yields a new form of infrasound absorption that can largely outweigh the direct effect the mountain induces on the low-level waveguide. For the opposite case, when the low-level flow is less statically stable (situations that are more common during day in summer), mountain wave dynamics do not produce dramatic responses downstream. It may even favor the passage of infrasound and mitigate the direct effect of the obstacle.

Explosion localization and characterization via infrasound using numerical modeling

NASA Astrophysics Data System (ADS)

Fee, D.; Kim, K.; Iezzi, A. M.; Matoza, R. S.; Jolly, A. D.; De Angelis, S.; Diaz Moreno, A.; Szuberla, C.

2017-12-01

Numerous methods have been applied to locate, detect, and characterize volcanic and anthropogenic explosions using infrasound. Far-field localization techniques typically use back-azimuths from multiple arrays (triangulation) or Reverse Time Migration (RTM, or back-projection). At closer ranges, networks surrounding a source may use Time Difference of Arrival (TDOA), semblance, station-pair double difference, etc. However, at volcanoes and regions with topography or obstructions that block the direct path of sound, recent studies have shown that numerical modeling is necessary to provide an accurate source location. A heterogeneous and moving atmosphere (winds) may also affect the location. The time reversal mirror (TRM) application of Kim et al. (2015) back-propagates the wavefield using a Finite Difference Time Domain (FDTD) algorithm, with the source corresponding to the location of peak convergence. Although it provides high-resolution source localization and can account for complex wave propagation, TRM is computationally expensive and limited to individual events. Here we present a new technique, termed RTM-FDTD, which integrates TRM and FDTD. Travel time and transmission loss information is computed from each station to the entire potential source grid from 3-D Green's functions derived via FDTD. The wave energy is then back-projected and stacked at each grid point, with the maximum corresponding to the likely source. We apply our method to detect and characterize thousands of explosions from Yasur Volcano, Vanuatu and Etna Volcano, Italy, which both provide complex wave propagation and multiple source locations. We compare our results with those from more traditional methods (e.g. semblance), and suggest our method is preferred as it is computationally less expensive than TRM but still integrates numerical modeling. RTM-FDTD could be applied to volcanic other anthropogenic sources at a wide variety of ranges and scenarios. Kim, K., Lees, J.M., 2015. Imaging

Effects of infrasound on cell proliferation in the dentate gyrus of adult rats.

PubMed

Liu, Juanfang; Lin, Tian; Yan, Xiaodong; Jiang, Wen; Shi, Ming; Ye, Ruidong; Rao, Zhiren; Zhao, Gang

2010-06-02

Adult rats were used to identify the effects of infrasound on neurogenesis in the hippocampal dentate gyrus. After 7 consecutive days' exposure to infrasound of 16 Hz at 130 dB, immunostaining of 5-bromo-2'-deoxyuridine (BrdU) and doublecortin (DCX) was preformed. Compared with those in normal groups, the numbers of BrdU+ and DCX+/BrdU+ cells in the subgranular zone in infrasound groups were significantly decreased at 3, 6, 10 and 14 days and returned to normal at 18 days. The percentage of BrdU+ cells that were co-labeled with DCX showed no significant differences between the infrasound and normal groups. These data suggest that infrasound inhibits the cell proliferation in adult rat dentate gyrus but has no effects on early migration and differentiation of these newborn cells.

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.

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.

Verification of retail food outlet location data from a local health department using ground-truthing and remote-sensing technology: assessing differences by neighborhood characteristics.

PubMed

Rossen, Lauren M; Pollack, Keshia M; Curriero, Frank C

2012-09-01

Obtaining valid and accurate data on community food environments is critical for research evaluating associations between the food environment and health outcomes. This study utilized ground-truthing and remote-sensing technology to validate a food outlet retail list obtained from an urban local health department in Baltimore, Maryland in 2009. Ten percent of outlets (n=169) were assessed, and differences in accuracy were explored by neighborhood characteristics (96 census tracts) to determine if discrepancies were differential or non-differential. Inaccuracies were largely unrelated to a variety of neighborhood-level variables, with the exception of number of vacant housing units. Although remote-sensing technologies are a promising low-cost alternative to direct observation, this study demonstrated only moderate levels of agreement with ground-truthing. Published by Elsevier Ltd.

75 FR 37742 - Addition of New Export Control Classification Number 6A981 Passive Infrasound Sensors to the...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-30

... or man-made infrasound sources including earthquakes, volcanic eruptions, rocket launch, and/or... rocket launch and/or nuclear explosions, or whether the parameters are overly broad. If the controls are...

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

[Pharmacokinetics of radiotracers in the ocular tissues exposed to infrasound and ultrasound phonophoreses].

PubMed

2006-01-01

The paper compares the efficiency of infrasound and ultrasound phonophoreses. The efficiency was evaluated on the basis of the rate of radiotracers within the eye after infrasound or ultrasound exposure of the eyeball. The exposure was made after preliminary putting the radiotracer-impregnated application into the bulbar conjunctiva of an animal. Radioactivity was recorded on a Siemens gamma camera in its lifetime. The time course of changes in the radioactivities measured 10, 30, and 60 minutes after termination of exposures strongly suggests its stable increase in the eye exposed to infrasound. At the same time 10 minutes after ultrasound exposure, the increased concentration of a radiotracer in the eye was less than that after infrasound exposure and then it progressively decreased. Thus, having a significant phoretic activity, infrasound, as ultrasound, creates more favorable conditions for long drug storage in the eye.

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

USDA-ARS?s Scientific Manuscript database

Successful development of approaches to quantify impacts of diverse landuse and associated agricultural management practices on ecosystem services is frequently limited by lack of historical and contemporary landuse data. We hypothesized that recent ground truth data could be used to extrapolate pre...

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.

Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for Infrasound

DTIC Science & Technology

2013-04-01

Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for Infrasound by W.C. Kirkpatrick Alberts, II...Windshield and Microphone for Infrasound W.C. Kirkpatrick Alberts, II, Stephen M. Tenney, and John M. Noble Sensors and Electron Devices Directorate...2013 4. TITLE AND SUBTITLE Assessment of Operational Progress of NASA Langley Developed Windshield and Microphone for Infrasound 5a. CONTRACT

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.

[Effects of infrasound on visual electrophysiology in mice].

PubMed

Shi, Li; Zhang, Zuo-ming; Chen, Jing-zao; Liu, Jing

2003-04-01

To investigate the possible effects of infrasound on visual functions. One hundred and fifty mature male Kunming-mice were divided into 5 groups, in which one was control and the other four were exposed to infrasound of 8 Hz, 90 dB; 8 Hz, 130 dB; 16 Hz, 90 dB and 16 Hz, 130 dB 2 h/d respectively. The exposure time for them were 0, 1, 4, 7, 14 and 21 d respectively, each group was divided into 6 sub-groups. Electroretinogram (ERG), oscillatory potentials (OPs), and visual evoked potential (VEP) were recorded after exposure. The visual electrophysiological indices after 8 Hz, 90 dB and 16 Hz, 90 dB exposures were similar except for a little difference at some temporal points (P<0.05). Most of the indices in 8 Hz, 130 dB group changed after 7 d exposure, and the longer the exposure, the more obvious changes were observed (P<0.01). The indices in 16 Hz, 130 dB group changed obviously after 1 d and reversed with increase of exposure time (P<0.01). The effect of infrasound on visual functions are related to its frequency and intensity. Infrasound of different frequencies causes different levels of retinal resonance, which leads to different degrees of cellular lesion and produces different electrical potentials.

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.

A large dataset of synthetic SEM images of powder materials and their ground truth 3D structures.

PubMed

DeCost, Brian L; Holm, Elizabeth A

2016-12-01

This data article presents a data set comprised of 2048 synthetic scanning electron microscope (SEM) images of powder materials and descriptions of the corresponding 3D structures that they represent. These images were created using open source rendering software, and the generating scripts are included with the data set. Eight particle size distributions are represented with 256 independent images from each. The particle size distributions are relatively similar to each other, so that the dataset offers a useful benchmark to assess the fidelity of image analysis techniques. The characteristics of the PSDs and the resulting images are described and analyzed in more detail in the research article "Characterizing powder materials using keypoint-based computer vision methods" (B.L. DeCost, E.A. Holm, 2016) [1]. These data are freely available in a Mendeley Data archive "A large dataset of synthetic SEM images of powder materials and their ground truth 3D structures" (B.L. DeCost, E.A. Holm, 2016) located at http://dx.doi.org/10.17632/tj4syyj9mr.1[2] for any academic, educational, or research purposes.

Acoustic Event Location and Background Noise Characterization on a Free Flying Infrasound Sensor Network in the Stratosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, Daniel C.; Albert, Sarah A.

We present that a variety of Earth surface and atmospheric sources generate low frequency sound waves that can travel great distances. Despite a rich history of ground-based sensor studies, very few experiments have investigated the prospects of free floating microphone arrays at high altitudes. However, recent initiatives have shown that such networks have very low background noise and may sample an acoustic wave field that is fundamentally different than that at Earth’s surface. The experiments have been limited to at most two stations at altitude, making acoustic event detection and localization difficult. We describe the deployment of four drifting microphonemore » stations at altitudes between 21 and 24 km above sea level. The stations detected one of two regional ground-based chemical explosions as well as the ocean microbarom while traveling almost 500 km across the American Southwest. The explosion signal consisted of multiple arrivals; signal amplitudes did not correlate with sensor elevation or source range. The waveforms and propagation patterns suggest interactions with gravity waves in the 35-45 km altitude. A sparse network method that employed curved wave front corrections was able to determine the backazimuth from the free flying network to the acoustic source. Episodic signals similar to those seen on previous flights in the same region were noted, but their source remains unclear. Lastly, background noise levels were commensurate with those on infrasound stations in the International Monitoring System below 2 seconds.« less

Acoustic Event Location and Background Noise Characterization on a Free Flying Infrasound Sensor Network in the Stratosphere

DOE PAGES

Bowman, Daniel C.; Albert, Sarah A.

2018-02-22

We present that a variety of Earth surface and atmospheric sources generate low frequency sound waves that can travel great distances. Despite a rich history of ground-based sensor studies, very few experiments have investigated the prospects of free floating microphone arrays at high altitudes. However, recent initiatives have shown that such networks have very low background noise and may sample an acoustic wave field that is fundamentally different than that at Earth’s surface. The experiments have been limited to at most two stations at altitude, making acoustic event detection and localization difficult. We describe the deployment of four drifting microphonemore » stations at altitudes between 21 and 24 km above sea level. The stations detected one of two regional ground-based chemical explosions as well as the ocean microbarom while traveling almost 500 km across the American Southwest. The explosion signal consisted of multiple arrivals; signal amplitudes did not correlate with sensor elevation or source range. The waveforms and propagation patterns suggest interactions with gravity waves in the 35-45 km altitude. A sparse network method that employed curved wave front corrections was able to determine the backazimuth from the free flying network to the acoustic source. Episodic signals similar to those seen on previous flights in the same region were noted, but their source remains unclear. Lastly, background noise levels were commensurate with those on infrasound stations in the International Monitoring System below 2 seconds.« less

The influence of periodic wind turbine noise on infrasound array measurements

NASA Astrophysics Data System (ADS)

Pilger, Christoph; Ceranna, Lars

2017-02-01

Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. These systems are equipped with highly sensitive micro pressure sensors accurately measuring acoustic signals in a frequency range inaudible to the human ear. Ten years of data (2006-2015) from the infrasound array IGADE in Northern Germany are analysed to quantify the influence of wind turbine noise on infrasound recordings. Furthermore, a theoretical model is derived and validated by a field experiment with mobile micro-barometer stations. Fieldwork was carried out 2004 to measure the infrasonic pressure level of a single horizontal-axis wind turbine and to extrapolate the sound effect for a larger number of nearby wind turbines. The model estimates the generated sound pressure level of wind turbines and thus enables for specifying the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. This aspect is particularly important to guarantee the monitoring performance of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and thus have to meet stringent specifications with respect to infrasonic background noise.

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.

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.

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.

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.

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.

Merge of Five Previous Catalogues Into the Ground Truth Catalogue and Registration Based on MOLA Data with THEMIS-DIR, MDIM and MOC Data-Sets

NASA Astrophysics Data System (ADS)

Salamuniccar, G.; Loncaric, S.

2008-03-01

The Catalogue from our previous work was merged with the date of Barlow, Rodionova, Boyce, and Kuzmin. The resulting ground truth catalogue with 57,633 craters was registered, using MOLA data, with THEMIS-DIR, MDIM, and MOC data-sets.

Looking for a correlation between infrasound and volcanic gas in strombolian explosions by using high resolution UV spectroscopy and thermal imagery

NASA Astrophysics Data System (ADS)

Delle Donne, Dario; Tamburello, Giancarlo; Ripepe, Maurizio; Aiuppa, Alessandro

2014-05-01

According to the linear theory of sound, acoustic pressure propagating in a homogeneous atmosphere can be modelled in terms of the rate of change of a volumetric source. At open-vent volcanoes, this acoustic source process is commonly related to the explosive dynamics triggered by the rise, expansion and bursting of a gas slug at the magma free surface with the conduit. Just before an explosion, the magma surface will undergo deformation by the expanding gas slug. The deformation of the magma surface will then produce an equivalent displacement of the atmosphere, inducing a volumetric compression and generating an excess pressure that scales to the rate of volumetric change of the atmosphere displaced. Linear theory of sound thus predicts that pressure amplitude of infrasonic waves associated to volcanic explosions should be generated by the first time-derivative of the gas mass flux during the burst. In some cases a correlation between the first time-derivative and the SO2 mass flux has been found. However no clear correlation has yet been established between infrasonic amplitude and total ejected gas mass; therefore, the origin of infrasound in volcanic systems remains matter of debate. In the framework of the FP7-ERC BRIDGE Project, we tested different possible hypotheses on the acoustic source model, by correlating infrasound with the total gas mass retrieved from high-resolution UV spectroscopy techniques (UV camera). Experiments were conducted at Stromboli volcano (Italy), where we also employed a thermal camera to measure the total fragments/gas mass. Both techniques allowed independent estimation of total mass flux of gas and fragments within the volcanic plume. During the experiments, explosions detected by the UV camera emitted between 2 and 55 kg SO2, corresponding to SO2 peak fluxes of 0.1-0.8 kg/s. SO2 mass was converted into a total (maximum) erupted gas of 1310 kg, which is generating a peak pressure of ~8 Pa recorded at ~450 m from the source vent

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 comparedmore » 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.« less

Recent enhancements of the PMCC infrasound signal detector

NASA Astrophysics Data System (ADS)

Brachet, N.; Mialle, P.; Matoza, R. S.; Le Pichon, A.; Cansi, Y.; Ceranna, L.

2010-12-01

The Progressive Multi-Channel Correlation (PMCC) is an antenna technique that is commonly being used by the scientific community for detecting coherent signals recorded on infrasound arrays. The PMCC detector, originally developed by CEA/DASE (Cansi, 1995), was installed in 2004 in the operational environment of the International Data Centre (IDC) of the Comprehensive nuclear Test Ban Treaty Organization (CTBTO) in Vienna. During the last 5 years, several changes have been made by the IDC to enhance the PMCC source code and parameter configuration, and the detector has exhibited good performance in terms of detection sensitivity and robustness. Recent studies performed at the CEA/DASE have shown that the IDC version (DFX/Geotool-PMCC) and the DASE version (WinPMCC) of PMCC software benefit from the implementation of the adaptive processing window duration and a log-spaced frequency bands. This tested configuration enables better detection and characterization of all received signals in their wave-front parameter space (e.g., frequency-azimuth space, frequency-trace-velocity space). A new release of the WinPMCC software - running under Windows or Linux operating systems - including a fully configurable filtering and detection parameters is now available upon request. We present the results of a statistical analysis on 10 years of infrasound data recorded at the IMS stations IS26, Germany and IS22, New Caledonia. A comparison is made between the automatic detections produced by the IDC, and the reprocessed detections using the optimized filtering and detection configuration parameters. Work is also underway at the CEA/DASE to determine more rigorously the azimuth and speed uncertainties. The current algorithm estimates the uncertainties based on statistical analysis of the distribution of PMCC detection pixels in the azimuth-speed space. The new code that is being considered performs the calculation of infrasound measurement errors as a function of physical

Is there evidence for an acoustic signal at IMS infrasound stations from the North Korean event of 12 May 2010?

NASA Astrophysics Data System (ADS)

Koch, K.; Pilger, C.

2016-12-01

Over the last two years more and more evidence has been presented that a small seismic event had occurred in North Korea on 12 May 2010. Most recent work has concluded that the event shows earthquake-like features when applying event identification methods based on regional phase amplitude ratios. These findings are in contrast to previous hypotheses and identification studies which claimed that low-yield nuclear testing had been carried out. Some of these studies were based solely on radionuclide and noble gas detections found at International Monitoring System (IMS) stations as well as at national facilities. Turning to another technology, it has been shown in several studies that underground nuclear tests carried out at the Punggye-ri test site in North Korea have produced infrasound signatures at the closest IMS stations I45RU and I30JP and at national infrasound stations in South Korea. In particular this holds for the tests carried out in 2009, 2013 and 2016. For the 2013 test infrasound arrivals have been included in the Reviewed Event Bulletin (REB) issued by the International Data Center of CTBTO. Based on this experience an effort was undertaken to analyze infrasound data from these IMS stations and to search for signals that may be associated to the 12 May 2010 event. While it is not expected to obtain such a signal for an earthquake source at depth, as would not be expected as well for a buried explosion source of rather small magnitude, the analysis of I45RU and I30JP data suggests a very weak arrival as obtained from frequency-wavenumber analysis showing parameters similar to those obtained for the announced tests. If the features found are indeed not artifacts then one could speculate that (1) the event of concern may not be an earthquake, even though it exhibits seismic signal characteristics causing it to be classified as an earthquake, or (2) the detections may be related to incidental blasting activity in nearby quarries. Propagation modeling of

CTBT infrasound network performance to detect the 2013 Russian fireball event

DOE PAGES

Pilger, Christoph; Ceranna, Lars; Ross, J. Ole; ...

2015-03-18

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 individualmore » 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. As a result, a strong dependence on the diurnal variability of background noise levels at each station is observed, favoring nocturnal detections.« less

Impact of infrasound on the human cochlea.

PubMed

Hensel, Johannes; Scholz, Günther; Hurttig, Ulrike; Mrowinski, Dieter; Janssen, Thomas

2007-11-01

Low-frequency tones were reported to modulate the amplitude of distortion product otoacoustic emissions (DPOAEs) indicating periodic changes of the operating point of the cochlear amplifier. The present study investigates potential differences between infrasound and low-frequency sounds in their ability to modulate human DPOAEs. DPOAEs were recorded in 12 normally hearing subjects in the presence of a biasing tone with f(B)=6Hz and a level L(B)=130dB SPL. Primary frequencies were fixed at f(1)=1.6 and f(2)=2.0kHz with fixed levels L(1)=51 and L(2)=30dB SPL. A new measure, the modulation index (MI), was devised to characterise the degree of DPOAE modulation. In subsequent measurements with biasing tones of f(B) = 12, 24 and 50Hz, L(B) was adjusted to maintain the MI as obtained individually at 6Hz. Modulation patterns lagged with increasing f(B). The necessary L(B) decreased by 12dB/octave with increasing f(B) and ran almost parallel to the published infrasound detection threshold. No signs of an abrupt change in transmission into the cochlea were found between infra- and low-frequency sounds. The results show clearly that infrasound enters the inner ear, and can alter cochlear processing.

Detection of infrasound generated by Clear Air Turbulence (CAT)

NASA Technical Reports Server (NTRS)

Meredith, R.; Badavi, F.; Becher, J.

1981-01-01

A unified data acquisiton system which is an AM carrier system consisting of a converter signal, conditioning electronics, and peripheral equipment was checked and calibrated and installed in a mobile van. A microphone array in the shape of a 244-m equilateral triangle was connected to the data acquisition system using 457-m long cables. Development of techniques for signal processing for interpreting the infrasonic signature (differentiating between CAT and other sources of infrasound) is summarized. Once patches of CAT are located in the atmosphere, corroboration can be achieved through test flights of aircraft into the suspected region.

[Effects of infrasound therapy on proliferation, apoptosis and ultrastructure of human B lymphoma Raji cells].

PubMed

Bao, Yong; Fan, Jian-Zhong; Li, Ke; Li, Chuan; Yang, Jun-Feng

2008-06-01

To investigate the effect of infrasound therapy on the proliferation, apoptosis and ultrastructure of human B lymphoma Raji cells. Human B lymphoma Raji cells were exposed to infrasound treatment for 15, 30, 60, 90 and 120 min and cultured subsequently for 24 or 48 h. MTT assay, flow cytometry analysis, and electron microscopy were performed to examine the proliferative status, cell apoptosis and ultrastructural changes of the exposed cells, respectively. MTT assay revealed no significant changes in the proliferation of the cells exposed to infrasound treatment (P>0.05), nor did flow cytometry analysis identified significant variation in the cell apoptosis (P>0.05). Scanning electron microscopy, however, identified shortened or reduced cell processes and microvilli on the surface of the cells with infrasound exposure and a subsequent 24-hour culture, and the cell membrane surface became smooth. Under transmission electron microscope, the cells with infrasound treatment presented with significantly reduced microvilli, and the cell nuclei appeared homogeneous, with cytoplasmic budding and losses after a 48-hour culture. Infrasound less than 90 dB does not obviously affect the proliferation and apoptosis of Raji cells, but may directly cause cell ultrastructural changes such as reduction of the cell processes.

[Characteristics of infrasound and its influence on workers in working environment of certain thermoelectricity works and department].

PubMed

Dang, Wei-Min; Wang, Sheng; Tian, Shi-Xiu; Zhao, Quan-Hong; Chen, Bing; Sun, Fei; He, Li-Hua; Zou, Zhi-Fang; Guo, Zhi-Bin; Ma, Wen-Jun

2008-12-01

To study the characteristics of infrasound and its effects on the workers at power plants. The audible noise and infrasound in three thermoelectricity plants were measured and by using Symptom Checklist 90 (SCL-90), the subjective sensation, and the physiological indices were compared between exposed workers and controls. The infrasound levels were different at different measure sites of the three thermoelectricity works ranging from 40 to 98 dB. There was still 40 approximately 80 dB infrasound even when the soot blower stopped running. Different apparatus produced different infrasound levels with the highest ranging from 62 to 115 dB. A single frequency (16 Hz) infrasound was produced in certain department during working hour with sound pressure levels of 110 to 120 dB, but the audible noise sound pressure level was less than 70 dB. There was no significant difference in the indices representing vision fatigue and neurobehaviour function between exposed workers and controls. Workers at certain department experienced evident subjective sensation of neurobehavioral dysfunction, and the scores of somatization, depression, hostility, phobic anxiety, and psychotism in the SCL-90 were significantly higher in the exposed group than in the control and the norm in China (P < 0.05). Infrasound is ubiquitous in the working environment, but usually, the noise levels are less than 120 dB. In some special production department, there is persistent infrasound above 110 to 120 dB. No obvious health effects are found among those who are exposed to infrasound below 100 dB. However, the workers who are chronically exposed to infrasound above 110 to 120 dB present notable subjective sensation of autonomic neurobehavioral dysfunction, and their psychological health status is not as good as those in the control and those in the domestic normal pattern.

Analysis and modeling of infrasound from a four-stage rocket launch

DOE PAGES

Blom, Philip Stephen; Marcillo, Omar Eduardo; Arrowsmith, Stephen

2016-06-17

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. As a result, this lack of signal is possibly due to inefficient aeroacousticmore » coupling in the rarefied upper atmosphere.« less

Analysis and modeling of infrasound from a four-stage rocket launch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blom, Philip Stephen; Marcillo, Omar Eduardo; Arrowsmith, Stephen

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. As a result, this lack of signal is possibly due to inefficient aeroacousticmore » coupling in the rarefied upper atmosphere.« less

Advancement of Techniques for Modeling the Effects of Atmospheric Gravity-Wave-Induced Inhomogeneities on Infrasound Propagation

DTIC Science & Technology

2010-09-01

ADVANCEMENT OF TECHNIQUES FOR MODELING THE EFFECTS OF ATMOSPHERIC GRAVITY-WAVE-INDUCED INHOMOGENEITIES ON INFRASOUND PROPAGATION Robert G...number of infrasound observations indicate that fine-scale atmospheric inhomogeneities contribute to infrasonic arrivals that are not predicted by...standard modeling techniques. In particular, gravity waves, or buoyancy waves, are believed to contribute to the multipath nature of infrasound

A Bayesian truth serum for subjective data.

PubMed

Prelec, Drazen

2004-10-15

Subjective judgments, an essential information source for science and policy, are problematic because there are no public criteria for assessing judgmental truthfulness. I present a scoring method for eliciting truthful subjective data in situations where objective truth is unknowable. The method assigns high scores not to the most common answers but to the answers that are more common than collectively predicted, with predictions drawn from the same population. This simple adjustment in the scoring criterion removes all bias in favor of consensus: Truthful answers maximize expected score even for respondents who believe that their answer represents a minority view.

Infrasound production by bolides: A global statistical study

NASA Astrophysics Data System (ADS)

Ens, T. A.; Brown, P. G.; Edwards, W. N.; Silber, E. A.

2012-05-01

We have examined a dataset consisting of 71 bolides detected by satellite sensors, which provide energy and location estimates, with simultaneous measurements of the same events on 143 distinct waveforms. These bolides have total source energies ranging from 0.02 kt TNT equivalent yield to ≈20 kt and probable diameters of order a few meters on average. We find that it is possible to detect large events with energies of ≈20 kt or more globally. Infrasonic detections of these events for stratospheric arrivals have ranges between 350-17,000 km and show clear wind-related amplitude modifications. We find that our period-yield relations are virtually identical to that found from AFTAC nuclear test data with the most robust period-yield correlation found for those events having multiple station averaged periods. We have also found empirical expressions relating maximum expected detection range for infrasound as a function of energy and low and high frequency cut-off as a function of energy. Our multi-variate fits suggest that 1/2 > yield-scaling is most appropriate for long range bolide infrasound measurements with a distance scaling exponent of ≈1.1 best representing the data. Our best-fit wind correction exponent is a factor of ≈3 smaller than found by previous studies which we suggest may indicate a decrease in the value of k with range. We find that the integral acoustic efficiency for bolides is ≥0.01% with a best lower limit estimate nearer 0.1%. Finally, we conclude that a range independent atmosphere implementation of the normal-mode approach to simulate bolide amplitudes is ineffective at large ranges due to the large change in atmospheric conditions along source-receiver paths.

Infrasound Assessment of Infrastructure Report 6: Scour Detection and Riverine Health Assessment Using Infrasound

DTIC Science & Technology

2016-05-01

construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED...20 Figure 14. Seismic and infrasound detection of a barge strike on the I-20 bridge pier during the...foundations meaning that no plans, either design or as-built, existed for the structure. Initially, bridges classified as having unknown foundations

Truth-Telling, Ritual Culture, and Latino College Graduates in the Anthropocene

ERIC Educational Resources Information Center

Gildersleeve, Ryan Evely

2017-01-01

This article seeks to trace the cartography of truth-telling through a posthuamanist predicament of ritual culture in higher education and critical inquiry. Ritual culture in higher education such as graduation ceremony produces and reflects the realities of becoming subjects. These spaces are proliferating grounds for truth telling and practical…

A new device for acquiring ground truth on the absorption of light by turbid waters

NASA Technical Reports Server (NTRS)

Klemas, V. (Principal Investigator); Srna, R.; Treasure, W.

1974-01-01

The author has identified the following significant results. A new device, called a Spectral Attenuation Board, has been designed and tested, which enables ERTS-1 sea truth collection teams to monitor the attenuation depths of three colors continuously, as the board is being towed behind a boat. The device consists of a 1.2 x 1.2 meter flat board held below the surface of the water at a fixed angle to the surface of the water. A camera mounted above the water takes photographs of the board. The resulting film image is analyzed by a micro-densitometer trace along the descending portion of the board. This yields information on the rate of attenuation of light penetrating the water column and the Secchi depth. Red and green stripes were painted on the white board to approximate band 4 and band 5 of the ERTS MSS so that information on the rate of light absorption by the water column of light in these regions of the visible spectrum could be concurrently measured. It was found that information from a red, green, and white stripe may serve to fingerprint the composition of the water mass. A number of these devices, when automated, could also be distributed over a large region to provide a cheap method of obtaining valuable satellite ground truth data at present time intervals.

Thunder-induced ground motions: 2. Site characterization

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Thunder-induced ground motion, near-surface refraction, and Rayleigh wave dispersion measurements were used to constrain near-surface velocity structure at an unconsolidated sediment site. We employed near-surface seismic refraction measurements to first define ranges for site structure parameters. Air-coupled and hammer-generated Rayleigh wave dispersion curves were used to further constrain the site structure by a grid search technique. The acoustic-to-seismic coupling is modeled as an incident plane P wave in a fluid half-space impinging into a solid layered half-space. We found that the infrasound-induced ground motions constrained substrate velocities and the average thickness and velocities of the near-surface layer. The addition of higher-frequency near-surface Rayleigh waves produced tighter constraints on the near-surface velocities. This suggests that natural or controlled airborne pressure sources can be used to investigate the near-surface site structures for earthquake shaking hazard studies.

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.

A ground truth based comparative study on clustering of gene expression data.

PubMed

Zhu, Yitan; Wang, Zuyi; Miller, David J; Clarke, Robert; Xuan, Jianhua; Hoffman, Eric P; Wang, Yue

2008-05-01

Given the variety of available clustering methods for gene expression data analysis, it is important to develop an appropriate and rigorous validation scheme to assess the performance and limitations of the most widely used clustering algorithms. In this paper, we present a ground truth based comparative study on the functionality, accuracy, and stability of five data clustering methods, namely hierarchical clustering, K-means clustering, self-organizing maps, standard finite normal mixture fitting, and a caBIG toolkit (VIsual Statistical Data Analyzer--VISDA), tested on sample clustering of seven published microarray gene expression datasets and one synthetic dataset. We examined the performance of these algorithms in both data-sufficient and data-insufficient cases using quantitative performance measures, including cluster number detection accuracy and mean and standard deviation of partition accuracy. The experimental results showed that VISDA, an interactive coarse-to-fine maximum likelihood fitting algorithm, is a solid performer on most of the datasets, while K-means clustering and self-organizing maps optimized by the mean squared compactness criterion generally produce more stable solutions than the other methods.

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.

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.

Technical Note: A new zeolite PET phantom to test segmentation algorithms on heterogeneous activity distributions featured with ground-truth contours.

PubMed

Soffientini, Chiara D; De Bernardi, Elisabetta; Casati, Rosangela; Baselli, Giuseppe; Zito, Felicia

2017-01-01

Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity. Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different 18 F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions. Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in 18 F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% and 443% of a uniform radioactive solution. Assembled phantom included eight lesions with volumes ranging from 1.86 to 7.24 ml and lesion to background contrasts ranging from 4.8:1 to 21.7:1. A novel phantom for the evaluation of PET-AS algorithms was developed. It is provided with both reference contours and activity ground truth, and it covers a wide range of volumes and lesion to background contrasts. The dataset is open to the community of PET-AS developers and utilizers. © 2016 American Association of Physicists in Medicine.

Monitoring the development of volcanic eruptions through volcanic lightning - Using a lightning mapping array, seismic and infrasound array, and visual plume analysis

NASA Astrophysics Data System (ADS)

Smith, C. M.; Thompson, G.; McNutt, S. R.; Behnke, S. A.; Edens, H. E.; Van Eaton, A. R.; Gaudin, D.; Thomas, R. J.

2017-12-01

The period of 28 May - 7 June 2015 at Sakurajima Volcano, Japan witnessed a multitude of Vulcanian eruptive events, which resulted in plumes reaching 500-3000m above the vent. These plumes varied from white, gas-rich plumes to dark grey and black ash-rich plumes, and were recorded on lowlight and infrared cameras. A nine-station lightning mapping array (LMA) was deployed to locate sources of VHF (67-73 MHz) radiation produced by lightning flashes and other types of electrical activity such as `continuous RF (radio frequency)'. Two Nanometrics Trillium broadband seismometers and six BSU infrasound sensors were deployed. Over this ten day period we recorded 1556 events that consisted of both seismic and infrasound signals, indicating explosive activity. There are an additional 1222 events that were recorded as only seismic or infrasound signals, which may be a result of precursory seismic signals or noise contamination. Plume discharge types included both distinct lightning flashes and `continuous RF'. The LMA ran continuously for the duration of the experiment. On 30 May 2015 at least seven lightning flashes were also detected by the Vaisala Global Lightning Detection 360 network, which detects VLF (3-30 kHz) radiation. However the University of Washington's World Wide Lightning Location Network, which also detects VLF radiation, detected no volcanic lightning flashes in this time period. This indicates that the electrical activity in Sakurajima's plume occurs near the lower limits of the VLF detection threshold. We investigate relationships between the plume dynamics, the geophysical signal and the corresponding electrical activity through: plume velocity and height; event waveform cross-correlation; volcano acoustic-seismic ratios; overall geophysical energy; RSAM records; and VHF sources detected by the LMA. By investigating these relationships we hope to determine the seismic/infrasound energy threshold required to generate measurable electrical activity

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

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.

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

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.

Truth in Testing Legislation and Private Property Concepts.

ERIC Educational Resources Information Center

Burns, Daniel J.

1981-01-01

Truth in testing laws are subject to challenge on the grounds that they invade federally protected rights and interests of the test-makers through the due process clauses of the Constitution and federal copyright protections. (Author/MLF)

Infrasound as a Geophysical Probe Using Earth as a Venus Analog

NASA Astrophysics Data System (ADS)

Komjathy, Attila; Cutts, James; Pauken, Michael; Kedar, Sharon; Smrekar, Suzanne

2016-10-01

JPL is in a process of developing an instrument to measure seismic activity on Venus by detecting infrasonic waves in the atmosphere. The overall objective of this research is to demonstrate the feasibility of using sensitive barometers to detect infrasonic signals from seismic and explosive activity on Venus from a balloon platform. Because of Venus' dense atmosphere, seismic signatures from even small quakes (magnitude ~3) are effectively coupled into the atmosphere. The seismic signals are known to couple about 60 times more efficiently into the atmosphere on Venus than on Earth. It was found that almost no attenuation below 80 km on Venus for frequency less than 1Hz. Whereas wind noise is a major source of background noise for terrestrial infrasonic arrays, it is expected that a balloon platform, which drifts with winds will be capable of very sensitive measurements with low noise.In our research we will demonstrate and apply techniques for discriminating upward propagating waves from a seismic event by making measurements with two or more infrasonic sensors using very sensitive barometers on a tether deployed from the balloon in a series of earth-based tests. We will first demonstrate and validate the technique using an artificial infrasound source in a deployment from a hot air balloon on Earth and then extend it with longer duration flights in the troposphere and stratosphere.We will report results on the first flight experiment that will focus on using the barometer instruments on a tethered helium-filled balloon. The balloon flight will be conducted in the vicinity of a known seismic source generated by a seismic hammer. Earlier tests conducted by Sandia National Laboratory demonstrated that this is a highly reproducible source of seismic and acoustic energy using infrasound sensors. The results of the experiments are intended to validate the two-barometer signal processing approach using a well-characterized point signal source.

Infrasound as a Geophysical Probe Using Earth as a Venus Analog

NASA Astrophysics Data System (ADS)

Komjathy, A.; Cutts, J. A.; Pauken, M.; Kedar, S.; Smrekar, S. E.; Hall, J. R.

2016-12-01

JPL is in a process of developing an instrument to measure seismic activity on Venus by detecting infrasonic waves in the atmosphere. The overall objective of this research is to demonstrate the feasibility of using sensitive barometers to detect infrasonic signals from seismic and explosive activity on Venus from a balloon platform. Because of Venus' dense atmosphere, seismic signatures from even small quakes (magnitude 3) are effectively coupled into the atmosphere. The seismic signals are known to couple about 60 times more efficiently into the atmosphere on Venus than on Earth. It was found that almost no attenuation below 80 km on Venus for frequency less than 1Hz. Whereas wind noise is a major source of background noise for terrestrial infrasonic arrays, it is expected that a balloon platform, which drifts with winds will be capable of very sensitive measurements with low noise. In our research we will demonstrate and apply techniques for discriminating upward propagating waves from a seismic event by making measurements with two or more infrasonic sensors using very sensitive barometers on a tether deployed from the balloon in a series of earth-based tests. We will first demonstrate and validate the technique using an artificial infrasound source in a deployment from a hot air balloon on Earth and then extend it with longer duration flights in the troposphere and stratosphere. We will report results on the first flight experiment that will focus on using the barometer instruments on a tethered helium-filled balloon. The balloon flight will be conducted in the vicinity of a known seismic source generated by a seismic hammer. Earlier tests conducted by Sandia National Laboratory demonstrated that this is a highly reproducible source of seismic and acoustic energy using infrasound sensors. The results of the experiments are intended to validate the two-barometer signal processing approach using a well-characterized point signal source.

IMS Seismic and Infrasound Stations Instrumental Challenges

NASA Astrophysics Data System (ADS)

Starovoit, Y. O.; Dricker, I. G.; Marty, J.

2016-12-01

The IMS seismic network is a set of monitoring facilities including 50 primary stations and 120 auxiliary stations. Besides the difference in the mode of data transmission to the IDC, technical specifications for seismographic equipment to be installed at both types of stations are essentially the same. The IMS infrasound network comprises 60 facilities with the requirement of continuous data transmission to IDC. The objective of this presentation is to report instrumental challenges associated with both seismic and infrasound technologies. In context of specifications for IMS seismic stations it was stressed that verification seismology is concerned with searching of reliable methods of signal detections at high frequencies. In the meantime MS/mb screening criteria between earthquakes and explosions relies on reliable detection of surface waves. The IMS seismic requirements for instrumental noise and operational range of data logger are defined as certain dB level below minimum background within the required frequency band from 0.02 to 16Hz. The type of sensors response is requested to be flat either in velocity or acceleration. The compliance with IMS specifications may thus introduce a challenging task when low-noise conditions have been recorded at the site. It means that as a station noise PSD approaches the NLNM it requires a high sensitive sensor to be connected to a quiet digitizer which may cause a quick system clip and waste of the available dynamic range. The experience has shown that hybrid frequency response of seismic sensors where combination of flat to velocity and flat to acceleration portions of the sensor frequency response may provide an optimal solution for utilization of the dynamic range and low digitizer noise floor. Vast efforts are also being undertaken and results achieved in the infrasound technology to standardize and optimize the response of the Wind-Noise Reduction System within the IMS infrasound passband from 0.02-4Hz and to deploy

Infrasound exposure induces apoptosis of rat cardiac myocytes by regulating the expression of apoptosis-related proteins.

PubMed

Pei, Zhao-Hui; Chen, Bao-Ying; Tie, Ru; Zhang, Hai-Feng; Zhao, Ge; Qu, Ping; Zhu, Xiao-Xing; Zhu, Miao-Zhang; Yu, Jun

2011-12-01

It has been reported that exposure to infrasound causes cardiac dysfunction. Allowing for the key role of apoptosis in the pathogenesis of cardiovascular diseases, the objective of this study was to investigate the apoptotic effects of infrasound. Cardiac myocytes cultured from neonatal rats were exposed to infrasound of 5 Hz at 130 dB. The apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. Also, the expression levels of a series of apoptosis-related proteins were detected. As a result, infrasound induced apoptosis of cultured rat cardiac myocytes in a time-dependant manner. The expression of proapoptotic proteins such as Bax, caspase-3, caspase-8, caspase-9, and FAS was significantly up-regulated, with concomitant down-regulated expression of antiapoptotic proteins such as Bcl-x, and the inhibitory apoptosis proteins family proteins including XIAP, cIAP-1, and cIAP-2. The expression of poly (ADP-ribose) polymerase and β-catenin, which are the substrate proteins of caspase-3, was significantly decreased. In conclusion, infrasound is an apoptotic inducer of cardiac myocytes.

Finding "truth" across different data sources.

PubMed

Rein, Alison; Simpson, Lisa A

2017-01-01

The proliferation of new technology platforms and tools is dramatically advancing our ability to capture, integrate and use clinical and other health related data for research and care. Another critical and increasingly common source of data comes directly from patients - often in the form of Patient Reported Outcomes (PRO). As more providers and payers recognize that patient experiences reflect a critical dimension of the value proposition, these data are informing broader strategies to achieve performance improvement and accountability in health systems. Combined with other traditional (e.g., claims) and more recent (e.g., Electronic Health Record) data assets, PROs can help to examine experiences and outcomes that convey a more complete picture of both individual and population health. One of the areas of research where this is most evident is cancer survivorship, including long-term adverse effects, as the population of survivors is increasing given advances in detection and treatment. Key questions remain as to how and under what conditions these new data resources can be used for research, and which are the best "sources of truth" for specific types of information. A recent IJHPR validation study by Hamood et al. reflects important progress in this regard, and establishes the necessary groundwork for a larger planned study. There are some important limitations worth noting, such as a small sample size (which does not support adequate subgroup analysis); a relatively narrow focus on women with only early stage or regionally advanced breast cancer; and a limited focus on outcomes that are primarily clinical and relatively severe in nature (e.g., cardiovascular disease). Finally, as use of EHRs becomes ubiquitous, as patient perspectives and outcome measures are considered, and as more types of data are systematically collected via electronic systems, further comparison and validation of non-clinical data elements captured via such tools will become

Thunder-induced ground motions: 1. Observations

NASA Astrophysics Data System (ADS)

Lin, Ting-L.; Langston, Charles A.

2009-04-01

Acoustic pressure from thunder and its induced ground motions were investigated using a small array consisting of five three-component short-period surface seismometers, a three-component borehole seismometer, and five infrasound microphones. We used the array to constrain wave parameters of the incident acoustic and seismic waves. The incident slowness differences between acoustic pressure and ground motions suggest that ground reverberations were first initiated somewhat away from the array. Using slowness inferred from ground motions is preferable to obtain the seismic source parameters. We propose a source equalization procedure for acoustic/seismic deconvolution to generate the time domain transfer function, a procedure similar to that of obtaining teleseismic earthquake receiver functions. The time domain transfer function removes the incident pressure time history from the seismogram. An additional vertical-to-radial ground motion transfer function was used to identify the Rayleigh wave propagation mode of induced seismic waves complementing that found using the particle motions and amplitude variations in the borehole. The initial motions obtained by the time domain transfer functions suggest a low Poisson's ratio for the near-surface layer. The acoustic-to-seismic transfer functions show a consistent reverberation series at frequencies near 5 Hz. This gives an empirical measure of site resonance that depends on the ratio of the layer velocity to layer thickness for earthquake P and S waves. The time domain transfer function approach by transferring a spectral division into the time domain provides an alternative method for studying acoustic-to-seismic coupling.

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.

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.

Infrasound and seismic analysis of the SpaceX Falcon9 explosion sequence of 1-September-2016

NASA Astrophysics Data System (ADS)

Thompson, G.; McNutt, S. R.; Brown, R. G.; Braunmiller, J.; Mehta, C.

2017-12-01

During a static launch test on 1-Sep-2016 at Kennedy Space Center, a SpaceX Falcon 9 rocket exploded causing loss of the rocket and the payload, and extensively damaging the launch complex. The sequence was captured by a 3-element infrasound array and a broadband 3-component seismometer at the Astronaut Beach House, just 0.87 miles (1.4 km) from the launch pad. Manual picking identified 153 impulsive airwave signals over a 26-minute interval and these were compared to video recordings of the sequence. The explosion onset consisted of a moderate signal on both seismic and infrasound (52 Pa) instruments. This corresponds to the rupture of the second-stage fuel tank. We found no signals before this, so we do not believe that there was an external cause. The primary fuel tank ruptured 4 seconds later and was the strongest event by far, producing an infrasound signal that exceeded 1400 Pa ( 2000 Pa in reduced pressure). The seismic signal consists mainly of air-coupled Rayleigh waves with frequencies of 5-23 Hz. The infrasound events occurred in four clusters. The first cluster included the onset and main events and 46 smaller events. This was followed by several minutes without infrasound signals during which a 3.5 minute continuous seismic vibration occurred. Cluster 2 consisted of 4 events ranging from 117-256 Pa. Cluster 3 comprised 96 events of 7-78 Pa. Cluster 4 consisted of 5 events with overpressures of 23-63 Pa. Gaps of several minutes without infrasound and seismic signals occurred between clusters 2 and 3, and 3 and 4. In terms of energy, the main event dominated; in terms of numbers, cluster 3 had the most infrasound events. The seismic and infrasound data are complementary to video recordings of the explosion, and provide additional characterization that may be useful to interpret the sequence of events. Because of the proximity of our array to this rocket explosion, our dataset may be unique.

Unveiling the truth: warnings reduce the repetition-based truth effect.

PubMed

Nadarevic, Lena; Aßfalg, André

2017-07-01

Typically, people are more likely to consider a previously seen or heard statement as true compared to a novel statement. This repetition-based "truth effect" is thought to rely on fluency-truth attributions as the underlying cognitive mechanism. In two experiments, we tested the nature of the fluency-attribution mechanism by means of warning instructions, which informed participants about the truth effect and asked them to prevent it. In Experiment 1, we instructed warned participants to consider whether a statement had already been presented in the experiment to avoid the truth effect. However, warnings did not significantly reduce the truth effect. In Experiment 2, we introduced control questions and reminders to ensure that participants understood the warning instruction. This time, warning reduced, but did not eliminate the truth effect. Assuming that the truth effect relies on fluency-truth attributions, this finding suggests that warned participants could control their attributions but did not disregard fluency altogether when making truth judgments. Further, we found no evidence that participants overdiscount the influence of fluency on their truth judgments.

Infrasonic wave accompanying a crack opening during the 2015 Hakone eruption

NASA Astrophysics Data System (ADS)

Yukutake, Yohei; Ichihara, Mie; Honda, Ryou

2018-03-01

To understand the initial process of the phreatic eruption of the Hakone volcano from June 29 to July 01, 2015, we analyzed infrasound data using the cross-correlation between infrasound and vertical ground velocity and compared the results of our analysis to the crustal deformation detected by tiltmeters and broadband seismometers. An infrasound signal and vertical ground motion due to an infrasound wave coupled to the ground were detected simultaneously with the opening of a crack source beneath the Owakudani geothermal region during the 2-min time period after 07:32 JST on June 29, 2015 (JST = UTC + 8 h). Given that the upper end of the open crack was approximately 150 m beneath the surface, the time for the direct emission of highly pressurized fluid from the upper end of the open crack to the surface should have exceeded the duration of the inflation owing to the hydraulic diffusivity in the porous media. Therefore, the infrasound signal coincident with the opening of the crack may reflect a sudden emission of volcanic gas resulting from the rapid vaporization of pre-existing groundwater beneath Owakudani because of the transfer of the volumetric strain change from the deformation source. We also noticed a correlation pattern corresponding to discrete impulsive infrasound signals during vent formation, which occurred several hours to 2 days after the opening of the crack. In particular, we noted that the sudden emission of vapor coincided with the inflation of the shallow pressure source, whereas the eruptive burst events accompanied by the largest vent formation were delayed by approximately 2 days. Furthermore, we demonstrated that the correlation method is a useful tool in detecting small infrasound signals and provides important information regarding the initial processes of the eruption.[Figure not available: see fulltext.

"#Factsmustfall"?--Education in a Post-Truth, Post-Truthful World

ERIC Educational Resources Information Center

Horsthemke, Kai

2017-01-01

Taking its inspiration from the name of the recent "#FeesMustFall" movement on South African university campuses, this paper takes stock of the apparent disrepute into which truth, facts and also rationality have fallen in recent times. In the post-truth world, the blurring of borders between truth and deception, truthfulness and…

[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.

Infrasound Sensor Calibration and Response

DTIC Science & Technology

2012-09-01

infrasound calibration chamber. Under separate funding a number of upgrades were made to the chamber. These include a Geotech Smart24 digitizer and...of upgrades were made to the chamber. These include a Geotech Smart24 digitizer and workstation, an LVDT sensor for piston phone phase measurement, a...20 samples per second on a GeoTech Instruments DL 24 digitizer. Fifty cycles of data were fit with the Matlab function NLINFIT that gave the peak

Beyond illusion: Psychoanalysis and the question of religious truth.

PubMed

Blass, Rachel B

2004-06-01

In this paper the author critically examines the nature of the positive, reconciliatory attitude towards religion that has become increasingly prevalent within psychoanalytic thinking and writing over the past 20 years. She shows how this positive attitude rests on a change in the nature of the prototype of religion and its reassignment to the realm of illusion, thus making irrelevant an issue most central both to psychoanalysis and to traditional Judeo-Christian belief--the passionate search for truth. The author demonstrates how the concern with truth, and specifically with the truth of religious claims, lies at the basis of the opposition between psychoanalysis and religion but, paradoxically, also provides the common ground for dialogue between the two. She argues that, as Freud developed his ideas regarding the origin of conviction in religious claims in his Moses and monotheism (1939), the nature of this common ground was expanded and the dialogue became potentially more meaningful. The author concludes that meaningful dialogue emerges through recognition of fundamental differences rather than through harmonisation within a realm of illusion. In this light, the present study may also be seen as an attempt to recognise fundamental differences that have been evolving within psychoanalysis itself.

Linking Volcano Infrasound Observations to Conduit Processes for Vulcanian Eruptions

NASA Astrophysics Data System (ADS)

Watson, L. M.; Dunham, E. M.; Almquist, M.; Mattsson, K.; Ampong, K.

2016-12-01

Volcano infrasound observations have been used to infer a range of eruption parameters, such as volume flux and exit velocity, with the majority of work focused on subaerial processes. Here, we propose using infrasound observations to investigate the subsurface processes of the volcanic system. We develop a one-dimensional model of the volcanic system, coupling an unsteady conduit model to a description of a volcanic jet with sound waves generated by the expansion of the jet. The conduit model describes isothermal two-phase flow with no relative motion between the phases. We are currently working on including crystals and adding conservation of energy to the governing equations. The model captures the descent of the fragmentation front into the conduit and approaches a steady state solution with choked flow at the vent. The descending fragmentation front influences the time history of mass discharge from the vent, which is linked to the infrasound signal through the volcanic jet model. The jet model is coupled to the conduit by conservation of mass, momentum, and energy. We compare simulation results for a range of models of the volcanic jet, ranging in complexity from assuming conservation of volume, as has been done in some previous infrasound studies, to solving the Euler equations for the surrounding compressible atmosphere and accounting for entrainment. Our model is designed for short-lived, impulsive Vulcanian eruptions, such as those seen at Sakurajima Volcano, with activity triggered by a sudden drop in pressure at the top of the conduit. The intention is to compare the simulated signals to observations and to devise an inverse procedure to enable inversion for conduit properties.

An optical fiber infrasound sensor: a new lower limit on atmospheric pressure noise between 1 and 10 Hz.

PubMed

Zumberge, Mark A; Berger, Jonathan; Hedlin, Michael A H; Husmann, Eric; Nooner, Scott; Hilt, Richard; Widmer-Schnidrig, Rudolf

2003-05-01

A new distributed sensor for detecting pressure variations caused by distant sources has been developed. The instrument reduces noise due to air turbulence in the infrasound band by averaging pressure along a line by means of monitoring strain in a long tubular diaphragm with an optical fiber interferometer. Above 1 Hz, the optical fiber infrasound sensor (OFIS) is less noisy than sensors relying on mechanical filters. Records collected from an 89-m-long OFS indicate a new low noise limit in the band from 1 to 10 Hz. Because the OFIS integrates pressure variations at light-speed rather than the speed of sound, phase delays of the acoustical signals caused by the sensor are negligible. Very long fiber-optic sensors are feasible and hold the promise of better wind-noise reduction than can be achieved with acoustical-mechanical systems.

Infrasound as a Long Standing Tool for Monitoring Continental Ecuadorean Volcanoes

NASA Astrophysics Data System (ADS)

Ruiz, M. C.; Ortiz, H. D.; Hernandez, S.; Palacios, P.; Anzieta, J. C.

2017-12-01

In the last 10 years, infrasound and seismic methods have been successfully used in the continuous monitoring of eruptive activity at Tunguruhua, Reventador, Sangay and Cotopaxi volcanoes. After a dormant period of 81 years, Tungurahua woke up in 1999 and has since been characterized by vulcanian and strombolian eruptions. Beginning in July 2006, a permanent seismo-infrasonic network with 5 collocated seismic and infrasound sensors was installed through a cooperation with Japan International Cooperation Agency (JICA). It recorded more than 6,000 explosions at Tungurahua with reduced amplitudes larger than 270 Pa at 1 km from the active crater, including 3 explosions greater than 6000 Pa associated with short-lived explosions. Major and long sustained eruptions (July 14-15, 2006; August 16-17, 2006; February 6-8, 2008, May 28, 2010; December 4, 2010; December 3-4, 2011; August 18, 2012) generated seismic and infrasound tremors with complex waveforms. In 2002, Reventador volcano produced the largest eruption in Ecuador in the last century (VEI-4). Since September 2012, alternating periods of strombolian activity and short-lived vulcanian explosions are monitored by seismic and microbarometer sensors located on the south-east border of the caldera rim. Non-steady activity with fluctuations between quiescence and frequent explosions, tremor, and chugging events is recorded. Infrasound of explosions ranges from 75 to 6350 Pa in reduced peak-to-peak amplitudes. Sangay, a remote and very active volcano, is monitored by a broadband seismometer and microbarometer collocated at 8 km from the summit. Active periods during the last few months are characterized by explosion events followed by lava flows and small ash emissions. In March 2016, more than 100 explosions were recorded in a single day. Finally, in 2015 Cotopaxi volcano began its recent eruptive period after 138 years of quiescence. One month after the initiation of its eruptive activity, 76 harmonic infrasound

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.

Ground Observation of the Hayabusa Reentry: The Third Opportunity of Man-made Fireball from Interplanetary Orbit

NASA Astrophysics Data System (ADS)

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

2010-12-01

After 7 years and 6,000,000,000 km of challenging cruise in the solar system, the Hayabusa did come back to the Earth on June 13, 2010. The Hayabusa, the first sample-return explorer to NEA, landed on 25243 Itokawa in 2005, capturing surface particles on the S-type asteroid into its sample return capsule (SRC). Following to the reentries of the Genesis in 2004 and the Stardust in 2006, the return of the Hayabusa 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 world first case of direct reentry of spacecraft from interplanetary transfer orbit. After the successful resumption of the SRC, it was carefully sent to ISAS/JAXA, and at present, small particles expected to be the first sample-return materials from the minor planet are carefully investigated. In order to obtain precise trajectory information to ensure the quick procedure for the Hayabusa SRC resumption team, we observed the Hayabusa SRC reentry by optically in Australian night sky. High-resolution imaging and spectroscopy were carried out with several high-sensitivity instruments to investigate thermal-protection process of thermal protection ablator (TPA) as well as interaction process between SRC surface materials and upper atmospheric neutral and plasma components. Moreover, shockwaves were observed by infrasound/seismic sensor arrays on ground to investigate reentry related shockwaves as well as air-to-ground coupling process at the extremely rare opportunity. With respect to nominal trajectory of the Hayabusa SRC reentry, four optical stations were set inside and near the Woomera Prohibited Area, Australia, targeting on peak-heat and/or front-heat profiles of ablating TPA for engineering aspect. Infrasound and seismic sensors were also deployed as three arrayed stations and three single stations to realize direction findings of sonic boom type shockwaves from the SRC and spacecraft and point source type

Tele-infrasonic studies of hard-rock mining explosions.

PubMed

McKenna, Mihan H; Stump, Brian W; Hayek, Sylvia; McKenna, Jason R; Stanton, Terry R

2007-07-01

The Lac-du-Bonnet infrasound station, IS-10, and the Minnesota iron mines 390 km to the southeast are ideally located to assess the accuracy of atmospheric profiles needed for infrasound modeling. Infrasonic data from 2003 associated with explosions at the iron mine were analyzed for effects of explosion size and atmospheric conditions on observations with well-constrained ground truth. Noise was the determining factor for observation; high noise conditions sometimes prevented unequivocal identification of infrasound arrivals. Observed arrivals had frequencies of 0.5 to 5 Hz, with a dominant frequency of 2 Hz, and generally had durations on the order of 10 s or less. There was no correlation between explosive amount and observability. Tele-infrasonic propagation distances (greater than 250 km) produce thermospheric ray paths. Modeling is based upon MSIS/HWM (Mass Spectrometer Incoherent Scatter/Horizontal Wind Model) and NRL-G2S (Naval Research Laboratory Ground to Space) datasets. The NRL-G2S dataset provided more accurate travel time predictions that the MSIS/HWM dataset. PE modeling for the NRL-G2S dataset indicates energy loss at higher frequencies (around 4 Hz). Additionally, applying the Sutherland/Bass model through the NRL-G2S realization of the atmosphere in InfraMAP results in predicted amplitudes too small to be observed.

Ground Truth Events with Source Geometry in Eurasia and the Middle East

DTIC Science & Technology

2016-06-02

source properties, including seismic moment, corner frequency, radiated energy , and stress drop have been obtained using spectra for S waves following...PARAMETERS Other source parameters, including radiated energy , corner frequency, seismic moment, and static stress drop were calculated using a spectral...technique (Richardson & Jordan, 2002; Andrews, 1986). The process entails separating event and station spectra and median- stacking each event’s

Status report on the establishment of 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.; Campus, P.; Bell, M.; Hoffmann, T. L.; Langlois, A.; Martysevich, P.; Demirovik, E.; Carvalho, J.; Kramer, A.

2002-11-01

The infrasound component of the International Monitoring System (IMS) for Comprehensive Nuclear-Test-Ban Treaty verification aims for global detection and localization of low-frequency sound waves originating from atmospheric nuclear explosions. The infrasound network will consist of 60 array stations, distributed as evenly as possible over the globe to assure at least two-station detection capability for 1-kton explosions at any point on earth. This network will be larger and more sensitive than any other previously operated infrasound network. As of today, 85% of the site surveys for IMS infrasound stations have been completed, 25% of the stations have been installed, and 8% of the installations have been certified and are transmitting high-quality continuous data to the International Data Center in Vienna. By the end of 2002, 20% of the infrasound network is expected to be certified and operating in post-certification mode. This presentation will discuss the current status and progress made in the site survey, installation, and certification programs for IMS infrasound stations. A review will be presented of the challenges and difficulties encountered in these programs, together with practical solutions to these problems.

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. © 2011 Acoustical Society of America

Status of the undisturbed mangroves at Brunei Bay, East Malaysia: a preliminary assessment based on remote sensing and ground-truth observations

PubMed Central

Izzaty Horsali, Nurul Amira; Mat Zauki, Nurul Ashikin; Otero, Viviana; Nadzri, Muhammad Izuan; Ibrahim, Sulong; Husain, Mohd-Lokman; Dahdouh-Guebas, Farid

2018-01-01

Brunei Bay, which receives freshwater discharge from four major rivers, namely Limbang, Sundar, Weston and Menumbok, hosts a luxuriant mangrove cover in East Malaysia. However, this relatively undisturbed mangrove forest has been less scientifically explored, especially in terms of vegetation structure, ecosystem services and functioning, and land-use/cover changes. In the present study, mangrove areal extent together with species composition and distribution at the four notified estuaries was evaluated through remote sensing (Advanced Land Observation Satellite—ALOS) and ground-truth (Point-Centred Quarter Method—PCQM) observations. As of 2010, the total mangrove cover was found to be ca. 35,183.74 ha, of which Weston and Menumbok occupied more than two-folds (58%), followed by Sundar (27%) and Limbang (15%). The medium resolution ALOS data were efficient for mapping dominant mangrove species such as Nypa fruticans, Rhizophora apiculata, Sonneratia caseolaris, S. alba and Xylocarpus granatum in the vicinity (accuracy: 80%). The PCQM estimates found a higher basal area at Limbang and Menumbok—suggestive of more mature vegetation, compared to Sundar and Weston. Mangrove stand structural complexity (derived from the complexity index) was also high in the order of Limbang > Menumbok > Sundar > Weston and supporting the perspective of less/undisturbed vegetation at two former locations. Both remote sensing and ground-truth observations have complementarily represented the distribution of Sonneratia spp. as pioneer vegetation at shallow river mouths, N. fruticans in the areas of strong freshwater discharge, R. apiculata in the areas of strong neritic incursion and X. granatum at interior/elevated grounds. The results from this study would be able to serve as strong baseline data for future mangrove investigations at Brunei Bay, including for monitoring and management purposes locally at present. PMID:29479500

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. Copyright © 2013 Elsevier B.V. All rights reserved.

[Effect of infrasound on ultrastructure and permeability of rat's blood-retinal barrier].

PubMed

Qiu, Ping; Zhang, Zuoming; Jiang, Yong; Gou, Qun; Wang, Bing; Gou, Lin; Chen, Jingzao

2002-08-01

To investigate the possible effect of infrasound on the ultra-structure and permeability of rat's blood-retinal barrier (BRB). Ultra-structural changes of BRB were observed through the injection of lanthanum nitrate (La), which was used as a tracer to demonstrate the breakdown of the BRB, into blood vessels. Fifteen mature male rats divided into 5 groups were exposed to infrasound at a 8 Hz frequency, 130 dB sound pressure level in a pressure chamber especially designed for the experiment for 0, 1, 7, 14, 21 days, respectively. Under the action of infrasound, along with the prolongation of exposure, the damage of BRB was severer and severer. On the 1st day, there was no significant change in La leakage. On the 7th day, La diffused in the interphotoreceptor space at nuclear level. On the 14th day, La granules could be seen in the space of nervous cells. Finally, on the 21st day, La was found between synapses, synapses and nerve cells, as well as between the nerve cells and supporting cells, then sometimes reached vitreous body. Under the electron microscope, there were no significant morphological changes, but changes related to metabolism, such as edematous mitochondria, dilated rough endoplasmic reticula, precipitation of glycogen grandules, widening of perinuclear space, etc. The results thus suggest that the exposure to infrasound cause the breakdown of rat's blood-retinal barrier and visual impairment.

Ground-truthing the Foraminifera-bound Nitrogen Isotope Paleo-proxy in the Modern Sargasso Sea

NASA Astrophysics Data System (ADS)

Smart, S.; Ren, H. A.; Fawcett, S. E.; Conte, M. H.; Rafter, P. A.; Ellis, K. K.; Weigand, M. A.; Sigman, D. M.

2016-02-01

We present the nitrogen isotope ratios (δ15N) of planktonic foraminifera, a type of calcifying zooplankton, collected from surface ocean net tows, moored sediment traps and core-top sediments at the Bermuda Atlantic Time-series Study site in the Sargasso Sea between 2009 and 2013. Consistent with previous measurements from low-latitude core-top sediments, the annually averaged δ15N of organic matter bound within the shells of euphotic zone-dwelling foraminifera approximates that of thermocline nitrate, the dominant source of new nitrogen to Sargasso Sea surface waters. Based on net tow collections in the upper 200 m of the water column, we observe no systematic difference between the biomass δ15N and shell-bound δ15N of a given foraminifera species. For multiple species, the δ15N of net tow-collected upper ocean shells is lower than shells from sediment traps (by 0.5-2.1‰) and lower than shells from seafloor sediments (by 0.5-1.4‰). We are currently investigating whether these differences reflect actual processes affecting shell-bound δ15N or instead relate to the different time periods over which the three sample types integrate. The foraminiferal biomass δ15N time-series from the surface Sargasso Sea exhibits significant seasonal variations, with the lowest values in fall and the highest values in spring. The roles of hydrography, biogeochemistry, and ecosystem dynamics in driving these seasonal variations will be discussed. These data from the modern subtropical ocean form part of a greater effort to ground-truth the use of foram-bound δ15N to reconstruct past nutrient conditions, not only as a recorder of the isotopic composition of nitrogen supply in oligotrophic environments but also as a recorder of the degree of nitrate consumption in high-latitude regions such as the Southern Ocean.

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.

Extending the testimony problem: evaluating the truth, scope, and source of cultural information.

PubMed

Bergstrom, Brian; Moehlmann, Bianca; Boyer, Pascal

2006-01-01

Children's learning--in the domains of science and religion specifically, but in many other cultural domains as well--relies extensively on testimony and other forms of culturally transmitted information. The cognitive processes that enable such learning must also administrate the evaluation, qualification, and storage of that information, while guarding against the dangers of false or misleading input. Currently, the development of these appraisal processes is not clearly understood. Recent work, reviewed here, has begun to address three important dimensions of the problem: how children and adults evaluate truth in communication, how they gauge the inferential potential of information, and how they encode and evaluate its source.

We get the algorithms of our ground truths: Designing referential databases in digital image processing

PubMed Central

Jaton, Florian

2017-01-01

This article documents the practical efforts of a group of scientists designing an image-processing algorithm for saliency detection. By following the actors of this computer science project, the article shows that the problems often considered to be the starting points of computational models are in fact provisional results of time-consuming, collective and highly material processes that engage habits, desires, skills and values. In the project being studied, problematization processes lead to the constitution of referential databases called ‘ground truths’ that enable both the effective shaping of algorithms and the evaluation of their performances. Working as important common touchstones for research communities in image processing, the ground truths are inherited from prior problematization processes and may be imparted to subsequent ones. The ethnographic results of this study suggest two complementary analytical perspectives on algorithms: (1) an ‘axiomatic’ perspective that understands algorithms as sets of instructions designed to solve given problems computationally in the best possible way, and (2) a ‘problem-oriented’ perspective that understands algorithms as sets of instructions designed to computationally retrieve outputs designed and designated during specific problematization processes. If the axiomatic perspective on algorithms puts the emphasis on the numerical transformations of inputs into outputs, the problem-oriented perspective puts the emphasis on the definition of both inputs and outputs. PMID:28950802

Infrasound-induced hemodynamics, ultrastructure, and molecular changes in the rat myocardium.

PubMed

Pei, Zhaohui; Sang, Hanfei; Li, Ruiman; Xiao, Pingxi; He, Jiangui; Zhuang, Zhiqiang; Zhu, Miaozhang; Chen, Jingzao; Ma, Hong

2007-04-01

Recent interest in adverse effects of infrasound on organisms arises from health concerns. We assessed the association between infrasound exposure of 5 Hz at 130 dB and changes of cardiac ultrastructure and function in rats. Thirty-two Sprague-Dawley rats were randomized into control, 1, 7, and 14 days groups for 2 h of infrasound once daily according to planned schedules. Changes of cardiac ultrastructure, hemodynamics indices, intracellular Ca(2+) concentrations ([Ca(2+)](i)), and sarcoplasmic reticulum Ca(2+)-ATPase 2 (SERCA2) were detected. Heart rates in 1 day group were significantly increased compared with control group and no significant changes in other groups. Left ventricular systolic pressures were significantly increased with time. Left ventricular diastolic end pressure and maximum rising rates of left ventricular pressure (+dl/dt) were significantly increased in 7 and 14 days groups and not changed in 1 day group, compared with control group. Maximum dropping rates of left ventricular pressure (-dl/dt) were significantly decreased in 7 and 14 days groups and not changed in 1 day group, compared with control group. In heart cells, there were several swelled mitochondria in 1 day group, more swelled mitochondria in 7 days group, platelet aggregation in the intercellular substance in 14 days group. [Ca(2+)](i) were significantly increased with time. There was a significant increase in SERCA2 in 1 day group, while a significant decrease in 7 and 14 days groups, compared with control group. Infrasound of 5 Hz at 130 dB can damage cardiac ultrastructure and function. Changes of [Ca(2+)](i) and SERCA2 play an important role in the secondary cardiac damage. (c) 2007 Wiley Periodicals, Inc.

Effect of infrasound on cochlear damage from exposure to a 4 kHz octave band of noise.

PubMed

Harding, Gary W; Bohne, Barbara A; Lee, Steve C; Salt, Alec N

2007-03-01

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 24h. For each animal, the tympanic membrane (TM) in one ear was perforated ( approximately 1 mm(2)) 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 to 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 OHC loss

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

Role of infrasound pressure waves in atherosclerotic plaque rupture: a theoretical approach.

PubMed

Tsatsaris, Athanasios; Koukounaris, Efstathios; Motsakos, Theodoros; Perrea, Despina

2007-01-01

To investigate the role of infrasound aortic pressure waves (IPW) in atherosclerotic plaque rupture. Atherosclerotic plaques have been simulated partly, in two dimensions, as being short or long Conical Intersections (CIS), that is to say elliptic, parabolic or hyperbolic surfaces. Consequently, the course and reflection of the generated aortic pressure wave (infrasound domain-less than 20Hz) has been examined around the simulated plaques. The incidence of IPW on plaque surface results both in reflection and "refraction" of the wave. The IPW course within tissue, seems to be enhanced by high Cu-level presence at these areas according to recent evidence (US2003000388213). The "refracted", derived wave travels through plaque tissue and is eventually accumulated to the foci of the respective CIS-plaque geometry. The foci location within or underneath atheroma declares zones where infrasound energy is mostly absorbed. This process, among other mechanisms may contribute to plaque rupture through the development of local hemorrhage and inflammation in foci areas. In future, detection of foci areas and repair (i.e. via Laser Healing Microtechnique) may attenuate atherosclerotic plaque rupture behavior.

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

[Effects of infrasound on activities of 3beta hydroxysteroid dehydrogenase and acid phosphatase of polygonal cells in adrenal cortex zona fasciculate in mice].

PubMed

Dang, Wei-min; Wang, Sheng; Tian, Shi-xiu; Chen, Bing; Sun, Fei; Li, Wei; Jiao, Yan; He, Li-hua

2007-02-01

To explore the biological effects of infrasound on the polygonal cells in adrenal cortex zona fasciculation in mice. The biological effects of infrasound on the activities of 3beta hydroxysteroid dehydrogenase (3-betaHSDH) and acid phosphatase(ACP) of the polygonal cells in adrenal cortex zona fasciculate were observed when exposure to 8 and 16 Hz infrasound at 80, 90, 100, 110, 120 and 130 dB for 1 day, 7 days and 14 days or 14 days after the exposure. When exposure to 8 Hz infrasound, the enzyme activities of 3-betaHSDH increase as the sound pressure levels increase. Only when the sound pressure levels reach 130 dB, the enzyme activities began to decrease exceptionally. When exposure to 16 Hz, 80 dB infrasound, no significant difference between the treatment and control group in the activities of 3-betaHSDH could be observed, but the injury of the polygonal cells had appeared. When exposure to 16 Hz, 100 dB infrasound, the activities of 3-betaHSDH started to increase. The cell injury still existed. When exposed to 16 Hz, 120 dB infrasound, the local tissue damage represented. Fourteen days after the mice exposure to 8 Hz, 90 dB and 130 dB infrasound for 14 days continuously, the local tissue injury of the adrenal cortex zona fasciculation began to recover at certain extent, but the higher the exposure sound pressure level, the poorer the tissue recovery. The biological effects of infrasound on the polygonal cells in adrenal cortex zona fasciculation response to the frequency of the infrasound are found at certain action strength range, but this characteristic usually is covered by the severe tissue injury. When exposure to infrasound is stopped for a period of time, the local tissue injury of the adrenal cortex zona fasciculation could recovers at certain extent, but the higher the exposure sound pressure level, the more poorer the tissue recovery.

Ash-plume dynamics and eruption source parameters by infrasound and thermal imagery: The 2010 Eyjafjallajökull eruption

NASA Astrophysics Data System (ADS)

Ripepe, M.; Bonadonna, C.; Folch, A.; Delle Donne, D.; Lacanna, G.; Marchetti, E.; Höskuldsson, A.

2013-03-01

During operational ash-cloud forecasting, prediction of ash concentration and total erupted mass directly depends on the determination of mass eruption rate (MER), which is typically inferred from plume height. Uncertainties for plume heights are large, especially for bent-over plumes in which the ascent dynamics are strongly affected by the surrounding wind field. Here we show how uncertainties can be reduced if MER is derived directly from geophysical observations of source dynamics. The combination of infrasound measurements and thermal camera imagery allows for the infrasonic type of source to be constrained (a dipole in this case) and for the plume exit velocity to be calculated (54-142 m/s) based on the acoustic signal recorded during the 2010 Eyjafjallajökull eruption from 4 to 21 May. Exit velocities are converted into MER using additional information on vent diameter (50±10 m) and mixture density (5.4±1.1 kg/m3), resulting in an average ∼9×105 kg/s MER during the considered period of the eruption. We validate our acoustic-derived MER by using independent measurements of plume heights (Icelandic Meteorological Office radar observations). Acoustically derived MER are converted into plume heights using field-based relationships and a 1D radially averaged buoyant plume theory model using a reconstructed total grain size distribution. We conclude that the use of infrasonic monitoring may lead to important understanding of the plume dynamics and allows for real-time determination of eruption source parameters. This could improve substantially the forecasting of volcano-related hazards, with important implications for civil aviation safety.

Damage to Hippocampus of Rats after Being Exposed to Infrasound.

PubMed

Zhang, Meng Yao; Chen, Chen; Xie, Xue Jun; Xu, Sheng Long; Guo, Guo Zhen; Wang, Jin

2016-06-01

The objective was to observe damage of hippocampus in rats after exposure to infrasound, and to assess HSP70 expression in hippocampus. SD rats in the experimental group were exposed to 140 dB (8 Hz) infrasound for 2 h per day for 3 days. The morphology of the hippocampus was examined by transmission electronic microscopic (TEM). Cell apoptosis was observed by TUNEL staining at 0 h, 24 h, 48 h, and 2 w after exposure. HSP70 expression was detected by immunohistochemistry (IHC) and Western blotting (WB). TEM showed that hippocampus was significantly damaged by exposure, and exhibited recovery 1 week after exposure. The TUNEL data showed that neuronal apoptosis after exposure was significantly higher than in the control rats at 24 h and 48 h, and the apoptotic cells decreased one week after exposure. IHC and WB showed HSP70 expression was significantly higher in the exposed rats, peaked at 24 h. Exposure to 140 dB (8 Hz) infrasound for 2 h per day for 3 days appeared to induce damage to the hippocampus of rats, based on changes in ultrastructure and increased cell apoptosis. However, recovery from the damage occurred overtime. HSP70 expression also increased after the exposure and decreased by 48. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

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.

Proceedings of the 2009 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marv A; Aguilar - Chang, Julio; Anderson, Dale

These proceedings contain papers prepared for the Monitoring Research Review 2009: Ground -Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2009 in Tucson, Arizona,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Test Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well asmore » potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A; Patterson, Eileen F

These proceedings contain papers prepared for the Monitoring Research Review 2010: Ground-Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2010 in Orlando, Florida,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, National Science Foundation (NSF), Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, asmore » well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Spinoza's error: memory for truth and falsity.

PubMed

Nadarevic, Lena; Erdfelder, Edgar

2013-02-01

Two theoretical frameworks have been proposed to account for the representation of truth and falsity in human memory: the Cartesian model and the Spinozan model. Both models presume that during information processing a mental representation of the information is stored along with a tag indicating its truth value. However, the two models disagree on the nature of these tags. According to the Cartesian model, true information receives a "true" tag and false information receives a "false" tag. In contrast, the Spinozan model claims that only false information receives a "false" tag, whereas untagged information is automatically accepted as true. To test the Cartesian and Spinozan models, we conducted two source memory experiments in which participants studied true and false trivia statements from three different sources differing in credibility (i.e., presenting 100% true, 50% true and 50% false, or 100% false statements). In Experiment 1, half of the participants were informed about the source credibility prior to the study phase. As compared to a control group, this precue group showed improved source memory for both true and false statements, but not for statements with an uncertain validity status. Moreover, memory did not differ for truth and falsity in the precue group. As Experiment 2 revealed, this finding is replicated even when using a 1-week rather than a 20-min retention interval between study and test phases. The results of both experiments clearly contradict the Spinozan model but can be explained in terms of the Cartesian model.

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.

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

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

Influence of infrasound exposure on the whole L-type calcium currents in rat ventricular myocytes.

PubMed

Pei, Zhaohui; Zhuang, Zhiqiang; Xiao, Pingxi; Chen, Jingzao; Sang, Hanfei; Ren, Jun; Wu, Zhenbiao; Yan, Guangmei

2009-06-01

This study was designed to examine the effect of infrasound exposure (5 Hz at 130 dB) on whole-cell L-type Ca2+ currents (WLCC) in rat ventricular myocytes and the underlying mechanism(s) involved. Thirty-two adult Sprague-Dawley rats were randomly assigned to infrasound exposure and control groups. [Ca2+](i), WLCC, mRNA expression of the a(1c) subunit of L-type Ca2+ channels (LCC), and SERCA2 protein were examined on day 1, 7, and 14 after initiation of infrasound exposure. Fluo-3/AM fluorescence and the laser scanning confocal microscope techniques were used to measure [Ca2+](i) in freshly isolated ventricular myocytes. The Ca2+ fluorescence intensity (FI), denoting [Ca2+](i) in cardiomyocytes, was significantly elevated in a time-dependent manner in the exposure groups. There was a significant increase in WLCC in the 1-day group and a further significant increase in the 7- and 14-day groups. LCC mRNA expression measured by RT-PCR revealed a significant rise in the 1-day group and a significant additional rise in the 7- and 14-day groups compared with control group. SERCA2 expression was significantly upregulated in the 1-day group followed by an overt decrease in the 7- and 14-day groups. Prolonged exposure of infrasound altered WLCC in rat cardiomyocytes by shifting the steady-state inactivation curves to the right (more depolarized direction) without altering the slope and biophysical properties of I (Ca,L). Taken together, our data suggest that changes in [Ca2+](I) levels as well as expression of LCC and SERCA2 may contribute to the infrasound exposure-elicited cardiac response.

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

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.

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.

Effects of charge design features on parameters of acoustic and seismic waves and cratering, for SMR chemical surface explosions

NASA Astrophysics Data System (ADS)

Gitterman, Y.

2012-04-01

A series of experimental on-surface shots was designed and conducted by the Geophysical Institute of Israel at Sayarim Military Range (SMR) in Negev desert, including two large calibration explosions: about 82 tons of strong IMI explosives in August 2009, and about 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 in different weather/wind conditions, for calibration of IMS infrasound stations in Europe, Middle East and Asia. Strong boosters and the upward charge detonation scheme were applied to provide a reduced energy release to the ground and an enlarged energy radiation to the atmosphere, producing enhanced infrasound signals, for better observation at far-regional stations. The following observations and results indicate on the required explosives energy partition for this charge design: 1) crater size and local seismic (duration) magnitudes were found smaller than expected for these large surface explosions; 2) small test shots of the same charge (1 ton) conducted at SMR with different detonation directions showed clearly lower seismic amplitudes/energy and smaller crater size for the upward detonation; 3) many infrasound stations at local and regional distances showed higher than expected peak amplitudes, even after application of a wind-correction procedure. For the large-scale explosions, 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. Empirical relations for air-blast parameters - peak pressure, impulse and the Secondary Shock (SS) time delay - depending on distance, were developed and analyzed. The parameters, scaled by the cubic root of estimated TNT equivalent charges, were found consistent for all analyzed explosions, except of SS

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.

Biometric correspondence between reface computerized facial approximations and CT-derived ground truth skin surface models objectively examined using an automated facial recognition system.

PubMed

Parks, Connie L; Monson, Keith L

2018-05-01

This study employed an automated facial recognition system as a means of objectively evaluating biometric correspondence between a ReFace facial approximation and the computed tomography (CT) derived ground truth skin surface of the same individual. High rates of biometric correspondence were observed, irrespective of rank class (R k ) or demographic cohort examined. Overall, 48% of the test subjects' ReFace approximation probes (n=96) were matched to his or her corresponding ground truth skin surface image at R 1 , a rank indicating a high degree of biometric correspondence and a potential positive identification. Identification rates improved with each successively broader rank class (R 10 =85%, R 25 =96%, and R 50 =99%), with 100% identification by R 57 . A sharp increase (39% mean increase) in identification rates was observed between R 1 and R 10 across most rank classes and demographic cohorts. In contrast, significantly lower (p<0.01) increases in identification rates were observed between R 10 and R 25 (8% mean increase) and R 25 and R 50 (3% mean increase). No significant (p>0.05) performance differences were observed across demographic cohorts or CT scan protocols. Performance measures observed in this research suggest that ReFace approximations are biometrically similar to the actual faces of the approximated individuals and, therefore, may have potential operational utility in contexts in which computerized approximations are utilized as probes in automated facial recognition systems. Copyright © 2018. Published by Elsevier B.V.

Proceedings of the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Benson, Jody; Patterson, Eileen F.

These proceedings contain papers prepared for the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 20-22 September, 2005 in Rancho Mirage, California. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well asmore » potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

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

USGS Publications Warehouse

Lyons, John; Haney, Matt; Werner, Cynthia A.; Kelly, Peter; Patrick, Matthew R.; Kern, Christoph; Trusdell, Frank A.

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.

On authenticity: the question of truth in construction and autobiography.

PubMed

Collins, Sara

2011-12-01

Freud was occupied with the question of truth and its verification throughout his work. He looked to archaeology for an evidence model to support his ideas on reconstruction. He also referred to literature regarding truth in reconstruction, where he saw shifts between historical fact and invention, and detected such swings in his own case histories. In his late work Freud pondered over the impossibility of truth in reconstruction by juxtaposing truth with 'probability'. Developments on the role of fantasy and myth in reconstruction and contemporary debates over objectivity have increasingly highlighted the question of 'truth' in psychoanalysis. I will argue that 'authenticity' is a helpful concept in furthering the discussion over truth in reconstruction. Authenticity denotes that which is genuine, trustworthy and emotionally accurate in a reconstruction, as observed within the immediacy of the analyst/patient interaction. As authenticity signifies genuineness in a contemporary context its origins are verifiable through the analyst's own observations of the analytic process itself. Therefore, authenticity is about the likelihood and approximation of historical truth rather than its certainty. In that respect it links with Freud's musings over 'probability'. Developments on writing 'truths' in autobiography mirror those in reconstruction, and lend corroborative support from another source. Copyright © 2011 Institute of Psychoanalysis.

Infrasound Signals as Basis for Event Discriminants

DTIC Science & Technology

2007-09-01

tests ( UGT ) at the NTS, some work was done on finding discriminants between UGTs and earthquakes. Plots of wind-corrected infrasound pressure amplitude...probably due to the longer duration of earthquake motion compared to the Figure 1. These figure illustrate the initial comparisons for UGTs and...earthquakes for signal duration (left) and wind corrected amplitude (right) as functions of Mb. relatively short duration for a UGT . On the other hand

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.

Automatic identification of alpine mass movements based on seismic and infrasound signals

NASA Astrophysics Data System (ADS)

Schimmel, Andreas; Hübl, Johannes

2017-04-01

The automatic detection and identification of alpine mass movements like debris flows, debris floods or landslides gets increasing importance for mitigation measures in the densely populated and intensively used alpine regions. Since this mass movement processes emits characteristically seismic and acoustic waves in the low frequency range this events can be detected and identified based on this signals. So already several approaches for detection and warning systems based on seismic or infrasound signals has been developed. But a combination of both methods, which can increase detection probability and reduce false alarms is currently used very rarely and can serve as a promising method for developing an automatic detection and identification system. So this work presents an approach for a detection and identification system based on a combination of seismic and infrasound sensors, which can detect sediment related mass movements from a remote location unaffected by the process. The system is based on one infrasound sensor and one geophone which are placed co-located and a microcontroller where a specially designed detection algorithm is executed which can detect mass movements in real time directly at the sensor site. Further this work tries to get out more information from the seismic and infrasound spectrum produced by different sediment related mass movements to identify the process type and estimate the magnitude of the event. The system is currently installed and tested on five test sites in Austria, two in Italy and one in Switzerland as well as one in Germany. This high number of test sites is used to get a large database of very different events which will be the basis for a new identification method for alpine mass movements. These tests shows promising results and so this system provides an easy to install and inexpensive approach for a detection and warning system.

Acoustic buffeting by infrasound in a low vibration facility.

PubMed

MacLeod, B P; Hoffman, J E; Burke, S A; Bonn, D A

2016-09-01

Measurement instruments and fabrication tools with spatial resolution on the atomic scale require facilities that mitigate the impact of vibration sources in the environment. One approach to protection from vibration in a building's foundation is to place the instrument on a massive inertia block, supported on pneumatic isolators. This opens the questions of whether or not a massive floating block is susceptible to acoustic forces, and how to mitigate the effects of any such acoustic buffeting. Here this is investigated with quantitative measurements of vibrations and sound pressure, together with finite element modeling. It is shown that a particular concern, even in a facility with multiple acoustic enclosures, is the excitation of the lowest fundamental acoustic modes of the room by infrasound in the low tens of Hz range, and the efficient coupling of the fundamental room modes to a large inertia block centered in the room.

On the use of remote infrasound and seismic stations to constrain eruptive sequences

NASA Astrophysics Data System (ADS)

Caudron, C.; Taisne, B.; Garces, M. A.

2014-12-01

The Kelud eruption was one of the strongest volcanic eruption of the decade. The eruption occurred on the 13th of February 2014 and ejected volcanic ash up to 20 km of altitude. The eruption also destroyed most of the instruments deployed in the near field. Therefore, not much information could be unraveled from the local volcano monitoring system. An explosion was clearly captured at many infrasound stations of the IMS network (and in Singapore), making it one of the biggest volcanic events recorded by the network. The high intensity, deep frequency, and infrasonic detection range of >10,000 km is characteristic of an eruptive column that injects ash into aircraft cruising altitudes and is an evident threat to aviation. The explosion signal was particularly rich in very long periods (~ 200s) and could be resolved as two distinct pulses at some sites. Interestingly, many broadband seismic instruments also recorded this event as far as 5000 kilometers. By inspecting the seismic data of the instruments located closer to the edifice (~ 150 km), we could clearly distinguish two different pulses separated by 17 minutes, followed by the arrival of very low frequencies (thanks to the coupling between ground and atmosphere). One pulse vs two pulses might have strong implications for the subsequent ash modelling. Due to the violence of the events, 4 stations out of 5 were destructed and the remaining one was saturated. This illustrates that data streams from broadband seismometers and infrasound sensors located at safe distances are extremely useful for deciphering the dynamic of the eruption and its implication in term of local, regional and global impact.

Using Simulated Ground Motions to Constrain Near-Source Ground Motion Prediction Equations in Areas Experiencing Induced Seismicity

NASA Astrophysics Data System (ADS)

Bydlon, S. A.; Dunham, E. M.

2016-12-01

Recent increases in seismic activity in historically quiescent areas such as Oklahoma, Texas, and Arkansas, including large, potentially induced events such as the 2011 Mw 5.6 Prague, OK, earthquake, have spurred the need for investigation into expected ground motions associated with these seismic sources. The neoteric nature of this seismicity increase corresponds to a scarcity of ground motion recordings within 50 km of earthquakes Mw 3.0 and greater, with increasing scarcity at larger magnitudes. Gathering additional near-source ground motion data will help better constraints on regional ground motion prediction equations (GMPEs) and will happen over time, but this leaves open the possibility of damaging earthquakes occurring before potential ground shaking and seismic hazard in these areas are properly understood. To aid the effort of constraining near-source GMPEs associated with induced seismicity, we integrate synthetic ground motion data from simulated earthquakes into the process. Using the dynamic rupture and seismic wave propagation code waveqlab3d, we perform verification and validation exercises intended to establish confidence in simulated ground motions for use in constraining GMPEs. We verify the accuracy of our ground motion simulator by performing the PEER/SCEC layer-over-halfspace comparison problem LOH.1 Validation exercises to ensure that we are synthesizing realistic ground motion data include comparisons to recorded ground motions for specific earthquakes in target areas of Oklahoma between Mw 3.0 and 4.0. Using a 3D velocity structure that includes a 1D structure with additional small-scale heterogeneity, the properties of which are based on well-log data from Oklahoma, we perform ground motion simulations of small (Mw 3.0 - 4.0) earthquakes using point moment tensor sources. We use the resulting synthetic ground motion data to develop GMPEs for small earthquakes in Oklahoma. Preliminary results indicate that ground motions can be amplified

An Economic Analysis of the Truth in Negotiations Act

DTIC Science & Technology

2016-01-27

SPONSORED REPORT SERIES An Economic Analysis of the Truth in Negotiations Act 27 January 2016 Dr. Chong Wang, Associate Professor Dr. Rene G. Rendon...source) to submit “cost or pricing data” when they negotiate the price of a contract with the federal government. The contractors must certify that...SERIES An Economic Analysis of the Truth in Negotiations Act 27 January 2016 Dr. Chong Wang, Associate Professor Dr. Rene G. Rendon, Associate

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.

Fiction Is Truth, and Sometimes Truth Is Fiction

ERIC Educational Resources Information Center

Hess, Carol Lakey

2008-01-01

The art of fiction tells truth because it is the truth of life that goes into making good fiction: love, hate, fear, courage, delight, sorrow, betrayal, loyalty, confusion, choice, circumstance, luck, injustice. These essential qualities, says the author, are also the qualities of sound theology, with a sense of time and place; and raising…

Comparing distinct ground-based lightning location networks covering the Netherlands

NASA Astrophysics Data System (ADS)

de Vos, Lotte; Leijnse, Hidde; Schmeits, Maurice; Beekhuis, Hans; Poelman, Dieter; Evers, Läslo; Smets, Pieter

2015-04-01

Lightning can be detected using a ground-based sensor network. The Royal Netherlands Meteorological Institute (KNMI) monitors lightning activity in the Netherlands with the so-called FLITS-system; a network combining SAFIR-type sensors. This makes use of Very High Frequency (VHF) as well as Low Frequency (LF) sensors. KNMI has recently decided to replace FLITS by data from a sub-continental network operated by Météorage which makes use of LF sensors only (KNMI Lightning Detection Network, or KLDN). KLDN is compared to the FLITS system, as well as Met Office's long-range Arrival Time Difference (ATDnet), which measures Very Low Frequency (VLF). Special focus lies on the ability to detect Cloud to Ground (CG) and Cloud to Cloud (CC) lightning in the Netherlands. Relative detection efficiency of individual flashes and lightning activity in a more general sense are calculated over a period of almost 5 years. Additionally, the detection efficiency of each system is compared to a ground-truth that is constructed from flashes that are detected by both of the other datasets. Finally, infrasound data is used as a fourth lightning data source for several case studies. Relative performance is found to vary strongly with location and time. As expected, it is found that FLITS detects significantly more CC lightning (because of the strong aptitude of VHF antennas to detect CC), though KLDN and ATDnet detect more CG lightning. We analyze statistics computed over the entire 5-year period, where we look at CG as well as total lightning (CC and CG combined). Statistics that are considered are the Probability of Detection (POD) and the so-called Lightning Activity Detection (LAD). POD is defined as the percentage of reference flashes the system detects compared to the total detections in the reference. LAD is defined as the fraction of system recordings of one or more flashes in predefined area boxes over a certain time period given the fact that the reference detects at least one

Ground Source Geothermal District Heating and Cooling System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowe, James William

2016-10-21

Ball State University converted its campus from a coal-fired steam boiler district heating system to a ground source heat pump geothermal district system that produces simultaneously hot water for heating and chilled water for cooling. This system will include the installation of 3,600 four hundred feet deep vertical closed loop boreholes making it the largest ground source geothermal district system in the country. The boreholes will act as heat exchangers and transfer heat by virtue of the earth’s ability to maintain an average temperature of 55 degree Fahrenheit. With growing international concern for global warming and the need to reducemore » worldwide carbon dioxide loading of the atmosphere geothermal is poised to provide the means to help reduce carbon dioxide emissions. The shift from burning coal to utilizing ground source geothermal will increase electrical consumption but an overall decrease in energy use and reduction in carbon dioxide output will be achieved. This achievement is a result of coupling the ground source geothermal boreholes with large heat pump chiller technology. The system provides the thermodynamic means to move large amounts of energy with limited energy input. Ball State University: http://cms.bsu.edu/About/Geothermal.aspx« less

Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marv A; Aguilar-chang, Julio; Arrowsmith, Marie

These proceedings contain papers prepared for the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 23-25 September, 2008 in Portsmouth, Virginia. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 2011 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Patterson, Eileen F.; Sandoval, Marisa N.

These proceedings contain papers prepared for the Monitoring Research Review 2011: Ground-Based Nuclear Explosion Monitoring Technologies, held 13-15 September, 2011 in Tucson, Arizona. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Defense Threat Reduction Agency (DTRA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), National Science Foundation (NSF), and other invited sponsors. The scientific objectives of the research are to improve the United States' capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is tomore » provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Ground-Truthing of Airborne LiDAR Using RTK-GPS Surveyed Data in Coastal Louisiana's Wetlands

NASA Astrophysics Data System (ADS)

Lauve, R. M.; Alizad, K.; Hagen, S. C.

2017-12-01

Airborne LiDAR (Light Detection and Ranging) data are used by engineers and scientists to create bare earth digital elevation models (DEM), which are essential to modeling complex coastal, ecological, and hydrological systems. However, acquiring accurate bare earth elevations in coastal wetlands is difficult due to the density of marsh grasses that prevent the sensors reflection off the true ground surface. Previous work by Medeiros et al. [2015] developed a technique to assess LiDAR error and adjust elevations according to marsh vegetation density and index. The aim of this study is the collection of ground truth points and the investigation on the range of potential errors found in existing LiDAR datasets within coastal Louisiana's wetlands. Survey grids were mapped out in an area dominated by Spartina alterniflora and a survey-grade Trimble Real Time Kinematic (RTK) GPS device was employed to measure bare earth ground elevations in the marsh system adjacent to Terrebonne Bay, LA. Elevations were obtained for 20 meter-spaced surveyed grid points and were used to generate a DEM. The comparison between LiDAR derived and surveyed data DEMs yield an average difference of 23 cm with a maximum difference of 68 cm. Considering the local tidal range of 45 cm, these differences can introduce substantial error when the DEM is used for ecological modeling [Alizad et al., 2016]. Results from this study will be further analyzed and implemented in order to adjust LiDAR-derived DEMs closer to their true elevation across Louisiana's coastal wetlands. ReferencesAlizad, K., S. C. Hagen, J. T. Morris, S. C. Medeiros, M. V. Bilskie, and J. F. Weishampel (2016), Coastal wetland response to sea-level rise in a fluvial estuarine system, Earth's Future, 4(11), 483-497, 10.1002/2016EF000385. Medeiros, S., S. Hagen, J. Weishampel, and J. Angelo (2015), Adjusting Lidar-Derived Digital Terrain Models in Coastal Marshes Based on Estimated Aboveground Biomass Density, Remote Sensing, 7

Reversing the Truth Effect: Learning the Interpretation of Processing Fluency in Judgments of Truth

ERIC Educational Resources Information Center

Unkelbach, Christian

2007-01-01

Repeated statements receive higher truth ratings than new statements. Given that repetition leads to greater experienced processing fluency, the author proposes that fluency is used in truth judgments according to its ecological validity. Thus, the truth effect occurs because people learn that fluency and truth tend to be positively correlated.…

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.

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.

Infrasonic Influences of Tornados and Cyclonic Weather Systems

NASA Astrophysics Data System (ADS)

Cook, Tessa

2014-03-01

Infrasound waves travel through the air at approximately 340 m/s at sea level, while experiencing low levels of friction, allowing the waves to travel over larger distances. When seismic waves travel through unconsolidated soil, the waves slow down to approximately 340 m/s. Because the speeds of waves in the air and ground are similar, a more effective transfer of energy from the atmosphere to the ground can occur. Large ring lasers can be utilized for detecting sources of infrasound traveling through the ground by measuring anomalies in the frequency difference between their two counter-rotating beams. Sources of infrasound include tornados and other cyclonic weather systems. The way systems create waves that transfer to the ground is unknown and will be continued in further research; this research has focused on attempting to isolate the time that the ring laser detected anomalies in order to investigate if these anomalies may be contributed to isolatable weather systems. Furthermore, this research analyzed the frequencies detected in each of the anomalies and compared the frequencies with various characteristics of each weather system, such as tornado width, wind speeds, and system development. This research may be beneficial for monitoring gravity waves and weather systems.

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.

Infrasound-induced changes on sexual behavior in male rats and some underlying mechanisms.

PubMed

Zhuang, Zhiqiang; Pei, Zhaohui; Chen, Jingzao

2007-01-01

To investigate some bioeffects of infrasound on copulation as well as underlying mechanisms, we inspected the changes of sexual behavior, serum testosterone concentration and mRNA expression levels of steroidogenic factor 1 (SF-1), steroidogenic acute regulatory protein (StAR) and cytochrome P450 cholesterol side chain cleavage enzyme (P450scc) in testes of rats exposed to infrasound of 8Hz at 90 or 130dB for 1, 7, 14 and 21 days (2h/day), respectively. Rats exposed to 90dB exhibited significant decrement in sexual behavior, serum testosterone levels and mRNA expression levels of StAR and P450scc at the time point of 1 day but not at the rest time points, and no significantly change of SF-1 mRNA expression was observed over the period of 21 days in spite of mild fluctuation. Rats exposed to 130dB exhibited significant decrement in all aspects above, which became more profound with prolonged exposure. Our conclusion is that adverse bioeffects of infrasound on reproduction depend on some exposure parameters, the mechanism of which could involve in the decreased expression of some key enzymes or regulator for testosterone biosynthesis. Copyright © 2006. Published by Elsevier B.V.

Proceedings of the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Benson, Jody; Patterson, Eileen F.

These proceedings contain papers prepared for the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 19-21 September, 2006 in Orlando, Florida. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Proceedings of the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetovsky, Marvin A.; Benson, Jody; Patterson, Eileen F.

These proceedings contain papers prepared for the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 25-27 September, 2007 in Denver, Colorado. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoringmore » agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.« less

Effects of infrasound on hippocampus-dependent learning and memory in rats and some underlying mechanisms.

PubMed

Yuan, Hua; Long, Hua; Liu, Jing; Qu, Lili; Chen, Jingzao; Mou, Xiang

2009-09-01

To investigate the effect of infrasound on the hippocampus-dependent spatial learning and memory as well as its underlying mechanisms, we measured the changes of cognitive abilities, brain-derived neurotrophic factor (BDNF)-tyrosine kinase receptor B (TrkB) signal transduction pathway and neurogenesis in the hippocampus of rats. The results showed that rats exposed to infrasound of 16 Hz at 130 dB for 14 days exhibited longer escape latency from day 2 and shortened time staying in the quadrant P in Morris water maze (MWM). It was found that mRNA and protein expression levels of hippocampal BDNF and TrkB were significantly decreased in real-time PCR and Western blot, and the number of BrdU-labeled cells in hippocampus was also reduced when compared to control. These results provided novel evidences that the infrasound of a certain exposure parameter can impair hippocampus-dependent learning and memory, in which the downregulation of the neuronal plasticity-related BDNF-TrkB signal pathway and less neurogenesis in hippocampus might be involved.

Near- Source, Seismo-Acoustic Signals Accompanying a NASCAR Race at the Texas Motor Speedway

NASA Astrophysics Data System (ADS)

Stump, B. W.; Hayward, C.; Underwood, R.; Howard, J. E.; MacPhail, M. D.; Golden, P.; Endress, A.

2014-12-01

Near-source, seismo-acoustic observations provide a unique opportunity to characterize urban sources, remotely sense human activities including vehicular traffic and monitor large engineering structures. Energy separately coupled into the solid earth and atmosphere provides constraints on not only the location of these sources but also the physics of the generating process. Conditions and distances at which these observations can be made are dependent upon not only local geological conditions but also atmospheric conditions at the time of the observations. In order to address this range of topics, an empirical, seismo-acoustic study was undertaken in and around the Texas Motor Speedway in the Dallas-Ft. Worth area during the first week of April 2014 at which time a range of activities associated with a series of NASCAR races occurred. Nine, seismic sensors were deployed around the 1.5-mile track for purposes of documenting the direct-coupled seismic energy from the passage of the cars and other vehicles on the track. Six infrasound sensors were deployed on a rooftop in a rectangular array configuration designed to provide high frequency beam forming for acoustic signals. Finally, a five-element infrasound array was deployed outside the track in order to characterize how the signals propagate away from the sources in the near-source region. Signals recovered from within the track were able to track and characterize the motion of a variety of vehicles during the race weekend including individual racecars. Seismic data sampled at 1000 sps documented strong Doppler effects as the cars approached and moved away from individual sensors. There were faint seismic signals that arrived at seismic velocity but local acoustic to seismic coupling as supported by the acoustic observations generated the majority of seismic signals. Actual seismic ground motions were small as demonstrated by the dominance of regional seismic signals from a magnitude 4.0 earthquake that arrived at

Characterization and identification of Na-Cl sources in ground water

USGS Publications Warehouse

Panno, S.V.; Hackley, Keith C.; Hwang, H.-H.; Greenberg, S.E.; Krapac, I.G.; Landsberger, S.; O'Kelly, D. J.

2006-01-01

Elevated concentrations of sodium (Na+) and chloride (Cl -) in surface and ground water are common in the United States and other countries, and can serve as indicators of, or may constitute, a water quality problem. We have characterized the most prevalent natural and anthropogenic sources of Na+ and Cl- in ground water, primarily in Illinois, and explored techniques that could be used to identify their source. We considered seven potential sources that included agricultural chemicals, septic effluent, animal waste, municipal landfill leachate, sea water, basin brines, and road deicers. The halides Cl-, bromide (Br-), and iodide (I-) were useful indicators of the sources of Na+-Cl- contamination. Iodide enrichment (relative to Cl-) was greatest in precipitation, followed by uncontaminated soil water and ground water, and landfill leachate. The mass ratios of the halides among themselves, with total nitrogen (N), and with Na+ provided diagnostic methods for graphically distinguishing among sources of Na+ and Cl- in contaminated water. Cl/Br ratios relative to Cl- revealed a clear, although overlapping, separation of sample groups. Samples of landfill leachate and ground water known to be contaminated by leachate were enriched in I- and Br-; this provided an excellent fingerprint for identifying leachate contamination. In addition, total N, when plotted against Cl/Br ratios, successfully separated water contaminated by road salt from water contaminated by other sources. Copyright ?? 2005 National Ground Water Association.