Science.gov

Sample records for infrasound source observed

  1. Volcanic eruptions observed with infrasound

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Aster, Richard C.; Kyle, Philip R.

    2004-07-01

    Infrasonic airwaves produced by active volcanoes provide valuable insight into the eruption dynamics. Because the infrasonic pressure field may be directly associated with the flux rate of gas released at a volcanic vent, infrasound also enhances the efficacy of volcanic hazard monitoring and continuous studies of conduit processes. Here we present new results from Erebus, Fuego, and Villarrica volcanoes highlighting uses of infrasound for constraining quantitative eruption parameters, such as eruption duration, source mechanism, and explosive gas flux.

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

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Hofstetter, R.

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Grecu, Bogdan; Popa, Mihaela

    2015-04-01

    Romanian Plostina infrasound array (IPLOR) is deployed in the central part of the country, in Vrancea region. Presently, IPLOR array configuration includes 6 elements equipped with Chaparral Physics sensors and with aperture of about 2.5 km. For the purpose of assessing the IPLOR performance in observing various types of infrasound sources, over five years of data (since June 2009 to present) were processed. Signal interactive analysis was performed using WinPMCC software. The detection results show that the station response was gradually improved, as the number of array elements increased from three to six, and wind noise reduction conditions were enhanced. A larger number of detected signals and a better array resolution at lower frequency were noticed as well. Microbaroms - the interaction of ocean swell with the atmosphere - represent a relevant type of infrasonic source present in the IPLOR detection plots, for which the signal characterization has been enhanced with the array upgrading process. IPLOR detection capability related to this energetic long-period infrasound waves, which propagate over large distances, shows an alternating behavior, being strongly influenced by the upper atmospheric winds, i.e. seasonally dependent stratospheric winds. The ocean swell can be considered as a seismo-acoustic source, leaving an imprint on both seismic and infrasonic recordings. The interaction with the atmosphere generates infrasound (microbarom), while the interaction with the sea floor emits seismic signal (microseism). Microbaroms have a sinusoidal wave character with a dominant period of 5 s. Due to low damping at this period in stratospheric wave duct, microbaroms are observed over large distance ranges up to a few thousand kilometres. Microseisms occur as an increasing of seismic background noise between 2 and 20 s; in this range, primary and secondary peaks, at 5 and 14 s, are observed. Common broad-band seismic data, recorded with Romanian dense seismic

  4. Infrasound Generation from the Source Physics Experiments

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. Infrasound observations at Panska Ves, Czech Republic

    NASA Astrophysics Data System (ADS)

    Sindelarova, Tereza; Kozubek, Michal; Chum, Jaroslav; Base, Jiri; Krizan, Peter

    2016-04-01

    Infrasound detection bulletins have been estimated for the infrasound array at Panska Ves (50°31'N 14°34'E). The signal arrivals in the frequency range 0.05-4 Hz were analysed. The bulletins are available from May 2014 to the present. From mid-September to beginning of April, arrivals of signals of frequencies 0.1-0.4 Hz from the North West dominate. The azimuths of 290-340° correspond to the position of microbarom source regions in the Northern Atlantic, south of Greenland (Landes, M. et al., 2012, J. Geophys. Res.). Signal elevations between 20° and 40° were most frequent. In summer (May-August), transient signals with highly variable azimuths of arrival frequently occur. Signal arrivals were repeatedly observed from the North East and from the South East. However, a stable source analogous to the microbarom source in Northern Atlantic was not found for signals arriving at Panska Ves array in summer.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Sources of volcano infrasound associated with explosive eruptions are typically modeled assuming an acoustic monopole and/or dipole. While the monopole represents the mass outflux of erupted materials, the dipole represents a force system acting in the source region during eruptions. Therefore, appropriate acoustic source inversions of volcano infrasound data can provide estimates of eruption parameters which are critical to understanding eruption dynamics. Reliability of the source parameters is dominantly controlled by the accuracy of the acoustic Green's functions between the source and receiver positions. Conventional source inversions of volcano infrasound, however, were typically performed using a simplified Green's function obtained in a free space or half space. This may result in intolerable errors in the source parameters, especially when the infrasound waveforms are significantly distorted by volcano topography and/or local atmospheric variability (i.e., layered velocity structure or wind). In this study we present a full waveform inversion technique for volcano infrasound using numerical Green's functions. A full 3-D Finite-Difference Time-Domain (FDTD) method accelerated with GPU is used to compute accurate Green's functions taking into account volcano topography and local atmospheric conditions. The presented method is applied to data recorded at Sakurajima volcano (Japan) and Tungurahua volcano (Ecuador), which provide a large volume of high-quality data recorded by azimuthally well-distributed stations within 2 -- 6 km distance of the volcanoes. We analyze infrasound signals associated with explosive eruptions exhibiting 1) distinct explosion waveforms followed by gas discharges and 2) strong anisotropic radiation patterns, which can be caused by either source directivity or topographic barriers/reflections. Here the role of topography in controlling the infrasound radiation is investigated through numerical modeling, and then the observed

  7. Infrasound Observations of the Massive Landslide at Bingham Canyon Copper Mine

    NASA Astrophysics Data System (ADS)

    Hale, J. M.; Arrowsmith, S.; Burlacu, R.; Hayward, C.; Pankow, K. L.

    2013-12-01

    On 10 April 2013 approximately 55 million m3 of rock collapsed from the northeastern wall of the approximately one-kilometer deep open-pit Bingham Canyon copper mine near Salt Lake City, Utah, generating clear seismic and infrasound signals. The material released in two sudden rock avalanches separated in time by about 1.5 hours. The magnitudes for the two slides were determined to be ML 2.5 and 2.4 and MSW 5.0 and 4.9, respectively. Seismic signals with durations approaching two minutes from both rock avalanches were recorded on stations of the University of Utah (UU) regional seismic network and other networks at distances of ~6 to greater than 400 km. In addition, the first event was recorded on seven UU infrasound arrays at distances of ~13 - 400 km and the second at five infrasound arrays between ~57 and 400 km distance. Comparison of the seismograms from the two slides show differences in the long-period energy. There are also clear differences in the infrasound observations. For example, at the closest array recording both slides, the duration of the infrasound signal for the first slide is much longer than for the second slide. In addition, infrasound attributed to the first rock avalanche resulted in multiple arrival observations at the three most distant arrays, while only one array had multiple arrivals for the latter event. For the five infrasound arrays, with detections for both rock avalanches, we look for signal differences by cataloging duration, amplitude, azimuth, dominant period, correlation coefficients, group and trace velocity. In addition, propagation modeling through ground-to-space (G2S) profiles will be performed to determine if atmospheric differences can account for the varying infrasound observations, and the source of the infrasound signal will be located using the Bayesian Infrasonic Source Location procedure. With a wealth of geophysical data we aim to determine if the seismic and infrasound signals have a common source and if the

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Silber, Elizabeth A.; Brown, Peter G.

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  11. Infrasound in Mesopause Temperatures: Modelling, Observations and Analyses

    NASA Astrophysics Data System (ADS)

    Pilger, Christoph; Schmidt, Carsten; Bittner, Michael

    2010-05-01

    Infrasound is typically observed in surface level measurements of the ambient air-pressure. A novel approach performed at the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) is the detection of infrasonic signals in temperature time series of the mesopause altitude region (at about 80-100 km). The infrasonic pressure fluctuations correspond to temperature fluctuations in the atmosphere via ideal gas law assumptions. The development and magnitude of these fluctuations can be modelled regarding propagation, attenuation and amplification processes in the atmosphere. The modelling results are quantified in order to compare it to instrumental observations of mesopause temperatures. The observations are performed at DLR-DFD using the airglow measurement technique and the GRIPS instruments (GRound-based Infrared P-branch Spectrometers). Their temporal resolution of 15 seconds permits the observation of signals within the infrasound period range. Spectral intensities are estimated applying the wavelet analysis to the complete data set of more than one year of routine measurements in order to derive a statistical distribution of wave activity in the frequency range from 0.5 to 5 minutes. Selected events are discussed with respect to the origin of the observed structures.

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

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

    SciTech Connect

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  15. Observation and Modeling of Infrasound Signals Generated By Rocket Motor Tests and Rocket Motor Demolitions in the Western US

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Ground-truth for infrasonic sources enables the documentation of time-varying atmospheric effects on infrasound observations. The associated source and observation data provide a basis for assessing current atmospheric models and estimating their contribution to infrasound detection and location. In this study, we utilize both seismic and acoustic data recorded at USArray Transportable Array (TA) stations and additional regional infrasound arrays in Utah and Nevada. Ground truth consists of a total of 25 rocket motor tests (static rocket motor burn tests) and 6 rocket motor demolitions in Utah for the time period from 2003 to 2013. Characteristics of infrasound signals generated by the rocket motor tests and rocket body demolitions are compared. The typical signal frequency band from the rocket motor tests is 5-10 Hz with durations of up to 60 seconds, while those from rocket body demolitions have relatively shorter durations (10 seconds) and lower frequencies (1-5 Hz). The distributions of stations that detect signals are quite variable in terms of both distance and azimuth and dependent on atmospheric conditions. Infrasound amplitudes document strong energy attenuation with range that must be quantified in order to assess the source strength. Ray tracing and parabolic equation (PE) modeling were conducted utilizing the ground-to-space (G2S) atmospheric specifications at the time of each event, in order to understand the predictability of the models and assess their utility in estimating amplitudes as a function of range. This unique dataset quantifies the contribution of temporal atmospheric conditions to infrasound detection and documents the predictive capabilities of current atmospheric model.

  16. Volcano Infrasound

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  17. Fluid Impact as a Source Mechanism for Surf Infrasound

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  18. Local and remote infrasound from explosive volcanism

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Explosive volcanic eruptions can inject large volumes of ash into heavily travelled air corridors and thus pose a significant societal and economic hazard. In remote volcanic regions, satellite data are sometimes the only technology available to observe volcanic eruptions and constrain ash-release parameters for aviation safety. Infrasound (acoustic waves ~0.01-20 Hz) data fill this critical observational gap, providing ground-based data for remote volcanic eruptions. Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. Advances in infrasound technology and the efficient propagation of infrasound in the atmosphere therefore greatly enhance our ability to monitor volcanoes in remote regions such as the North Pacific Ocean. Infrasound data can be exploited to detect, locate, and provide detailed chronologies of the timing of explosive volcanic eruptions for use in ash transport and dispersal models. We highlight results from case studies of multiple eruptions recorded by the International Monitoring System and dedicated regional infrasound networks (2008 Kasatochi, Alaska, USA; 2008 Okmok, Alaska, USA; 2009 Sarychev Peak, Kuriles, Russian Federation; 2010 Eyjafjallajökull, Icleand) and show how infrasound is currently used in volcano monitoring. We also present progress towards characterizing and modeling the variability in source mechanisms of infrasound from explosive eruptions using dedicated local infrasound field deployments at volcanoes Karymsky, Russian Federation and Sakurajima, Japan.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  20. 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

  1. 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.

  2. First observations of sprites in the eastern Mediterranean using the Israeli infrasound network

    NASA Astrophysics Data System (ADS)

    Applbaum, David; Price, Colin; Ben Horin, Yochai; Yair, Yoav

    2014-05-01

    As outlined by Farges et al (2005) as part of the Sprite2003 campaign in Europe, sprites at close range (less than a few hundred km) exhibit a unique signal in infrasound. This signal consists of an 'inverted chirp,' lasting up to several minutes and in which the higher frequencies arrive prior to the lower frequencies. The ILAN (Imaging of Lightning and Nocturnal Flashes) science team at Tel Aviv University maintains a database of optically observed sprites occurring within a few hundred kilometers of the Mediterranean coast of Israel. Using the observed azimuths of these sprites' locations with respect to the detectors, combined with an acoustic propagation model and the observed delays associated with propagation of the signals between the sprites and the infrasound arrays, we present here observations of several sprites that are consistent with the observations made by Farges et al. These constitute the first observations of sprites made using the Israeli infrasound network.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    PubMed

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

    2014-01-01

    The long-range propagation of infrasound from a surface explosion with an explosive yield of about 17.6 t TNT that occurred on June 16, 2008 at the Utah Test and Training Range (UTTR) in the western United States is simulated using an atmospheric model that includes fine-scale layered structure of the wind velocity and temperature fields. Synthetic signal parameters (waveforms, amplitudes, and travel times) are calculated using parabolic equation and ray-tracing methods for a number of ranges between 100 and 800 km from the source. The simulation shows the evolution of several branches of stratospheric and thermospheric signals with increasing range from the source. Infrasound signals calculated using a G2S (ground-to-space) atmospheric model perturbed by small-scale layered wind velocity and temperature fluctuations are shown to agree well with recordings made by the dense High Lava Plains seismic network located at an azimuth of 300° from UTTR. The waveforms of calculated infrasound arrivals are compared with those of seismic recordings. This study illustrates the utility of dense seismic networks for mapping an infrasound field with high spatial resolution. The parabolic equation calculations capture both the effect of scattering of infrasound into geometric acoustic shadow zones and significant temporal broadening of the arrivals. PMID:24437743

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  7. 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

    The term infrasound describes atmospheric sound waves with frequencies below 20 Hz, while acoustics are classified within the audible range of 20 Hz to 20 kHz. Infrasound and acoustic monitoring in the scientific community is hampered by low signal-to-noise ratios and a limited number of studies on regional and short-range noise and source characterization. The JASON Report (2005) suggests the infrasound community focus on more broad-frequency, observational studies within a tactical distance of 10 km. In keeping with that recommendation, this paper presents a study of regional and short-range atmospheric acoustic and infrasonic noise characterization, at a desert site in West Texas, covering a broad frequency range of 0.2 to 100 Hz. To spatially sample the band, a large number of infrasound gauges was needed. A laboratory instrument analysis is presented of the set of low-cost infrasound sensors used in this study, manufactured by Inter-Mountain Laboratories (IML). Analysis includes spectra, transfer functions and coherences to assess the stability and range of the gauges, and complements additional instrument testing by Sandia National Laboratories. The IMLs documented here have been found reliably coherent from 0.1 to 7 Hz without instrument correction. Corrections were built using corresponding time series from the commercially available and more expensive Chaparral infrasound gauge, so that the corrected IML outputs were able to closely mimic the Chaparral output. Arrays of gauges are needed for atmospheric sound signal processing. Our West Texas experiment consisted of a 1.5 km aperture, 23-gauge infrasound/acoustic array of IMLs, with a compact, 12 m diameter grid-array of rented IMLs at the center. To optimize signal recording, signal-to-noise ratio needs to be quantified with respect to both frequency band and coherence length. The higher-frequency grid array consisted of 25 microphones arranged in a five by five pattern with 3 meter spacing, without

  8. 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

    The term infrasound describes atmospheric sound waves with frequencies below 20 Hz, while acoustics are classified within the audible range of 20 Hz to 20 kHz. Infrasound and acoustic monitoring in the scientific community is hampered by low signal-to-noise ratios and a limited number of studies on regional and short-range noise and source characterization. The JASON Report (2005) suggests the infrasound community focus on more broad-frequency, observational studies within a tactical distance of 10 km. In keeping with that recommendation, this paper presents a study of regional and short-range atmospheric acoustic and infrasonic noise characterization, at a desert site in West Texas, covering a broad frequency range of 0.2 to 100 Hz. To spatially sample the band, a large number of infrasound gauges was needed. A laboratory instrument analysis is presented of the set of low-cost infrasound sensors used in this study, manufactured by Inter-Mountain Laboratories (IML). Analysis includes spectra, transfer functions and coherences to assess the stability and range of the gauges, and complements additional instrument testing by Sandia National Laboratories. The IMLs documented here have been found reliably coherent from 0.1 to 7 Hz without instrument correction. Corrections were built using corresponding time series from the commercially available and more expensive Chaparral infrasound gauge, so that the corrected IML outputs were able to closely mimic the Chaparral output. Arrays of gauges are needed for atmospheric sound signal processing. Our West Texas experiment consisted of a 1.5 km aperture, 23-gauge infrasound/acoustic array of IMLs, with a compact, 12 m diameter grid-array of rented IMLs at the center. To optimize signal recording, signal-to-noise ratio needs to be quantified with respect to both frequency band and coherence length. The higher-frequency grid array consisted of 25 microphones arranged in a five by five pattern with 3 meter spacing, without

  9. Long-range infrasound observations of eruptions April-May 2010 Eyjafjallajökull, Iceland and June 2009 Sarychev Peak, Kuril Islands

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Le Pichon, A.; Vergoz, J.; Herry, P.; Lalande, J.; Ceranna, L.; Green, D. N.; Evers, L. G.; Marchetti, E.; Ripepe, M.; Campus, P.; Liszka, L. J.; Kvaerna, T.; Lee, H.; Che, I.; Rybin, A.

    2010-12-01

    During explosive volcanic eruptions, release of overpressure and rapid and sustained injection of mass into the atmosphere are typically significant sources of low-frequency sound. Acoustic waves with frequencies in the band ~0.01-20 Hz, or infrasound, can propagate over large distances in atmospheric waveguides with low attenuation. We present two case studies of long-range infrasound observations of volcanism producing significant ash clouds. The 2010 summit eruption of Eyjafjallajökull was recorded during April-May at 14 infrasound recording arrays across Europe and beyond, to a maximum range of >3,500 km. Such long-range propagation is remarkable considering the relatively modest level of explosive activity. The larger June 2009 Sarychev Peak (SP) eruption was recorded at six International Monitoring System (IMS) infrasound arrays of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) and several KIGAM infrasound arrays located at ranges of ~640-6,400 km from SP. Signals at the three closest recording stations IS44 (643 km, Petropavlovsk-Kamchatskiy, Kamchatka Krai, Russian Federation), IS45 (1,690 km, Ussuriysk, Russian Federation), and IS30 (1,774 km, Isumi, Japan) represent a detailed record of the explosion chronology that correlates well with an eruption chronology based on satellite data (TERRA, NOAA, MTSAT). The eruption chronology inferred from infrasound data has a higher temporal resolution than that obtained with satellite data. Atmosphere-corrected infrasonic source locations determined from backazimuth cross-bearings have a mean centroid ~15 km from the true location of SP. The air space above the Kuril Islands represents a major air corridor linking Europe, North America and northern Asia, yet seismic network coverage is sparse in the region. This study therefore highlights the significant potential of the IMS infrasound network for aiding with monitoring remote volcanic regions of the planet.

  10. Infrasound Observations at the Lützow-Holm Bay region, East Antarctica

    NASA Astrophysics Data System (ADS)

    Kanao, M.; Murayama, T.; Yamamoto, M.; Ishihara, Y.; Kakinami, Y.

    2013-12-01

    Characteristic infrasound waves observed at Antarctic stations demonstrate physical interaction involving surface environmental changes in the continent and surrounding oceans. A Chaparral type infrasound sensor was installed at Syowa Station (SYO; 39E, 69S), East Antarctica, as one of the projects of the International Polar Year (IPY2007-2008). Continuous recording data during the three seasons in 2008-2010 clearly indicate a contamination of the background oceanic signals (microbaroms) with peaks between 4 and 10 s observed during a whole season. The peak amplitudes of the microbaroms has relatively lower amplitudes during austral winters, caused by a larger amount of sea-ice extending around the Lützow-Holm Bay near SYO, with decreasing ocean wave loading effects. Microbaroms measurements are a useful tool for characterizing ocean wave climate, complementing other oceanographic and geophysical data. In the austral summer in 2013, a few number of infrasound stations was established along the coast of LHB. Two different size of infrasound arrays were installed at SYO (100m spacing triangle) and S16 area on the continental ice sheet (1000m spacing triangle). In addition, isolated single stations were developed at two outcrops along the LHB. The new two infrasound arrays clearly detected the microbaroms with their propagating directions from the Southern Ocean. Moreover, characteristic signals associated with calving of the edge of glaciers, as well as the shock waves generated from meteorite injection at the Russian Republic on 15 February 2013. In this presentation, several kind of remarkable data are demonstrated. Detail measurements of the infrasound waves in Antarctica could be a new proxy for monitoring a regional environmental change together with temporal climate variations in polar region.

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

    PubMed

    Lonzaga, Joel B

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Magnetic infrasound sensor

    DOEpatents

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

    2006-11-14

    A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.

  14. Infrasound research of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Marchetti, Emanuele; Ripepe, Maurizio

    2016-04-01

    Volcanic eruptions are efficient sources of infrasound produced by the rapid perturbation of the atmosphere by the explosive source. Being able to propagate up to large distances from the source, infrasonic waves from major (VEI 4 or larger) volcanic eruptions have been recorded for many decades with analogue micro-barometers at large regional distances. In late 1980s, near-field observations became progressively more common and started to have direct impact on the understanding and modeling of explosive source dynamics, to eventually play a primary role in volcano research. Nowadays, infrasound observation from a large variety of volcanic eruptions, spanning from VEI 0 to VEI 5 events, has shown a dramatic variability in terms of signature, excess pressure and frequency content of radiated infrasound and has been used to infer complex eruptive source mechanisms for the different kinds of events. Improved processing capability and sensors has allowed unprecedented precise locations of the explosive source and is progressively increasing the possibility to monitor volcanoes from distant records. Very broadband infrasound observations is also showing the relation between volcanic eruptions and the atmosphere, with the eruptive mass injection in the atmosphere triggering acoustic-gravity waves which eventually might control the ash dispersal and fallout.

  15. Infrasound from volcanic rockfalls

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Ronan, Timothy J.

    2015-12-01

    Proximal infrasound arrays can robustly track rapidly moving gravity-driven mass wasting, which occurs commonly at erupting volcanoes. This study reports on detection, localization, and quantification of frequent small rockfalls and infrequent pyroclastic density currents descending the southeast flanks of Santiaguito's active Caliente Dome in January of 2014. Such activities are identified as moving sources, which descend several hundred meters at bulk flow speeds of up to ~10 m/s, which is considerably slower than the descent velocity of individual blocks. Infrasound rockfall signal character is readily distinguishable from explosion infrasound, which is manifested by a relatively fixed location source with lower frequency content. In contrast, the rockfalls of Santiaguito possess higher frequencies dominated by 7.5 to 20 Hz energy. During our observation periods typical rockfall signals occurred ~10 times per hour and lasted tens of seconds or more. Array beamforming permitted detection of rockfall transients with amplitudes of only a few tens of millipascals that would be impossible to distinguish from noise using a single sensor. Conjoint time-synchronized video is used to corroborate location and to characterize various gravity-driven events.

  16. Station characteristics of the Singapore Infrasound Array

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Singapore, located in Southeast Asia, presents an ideal location for an additional regional infrasound array, with diverse persistent natural and anthropogenic regional infrasound sources, including ~750 active or potentially active volcanoes within 4,000 kilometers. Previous studies have focused on theoretical and calculated regional signal detection capability improvement with the addition of a Singapore array. The Earth Observatory of Singapore installed a five element infrasound array in northcentral Singapore in late 2014, and this station began consistent real-time data transmission mid-2015. The Singapore array uses MB2005s microbarometers and Nanometrics Taurus digitizers. Automated array processing is carried out with the INFrasonic EneRgy Nth Octave (INFERNO) energy estimation suite, and PMCC (Progressive MultiChannel Correlation). The addition of the Singapore infrasound array to the existing International Monitoring System (IMS) infrasound stations in the region has increased regional infrasound detection capability, which is illustrated with the preliminary work on three observed meteor events of various sizes in late 2015. A meteor observed in Bangkok, Thailand in early September, 2015 was picked up by the CTBTO, however, another meteor observed in Bangkok in November was only recorded on the Singapore array. Additionally, another meteor observed over Sumatra was only recorded by one IMS station and the Singapore array. This study uses array processing and Power Spectral Density results for both the Singapore and publicly available regional IMS stations to examine station characteristics and detection capability of the Singapore array in the context of the regional IMS network.

  17. Improved Bayesian Infrasonic Source Localization for regional infrasound

    DOE PAGESBeta

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

    2015-10-20

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

  18. Improved Bayesian Infrasonic Source Localization for regional infrasound

    SciTech Connect

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

    2015-10-20

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

  19. Improved Bayesian Infrasonic Source Localization for regional infrasound

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Infrasound observed in the Czech Republic during convective storms 9 - 10 July 2011

    NASA Astrophysics Data System (ADS)

    Sindelarova, Tereza; Skripnikova, Katerina; Chum, Jaroslav; Lastovicka, Jan; Base, Jiri; Mosna, Zbysek

    2013-04-01

    An experimental array has been built at the observatory Panska Ves, Czech Republic (50°31' N 14°34' E). It is equipped with three differential microbarographs (type ISGM03). The sensors are arranged in an equilateral triangle; the distance between sensors is approximately 200 m. Using this array, we studied infrasound phenomena related with intense convective storms on 9-10 July 2011. In the studied frequency range 0.1-4 Hz, we observed phenomena of short duration related to lightning activity and also signals that persisted tens of seconds. The latter type of infrasound signals is the object of the current study. Azimuth of arrival of the signals corresponded well with position of convective storms towards the observatory and changed as convective storms were travelling across the Czech Republic from the south west to the north east. Apparent velocity often exceeded 340 m/s (considered as the local speed of sound); it means the signals arrived under some elevation angle (up to 40°). The azimuth of arrival showed higher variability at the beginning of the event; we repeatedly observed gradual variations in azimuth up to the change of 90°. The azimuth of arrival was more stable after 02 UT on 10 July 2011.

  1. Infrasound Event Analysis into the IDC Operations

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    The first atmospheric event built only from infrasound arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 42 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. The growing amount of infrasound data and detections produced by the automatic system challenged the station and network processing at the IDC, which required the Organization to redesign the way infrasound data are processed. Each infrasound array is processed separately for signal detection using a progressive multi-channel correlation method (DFX-PMCC). For each detection, signal features - onset time, amplitude, frequency, duration, azimuth, phase velocity, F-statistics - are measured and used to identify a detection as infrasonic, seismic, or noise (including clutter). Infrasonic signals along with seismic and hydroacoustic signals are subsequently associated with Global Association software (GA) between stations to locate events. During detection and association phases, criteria are applied to eliminate clutter, identify signals of interest, and keep the number of automatic events containing infrasound detections to a manageable level for analyst review. The IDC has developed analysis and visualization tools specifically for infrasound review (e.g. Geotool-PMCC). The IDC has continued to build the Infrasound Reference Event Database (IRED) from observations on the IMS network. This database assists both the routine IDC infrasound analysis and analyst training as it reflects the global detection capability of the network, illustrates the spatial and temporal variability of the observed phenomena, and demonstrates the various origins of infragenic sources. Since 2007, the IDC has introduced new analyst procedures to review and add selected infrasound events to the REB. In early 2010, the IDC

  2. Topographic effects on infrasound propagation.

    PubMed

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

    2012-01-01

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

  3. Topographic effects on infrasound propagation.

    PubMed

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

    2012-01-01

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

  4. Infrasound from thunderstorms

    NASA Astrophysics Data System (ADS)

    Liszka, L. J.

    2006-12-01

    The present work summarizes the results of infrasonic observations of thunderstorms recorded by the Swedish Infrasound Network (SIN). A lightning in the atmosphere is a source of cylindrical shock waves. When the distance from the source increases, more and more energy is transferred into the low-frequency range through the same mechanism as for shock waves from supersonic aircraft. It is difficult to estimate maximal distances at which infrasound from a single lightning may be detected. It is, however, clear that distances between the SIN arrays (250 600 km) are in most cases too large in order to identify the same lightning from at least two arrays. During the recent summer, at few occasions, the same thunderstorm cell, and even the same lightning, could be observed by two arrays. That means that intense lightning may be, during favourable meteorological conditions, observed at distances up to 300 km. The infrasonic data may be used to determine the angular extent of the discharge, as seen by the array, its radial extent (in kilometres) and its acoustical intensity. Recent results of these morphological studies are presented.

  5. Infrasound Monitoring of Natural Hazards

    NASA Astrophysics Data System (ADS)

    Arrowsmith, S.

    2015-12-01

    Infrasound is generated by a wide variety of energetic natural and anthropogenic phenomena that originate in the solid earth, ocean, and atmosphere. Because the absorption of infrasound is low, it can propagate long distances through atmospheric waveguides, making it a valuable tool for remote monitoring of hazards. Advances in using infrasound for monitoring energetic events in the solid earth, oceans, and atmosphere are being driven by the wealth of new datasets in addition to advances in modeling source and propagation physics. This presentation provides an overview of recent advances in infrasound monitoring of natural hazards, focusing on selected hazards in the earth (earthquakes and volcanoes), ocean (tsunamis), and atmosphere (meteoroids).

  6. 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.

  7. Effect of time-varying tropospheric models on near-regional and regional infrasound propagation as constrained by observational data

    NASA Astrophysics Data System (ADS)

    McKenna, Mihan H.; Stump, Brian W.; Hayward, Chris

    2008-06-01

    The Chulwon Seismo-Acoustic Array (CHNAR) is a regional seismo-acoustic array with co-located seismometers and infrasound microphones on the Korean peninsula. Data from forty-two days over the course of a year between October 1999 and August 2000 were analyzed; 2052 infrasound-only arrivals and 23 seismo-acoustic arrivals were observed over the six week study period. A majority of the signals occur during local working hours, hour 0 to hour 9 UT and appear to be the result of cultural activity located within a 250 km radius. Atmospheric modeling is presented for four sample days during the study period, one in each of November, February, April, and August. Local meteorological data sampled at six hour intervals is needed to accurately model the observed arrivals and this data produced highly temporally variable thermal ducts that propagated infrasound signals within 250 km, matching the temporal variation in the observed arrivals. These ducts change dramatically on the order of hours, and meteorological data from the appropriate sampled time frame was necessary to interpret the observed arrivals.

  8. 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

  9. Preliminary Seismic, Infrasound and Lightning Observations of the July 2008 Eruptions of Okmok Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.; Arnoult, K. M.; Szuberla, C. A.; Stihler, S. D.

    2008-12-01

    Okmok volcano began to erupt July 12, 2008, following an 11 year hiatus. The previous eruption in 1997 was from Cone A whereas the new activity occurred on the north flank of Cone D, a structure that had not been active for 800 years. Seismic activity at Okmok is monitored by a network of eight short-period and four broadband seismometers. The eruption was preceded by a swarm of earthquakes lasting just 5 hours, with events large enough to be located only occurring in the last hour. The bulk of these events occurred under Cone D with a few near Cone A. The eruption began with the onset of continuous tremor at 19:43 UT, which increased abruptly at 19:48 UT and lasted about 12 hours, strongest at about 22:00 UT. The tremor was strong enough to appear on stations out to 260 km distance. The ash cloud quickly grew to an elevation of 16 km or more. Infrasonic waves from the eruption were recorded on the I53US infrasound array in Fairbanks as three groups of waves starting at 21:44 UT, 01:14 UT July 13, and 05:41 UT July 13 and lasting 29-95 minutes. The time of flight is estimated to be 94 minutes along a great circle path. The waves were strongest between 0.1 and 0.5 Hz and had amplitudes of 0.1-0.3 Pa at the array. Low-pass filtered broadband seismic data showed extremely long-period waves with a period of 540 sec starting at about 22:45 UT. However, these waves, which were also visible in GOES satellite images and are thought to be gravity waves, have not yet been found in the infrasound data. Vigorous lightning was observed in the eruption column by observers at Fort Glenn, 12 km from the vent, on July 12 and several occasions after that. Unfortunately no instrumental data were obtained for the lightning.

  10. Infrasound Rocket Signatures

    NASA Astrophysics Data System (ADS)

    Olson, J.

    2012-09-01

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

  11. Infrasound research in Spitsbergen

    NASA Astrophysics Data System (ADS)

    Vinogradov, Yuri; Kremenetskaya, Elena

    2013-04-01

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

  12. Three-Dimensional, Finite-Difference, Time-Domain Modeling of Local Volcano Infrasound Radiation Using GPU

    NASA Astrophysics Data System (ADS)

    Kim, K.; Lees, J. M.

    2013-12-01

    Since volcano infrasound is a direct measure of atmospheric pressure fluctuation near open-vent activity, it can provide important constraints on eruption source parameters including the volume of gas released and eruption velocity. Local infrasound data (<15 Km) have been used to quantify and characterize acoustic sources of volcanic eruptions since they are relatively less affected by atmospheric velocity structures in the near field. The interaction of volcano infrasound sources and complex topography near the volcanic edifice, however, has not been fully explored. Infrasound observations from world-wide volcanoes and two-dimensional numerical modeling of infrasound radiation in the vicinity of the crater suggest a strong distortion of the wavefield by local topography [Kim and Lees, GRL, 2011]. To get a complete picture of these effects, however, full three-dimensional modeling is required. We have developed a new, accelerated, 3D finite-difference time-domain program using GPU (Grpahic Processing Units) to simulate local infrasound propagation near volcanoes, while taking into account complex topography, local wind distortion, and atmospheric sound velocity structures. While CPU-based 3D FDTD method requires a prohibitive amount of computational resources, GPU-based algorithms significantly reduce the computational time of infrasound modeling, making parallel processing practical even on a desktop computer. In these simulations we provide a comprehensive solution of volcano infrasound radiation assuming different acoustic sources and real volcano topography. We illustrate the interaction of local vent topography and difference acoustic sources and how they combine to affect the infrasound wavefield. By removing topographic effects from local infrasound observation we can begin to quantitatively model acoustic sources and finally establish the partitioning of energy, at the vent, between the acoustic and seismic wavefields.

  13. 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

  14. Characterization of volcanic activity using observations of infrasound, volcanic emissions, and thermal imagery at Karymsky Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Lopez, T.; Fee, D.; Prata, F.

    2012-04-01

    Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, with activity ranging from vigorous degassing, frequent ash emissions, and apparent vent sealing, all punctuated by daily to weekly explosive magmatic eruptions. Recent studies have highlighted the strengths in using complementary infrasound measurements and remote volcanic emission measurements to characterize volcanic activity, with the potential to discriminate emission-type, approximate ash-cloud height, and estimate SO2 emission mass. Here we use coincident measurements of infrasound, SO2, ash, and thermal radiation collected over a ten day period at Karymsky Volcano in August 2011 to characterize the observed activity and elucidate vent processes. The ultimate goal of this project is to enable different types of volcanic activity to be identified using only infrasound data, which would significantly improve our ability to continuously monitor remote volcanoes. Four types of activity were observed. Type 1 activity is characterized by discrete ash emissions occurring every 1 - 5 minutes that either jet or roil out of the vent, by plumes from 500 - 1500 m (above vent) altitudes, and by impulsive infrasonic onsets. Type 2 activity is characterized by periodic pulses of gas emission, little or no ash, low altitude (100 - 200 m) plumes, and strong audible jetting or roaring. Type 3 activity is characterized by sustained emissions of ash and gas, with multiple pulses lasting from ~1 - 3 minutes, and by plumes from 300 - 1500 m. Type 4 activity is characterized by periods of relatively long duration (~30 minutes to >1 hour) quiescence, no visible plume and weak SO2 emissions at or near the detection limit, followed by an explosive, magmatic eruption, producing ash-rich plumes to >2000 m, and centimeter to meter (or greater) sized pyroclastic bombs that roll down the flanks of the edifice. Eruption onset is accompanied by high-amplitude infrasound and occasionally visible shock

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

    NASA Astrophysics Data System (ADS)

    Ali, Sherif M.; Polich, Paul

    2015-04-01

    Infrasound is one of three waveform technologies which are part of the Comprehensive Nuclear Test Ban Treaty (CTBT) verification regime. The International Monitoring System (IMS) of the CTBT consists of 337 monitoring stations and laboratories world-wide. These facilities include 45 infrasound stations, installed world-wide and transmitting data to the International Data Centre (IDC). Since early 2010, the IDC began routine automatic and interactive processing of infrasound data; the detected and located events are systematically included in the Reviewed Event Bulletin (REB). Infrasound events are frequently characterized by a small number of infrasound phase associations. This poses a challenge to obtaining high-confidence event solutions during routine processing of infrasound data. This study focuses on six infragenic events from the REB, occurring between January 2011 and December 2014, which were thoroughly analyzed at the IDC. The selected events were characteristically seismo-acoustic, and corroborated by seismic recordings of the Egyptian National Seismic Network (ENSN) operated by the National Research Institute of Astronomy and Geophysics (NRIAG). Utilizing this additional local network data of ENSN enables sharper assessment of the IDC published event solutions. Notably, the events were recorded within Egypt and regional surroundings where infrasound waves were generated. The events were detected by IMS infrasound stations located up to 7000 kilometers away. Additional analyses, beyond the six infragenic events from the REB, will also consider some valid infragenic events that fall short of stringent REB Event Definition Criteria. The events will primarily consist of two defining stations with lower-confidence event solutions. The selected events, when confirmed by the seismic observations at ENSN, provide a unique dataset for evaluating IDC infrasound event solutions. Further objectives of the study seek to measure the performance of the IMS network for

  16. Long-range infrasound monitoring of eruptive volcanoes.

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The efficient long-range propagation in the atmosphere makes infrasound of active volcanoes extremely promising and opens new perspectives for volcano monitoring at large scale. In favourable propagation conditions, long-range infrasound observations can be used to track the occurrence and the duration of volcanic eruptions also at remote non-monitored volcanoes, but its potential to infer volcanic eruptive source term is still debated. We present results of comparing five years of infrasound of eruptive activity at Mt.Etna volcano (Italy) recorded both at local (~5 km) and at regional distances (~600 km) from the source. Infrasound of lava fountains at Etna volcano, occurring in between 2010 and 2015, are analysed in terms of the local and regional wavefield record, and by comparing to all available volcanic source terms (i.e. plume height and mass eruption rates). Besides, the potential of near real-time notification of ongoing volcanic activity at Etna volcano at a regional scale is investigated. In particular we show how long range infrasound, in the case of Etna volcano, can be used to promptly deliver eruption notification and reliability is constrained by the results of the local array. This work is performed in the framework of the H2020 ARISE2 project funded by the EU in the period 2015-2018.

  17. Use of the IMS infrasound network for global atmospheric studies

    NASA Astrophysics Data System (ADS)

    Blanc, Elisabeth; Le Pichon, Alexis; Ceranna, Lars; Farges, Thomas

    2010-05-01

    The development of the Infrasound International Monitoring System (IMS), used for the verification of the Comprehensive Test Ban Treaty, represents a powerful tool to measure permanently, at a global scale and over large periods of time, the disturbances of the atmosphere. The network is mostly sensitive to infrasound in the range 0.02 to 5 Hz, but it also measures gravity waves at lower frequencies and tidal waves. Measurements with the IMS infrasound network provide both the state of the atmospheric wave guide and of the atmospheric waves which can be used to study the dynamics of the atmosphere. The first way is to study the variability of infrasound from quasi continuous sources such as ocean swells or volcanoes in relation with changes in large scale atmospheric structures. Since infrasound propagate in the stratosphere and mesosphere, atmospheric parameters which affect the infrasound propagation can be investigated from ground measurements of infrasound. Azimuth changes of infrasound from volcanis eruption were used to retrieve mesospheric zonal winds. The amplitude fluctuations of infrasound from ocean swells represent planetary waves which modulate the atmospheric wave guide. Fluctuations are much larger in Northern hemispheres than in Southern hemisphere, because the amplitude of planetary waves is larger in Northern hemisphere where continental areas are more important. Infrasound monitoring also revealed anomalies at a seasonal scale in Antarctica or at the scale of several days in Arctic regionsin relation with Sudden Stratospheric Warming. The second way is the direct observation of large scale gravity waves. These waves, mainly produced in the troposphere, propagate upwards and break in the stratosphere producing a chaotic forcing of the stratosphere. This is at the origin of a slow and large scale motion in which air masses are driven upward and poleward from the tropical lower stratosphere. In polar regions, they are pushed downward producing

  18. 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.

  19. Local seismic and infrasound observations of the 2009 explosive eruptions of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.; Thompson, G.; West, M. E.; Fee, D.; Stihler, S.; Clark, E.

    2013-06-01

    Local seismic and infrasound data are used to characterize the March-April 2009 eruptions of Redoubt volcano, Alaska. Data are from a network of ten seismic stations ranging from 2.6 to 21 km from the vent and a single infrasound sensor 12.2 km from the vent. Measurements were made for more than 30 explosive eruptions including the 19 numbered events that were identified during the eruption response. More than 30 smaller explosions were also identified. Measured parameters include onset time, duration, reduced displacement (DR), pressure, seismic energy, and acoustic energy. Results were compared with complementary gas and lightning data. Based on ratios of pressure to DR and acoustic to seismic energy we find that the initial group of explosive eruptions on 23-24 March was relatively stronger seismically and included the four highest DR values. We infer that these represent vent enlargement or stronger coupling between the magma and wall rocks. One event, at 12:31 UT on 23 March had an extremely high pressure of 250 Pa for the initial pulse and was likely weakly seismically coupled. A second group of explosive eruptions on 27-29 March was relatively stronger acoustically. Deposits were finer grained and of different lithology, with less scoria and more dense clasts. These two groups may represent different modes of gas release. Cumulative acoustic energy as a function of time correlates well with comparable lightning and SO2 data, suggesting that all three provide insight regarding different factors of gas release for the eruption as a whole. The number of events identified depends on criteria measured, and depends on the goals of the investigations. Overall the eruptions were substantially stronger than recent eruptions in Alaska, with some durations exceeding 1 h and pressures an order of magnitude higher.

  20. Infrasound and Seismic Observation of the Hayabusa Reentry: Burst Signals and Air-to-Ground Coupling Process

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The Hayabusa, the world's first sample-return minor body explorer, reentered the Earth's atmosphere on June 13, 2010. This was the third direct reentry event from the interplanetary transfer orbit to the Earth at a velocity of over 11.2 km/s, and was the world's first case of a direct reentry of the spacecraft itself from the interplanetary transfer orbit. This was the very good and rare opportunity to study bolide class meteor phenomena by various aspects. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area, Australia (Fujita et al., 2011). The observations were configured with optical imaging, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations (GOS2, GOS2A, and GOS2B), we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations (GOS2B-sub1, to GOS2B-sub3) (Yamamoto et al., 2011; Ishihara et al., 2012). The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa sample return capsule (Ishihara et al., 2012). In addition, following capsule signal, lots of signals that probably correspond shockwave from disrupted fragments of spacecraft and energetic bursts of the spacecraft were also recorded (Yamamoto et al., 2011). In this study, we analyze signals generated by hypersonic motion of the disrupted fragments and energetic burst of the spacecraft. In addition, we examine the air-to-ground coupling process by comparing the waveforms computed by finite difference scheme with the actual ones. At all three arrayed main stations, after the capsule's shockwave arrival, we detect multiple shockwave signals by both infrasound and seismic sensors. For some of these signals arrive within 10 seconds after capsule's signal, we can identify one to one correspondence with optically tracked disrupted fragments of the spacecraft. Far after the capsule's signal, we also detect some arrivals of wave

  1. Health effects from low-frequency noise and infrasound in the general population: Is it time to listen? A systematic review of observational studies.

    PubMed

    Baliatsas, Christos; van Kamp, Irene; van Poll, Ric; Yzermans, Joris

    2016-07-01

    A systematic review of observational studies was conducted to assess the association between everyday life low-frequency noise (LFN) components, including infrasound and health effects in the general population. Literature databases Pubmed, Embase and PsycInfo and additional bibliographic sources such as reference sections of key publications and journal databases were searched for peer-reviewed studies published from 2000 to 2015. Seven studies met the inclusion criteria. Most of them examined subjective annoyance as primary outcome. The adequacy of provided information in the included papers and methodological quality of studies was also addressed. Moreover, studies were screened for meta-analysis eligibility. Some associations were observed between exposure to LFN and annoyance, sleep-related problems, concentration difficulties and headache in the adult population living in the vicinity of a range of LFN sources. However, evidence, especially in relation to chronic medical conditions, was very limited. The estimated pooled prevalence of high subjective annoyance attributed to LFN was about 10%. Epidemiological research on LFN and health effects is scarce and suffers from methodological shortcomings. Low frequency noise in the everyday environment constitutes an issue that requires more research attention, particularly for people living in the vicinity of relevant sources. PMID:26994804

  2. Frequency and Size of Strombolian Eruptions from the Phonolitic Lava Lake at Erebus Volcano, Antarctica: Insights from Infrasound and Seismic Observations on Bubble Formation and Ascent

    NASA Astrophysics Data System (ADS)

    Rotman, H. M. M.; Kyle, P. R.; Fee, D.; Curtis, A.

    2015-12-01

    Erebus, an active intraplate volcano on Ross Island, commonly produces bubble burst Strombolian explosions from a long-lived, convecting phonolitic lava lake. Persistent lava lakes are rare, and provide direct insights into their underlying magmatic system. Erebus phonolite is H2O-poor and contains ~30% anorthoclase megacrysts. At shallow depths lab measurements suggest the magma has viscosities of ~107 Pa s. This has implications for magma and bubble ascent rates through the conduit and into the lava lake. The bulk composition and matrix glass of Erebus ejecta has remained uniform for many thousands of years, but eruptive activity varies on decadal and shorter time scales. Over the last 15 years, increased activity took place in 2005-2007, and more recently in the 2013 austral summer. In the 2014 austral summer, new infrasound sensors were installed ~700 m from the summit crater hosting the lava lake. These sensors, supplemented by the Erebus network seismic stations, recorded >1000 eruptions between 1 January and 7 April 2015, with an average infrasound daily uptime of 9.6 hours. Over the same time period, the CTBT infrasound station IS55, ~25 km from Erebus, detected ~115 of the >1000 locally observed eruptions with amplitude decreases of >100x. An additional ~200 eruptions were recorded during local infrasound downtime. This represents an unusually high level of activity from the Erebus lava lake, and while instrument noise influences the minimum observable amplitude each day, the eruption infrasound amplitudes may vary by ~3 orders of magnitude over the scale of minutes to hours. We use this heightened period of variable activity and associated seismic and acoustic waveforms to examine mechanisms for bubble formation and ascent, such as rise speed dependence and collapsing foam; repose times for the larger eruptions; and possible eruption connections to lava lake cyclicity.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    On 28 June, 2002, a deep-focus (566 km) earthquake with a moment magnitude of 7.3 occurred in the China-Russia-North Korea border region. Despite its deep focus, the earthquake produced an infrasound signal that was observed by the remote infrasound array (CHNAR), 682 km from the epicenter, in South Korea. Coherent infrasound signals were detected sequentially at the receiver, with different arrival times and azimuths indicating that the signals were generated both near the epicenter and elsewhere. On the basis of the azimuth, arrival time measurements, and atmospheric ray simulation results, the source area of the infrasonic signals that arrived earlier were located along the eastern coastal areas of North Korea and Russia, whereas later signals were sourced throughout Japan. The geographically-constrained, and discrete, distribution of the sources identified is explained by infrasound propagation effects caused by a westward zonal wind that was active when the event occurred. The amplitude of the deep quake's signal was equivalent to that of a shallow earthquake with a magnitude of approximately 5. This study expands the breadth of seismically-associated infrasound to include deep earthquakes, and also supports the possibility that infrasound measurements could help determine the depth of earthquakes.

  4. 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.

  5. Combining Infrasound and Imaging Techniques to Characterize and Quantify Eruptive Activity at Karymsky Volcano, Kamchatka, Russia

    NASA Astrophysics Data System (ADS)

    Fee, D.; Lopez, T. M.; Rowell, C.; Matoza, R. S.; Szuberla, C.; Prata, F.; Firstov, P.; Makhmudov, E.

    2012-12-01

    Changes in atmospheric pressure at volcanic vents caused by the rapid release and expansion of volcanic material (e.g., gas, ash, lava) produce low frequency sound waves known as infrasound. Because of the direct link between the infrasound source and the eruption and emission of volcanic material, complementary direct and remote observations of gas, ash, and other eruptive phenomena can be combined with infrasound measurements to characterize and quantify volcanic activity. Here we present coincident measurements collected over two 10-day periods at Karymsky Volcano in August 2011 and July 2012 of infrasound, SO2, thermal radiation, ash (2011 only), and visual imagery. Infrasound and audible (up to 250 Hz) acoustic data were recorded using arrays of portable digital microphones. SO2 emissions were measured using both a scanning FLYSPEC ultraviolet spectrometer system as well as a CyClops infrared camera equipped with broadband, 8.6, 10, and 11 micron filters permitting detection and quantification of both SO2 and ash. A FLIR infrared camera was utilized to record high temporal resolution thermal observations of the volcanic emissions and hot eruption deposits. Lastly, visual imagery was taken with an HD camcorder. Correlations between this multiparameter dataset allow a better understanding of both the infrasound data and eruptive activity. Karymsky Volcano is one of the most active and dynamic volcanoes in Kamchatka, Russia, with activity during our experiments consisting of vigorous degassing, frequent ash explosions, apparent vent sealing, and intermittent explosive magmatic eruptions. This varied activity produced diverse acoustic and emissions signals. Large explosive eruptions in 2011 are preceded by vent sealing and produce high-amplitude infrasound with occasional visible shock waves. Vigorous gas jetting is also observed and accompanied by elevated SO2 emissions and low infrasound levels. The gas jetting produced clear audible sound (~20-100 Hz) that

  6. 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

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

    USGS Publications Warehouse

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

    2009-01-01

    During the early stages of the 2004-2008 Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and source configuration are considered. The simulations show that a shallow source buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from , the source epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point source. The observations therefore require a more complex source process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the "valve" sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as

  8. Ground motions and the infrasound signal: A new model and the discovery of a significant cavity rebound signal. Los Alamos Source Region Program

    SciTech Connect

    Jones, E.M.; App, F.N.; Whitaker, R.W.

    1993-03-01

    A model is presented that relates infrasound signals from underground nuclear tests to the peak vertical velocity at surface-ground-zero. For the most part, agreement between the model and observations is good, the exceptions being events conducted in shallow tuff layers in Yucca Flat. These events all have low values of the peak surface velocity. The authors have determined that the lack of agreement for these events is due to an unusual, second spall event. A stress-wave calculation is presented that reproduces the second-spall phenomenon and indicates that it is due to interference of cavity-rebound-associated signal with the initial ballistic motion of the surface layers. The effect of the rebound signal is to increase the amplitude of the infrasound signal and thus make low velocity events more detectable.

  9. Infrasound observation of the apparent North Korean nuclear test of 25 May 2009

    NASA Astrophysics Data System (ADS)

    Che, Il-Young; Kim, Tae Sung; Jeon, Jeong-Soo; Lee, Hee-Il

    2009-11-01

    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 by North Korea. For the more recent test, five seismo-acoustic arrays in South Korea recorded epicentral infrasonic signals. The signals are characterized by amplitudes from 0.16 to 0.35 microbar and dominant frequencies between 0.8 and 4.3 Hz. Celerities determined for the arrivals suggest that most of the infrasonic energy travelled as a stratospheric phase. Based on observed stratospheric amplitudes, the epicentral infrasonic energy was estimated to be equivalent to that expected from 3.0 tons of high explosives detonated on the surface. We conclude that this small energy estimate is due to the atmospheric coupling from the strong surface ground motion rather than the direct transfer of explosion energy to the air. This relatively small infrasonic to seismic energy ratio could be used to distinguish the event from a common surface explosion.

  10. Volcano infrasound: A review

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey Bruce; Ripepe, Maurizio

    2011-09-01

    Exploding volcanoes, which produce intense infrasound, are reminiscent of the veritable explosion of volcano infrasound papers published during the last decade. Volcano infrasound is effective for tracking and quantifying eruptive phenomena because it corresponds to activity occurring near and around the volcanic vent, as opposed to seismic signals, which are generated by both surface and internal volcanic processes. As with seismology, infrasound can be recorded remotely, during inclement weather, or in the dark to provide a continuous record of a volcano's unrest. Moreover, it can also be exploited at regional or global distances, where seismic monitoring has limited efficacy. This paper provides a literature overview of the current state of the field and summarizes applications of infrasound as a tool for better understanding volcanic activity. Many infrasound studies have focused on integration with other geophysical data, including seismic, thermal, electromagnetic radiation, and gas spectroscopy and they have generally improved our understanding of eruption dynamics. Other work has incorporated infrasound into volcano surveillance to enhance capabilities for monitoring hazardous volcanoes and reducing risk. This paper aims to provide an overview of volcano airwave studies (from analog microbarometer to modern pressure transducer) and summarizes how infrasound is currently used to infer eruption dynamics. It also outlines the relative merits of local and regional infrasound surveillance, highlights differences between array and network sensor topologies, and concludes with mention of sensor technologies appropriate for volcano infrasound study.

  11. IPLOR performance in detecting infrasound from volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Popa, Mihaela

    2016-04-01

    Plostina infrasound array (IPLOR) is located in the central part of Romania, in Vrancea region, its current configuration consisting of 6 elements equipped with Chaparral Physics sensors deployed over a 2.5 km aperture. The array detectability observed after processing of more than 6 years of data has shown that IPLOR is more effective in measuring mainly infrasound signals produced by natural and anthropogenic impulsive sources. This can be explained by the sensors' characteristics (frequency response, dynamic range) and the large aperture of array. Among the types of events observed with IPLOR, an emphasis can be given to the Mt. Etna volcanic eruptions as one of the powerful infrasound source recorded by the array. Located at about 1320 km distance from volcano, the array has proved efficient in observing both large and small eruptions. In case of the most large eruptive episodes occurred lately (April and October 2013, December 2015), long duration infrasonic signals were detected, the initial impulsive signature of the volcanic explosion being followed by a long train of irregular waves with smaller amplitudes and higher frequency, extended over periods ranging from 6 hours to more than three days (in December 2015). For the purpose of assessing the IPLOR performance in detecting Etna eruptions, the signal interactive analysis was performed using WinPMCC, CEA/DASE version of PMCC software. The infrasound detections obtained were plotted in function of back-azimuth, velocity and frequency, showing that the detectability is dependent both on the diurnal variations of the noise around the array (during the night the human activity diminishes) and on the seasonally dependent stratospheric winds (westward propagation during summer and eastward propagation during winter). In case of the Etna eruptive episodes detected by IPLOR, the back azimuth observed is in good agreement with the expected value (230o), i.e. an average value of 232±2o could be resolved. The

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

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine; Hedlin, Michael

    2014-05-01

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

  13. Infrasound Sensor Coverage at Regional Ranges as driven by the Atmospheric State

    NASA Astrophysics Data System (ADS)

    Norris, D.

    2010-12-01

    Infrasound is an attractive regional sensor modality in explosion monitoring applications due to its non line-of-sight, long-range detection capability. Anthropomorphic activity, including impulsive events such as explosions and continuous events such as vehicle operation, can be routinely detected over tens of kilometer ranges and beyond. This study addresses the issues associated with effectively leveraging infrasound for regional monitoring applications. A key challenge in applying infrasound at these ranges is adequately understanding the propagation. Spatial and temporal features of the atmospheric state create evolving regions of acoustic focusing and shadowing at the surface. Understanding this acoustic "footprint" and having the capability to predict it over time is necessary for two reasons. It drives the planning process of where to deploy a given permanent or temporary suite of infrasound sensors. In addition, knowing the observability of a stationary or mobile source supports the interpretation of operational data. This research includes a sample study on characterization of atmospheric effects on regionally deployed infrasound networks. Predictions are made from real atmospheric states to illustrate the range of observability conditions that may occur. It was found that the observability can have significant frequency dependence.

  14. Evaluation of infrasound sensors

    SciTech Connect

    Kromer, R.P.; McDonald, T.S.

    1998-08-01

    Sandia is evaluating the performance of various infrasound sensors that could be used as part of the International Monitoring Systems (IMS). Specifications for infrasound stations are outlined in CTBT/PC/II/1/Add.2. This document specifies minimum requirements for sensor, digitizer and system. The infrasound sensors evaluation task has the following objectives: provide an overview of the sensors presently in use; evaluate these sensors with respect to the requirements of the IMS.

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Jones, K. R.

    2015-12-01

    As a part of the Source Physics Experiment (SPE) site characterization and explosive test series, we developed and deployed an airborne octocopter infrasound platform. Traditionally, infrasound data is collected with sensors and arrays that are installed on the ground. For most applications this is sufficient but can be limiting when observing non-isotropic sources, such as underground explosions, at close range. To develop and test the airborne infrasound platform we recorded data from a seismo-acoustic hammer source at the Nevada National Security Site (NNSS). During early field-testing of the hammer source we found that, as the 13 metric ton mass hit the ground, a significant downward deflection of the surrounding surface imparted an observable infrasound pressure wave into the atmosphere. We compared waveforms collected at various vertical and horizontal offsets from the hammer source and found that the peak frequencies differed when observed directly above the source compared to the horizontal offsets. This work was done under award number DE-AC52-06NA25946. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Infrasound from the Chelyabinsk Meteor recorded at the USArray

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  18. Charting a Course for the Infrasound Renaissance

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Gao, Y.; Liu, K. H.; Gao, S. S.

    2011-12-01

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

  1. 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.

  2. 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.

  3. Infrasound emission generated by wind turbines

    NASA Astrophysics Data System (ADS)

    Ceranna, Lars; Pilger, Christoph

    2014-05-01

    Aerodynamic noise emissions from the continuously growing number of wind turbines in Germany are creating increasing problems for infrasound recording systems. Such systems are equipped with highly sensitive micro pressure sensors, which are accurately measuring acoustic signals in a frequency range inaudible to humans. At infrasound station IGADE, north of Bremen, a constantly increasing background noise has been observed throughout the years since its installation in 2005. The spectral peaks are reflecting well the blade passing harmonics, which vary with prevailing wind speeds. Overall, a decrease is noted for the infrasound array's detection capability. This aspect is particularly important for the other two sites of the German infrasound stations I26DE in the Bavarian Forest and I27DE in Antarctica, because plans for installing wind turbines near these locations are being under discussion. These stations are part of the International Monitoring System (IMS) verifying compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT), and have to meet stringent specifications with respect to infrasonic background noise. Therefore data obtained during a field experiment with mobile micro-barometer stations for measuring the infrasonic pressure level of a single horizontal-axis wind turbine have been revisited. The results of this experiment successfully validate a theoretical model which estimates the generated sound pressure level of wind turbines and makes it possible to specify the minimum allowable distance between wind turbines and infrasound stations for undisturbed recording. Since the theoretical model also takes wind turbine design parameters into account, suitable locations for planned infrasound stations outside the determined disturbance range can be found, which will be presented; and vice versa, the model calculations' results for fixing the minimum distance for wind turbines planned for installation in the vicinity of an existing infrasound array.

  4. Spall Effects on Infrasound Generation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Spall effects from buried explosions are seen in near-source surface accelerations and depend on explosion yield, emplacement depth-of-burial and material strength. Investigations of infrasound from buried explosions have shown how atmospheric overpressure can be derived from surface acceleration through application of the Rayleigh Integral (Bannister, 1980). Recently, underground chemical explosions as part of the Source Physics Experiment (SPE) at the Nevada National Security Site (NNSS) have been shown to generate spall signatures in local-distance infrasound (Jones et al. 2014). We are investigating the effects of spall on infrasound generation using two approaches. The first approach uses the Rayleigh integral to compute overpressures for buried explosions from synthetic vertical acceleration data at surface ground zero. To obtain the synthetic surface accelerations we use reported models from nuclear explosion studies and systematically vary parameters such as the spall duration, depth of burial and magnitude. The effect on the resulting acoustic waveform shape will be investigated. The second method uses a hydrodynamic approach to more fully characterize the varied parameters to produce the acoustic waveforms. As the spall decreases we find that the acoustic waveform shape changes dramatically. This waveform signature may provide diagnostics on the explosive source and may be a useful metric for underground explosion monitoring. This work was done under award number DE-AC52-06NA25946. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  5. 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.

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

    SciTech Connect

    Hart, Darren

    2004-07-01

    MatSeis's infrasound analysis tool, Infra Tool, uses frequency slowness processing to deconstruct the array data into three outputs per processing step: correlation, azimuth and slowness. Until now, an experienced analyst trained to recognize a pattern observed in outputs from signal processing manually accomplished infrasound signal detection. Our goal was to automate the process of infrasound signal detection. The critical aspect of infrasound signal detection is to identify consecutive processing steps where the azimuth is constant (flat) while the time-lag correlation of the windowed waveform is above background value. These two statements describe the arrival of a correlated set of wavefronts at an array. The Hough Transform and Inverse Slope methods are used to determine the representative slope for a specified number of azimuth data points. The representative slope is then used in conjunction with associated correlation value and azimuth data variance to determine if and when an infrasound signal was detected. A format for an infrasound signal detection output file is also proposed. The detection output file will list the processed array element names, followed by detection characteristics for each method. Each detection is supplied with a listing of frequency slowness processing characteristics: human time (YYYY/MM/DD HH:MM:SS.SSS), epochal time, correlation, fstat, azimuth (deg) and trace velocity (km/s). As an example, a ground truth event was processed using the four-element DLIAR infrasound array located in New Mexico. The event is known as the Watusi chemical explosion, which occurred on 2002/09/28 at 21:25:17 with an explosive yield of 38,000 lb TNT equivalent. Knowing the source and array location, the array-to-event distance was computed to be approximately 890 km. This test determined the station-to-event azimuth (281.8 and 282.1 degrees) to within 1.6 and 1.4 degrees for the Inverse Slope and Hough Transform detection algorithms, respectively, and

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

    SciTech Connect

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

    2001-12-01

    Laboratory tests were conducted using juvenile chinook salmon Oncorhynchus tshawytscha, brook trout Salvelinus fontinalis, and rainbow trout O. mykiss to determine specific behavior responses to infrasound (< 20 Hz) and flashing strobe lights. The objective of these tests was to determine if juvenile salmonids could be deterred from entrainment at water diversion structures. Caged fish were acclimated in a static test tank and their behavior was recorded using low light cameras. Species-specific behavior was characterized by measuring movements of the fish within the cage and by observing startle and habituation responses. Wild chinook salmon (40-45 mm TL) and hatchery reared chinook salmon (45-50 mm TL) exhibited avoidance responses when initially exposed to a 10-Hz volume displacement source of infrasound. Rainbow and eastern brook trout (25-100 mm TL) did not respond with avoidance or other behaviors to infrasound. Evidence of habituation to the infrasound source was evident for chinook salmon during repeated exposures. Wild and hatchery chinook displayed a higher proportion of movement during the initial exposures to infrasound when the acclimation period in the test tank was 2-3 h as compared to a 12-15 h acclimation period. A flashing strobe light produced consistent movement in wild chinook salmon (60% of the tests), hatchery reared chinook salmon (50%), and rainbow trout (80%). No measurable responses were observed for brook trout. Results indicate that consistent, repeatable responses can be elicited from some fish using high-intensity strobe lights under a controlled laboratory testing. The species specific behaviors observed in these experiments might be used to predict how fish might react to low-frequency sound and strobe lights in a screening facility.

  8. Global Infrasound Monitoring of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Bass, Henry

    2003-03-01

    As a signatory to the Comprehensive Nuclear Test Ban Treaty (CTBT), the United States has responsiblity for establishing and operating eight infrasound arrays from Alaska to the Antarctic through the Pacific Basin, and along the U. S. west coast. (In this context, infrasound is defined as acoustic waves in the frequency range 0.02 Hz to 4Hz.) In addition, the U. S. has non-CTBTO infrasound arrays in New Mexico, Utah, Nevada, Wyoming, Texas, and Maryland. The CTBT Office will install and operate an additional 52 states to provide worldwide coverage. This immense array of sensors provides a rare opportunity to study low frequency sound on a global scale. An international community of interested scieintists is beginning to emerge with different interests in the use of data from this global network. Much of the research interest lies in the ability to remotely monitor events of interest. These include volcanoes, severe storms, and bolides. The signals received at the individual stations are strongly dependent on the state of the intervening atmosphere therefore there is an opportunity to use tomography to gain more detailed knowledge of changes in the upper atmosphere. There are still great opportunities to improve the quality of the infrasound stations. Wind noise continues to limit the signal to noise level. Modern signal processing techniques might be used to lower wind noise levels and allow the detection of even weaker signals. Current generation infrasound stations are large and expensive. Reduction in complexity would allow a finer grid of stations and the study of higher frequency signals. There are numerous opportunities for collaborations in the use of this unique data source at the national and international levels. The US Infrasound Team and international collaborators are open to new ideas and colleagues.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed

    de Groot-Hedlin, C D

    2012-08-01

    An accurate and efficient method to predict infrasound amplitudes from large explosions in the atmosphere is required for diverse source types, including bolides, volcanic eruptions, and nuclear and chemical explosions. A finite-difference, time-domain approach is developed to solve a set of nonlinear fluid dynamic equations for total pressure, temperature, and density fields rather than acoustic perturbations. Three key features for the purpose of synthesizing nonlinear infrasound propagation in realistic media are that it includes gravitational terms, it allows for acoustic absorption, including molecular vibration losses at frequencies well below the molecular vibration frequencies, and the environmental models are constrained to have axial symmetry, allowing a three-dimensional simulation to be reduced to two dimensions. Numerical experiments are performed to assess the algorithm's accuracy and the effect of source amplitudes and atmospheric variability on infrasound waveforms and shock formation. Results show that infrasound waveforms steepen and their associated spectra are shifted to higher frequencies for nonlinear sources, leading to enhanced infrasound attenuation. Results also indicate that nonlinear infrasound amplitudes depend strongly on atmospheric temperature and pressure variations. The solution for total field variables and insertion of gravitational terms also allows for the computation of other disturbances generated by explosions, including gravity waves. PMID:22894187

  15. 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.

  16. 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.

  17. Infrasound monitoring, acoustic-gravity waves and global atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Blanc, E.; Le Pichon, A.; Ceranna, L.; Farges, T.

    2008-12-01

    For the verification of the Comprehensive nuclear Test Ban Treaty, the International Monitoring System has been developed. As part of this system, the infrasound network provides an unique opportunity to monitor continuously pressure waves in the atmosphere. Such infrasonic waves propagate in the channel formed by the temperature and wind gradients of the atmosphere. Long term observations provide information about the evolution of the propagation conditions and then of atmospheric parameters. The monitoring of continuous sources, as ocean swell, gives the characteristics of the stratospheric wave channel submitted to stratospheric warming effects. Large scale gravity waves, which are also observed by the network, produce a forcing of the stratosphere at low and middle latitudes and long-lived changes in the stratospheric circulation towards high latitudes, leading to fluctuations in the strength of the polar vortex. These fluctuations move down to the lower stratosphere with possible effects on the tropospheric temperature. Gravity wave monitoring in Antarctica reveals a gravity wave system probably related to the wind effect over mountains. At mid latitudes an additional main sources of disturbances is the thunderstorm activity. The infrasound monitoring system allows a better knowledge of the atmospheric wave systems and of the dynamics of the atmosphere. In return this better knowledge of the wave systems allow a better identification of the possible explosion signals in the background of the atmospheric waves and then to improve the discrimination methods

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The explosive fragmentation of the 2013 Chelyabinsk meteorite generated a large airburst with an equivalent yield of 500 kT TNT. It is the most energetic event recorded by the infrasound component of the CTBT-IMS, globally detected by 20 out of 42 operational stations. This study performs a station-by-station estimation of the IMS detection capability to explain infrasound detections and non-detections from short to long distances, using the Chelyabinsk meteorite as global reference event. Investigated parameters influencing the detection capability are the directivity of the line source signal, the ducting of acoustic energy and the individual noise conditions at each station. Findings include a clear detection preference for stations perpendicular to the meteorite trajectory, even over large distances. Only a weak influence of stratospheric ducting is observed for this low-frequency case. Furthermore, a strong dependence on the diurnal variability of background noise levels at each station is observed, favoring nocturnal detections.

  20. 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.

  1. IDC infrasound analysis of the 15 February 2013 Chelyabinsk fireball

    NASA Astrophysics Data System (ADS)

    Mialle, P.; Bittner, P.; Brown, D.; Polich, P.; Gore, J.

    2013-12-01

    The first atmospheric event built only from infrasound arrivals was reported in the Reviewed Event Bulletin (REB) of the International Data Centre (IDC) of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO) in 2003. In the last decade, 45 infrasound stations from the International Monitoring System (IMS) have been installed and are transmitting data to the IDC. In early 2010 the IDC began routine automatic processing of infrasound data reviewed by interactive analysis; the detected and located events are now systematically included in the REB. This study focuses on a major infragenic event that occurred in February 2013 and was thoroughly analyzed at the IDC. On February 15 a fireball in the Chelyabinsk region (Russia) was observed generating infrasound waves that were recorded by 20 infrasound IMS stations globally spread from Greenland to Antarctica. Chronology of the analysis and specificities of this event will be introduced. This event is the largest ever recorded by the infrasound component of the IMS network. Related seismic observations were also found.

  2. 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.

  3. 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

  4. 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

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

    SciTech Connect

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

    1999-02-01

    Experimental tests were conducted using hatchery reared and wild juvenile chinook salmon Oncorhynchus tshawytscha, eastern brook trout Salvelinus fontinalis, and rainbow trout O. mykiss to determine specific behavior responses to infrasound (<20 Hz) and flashing strobe lights. Caged fish were acclimated in a static test tank and their behavior was recorded using low light cameras. Species specific behavior was characterized by measuring movements of the fish within the cage as well as observing startle and habituation responses. Wild chinook salmon (40-45 mm) and hatchery reared chinook salmon (45-50mm) exhibited avoidance responses when initially exposed to a 10 Hz volume displacement source. Rainbow and eastern brook trout (25-100 mm) did not respond with avoidance or other behaviors to infrasound. Habituation to the infrasound source was evident for chinook salmon during repeated exposures. Wild and hatchery chinook displayed a higher proportion of movement during the initial exposures to infrasound when the acclimation period in the test tank was 2-3 h as compared to a 12-15 h acclimation period. A flashing strobe light produced higher and more consistent movement rates in wild chinook (60% of the tests); hatchery reared chinook salmon (50%) and rainbow trout (80%). No measurable movement or other responses was observed for eastern brook trout. Little if any habituation was observed during repeated exposures to strobe lights. Results from this study indicate that consistent repeatable responses can be elicited from some fish using high intensity strobe lights under a controlled laboratory testing. The specific behaviors observed in these experiments might be used to predict how fish might react to low frequency sound and strobe lights in a screening facility. Because sub-yearling salmonids and resident species are susceptible from becoming entrained at water diversion structures we conducted tests in conjunction with our evaluation of juvenile fish screening

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  8. 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.

  9. Nonlinear Propagation of Infrasound from Large Explosions

    NASA Astrophysics Data System (ADS)

    de Groot-Hedlin, Catherine

    2015-04-01

    Atmospheric explosions release immense quantities of infrasound energy that can be detected at receivers located from hundreds to thousands of kilometers from the origin. This has led to the deployment of a global 60-station network of micro-barometer arrays to aid in nuclear explosion monitoring. Current methods of estimating the radiated source energy from remote recordings of infrasound signals use simplified empirical source-yield relations that account for stratospheric winds along the source-receiver path. These formulations apply only to direct and stratospherically ducted arrivals. More recently, considerable progress has been made in applying numerical modeling techniques to develop more accurate source-yield formulations for realistic sound and wind speed profiles. However, these methods assume linear infrasound propagation along the travel path even though nonlinear effects - which arise when the amplitude of the acoustic pressure perturbation is a finite fraction of the ambient atmospheric pressure - are known to significantly alter infrasound frequencies, velocities and amplitudes, and thus can affect derived source yield estimates. For realistic atmospheric profiles, nonlinearity can be significant both in the vicinity of a large explosive source as well as at much greater distances. Within the stratosphere, nonlinearity may arise at caustics created by ducting; in the thermosphere, nonlinearity may arise due to very low ambient pressures at high altitudes. In this study, the effects of nonlinearity on infrasound signal amplitudes and frequencies are simulated using a nonlinear finite difference, time-domain (FDTD) method. The key features that allow for accurate and efficient nonlinear synthesis of infrasound propagation through realistic media are that 1) it includes for atmospheric viscosity, and 2) the environmental models are constrained to have axial symmetry, yielding solutions relevant to a point source in a fully 3D model with rotational

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    Three large-scale infrasound calibration experiments were conducted in 2009 and 2011 to test the International Monitoring System (IMS) infrasound network and provide ground truth data for infrasound propagation studies. Here we provide an overview of the deployment, detonation, atmospheric specifications, infrasound array observations, and propagation modeling for the experiments. The experiments at the Sayarim Military Range, Israel, had equivalent TNT yields of 96.0, 7.4, and 76.8 t of explosives on 26 August 2009, 24 January 2011, and 26 January 2011, respectively. Successful international collaboration resulted in the deployment of numerous portable infrasound arrays in the region to supplement the IMS network and increase station density. Infrasound from the detonations is detected out to ~3500 km to the northwest in 2009 and ~6300 km to the northeast in 2011, reflecting the highly anisotropic nature of long-range infrasound propagation. For 2009, the moderately strong stratospheric wind jet results in a well-predicted set of arrivals at numerous arrays to the west-northwest. A second set of arrivals is also apparent, with low celerities and high frequencies. These arrivals are not predicted by the propagation modeling and result from unresolved atmospheric features. Strong eastward tropospheric winds (up to ~70 m/s) in 2011 produce high-amplitude tropospheric arrivals recorded out to >1000 km to the east. Significant eastward stratospheric winds (up to ~80 m/s) in 2011 generate numerous stratospheric arrivals and permit the long-range detection (i.e., >1000 km). No detections are made in directions opposite the tropospheric and stratospheric wind jets for any of the explosions. Comparison of predicted transmission loss and observed infrasound arrivals gives qualitative agreement. Propagation modeling for the 2011 experiments predicts lower transmission loss in the direction of the downwind propagation compared to the 2009 experiment, consistent with the

  11. Assessing Infrasound Network Performance Using the Ambient Ocean Noise

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  12. Using infrasound to constrain ash plume height

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  13. 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.

  14. 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

  15. HEGRA Observations of Galactic Sources

    NASA Astrophysics Data System (ADS)

    Völk, H.; Hegea Collaboration

    2000-06-01

    In this talk I will first give a summary of the observations of expected Galactic TeV gamma-ray sources with the HEGRA CT-Sytem since the Kruger Park Workshop in 1997. Then I will go into some detail regarding the observations of Supernova Remnants (SNRs), especially those of Tycho's SNR and of Cas A. The emphasis will not be on all aspects of these published data. I will rather review the selection of these observational targets, and discuss some of the physical implications of the results.

  16. HEGRA observations of Galactic sources

    NASA Astrophysics Data System (ADS)

    HEGRA Collaboration

    2000-06-01

    In this talk I will first give a summary of the observations of expected Galactic TeV γ-ray sources with the HEGRA CT-System since the Kruger Park Workshop in 1997. Then I will go into some detail regarding the observations of Supernova Remnants (SNRs), especially those of Tycho's SNR and of Cas A. The emphasis will not be on all aspects of these published data. I will rather review the selection of these observational targets, and discuss some of the physical implications of the results. .

  17. Probabilistic infrasound propagation using ensemble based atmospheric perturbations

    NASA Astrophysics Data System (ADS)

    Smets, Pieter; Evers, Läslo

    2015-04-01

    The state of the atmosphere is of utmost importance for infrasound propagation. In propagation modelling, still, the true state of the atmosphere is mainly represented by the analysis. The analysis is the best deterministic estimate of the atmosphere using a data assimilation system existing of a General Circulation Model (GCM). However, the analysis excludes error variances of both model and observations. In addition, the coarse resolution of GCM results in averaging of, e.g., clouds or gravity waves, over larger regions known as parameterisation. Consequentially, arrivals due to fine-scale structure in wind and temperature can be missing. Therefore, infrasound propagation including the atmospheric best-estimate error variances based on the ensemble model is proposed. The ensemble system exists of model perturbations with an amplitude comparable to analysis error estimates to obtain a probability density function rather than one specific state as obtained from a deterministic system. The best-estimate analysis error variances are described by a set of perturbations using the European Centre for Medium-range Weather Forecasts (ECMWF) Ensemble Data Assimilation (EDA) system. Probabilistic infrasound propagation using 3-D ray tracing is demonstrated by one year of mining activity, e.g., blasting, in Gällivare, northern Sweden, observed at infrasound array IS37 in Norway, part of the International Monitoring System (IMS) for verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Probabilistic infrasound propagation is compared with the standard deterministic result obtained using the analysis.

  18. On the fingerprint of ssw events in infrasound recordings at IMS stations

    NASA Astrophysics Data System (ADS)

    Ceranna, Lars; Pilger, Christoph; Ross, Ole; Le Pichon, Alexis

    2013-04-01

    It has been recently shown that sudden stratospheric warming (ssw) events have an impact on the detection of coherent infrasonic waves at dedicated arrays (e.g., Evers & Siegmund, 2009). During ssw events the polar vortex of prevailing stratospheric westerly winds in a winter hemisphere abruptly slows down or even reverses its direction along with an increase of stratospheric temperatures up to several tens of °C. Since infrasound arrays are mostly recording signals ducted in stratospheric wave-guides, such antennas are sensitive to changes in effective sound speed profiles - temperature plus wind speed in direction of propagation. Considering continuous infrasonic waves emitted by ocean swell (microbaroms), volcanoes or even anthropogenic sources as flares, a gap or a change in the back-azimuth of these detected signals can be observed at arrays. For the compliances with the verification of the Comprehensive Nuclear-Test-Ban Treaty a global network of 60 infrasound stations is under construction as a part of the International Monitoring System (IMS); whereas 45 have already been installed. Analysis of waveform data recorded at these stations has demonstrated the capability of infrasound as a supplementary tool for remote sensing of the atmosphere. In our study we compare the re-analysis, using PMCC, of more than five years of continuous data at all available sites (see Matoza et al., 2013) with atmospheric descriptions provided by the EMCWF. We present a synoptic view of the fingerprint of ssw events in detection of coherent signals at IMS infrasound stations both on northern and southern hemisphere, covering the full latitude range from Antarctica to Greenland.

  19. On the fingerprint of ssw events in infrasound recordings at IMS stations

    NASA Astrophysics Data System (ADS)

    Ceranna, L.; Le Pichon, A.; Pilger, C.; Ross, O.

    2013-12-01

    It has been recently shown that sudden stratospheric warming (ssw) events have an impact on the detection of coherent infrasonic waves at dedicated arrays (e.g., Evers & Siegmund, 2009). During ssw events the polar vortex of prevailing stratospheric westerly winds in a winter hemisphere abruptly slows down or even reverses its direction along with an increase of stratospheric temperatures up to several tens of °C. Since infrasound arrays are mostly recording signals ducted in stratospheric wave-guides, such antennas are sensitive to changes in effective sound speed profiles - temperature plus wind speed in direction of propagation. Considering continuous infrasonic waves emitted by ocean swell (microbaroms), volcanoes or even anthropogenic sources as flares, a gap or a change in the back-azimuth of these detected signals can be observed at arrays. For the compliances with the verification of the Comprehensive Nuclear-Test-Ban Treaty a global network of 60 infrasound stations is under construction as a part of the International Monitoring System (IMS); whereas 45 have already been installed. Analysis of waveform data recorded at these stations has demonstrated the capability of infrasound as a supplementary tool for remote sensing of the atmosphere. In our study we compare the re-analysis, using PMCC, of more than five years of continuous data at all available sites (see Matoza et al., 2013) with atmospheric descriptions provided by the EMCWF. We present a synoptic view of the fingerprint of ssw events in detection of coherent signals at IMS infrasound stations both on northern and southern hemisphere, covering the full latitude range from Antarctica to Greenland.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Infrasound Sensors have been used for many years to monitor a large number of geophysical phenomena and manmade sources. Due to their large size and power consumption these sensors have typically been deployed in fixed arrays, portable arrays have required trucks to transport the sensors and support equipment. A high performance, miniaturized, infrasound microphone has been developed to enable mobile infrasound measurements that would otherwise be impractical. The new device is slightly larger than a hockey puck, weighs 200g, and consumes less than 150mW. The sensitivity is 0.4V/Pa and self noise at 1Hz is less than 0.63μPa²/Hz. The characteristics were verified using a calibrator tracable to the Los Alamos calibration chamber. Field tests have demonstrated the performance is comparable to a Chaparral model 25. Applications include man portable arrays, mobile installations, and UAV based measurements.

  1. Deep infrasound radiated by the Sumatra earthquake and tsunami

    NASA Astrophysics Data System (ADS)

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

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

  2. Ultraviolet observations of astronomical sources

    NASA Technical Reports Server (NTRS)

    Eaton, Joel A.

    1994-01-01

    The final report on 'Ultraviolet Observations of Astronomical Sources,' which ran for a total of three years, roughly between 1 July 1988 and 14 Feb. 1993 is presented. During the first year, I worked at Indiana University; since October, 1989, I have been at Tennessee State University. This grant has supported my studies of archival International Ultraviolet Explorer (IUE) observations of zeta Aur binaries, cool stars that are paired with hot stars in binary systems. Such systems are important as a source of detailed knowledge about the structures of chromospheres and winds in cool giant and supergiant stars, since the hot star serves as a probe of many lines of sight through the cool supergiant star's outer atmosphere. By determining the physical conditions along many such lines of sight, a detailed two-dimensional map of the chromosphere and wind may be constructed. The grant grew out of my analysis of archival IUE observations of 31 Cyg in which I analyzed five epochs of an atmospheric eclipse that occurred in 1982. I fit the attenuation spectra of atmospheric eclipse throughout the ultraviolet (lambda(lambda)1175-1950 and lambda(lambda)2500-3100) with theoretically calculated spectra, thereby determining the physical properties of gas (mass column density of absorbers, temperature, and velocity spread) along each observed line of sight. A similar analysis for other such zeta Aur binaries was accomplished and theoretical models for the chromospheres of these stars based on my observations were constructed.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Pepyne, D.

    2012-04-01

    Each year tornadoes cause property damage and death, some of which could be avoided with increased warning lead time. The year 2011 was particularly severe, with more than 1600 tornadoes causing in excess of 500 deaths in the U.S. It is known that tornadoes and their precursors generate infrasound in the 0.5Hz to 10Hz frequency band, with precursors occurring some 30-60 minutes prior to tornado touch down, which is some 15-45 minutes earlier than the average tornado warning lead time in the U.S. Given the potential of infrasound to improve tornado early warning and emergency response, the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA), in conjunction with its research on small, boundary-layer observing X-band weather radars, has begun a research project whose goal is to combine the passive detection of tornado infrasound with active tracking of the parent storms that carry the tornadoes with its weather radars. In the spring of 2011 CASA conducted an infrasound field-test in Oklahoma, in the heart of the so-called "tornado-alley" where statistically the majority of springtime tornadoes in the U.S. occur. This being CASA's first infrasound experiment, the goal of the field-test was to gain an understanding of the issues involved in the design and operation of infrasound stations for severe weather monitoring and early warning. In this application, it is not so much the ability of infrasound to travel long distances that is of importance, but rather the fact that there can be precursor signals that unlike radar do not require line-of-sight to detect. In fact, for early warning, detection distance would generally need to be less than 100 km, since a propagation delay of much more than 5 minutes would be too late. Challenges encountered included persistent infrasound "clutter" from a nearby large windfarm, accurate bearing detection over a wide bandwidth with a fixed four sensor aperture, and the need to operate in the the high winds that surround

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

    PubMed

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

    2013-12-01

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

  6. 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.

  7. 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.

  8. Hyperion 5113/A Infrasound Sensor Evaluation

    SciTech Connect

    Merchant, Bion John

    2015-09-01

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

  9. 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.

  10. Neural network approach to classification of infrasound signals

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Chang

    As part of the International Monitoring Systems of the Preparatory Commissions for the Comprehensive Nuclear Test-Ban Treaty Organization, the Infrasound Group at the University of Alaska Fairbanks maintains and operates two infrasound stations to monitor global nuclear activity. In addition, the group specializes in detecting and classifying the man-made and naturally produced signals recorded at both stations by computing various characterization parameters (e.g. mean of the cross correlation maxima, trace velocity, direction of arrival, and planarity values) using the in-house developed weighted least-squares algorithm. Classifying commonly observed low-frequency (0.015--0.1 Hz) signals at out stations, namely mountain associated waves and high trace-velocity signals, using traditional approach (e.g. analysis of power spectral density) presents a problem. Such signals can be separated statistically by setting a window to the trace-velocity estimate for each signal types, and the feasibility of such technique is demonstrated by displaying and comparing various summary plots (e.g. universal, seasonal and azimuthal variations) produced by analyzing infrasound data (2004--2007) from the Fairbanks and Antarctic arrays. Such plots with the availability of magnetic activity information (from the College International Geophysical Observatory located at Fairbanks, Alaska) leads to possible physical sources of the two signal types. Throughout this thesis a newly developed robust algorithm (sum of squares of variance ratios) with improved detection quality (under low signal to noise ratios) over two well-known detection algorithms (mean of the cross correlation maxima and Fisher Statistics) are investigated for its efficacy as a new detector. A neural network is examined for its ability to automatically classify the two signals described above against clutter (spurious signals with common characteristics). Four identical perceptron networks are trained and validated (with

  11. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Meteorites are always the events that testing the capability of the International Monitoring System to measure and the International Data Centre to analyze sources similar to nuclear explosions. Monitoring of the Comprehensive Nuclear-Test-Ban Treaty suggests the possibility to detect infrasound (acoustic) and seismic signals from atmospheric and underground events and to locate their sources. Chelyabinsk meteor was one of the best exemplar in a row of other atmospheric events exposing the ability of IDC and IMS to handle the atmospheric explosions. The uniqueness of this event is that the generated seismic, acousto-seismic and infrasound wave fields were recorded by considerable number of IMS stations of different technologies at wide distance range. The shock waves from the Chelyabinsk meteor generated an I-phase recorded by IMS infrasound stations and a series of seismic phases. The Pn-waves were observed by five near-regional seismic stations together with Sn- and Lg-waves. They are most likely associated with the impact of the meteor debris and the location associated with their source differs by tens of kilometers from that obtained by Rayleigh and Love waves. The latter were generated by acoustic (low-amplitude shock) waves hitting the ground beneath the trajectory of the meteor. Surprisingly, these surface waves associated with the meteor and observed at least at distances of 45º were not associated with the event in the Reviewed Event Bulletin. This implies a conceptual gap in the IDC processing and fusion of acoustic and seismic waves. The trajectory of the meteorite built with the epicenters of seismic, acousto-seismic and infrasound events is in good compliance with the trajectories built by different scientific institutions including NASA. We present an approximate distribution of energy release along the trajectory and thus the amplitude of the generated shock wave. It allows interpreting the period and amplitude dependence of the LR and LQ waves on

  13. 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

    The establishment of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has stimulated infrasound research and development. However, as the network comes closer to completion there exists a lack of large, well-constrained sources to test the network and its capabilities. Also, significant uncertainties exist in long-range acoustic propagation due to a dynamic, difficult to characterize atmosphere, particularly the thermosphere. In 2009 and 2011 three large scale infrasound calibration experiments were performed in Europe, the Middle East, Africa, and Asia. The goal of the calibration experiments were to test the IMS infrasound network and validate atmospheric and propagation models with large, well-constrained infrasound sources. This presentation provides an overview of the calibration experiments, including deployment, atmospheric conditions during the experiments, explosion characterization, infrasonic signal detection and identification, and a discussion of the results and implications. Each calibration experiment consisted of singular surface detonation of explosives with nominal weights of 82, 10.24, and 102.08 tons on 26 August 2009, 24 January 2011, and 26 January 2011, respectively. These explosions were designed and conducted by the Geophysical Institute of Israel at Sayarim Military Range, Israel and produced significant infrasound detected by numerous permanent and temporary infrasound arrays in the region. The 2009 experiment was performed in the summer to take advantage of the westerly stratospheric winds. Infrasonic arrivals were detected by both IMS and temporary arrays deployed to the north and west of the source, including clear stratospheric arrivals and thermospheric arrivals with low celerities. The 2011 experiment was performed during the winter, when strong easterly stratospheric winds dominated in addition to a strong tropospheric jet (the jet stream). These wind jets allowed detection

  14. Hyperion 5113/GP Infrasound Sensor Evaluation.

    SciTech Connect

    Merchant, Bion J.

    2015-08-01

    Sandia National Laboratories has tested and evaluated an infrasound sensor, the 5113/GP manufactured by Hyperion. These infrasound sensors measure pressure output by a methodology developed by the University of Mississippi. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, and seismic sensitivity. These sensors are being evaluated prior to deployment by the U.S. Air Force.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  16. MB3a Infrasound Sensor Evaluation.

    SciTech Connect

    Merchant, Bion J.; McDowell, Kyle D.

    2014-11-01

    Sandia National Laboratories has tested and evaluated a new infrasound sensor, the MB3a, manufactured by Seismo Wave. These infrasound sensors measure pressure output by a methodology developed by researchers at the French Alternative Energies and Atomic Energy Commission (CEA) and the technology was recently licensed to Seismo Wave for production and sales. The purpose of the infrasound sensor evaluation was to determine a measured sensitivity, transfer function, power, self-noise, dynamic range, seismic sensitivity, and self- calibration ability. The MB3a infrasound sensors are being evaluated for potential use in the International Monitoring System (IMS) of the Comprehensive Nuclear Test-Ban-Treaty Organization (CTBTO).

  17. Seismo-Acoustic Observations of Explosive Sources

    NASA Astrophysics Data System (ADS)

    Chael, E. P.; Hart, D. M.; Jones, K. R.

    2011-12-01

    Since January 2011, the Sandia National Laboratories Facility for Acceptance, Calibration and Testing (FACT) has operated a seismo-acoustic station with the purpose of recording local explosions on Kirtland Air Force Base (KAFB). Our immediate goals are to develop a catalog of events and a database of seismo-acoustic waveforms from ordnance disposal and Defense Threat Reduction Agency (DTRA) events. The catalog of events will include metadata such as shot time, size, type and location. The waveform archive includes a three-channel GS-13 seismometer and a single infrasound sensor (Chaparral 25 with 50' porous hose wind reduction system). In June of 2011 a weather station was added to complement the monitoring system by providing accurate wind conditions at the times of the explosive events. Monthly internal reports compiled by KAFB provided us with the metadata for the ordnance disposal explosions, and an agreement with DTRA has enabled us to obtain metadata on their events. To date 157 explosions have been identified, including 153 ordnance disposal events and 4 DTRA tests. Along with the catalog of events we have developed automated processing routines to extract both seismic and infrasound arrivals and measure basic waveform characteristics. These include amplitudes of pre-event noise, the direct seismic arrival, air-coupled seismic arrival, infrasound arrival, and wind speed/direction. Using the waveform measurements from the pre-event noise and air-coupled seismic arrival we calculate the SNR for the seismic component of the event. We also calculate the SNR for the infrasonic component of the event using pre-event noise and the direct infrasound arrival. Using the metadata and seismic and infrasonic SNR values we are able to calculate an air-to-ground coupling ratio for each event. For local (<10 km) explosion monitoring, the wind speed and direction can influence all of the analysis parameters. It will affect the pre-event noise level as well as the infrasound

  18. Upgrade of the Plostina infrasound array

    NASA Astrophysics Data System (ADS)

    Ghica, Daniela; Ionescu, Constantin; Tataru, Stefan

    2014-05-01

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

  19. 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.

  20. 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.

  1. Infrasound Sensor Models and Evaluations

    SciTech Connect

    KROMER,RICHARD P.; MCDONALD,TIMOTHY S.

    2000-07-31

    Sandia National Laboratories has continued to evaluate the performance of infrasound sensors that are candidates for use by the International Monitoring System (IMS) for the Comprehensive Nuclear-Test-Ban Treaty Organization. The performance criteria against which these sensors are assessed are specified in ``Operational Manual for Infra-sound Monitoring and the International Exchange of Infrasound Data''. This presentation includes the results of efforts concerning two of these sensors: (1) Chaparral Physics Model 5; and (2) CEA MB2000. Sandia is working with Chaparral Physics in order to improve the capability of the Model 5 (a prototype sensor) to be calibrated and evaluated. With the assistance of the Scripps Institution of Oceanography, Sandia is also conducting tests to evaluate the performance of the CEA MB2000. Sensor models based on theoretical transfer functions and manufacturer specifications for these two devices have been developed. This presentation will feature the results of coherence-based data analysis of signals from a huddle test, utilizing several sensors of both types, in order to verify the sensor performance.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The explosive fragmentation of the 2013 Chelyabinsk meteorite generated a large airburst with an equivalent yield of 500 kT TNT. It is the most energetic event recorded by the infrasound component of the Comprehensive Nuclear-Test-Ban Treaty-International Monitoring System (CTBT-IMS), globally detected by 20 out of 42 operational stations. This study performs a station-by-station estimation of the IMS detection capability to explain infrasound detections and nondetections from short to long distances, using the Chelyabinsk meteorite as global reference event. Investigated parameters influencing the detection capability are the directivity of the line source signal, the ducting of acoustic energy, and the individual noise conditions at each station. Findings include a clear detection preference for stations perpendicular to the meteorite trajectory, even over large distances. Only a weak influence of stratospheric ducting is observed for this low-frequency case. Furthermore, a strong dependence on the diurnal variability of background noise levels at each station is observed, favoring nocturnal detections.

  5. 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.

  6. Atmospheric Infrasound from Hurricanes Felicia and Neki of 2009

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  7. The stratospheric arrival pair in infrasound propagation.

    PubMed

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

    2015-04-01

    The ideal case of a deep and well-formed stratospheric duct for long range infrasound propagation in the absence of tropospheric ducting is considered. A canonical form, that of a pair of arrivals, for ground returns of impulsive signals in a stratospheric duct is determined. The canonical form is derived from the geometrical acoustics approximation, and is validated and extended through full wave modeling. The full caustic structure of the field of ray paths is found and used to determine phase relations between the contributions to the wavetrain from different propagation paths. Finally, comparison with data collected from the 2005 fuel gas depot explosion in Buncefield, England is made. The correspondence between the theoretical results and the observations is shown to be quite good. PMID:25920837

  8. Microseism and infrasound generation by cyclones.

    PubMed

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

    2003-05-01

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

  9. Characterization of NCPA Infrasound Sensors

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Infrasound workshop for CTBT monitoring: Proceedings

    SciTech Connect

    Christie, D.; Whitaker, R.

    1998-11-01

    It is expected that the establishment of new infrasound stations in the global IMS network by the Provisional Technical Secretariat of the CTBTO in Vienna will commence in the middle of 1998. Thus, decisions on the final operational design for IMS infrasound stations will have to be made within the next 12 months. Though many of the basic design problems have been resolved, it is clear that further work needs to be carried out during the coming year to ensure that IMS infrasound stations will operate with maximum capability in accord with the specifications determined during the May 1997 PrepCom Meeting. Some of the papers presented at the Workshop suggest that it may be difficult to design a four-element infrasound array station that will reliably detect and locate infrasound signals at all frequencies in the specified range from 0.02 to 4.0 Hz in all noise environments. Hence, if the basic design of an infrasound array is restricted to four array elements, the final optimized design may be suited only to the detection and location of signals in a more limited pass-band. Several participants have also noted that the reliable discrimination of infrasound signals could be quite difficult if the detection system leads to signal distortion. Thus, it has been emphasized that the detection system should not, if possible, compromise signal fidelity. This report contains the workshop agenda, a list of participants, and abstracts and viewgraphs from each presentation.

  11. Measurement and simulation of ground-coupled air waves and diffracted infrasound from the Kokoxili Earthquake, 14th Nov. 2001

    NASA Astrophysics Data System (ADS)

    Guilbert, J.; Le Pichon, A.; Vallee, M.; Alcoverro, B.; Ulziibat, M.

    2002-12-01

    On November 14, 2001, a strong earthquake measuring Mm 7.8 occurred in the Qinghai Province (China). Coherent infrasonic waves were detected during more than one hour by the IS34 infrasound station in Mongolia (~1500 km from the epicenter). Using an appropriate acoustic propagation model, the inversion of the infrasonic measurements allows a precise localization of the secondary sources distribution along the Qinghai mountains. The predominant source of infrasound is likely ground-coupled air waves generated by the strong variations of topography due to energy carried out by surface seismic waves that travel from the epicenter region through the Qinghai mountains. To confirm the locations of these distant source regions, the pressure field has been reconstructed at IS34. For each element of the topography, a synthetic seismogram used as an input of the integral relation of Huygens-Rayleigh permits to estimate the pressure variation. The synthetic pressure field fit the recorded data in azimuth and in relative amplitude. These results confirm the hypothesis of a strong coupling between the Rayleigh waves and the atmosphere, as it has already been observed during the Arequipa earthquake of June 23rd 2001. The simulations also permit to validate the infrasonic propagation model. This favorable setting within a region of high mountains makes easier the evaluation of the relative contribution of the different source mechanisms involved in large earthquake.

  12. 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).

  13. 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.

  14. Upper atmospheric processes as measured by collocated Lidar, infrasound, radiometer and airglow measurements

    NASA Astrophysics Data System (ADS)

    Le Pichon, A.; Blanc, E.; Assink, J. D.; Ceranna, L.; Pilger, C.; Ross, O.; Keckhut, P.; Hauchecorne, A.; Schmidt, C.; Bittner, M.; Wuest, S.; Rüfenacht, R.; Kaempfer, N.; Smets, P.

    2013-12-01

    To better initialize weather forecasting systems, a key challenge is to understand stratosphere-resolving climate models. The ARISE project (http://arise-project.eu/) aims to design a novel infrastructure integrating different atmospheric observation networks to accurately recover the vertical structure of the wind and temperature from the ground to the mesosphere. This network includes Lidar and mesospheric airglow observations, complemented by continuous infrasound measurements. Together with additional ground-based wind radar system, such complementary techniques help to better describe the interaction between atmospheric layers from the ground to the mesosphere and the influence of large scale waves on the atmospheric dynamics. Systematic comparisons between these observations and the ECMWF upper wind and temperature models (http://www.ecmwf.int/) have been performed at the OHP site (Haute-Provence Observatory, France). The main results are outlined below. - Systematic comparisons between Lidar soundings (NDACC, http://ndacc-lidar.org/) and ECMWF highlight differences increasing with altitude. Below 50 km altitude, differences are as large as 20°K. In average, the temperature appears to be overestimated by ~5 m/s in the stratosphere and underestimated by ~10 m/s in the mesopause. - Comparisons with collocated infrasound measurements provide additional useful integrated information about the structure of the stratospheric waveguide. Below 0.5 Hz, most infrasound signals originate from ocean swells in the North Atlantic region. As expected, since most long-range propagating signals travel in the stratospheric waveguide, improved detection capability occurs downwind. Deviations from this trend are either related to short time-scale variability of the atmosphere (e.g., large-scale planetary waves, stratospheric warming effects), or can be explained by changes in the nature of the source. We investigate possible correlation between unexpected propagation paths and

  15. Infrasound from Bolides: Inverse Remote Sensing

    NASA Astrophysics Data System (ADS)

    Revelle, D. O.

    2003-12-01

    The entry of large meteor-fireballs (bolides) into the atmosphere generates numerous physical phenomena that allows its detection including the generation of substantial amounts of heat, light, propagating blast waves, dissociation, ionization, aerosols, remnant wake turbulence, upward propagating ionospheric waves, VLF radio wave emission, etc. The low frequency remnant of the blast wave at great range (from 10 Hz to as long as a few minutes in period) can be detected by ground-based infrasonic pressure sensor arrays at ranges of hundreds to tens of thousands of kilometers depending on the kinetic energy of the bolide and on local wind-noise. The multiple array detection allows the location of the source to be determined (latitude, longitude) with uncertainties in the determined great-circle bearing increasing substantially beyond about 10,000 km in range. A reverse ray tracing or ray-mode analysis can also allow the range and altitude of the source to be estimated as well even with data from only a single array. While these IMS on-going detection's will add new and different types of bolides to the already existing database regarding the global influx rate, the data can also be used to ascertain detailed properties of the bolide. Using this information in combination with realistic models of entry and possible satellite detection's, we can also infer detailed aspects about the bolide's properties. We will review this detection problem utilizing infrasound data from some recent events and in combination with ground-based cameras/radiometers detections.

  16. Large meteoroid detection using the global IMS infrasound system

    SciTech Connect

    ReVelle, D. O.

    2002-01-01

    Numerous signals will be routinely detected using the 60 array, global IMS (International Monitoring System) infrasound network. Infrasonic signals are sub-audible quasi longitudinal, atmospheric waves in the frequency band from about 10 Hz to -5 minutes in period (limited by human acoustic audibility in the high frequency limit and by the wave-guide acoustic cut-off frequency and the Brunt Vaisalla frequency in the low frequency limit) These small amplitude waves are a natural subset of the well-known atmospheric acoustic-gravity wave regime which has been identified from the linearized equations of geophysical fluid mechanics in the flat earth approximation, neglecting the earth's rotation, etc. For the IMS network the instrumental pressure sensor response was chosen to range from -4 to 0.02 Hz. These are ground-based arrays of typically 4 to 9 sensors with separations of about 1-2 km between the array elements. Examples of naturally occurring impulsive sources of infrasound include volcanic eruptions, earthquakes, bolides (large meteor-fireballs entering the atmospheric at very high speeds up to -300 times faster than ground-level sound waves), microbaroms (the 'voice of the sea' due to the interaction of atmospheric storms and surface ocean waves) and the supersonic motion of the auroral electrojet at about 100 km altitude (auroral infrasonic waves), etc. In this paper we will briefly summarize our current state of knowledge of infrasound signals from bolides. This summary will include the generation of the signals at the complex, quasi-cylindrical line source, to the refraction and diffraction of the propagating waves by the middle atmospheric and tropospheric temperature and wind systems and finally, the detection of the signals and their interpretation by inferring the source properties, Le., source altitude, blast radius (see below) and the source energy, etc. In addition, we will use infrasound from energetic bolides to estimate the expected steady state

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

    PubMed

    Naugolnykh, Konstantin; Rybak, Samuil

    2008-12-01

    A sound wave in supersaturated water vapor can modulate both the process of heat release caused by condensation, and subsequently, as a result, the resonance interaction of sound with the modulated heat release provides sound amplification. High-intensity atmospheric perturbations such as cyclones and thunderstorms generate infrasound, which is detectable at large distances from the source. The wave-condensation instability can lead to variation in the level of infrasound radiation by a developing cyclone, and this can be as a precursor of these intense atmospheric events. PMID:19206769

  18. 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.

  19. Characterization of absorption and nonlinear effects in infrasound propagation using an augmented Burgers' equation

    NASA Astrophysics Data System (ADS)

    Sabatini, R.; Bailly, C.; Marsden, O.; Gainville, O.

    2016-09-01

    The long-range atmospheric propagation of explosion-like waves of frequency in the infrasound range is investigated using nonlinear ray theory. Simulations are performed for sources of increasing amplitude on rays up to the lower thermosphere and for distances of hundreds of kilometres. A study of the attenuation of the waveforms observed at ground level induced by both the classical mechanisms and the vibrational relaxation of the molecules comprising the atmospheric gas is carried out. The relative importance of classical absorption and vibrational relaxation along the typical atmospheric propagation trajectories is assessed. Nonlinear effects are highlighted as well and particular emphasis is placed on their strong interaction with absorption phenomena. A detailed description of the propagation model and of the numerical algorithm used in the present work is first reported. Results are then discussed and the importance of the different mechanisms is clarified.

  20. Reduction of infrasounds in machines with hydrostatic drive.

    PubMed

    Kudźma, Zygmunt; Stosiak, Michał

    2013-01-01

    Some hazards posed by the operation of hydraulic systems, connected with low-frequency vibrations and noise are presented. Special attention is focused on infrasounds. The sources of low-frequency vibrations and noise and ways of reducing them are indicated. An original solution ensuring the effective reduction of vibrations and noise in a wide frequency range, i.e., a wide-band damper of pressure fluctuations, also performing the function of an acoustic filter, is proposed. The effectiveness of the damper was confirmed by the results of laboratory tests and tests carried out on engineering machines working in real conditions.

  1. Observational Evaluation of Mobile Source Emissions

    NASA Astrophysics Data System (ADS)

    Frost, G. J.; McKeen, S.; Trainer, M.; Aikin, K.; Peischl, J.; Ryerson, T.; Holloway, J.; Petron, G.; Tans, P.; Harley, R.

    2007-12-01

    Ambient ratios of NOx, CO, and CO2 sampled by aircraft in Houston and Dallas during the 2000 and 2006 Texas Air Quality Study (TexAQS) are compared with each other and with observations at a Houston highway tunnel. From these measurements we estimate 2000 and 2006 emissions for Houston and Dallas mobile sources. The observations demonstrate time-of-day variations in the relative contributions from gasoline and diesel combustion which are consistent with known traffic patterns. We incorporate CO2 emissions derived from the Federal Highway Administration's motor vehicle fuel use statistics into the EPA's National Emission Inventory (NEI), resulting in an emission data set for NOx, CO, and CO2 with 4-km spatial and hourly temporal resolution. Comparison of the emission ratios derived from the TexAQS observations with this inventory allows a direct evaluation of the NEI mobile source NOx and CO emissions.

  2. 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

  3. 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

  4. 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

  5. Evaluation of a prototype infrasound system

    SciTech Connect

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

    1997-08-01

    Under Department of Energy sponsorship, Sandia National Laboratories and Los Alamos National Laboratory cooperated to develop a prototype infrasonic array, with associated documentation, that could be used as part of the International Monitoring System. The United States Government or foreign countries could procure commercially available systems based on this prototype to fulfill their Comprehensive Test Ban Treaty (CTBT) obligations. The prototype is a four-element array in a triangular layout as recommended in CD/NTB/WP.224 with an element at each corner and one in the center. The prototype test configuration utilize an array spacing of 1 km. The prototype infrasound system has the following objectives: (1) Provide a prototype that reliably acquires and transmits near real-time infrasonic data to facilitate the rapid location and identification of atmospheric events. (2) Provide documentation that could be used by the United States and foreign countries to procure infrasound systems commercially to fulfill their CTBT responsibilities. Infrasonic monitoring is an effective, low cost technology for detecting atmospheric explosions. The low frequency components of explosion signals propagate to long ranges (few thousand kilometers) where they can be detected with an array of sensors. Los Alamos National Laboratory`s expertise in infrasound systems and phenomenology when combined with Sandia`s expertise in providing verification quality system for treaty monitoring make an excellent team to provide the prototype infrasound sensor system. By September 1997, the prototype infrasound system will have been procured, integrated, evaluated and documented. Final documentation will include a system requirements document, an evaluation report and a hardware design document. The hardware design document will describe the various hardware components used in the infrasound prototype and their interrelationships.

  6. The effects of high level infrasound

    SciTech Connect

    Johnson, D.L.

    1980-02-01

    This paper will attempt to survey the current knowledge on the effects of relative high levels of infrasound on humans. While this conference is concerned mainly about hearing, some discussion of other physiological effects is appropriate. Such discussion also serves to highlight a basic question, 'Is hearing the main concern of infrasound and low frequency exposure, or is there a more sensitive mechanism'. It would be comforting to know that the focal point of this conference is indeed the most important concern. Therefore, besides hearing loss and auditory threshold of infrasonic and low frequency exposure, four other effects will be provided. These are performance, respiration, annoyance, and vibration.

  7. Locating industrial VOC sources with aircraft observations.

    PubMed

    Toscano, P; Gioli, B; Dugheri, S; Salvini, A; Matese, A; Bonacchi, A; Zaldei, A; Cupelli, V; Miglietta, F

    2011-05-01

    Observation and characterization of environmental pollution, focussing on Volatile Organic Compounds (VOCs), in a high-risk industrial area, are particularly important in order to provide indications on a safe level of exposure, indicate eventual priorities and advise on policy interventions. The aim of this study is to use the Solid Phase Micro Extraction (SPME) method to measure VOCs, directly coupled with atmospheric measurements taken on a small aircraft environmental platform, to evaluate and locate the presence of VOC emission sources in the Marghera industrial area. Lab analysis of collected SPME fibres and subsequent analysis of mass spectrum and chromatograms in Scan Mode allowed the detection of a wide range of VOCs. The combination of this information during the monitoring campaign allowed a model (Gaussian Plume) to be implemented that estimates the localization of emission sources on the ground.

  8. 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

  9. Evolution of the CTBTO Infrasound Technology Roadmap

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    The CTBTO's nuclear explosion monitoring program needs to maintain its effectiveness and ensure its long-term relevance to the verification regime. The aims of its Infrasound Technology Roadmap (ITR) are to (1) establish a clear way forwards in accordance with the overall CTBTO nuclear monitoring vision, (2) couple scientific work with technology management, and (3) build upon existing technological accomplishments and project them into near-future technical targets. This ITR has a time horizon of seven years, and its activities are closely aligned to the Provisional Technical Secretariat's Technology Foresight Program, which extends its perspective to 20+ years. Phase 1 of the Roadmap effort requested input from the international infrasound community through the Request for Contributions released on 15 November 2012 (RFC R1). A set of metrics were selected to lend fairness, accountability, and scientific integrity to the evaluation of technical topics. The RFC was an inclusive, participatory effort inviting individual scientists to identify and assess technologies and procedures that can be infused into the IMS to meet its monitoring requirements and help evolve technology to achieve a reliable, sustainable and trustworthy monitoring system. We received over 680 individual topic evaluations from 52 members of the international infrasound community, with a 93% response rate. We present the statistical results from our survey as well as the highlights of the draft Infrasound Technology Roadmap Document.

  10. How to estimate yield using remote infrasound recordings?

    NASA Astrophysics Data System (ADS)

    Ceranna, L.; Le Pichon, A.

    2011-12-01

    Currently, estimates of radiated source energy or yield are based on empirical yield-scaling relations, which account for prevailing stratospheric winds. The most commonly used relation is derived from a high explosive dataset (Whitaker and Mutschlecner, 2008). However, limitations of this approach have been found by comparisons with reference events where problems arise either due to a fixed stratospheric wind speed or by an over-estimate of a known yield (e.g., Green et al., 2010). More realistic predictions can be achieved by using improved atmospheric specifications and measured station noise characteristics, as well as attenuation relations derived from operational propagation tools. An improved yield-scaling relation is considered (Le Pichon et al., 2011) which accounts for near-real time atmospheric up-dates and background noise calculations at various times of day for each month. This relation depends on a limited number of parameters describing the source (source altitudes between 0 and 30 km, dominant frequencies between 0.01 and 4.0 Hz) and the atmosphere (including naturally occurring gravity waves, altitude and strength of the stratospheric wind jet). All these parameters have a significant impact on infrasound propagation. We present a first approach for source energy (yield) estimates by combining all this information which provides a realistic picture of both station specific recording conditions and infrasound propagation from source to receiver. The spectrum of a full wave-train, whereas the local background noise is removed, can be inverted to a noise-free source spectrum at a certain reference distance, which is in turn related to certain yield based on empirical relations (e.g., Glasstone & Dolan, 1977). The capability of our approach is demonstrated for the two Sayarim explosion data-sets.

  11. How to estimate yield using remote infrasound recordings?

    NASA Astrophysics Data System (ADS)

    Ceranna, L.; Le Pichon, A.

    2012-04-01

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

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

    SciTech Connect

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

    1998-12-31

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

  13. 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.

  14. Ground-coupled air waves and diffracted infrasound from the Arequipa earthquake of June 23, 2001

    NASA Astrophysics Data System (ADS)

    Le Pichon, A.; Guilbert, J.; Vega, A.; Garcés, M.; Brachet, N.

    2002-09-01

    On June 23, 2001, a strong earthquake measuring Mw 8.4 occurred along the coast of south-central Peru. Coherent infrasonic waves were detected over a period of one hour by the IS08 infrasound station in Bolivia. Analysis of the ground-coupled air waves shows that the rupture propagated from the northwestern to the southeastern part of the fault with a rupture velocity of 3.3 km/s. The azimuth variation of the infrasonic waves is attributed to a distribution of secondary sources along the highest mountain ranges, which excite infrasonic waves that are diffracted to the ground. The predominant source of infrasound is likely distributed along the Andean Cordillera. Using the azimuth and arrival time determination, the horizontal scale size of the distant source regions of infrasonic waves is reconstructed over distances greater than 400 km.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    PubMed

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

    2012-01-01

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

  18. 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

  19. Infrasound and Seismic Recordings of a US Airstrike on an ISIS Car Bomb Factory on June 3, 2015

    NASA Astrophysics Data System (ADS)

    Aleqabi, G. I.; Ghalib, H. A. A.; Wysession, M. E.

    2015-12-01

    Concurrent infrasound and seismic records of a jet airstrike in Iraq are presented. Media reports stated that US jets carried out a large airstrike on June 3, 2015, just after midnight local time, that targeted and destroyed an ISIS car bomb factory in Hawija, Iraq, just south of the city of Kirkuk, Iraq. The resulting explosion was felt within Kirkuk and at other locations as far as 34 km away from the Hawija factory. Seismic broadband stations located in northern Iraq, at a distance of about 160 km, show clear simultaneous signals of infrasound waves on the seismometers as well as on collocated infrasound equipment. From an analysis of the body waves, the Pg to Lg time difference is nearly ~20 sec, with a back azimuth of 250o to 260o, which is consistent with explosion location. The time difference between the Pg and infrasound signals is just over 7 minutes, consistent with sound speed in the atmosphere. No clear Rg wave was observed. As was demonstrated by Aleqabi, Wysession, and Ghalib [2015, BSSA, in press], broadband seismic recordings are able to identify and distinguish between several different kinds of MOUT (military operations in urban terrain) and even determine the magnitudes of ordinance used in certain blasts. The addition of collocated infrasound equipment provides additional constraints that can be used in the analysis of the size and form of the MOUT.

  20. Infrasonic observations of the June 2009 Sarychev Peak eruption, Kuril Islands: Implications for infrasonic monitoring of remote explosive volcanism

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Le Pichon, Alexis; Vergoz, Julien; Herry, Pascal; Lalande, Jean-Marie; Lee, Hee-il; Che, Il-Young; Rybin, Alexander

    2011-02-01

    Sarychev Peak (SP), located on Ostrov Matua, Kurils, erupted explosively during 11-16 June 2009. Whereas remote seismic stations did not record the eruption, we report atmospheric infrasound (acoustic wave ~ 0.01-20 Hz) observations of the eruption at seven infrasound arrays located at ranges of ~ 640-6400 km from SP. The infrasound arrays consist of stations of the International Monitoring System global infrasound network and additional stations operated by the Korea Institute of Geoscience and Mineral Resources. Signals at the three closest recording stations IS44 (643 km, Petropavlovsk-Kamchatskiy, Kamchatka Krai, Russia), IS45 (1690 km, Ussuriysk, Russia), and IS30 (1774 km, Isumi, Japan) represent a detailed record of the explosion chronology that correlates well with an eruption chronology based on satellite data (TERRA, NOAA, MTSAT). The eruption chronology inferred from infrasound data has a higher temporal resolution than that obtained with satellite data. Atmosphere-corrected infrasonic source locations determined from backazimuth cross-bearings of first-arrivals have a mean centroid ~ 15 km from the true location of SP. Scatter in source locations of up to ~ 100 km result from currently unresolved details of atmospheric propagation and source complexity. We observe systematic time-variations in trace-velocity, backazimuth deviation, and signal frequency content at IS44. Preliminary investigation of atmospheric propagation from SP to IS44 indicates that these variations can be attributed to solar tide variability in the thermosphere. It is well known that additional information about active volcanic processes can be learned by deploying infrasonic sensors with seismometers at erupting volcanoes. This study further highlights the significant potential of infrasound arrays for monitoring volcanic regions such as the Kurils that have only sparse seismic network coverage.

  1. Acoustic buffeting by infrasound in a low vibration facility

    NASA Astrophysics Data System (ADS)

    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.

  2. 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

    ... to detect natural or man-made infrasound sources including earthquakes, volcanic eruptions, rocket... recent being that of August 13, 2009 (74 FR 41325 (August 14, 2009)), has continued the EAR in effect... seq.; 22 U.S.C. 7210; Sec 1503, Pub. L. 108-11, 117 Stat. 559; E.O. 12058, 43 FR 20947, 3 CFR,...

  3. Effects of topography and atmospheric structure on volcano infrasound

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Proper interpretation of infrasonic waves produced by volcanic explosions requires understanding of weather and topographic effects. We have studied infrasound produced by two different volcanoes (Kilauea and Tungurahua) to determine the influence of topographic and atmospheric conditions on the infrasonic records corresponding to several weeks of eruptive activity. This analysis is necessary to understand and correct for phase and amplitude responses in order to properly perform waveform modeling. For instance, these corrections are necessary to obtain a better estimate of volume flux from the volcanic vent. The first case study is a dataset acquired during June of 2008 at Kilauea volcano in Hawaii, focused on the active Halemaumau Vent. Several days of infrasonic tremor were recorded by a 3-station infrasound network. These records show a strong influence of wind and topography in one of the three stations of the network. This station was located 2370 m from the vent, at a comparable distance to the other stations, but line of sight to the vent was obstructed by a 50-meter high crater edge, which introduced diffraction effects. Periods when wind blew in the vent-station direction are correlated with increase in infrasonic energy in the 0.5 - 1 Hz bandwidth. The second case focuses on a campaign conducted in June 2009 at Tungurahua Volcano, Ecuador. This study implemented two infrasonic arrays located on the flanks of the volcano 6000m north of the vent and on the flanks of an adjacent hill, 11,500m northeast. Compared to the proximal array a distinctive attenuation is evident at certain frequencies (0.5-1.5 Hz) at the distal array. This degree of attenuation is time-variant and is mostly likely related to changing atmospheric structure. An alternative explanation for the apparent spectral differences between near and far stations (and their evolution over time) is a complex (and changing) source geometry due to non-compact sources.

  4. Infrasound records from U.S. atmospheric tests

    SciTech Connect

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

    1998-07-01

    The United States conducted over 100 atmospheric nuclear tests at the Nevada Test Site from 1951 through 1962. Some of the earliest tests caused unexpected damage, primarily broken glass and cracked plaster, in Las Vegas and other surrounding communities. To address this problem, Sandia initiated a program to monitor and predict the pressure waves around NTS. Infrasound recording systems were developed, then field for all tests beginning with Operation Buster in October 1951. Investigators soon discovered that near-surface temperature inversions and wind profiles caused the damaging pressures in Las Vegas. A typical test was recorded at about a dozen stations from the Control Point on NTS to as far away as Pasadena, CA. In addition, some tests in the South Pacific were monitored, as well as numerous chemical explosions. Strip charts recorded signals in the frequency band from 0.05 to 30 Hz, and the paper tapes were achieved at Sandia in the early 1970s. The NTS events ranged in yield from below 1 ton to 74 kilotons; source altitudes varied from near ground level (including some cratering experiments) to as high as 11 km. The resulting data contain a wealth of information on the source function, yield scaling and regional propagation of infrasound signals from atmospheric explosions. The renewed interest in infrasonic monitoring for CTBT verification has prompted the authors to exhume some of the archived records. The authors plan to digitize the signals from several tests and evaluate their applicability to CTBT issues. In addition, they will collect any existing parametric measurements for these records (arrival times, amplitudes, etc.). All data will be converted to CSS database format and made available to the research community. If appropriate, the resulting information could also be included in the Knowledge Base under development for CTBT monitoring.

  5. 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

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

    NASA Astrophysics Data System (ADS)

    Howard, J. E.

    2014-12-01

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

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

    PubMed

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

    2013-11-01

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

  8. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  10. IGRINS observations toward Class I disk sources

    NASA Astrophysics Data System (ADS)

    Lee, Seokho; Lee, Jeong-Eun; Park, Sunkyung; Jaffe, Daniel T.; Lee, Jae-Joon

    2015-08-01

    We present the high-resolution Immersion GRating INfrared spectrograph (IGRINS) spectra of Class I sources, including IRAS03445+3242 and IRAS04239+2436. These sources show the evidence of Keplerian disks; the broadened CO overtone (Δ v=2) transitions in emission and neutral metal lines (Mg I, Fe I, and Al I) in absorption. The thin Keplerian disk with a rotational velocity of ~100 km s-1 and a gas temperature of 5000 K at the innermost annulus can reproduce the CO overtone transitions including the bandhead emission. The temperature is assumed to have a power-law distribution with p=0.5. The outer colder disk or the envelope needs to fit the narrow absorption features overlaid on the broad emission lines in the CO overtone transitions. Other atomic and molecular emission lines likely radiated from the disk and/or wind are also detected.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    On August 24th 2015, a 67 days long eruptive activity started at Piton de la Fournaise Volcano. During the last phases of the eruption we deployed a portable, small aperture, infrasonic array which allowed us to record unprecedented data from effusive volcanic activity. The array consisted on four, few tens of meters spaced, infrasound pressure sensors and was installed on the outer rim of the Enclos Foqué, roughly 2.5 km far from the active vent, sited on the southern flank of the central cone. The system was almost continuously operating from October, 15th to December, 7th 2015, thus recording the end of the first eruptive phase (Autust 24th - October 17th) as well as the two short-living following phases (from 22 to 24 and from 29 to 31 October, 2015). The infrasound records have been coupled with discrete high-rate (30 Hz) thermal and visible imagery acquisitions located at a short distance from the vent (100-200 m) providing detailed information on the eruptive source dynamics. The comparison with seismic and ground tilt data recorded by the permanent network operated by the Observatoire Volcanologique du Piton de la Fournaise (OVPF), shows that infrasound can be succesfully used to locate the source, detect the onset, and the end, of the effusive phases as well as accurately track the time evolution of the effusive process. We present results which allows a detailed analysis of the shallow magma dynamics during the effusive activity at Piton de la Fournaise Volcano. As far as we know these are amongst the few rare infrasound dataset reported for this style of basaltic volcanic activity.

  13. Ultraviolet observations of selected astronomical sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1988-01-01

    The results of the 9th and 10th IUE episode programs listed are summarized. Observations and basic data reductions were completed for 4 extragalactic programs which were allocated a total of 9 US1 shifts, and 2 stellar investigations which used 10 US2 shifts. Use was made of the Goddard RDAF to obtain better signal to noise ratio spectra using the Gaussian extraction routines. Highlights include the first IUE observations of H1821+643, the second brightest quasar in the sky, and the discovery of accretion disk emission line profiles in the elliptical Seyfert galaxy Arp 102B. Both of these observations were accompanied by nearly simultaneous optical spectrophotometry. As a result of the stellar programs, large amplitude variability associated with the rotation period of the Ap stars 78 Vir and 53 Cam was found.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Vinogradov, Y.; Vinogradov, A.

    2003-04-01

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

  16. Electromagnetic geophysical observation with controlled source

    NASA Astrophysics Data System (ADS)

    Hachay, Olga; Khachay, Oleg

    2016-04-01

    In the paper the new theoretical and methodical approaches are examined for detailed investigations of the structure and state of the geological medium, and its behavior as a dynamic system in reaction to external man-made influences. To solve this problem it is necessary to use geophysical methods that have sufficient resolution and that are built on more complicated models than layered or layered-block models. One of these methods is the electromagnetic induction frequency-geometrical method with controlled sources. Here we consider new approaches using this method for monitoring rock shock media by means of natural experiments and interpretation of the practical results. That method can be used by oil production in mines, where the same events of non stability can occur. The key ideas of twenty first century geophysics from the point of view of geologist academician A.N. Dmitrievskiy [Dmitrievskiy, 2009] are as follows. "The geophysics of the twenty first century is an understanding that the Earth is a self-developing, self-supporting geo-cybernetic system, in which the role of the driving mechanism is played by the field gradients; the evolution of geological processes is a continuous chain of transformations and the interaction of geophysical fields in the litho- hydro- and atmosphere. The use of geophysical principles of a hierarchical quantum of geophysical space, non-linear effects, and the effects of reradiating geophysical fields will allow the creation of a new geophysics. The research, in which earlier only pure geophysical processes and technologies were considered, nowadays tends to include into consideration geophysical-chemical processes and technologies. This transformation will allow us to solve the problems of forecasting geo-objects and geo-processes in previously unavailable geological-technological conditions." The results obtained allow us to make the following conclusions, according to the key ideas of academician A.N. Dmitrievskiy: the rock

  17. Frequency-wavenumber processing for infrasound distributed arrays.

    PubMed

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

    2013-10-01

    The work described herein discusses the application of a frequency-wavenumber signal processing technique to signals from rectangular infrasound arrays for detection and estimation of the direction of travel of infrasound. Arrays of 100 sensors were arranged in square configurations with sensor spacing of 2 m. Wind noise data were collected at one site. Synthetic infrasound signals were superposed on top of the wind noise to determine the accuracy and sensitivity of the technique with respect to signal-to-noise ratio. The technique was then applied to an impulsive event recorded at a different site. Preliminary results demonstrated the feasibility of this approach. PMID:24116535

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. ASTERIA: A Balloon-Borne Experiment for Infrasound Detection

    NASA Astrophysics Data System (ADS)

    Young, Eliot; Wahl, Kerry; Ballard, Courtney; Daugherty, Emily; Dullea, Connor; Garner, Kyle; Heaney, Martin; Thom, Ian; Von Hendy, Michael; Young, Emma; Diller, Jed; Dischner, Zach; Drob, Douglas; Boslough, Mark; Brown, Peter

    2015-04-01

    ASTERIA (Aloft Stratospheric Testbed for Experimental Research on Infrasonic Activity) is a small (<20 kg) payload designed to measure infrasound disturbances from a balloon-borne platform at altitudes near 60,000 ft (~20 km). A balloon platform is expected to have two advantages over ground-based infrasound stations: a relatively benign wind environment and exposure to higher signal strengths within a stratospheric duct. ASTERIA's nominal sensitivity requirements are to measure waves between 0.1 to 20 Hz at the 0.1 Pa level with signal-to-noise ratios of 5 or better. At the time of this writing, we have tested wave sensors based on the differential pressure transducers recently flown by Bowman et al. (2014) on a NASA/HASP (High Altitude Student Payload); our modified pressure sensor was tested in a NOAA piston-bellows facility in Boulder, CO. Our goal of characterizing 0.1 Pa amplitude waves requires that combined noise sources are below the the 0.02 Pa rms level. ASTERIA carries five differential transducers with port inlets arranged a diamond-like pattern (one zenith- and one nadir-facing port, plus three horizontal ports equally spaced in azimuth). Baffling for these sensors is a hybrid of perforated tubing and porous barriers, as described in Hedlin (2014). Other noise sources of concern include the electronic amplification of the transducer voltages and low-frequency pressure waves caused by pendulum or twisting modes of the payload. We will report on our plans to characterize and reduce these noise sources. The ASTERIA payload is intended to fly on long-duration super-pressure balloons for intervals of ~100 days. We plan to conduct an experiment in the summer or fall of 2015 in which a calibrated disturbance is set off and detected simultaneously from stratospheric ASTERIA payloads and ground-based stations. References: 1) Bowman et al. 2014, "Balloons over Volcanoes Scientific Report," HASP 2014 final report. 2) Hedlin 2003, "Infrasonic Wind-noise Reduction

  20. Infrasonic Observations of the Final Flight of Space Shuttle Atlantis

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Infrasound arrivals from the July 2011 Space Shuttle Atlantis launch and re-entry were observed ~2,500 km away at Sandia's (SNL) Facility for Acceptance, Calibration and Testing (FACT) seven-element infrasound array. Space Shuttle Atlantis (STS-135) launched from the Kennedy Space Center (Florida) on July 8, 2011 for its final 14 day mission, culminating in a successful re-entry and landing on July 21, 2011. Infrasound from both the launch and the re-entry were clearly observed at the SNL FACT array due to the seasonal zonal wind reversals in the stratosphere and the quiet of early morning for the re-entry. In the northern hemisphere summer infrasound sources originating east of the array are observed more clearly than sources west of the array. While both the launch and re-entry were observed, the duration of detection, trace velocity, and correlation across the array varied. The launch was detected at the array for ~2 minutes while the re-entry was observed for a considerably greater amount of time, ~25 minutes. The launch of the shuttle produced less detectable infrasound because the trajectory carried the shuttle east, away from the array and disturbed the atmosphere to a lesser extent than at re-entry. During re-entry the shuttle passed much closer to the array, displaced more atmosphere, and generated infrasound for a longer period of time. The correlation across the array increased dramatically over background, peaking above 0.4 for the launch and over 0.9 for re-entry. In both cases the trace velocity stabilized between 0.35 and 0.38 km/s above background. Using FK processing we determined a back azimuth for the launch that correlated well to the location of the launch site at ~100°. Due to the higher, supersonic velocities of the shuttle and the atmospheric disturbance of re-entry, we were able to calculate several back azimuths over the duration of the observed signal. The back azimuths correlated very well with trajectory data provided by NASA and

  1. 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.

  2. Can Gamma Ray Bursts be Detected Using Infrasound

    NASA Astrophysics Data System (ADS)

    Palmer, Jahi; McGruder, C.; Hetzer, C.

    2010-01-01

    CAN GAMMA RAY BURST BE DETECTED USING INFRASOUND Infrasound has been used to detect sonic disturbances in earth's atmosphere caused by terrestrial events such as earthquakes and lightning. It may be possible to detect celestial events such as Gamma Ray Bursts (GRB's) through this method. We have searched for GRB's which are known to have caused ionospheric disturbances in infrasonic data. None of the selected GRB's were found to be associated with infrasonic disturbances.

  3. Infrared observations of galactic bulge X-ray sources

    NASA Technical Reports Server (NTRS)

    Hertz, P.; Grindlay, J. E.

    1984-01-01

    Nine unidentified galactic bulge X-ray sources, the recently identified X-ray burster MXB 1728-34, and two optically identified sources (Sco X-1 and MXB 1735-44) were observed with the NASA 3 m Infrared Telescope Facility. The data constrain both the presence of diffuse infrared sources near the X-ray positions and the flux of possible infrared counterparts. None of the nine unidentified sources lies within obscured globular clusters, although there is marginal evidence for diffuse infrared emission near 4U 1822-00 and 4U 1916-05. This implies that at most two additional luminous galactic bulge X-ray sources lie within undiscovered, obscured globular clusters. No infrared counterparts were detected for unidentified sources; the limits derived are consistent with all of the sources observed being similar to the low mass X-ray binary Sco X-1.

  4. IVS Observation of ICRF2-Gaia Transfer Sources

    NASA Astrophysics Data System (ADS)

    Le Bail, K.; Gipson, J. M.; Gordon, D.; MacMillan, D. S.; Behrend, D.; Thomas, C. C.; Bolotin, S.; Himwich, W. E.; Baver, K. D.; Corey, B. E.; Titus, M.; Bourda, G.; Charlot, P.; Collioud, A.

    2016-03-01

    The second realization of the International Celestial Reference Frame (ICRF2), which is the current fundamental celestial reference frame adopted by the International Astronomical Union, is based on Very Long Baseline Interferometry (VLBI) data at radio frequencies in X band and S band. The European Space Agency’s Gaia mission, launched on 2013 December 19, started routine scientific operations in 2014 July. By scanning the whole sky, it is expected to observe ∼500,000 Quasi Stellar Objects in the optical domain an average of 70 times each during the five years of the mission. This means that, in the future, two extragalactic celestial reference frames, at two different frequency domains, will coexist. It will thus be important to align them very accurately. In 2012, the Laboratoire d’Astrophysique de Bordeaux (LAB) selected 195 sources from ICRF2 that will be observed by Gaia and should be suitable for aligning the radio and optical frames: they are called ICRF2-Gaia transfer sources. The LAB submitted a proposal to the International VLBI Service (IVS) to regularly observe these ICRF2-Gaia transfer sources at the same rate as Gaia observes them in the optical realm, e.g., roughly once a month. We describe our successful effort to implement such a program and report on the results. Most observations of the ICRF2-Gaia transfer sources now occur automatically as part of the IVS source monitoring program, while a subset of 37 sources requires special attention. Beginning in 2013, we scheduled 25 VLBI sessions devoted in whole or in part to measuring these 37 sources. Of the 195 sources, all but one have been successfully observed in the 12 months prior to 2015 September 01. Of the sources, 87 met their observing target of 12 successful sessions per year. The position uncertainties of all of the ICRF2-Gaia transfer sources have improved since the start of this observing program. For a subset of 24 sources whose positions were very poorly known, the uncertainty

  5. 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.

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

    PubMed

    Blom, Philip; Marcillo, Omar; Arrowsmith, Stephen

    2016-06-01

    Infrasound from a four-stage sounding rocket was recorded by several arrays within 100 km of the launch pad. Propagation modeling methods have been applied to the known trajectory to predict infrasonic signals at the ground in order to identify what information might be obtained from such observations. There is good agreement between modeled and observed back azimuths, and predicted arrival times for motor ignition signals match those observed. The signal due to the high-altitude stage ignition is found to be low amplitude, despite predictions of weak attenuation. This lack of signal is possibly due to inefficient aeroacoustic coupling in the rarefied upper atmosphere. PMID:27369137

  7. Observe Z sources at High Mass Accretion Rates

    NASA Astrophysics Data System (ADS)

    Canizares, Claude

    2008-09-01

    We propose to test a new interpretation that links mass accretion rate to observed spectral changes in Z-sources in a diffwrent way than previously though. Integral part of the test is to catch Z-source on the horizontal branch (HB). There are a few sources where RXTE and previous observatories established a fairly accurate record of how often they appear on a specific spectral branch. 4 observations for 8 ks each has a 50% chance to observe GX 5-1 on the HB.

  8. Detailed observations of the source of terrestrial narrowband electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.

    1982-01-01

    Detailed observations are presented of a region near the terrestrial plasmapause where narrowband electromagnetic radiation (previously called escaping nonthermal continuum radiation) is being generated. These observations show a direct correspondence between the narrowband radio emissions and electron cyclotron harmonic waves near the upper hybrid resonance frequency. In addition, electromagnetic radiation propagating in the Z-mode is observed in the source region which provides an extremely accurate determination of the electron plasma frequency and, hence, density profile of the source region. The data strongly suggest that electrostatic waves and not Cerenkov radiation are the source of the banded radio emissions and define the coupling which must be described by any viable theory.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    amplitude and lower atmosphere effective sound speed structure. At times of increased sound speed gradient, higher amplitude decay rates are observed, consistent with increased upward refraction of acoustic energy along the propagation path. This study indicates that whilst monitoring activity levels at near-regional ranges can be successful, variable amplitude decay rate means quantitative analysis of infrasound data for eruption intensity and magnitude is not advisable without the consideration of local atmospheric sound speed structure.

  10. International Monitoring System infrasound measurements for the study of large-scale atmospheric waves

    NASA Astrophysics Data System (ADS)

    Marty, Julien; Dalaudier, Francis; Ponceau, Damien; Blanc, Elisabeth

    2010-05-01

    microphones but can still reaches 10 Pa/K. A spectral analysis as well as a study based on diurnal pressure oscillations show that the influence of temperature on IMS pressure measurement is very low. This is mainly due to the fact that microbarometers are set up underground and not subjected to large temperature variations. The seasonal variation of atmospheric tides detected by IMS stations is studied in several Earth locations. It is found that the diurnal pressure oscillation (S1) is comparable in magnitude to the semidiurnal pressure oscillation (S2) over much of the globe except for the low-latitude open oceans, where S2 is about twice as strong as S1. These results are in good agreement with previous modelling and observations. However strong S1 variations, not predicted by global modelling, are also observed during short time-period on continental stations. These variations are not only detected by IMS infrasound sensors but also by absolute pressure sensors part of IMS meteorological stations. The study of these phenomena is of high importance as it can modify atmospheric wind profiles and therefore influence infrasonic wave propagation.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  13. Complementary 45 GHz Observations of the MALT-90 Pilot Sources

    NASA Astrophysics Data System (ADS)

    Fuller, Gary; Rathborne, Jill; Muller, Erik; Cunningham, Maria; Brooks, Kate; Barnes, Peter; Ellingsen, Simon; Longmore, Steven; Wyrowski, Friedrich; Walsh, Andrew; Peretto, Nicolas; Jackson, James

    2009-10-01

    The MALT-90 pilot survey is mapping 200 sources selected from different "finder charts" of massive star forming cores. This pilot survey is designed to provide detection rates, typical line strengths, and source sizes for the various types of objects. Such information is crucial, along with an understanding of the nature of the sources observed, for a rational design of a complete 90 GHz MALT survey. In this proposal we request time to obtain 45 GHz spectra of all the targets in MALT-90 pilot. As well as providing observations of a complementary set of lines to the 90 GHz data, better constraining the properties of the sources, these observations will provide a link allowing a comparison of the results of the MALT-90 and the 45GHz ATCA galactic plane pilot projects.

  14. Gas mass derived by infrasound and UV cameras: Implications for mass flow rate

    NASA Astrophysics Data System (ADS)

    Delle Donne, D.; Ripepe, M.; Lacanna, G.; Tamburello, G.; Bitetto, M.; Aiuppa, A.

    2016-10-01

    Mass Flow Rate is one of the most crucial eruption source parameter used to define magnitude of eruption and to quantify the ash dispersal in the atmosphere. However, this parameter is in general difficult to be derived and no valid technique has been developed yet to measure it in real time with sufficient accuracy. Linear acoustics has been applied to infrasonic pressure waves generated by explosive eruptions to indirectly estimate the gas mass erupted and then the mass flow rate. Here, we test on Stromboli volcano (Italy) the performance of such methodology by comparing the acoustic derived results with independent gas mass estimates obtained with UV cameras, and constraining the acoustic source by thermal imagery. We show that different acoustic methods give comparable total gas masses in the 2 to 1425 kg range, which are fully consistent with the gas masses derived by UV cameras and previous direct SO2 measurements. We show that total erupted gas mass, estimated by infrasound is not simply a function of the initial pressure, but rather the full infrasonic waveform should be considered. Thermal imagery provides evidence that infrasound is generated during the entire gas thrust phase. We provide examples to show how total gas masses derived by infrasonic signals can be affected by large uncertainties if duration of the signal is neglected. Only when duration of infrasound is included, the best correlation (0.8) with UV cameras and the 1:1 direct linear proportionality is obtained. Our results open new perspective for remotely derived gas mass and mass flow rates from acoustic signals.

  15. Characterizing Explosive Eruptions at Sakurajima Volcano, Japan, Using Seismic, Infrasound, Lightning and Video Data

    NASA Astrophysics Data System (ADS)

    Smith, C. M.; Behnke, S. A.; Thomas, R. J.; Edens, H. E.; Cimarelli, C.; Cigala, V.; Van Eaton, A. R.; Iguchi, M.; Miki, D.; McNutt, S. R.

    2015-12-01

    The ability to determine volcanic ash plume characteristics from seismic and/or infrasonic records would enable increased accuracy in volcanic monitoring during times of low visibility. During May-June 2015 a field deployment of 6 infrasound sensors, 2 seismometers, multiple cameras, and 10 Lightning Mapping Array (LMA) stations were deployed around Sakurajima Volcano in Japan. During one month of observations (13 May to 10 June) hundreds of explosive eruptions were observed with plume heights reaching 4.3 km above the vent. The plumes varied in duration, ash content, and physical form. The resulting explosions exhibited a variety of infrasound waveforms including the classic long-period N shape as well as events with a mixture of high and low frequencies. For a subset of larger events, peak pressures ranged from 16 to 741 Pa at a distance of 3.6 km from the vent. The seismic signals are long period and emergent with no clear P or S-waves, although high frequency ground-coupled airwaves are visible in conjunction with the infrasonic record of some of the explosive eruptions. Peak ground displacements on the vertical component ranged from 2.1 to 183 um for the same subset of events. Volcanic lightning was both visually observed and recorded on the LMA stations. One of the goals of this project to determine if there are intrinsic relationships between ash plume characteristics, such as initial velocity or acceleration, ash grain size, texture, and composition, seismic and infrasound waveforms, and the presence and type of volcanic lightning. The rich variety of observations provides a good opportunity to determine such relationships.

  16. The role of infrasounds in maintaining whale herds

    NASA Astrophysics Data System (ADS)

    Payne, Roger S.

    2001-05-01

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

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

    SciTech Connect

    Hart, Darren M.

    2007-10-01

    Sandia National Laboratories has tested and evaluated three Inter Mountain Labs infrasound sensors. The test results included in this report were in response to static and tonal-dynamic input signals. Most test methodologies used were based on IEEE Standards 1057 for Digitizing Waveform Recorders and 1241 for Analog to Digital Converters; others were designed by Sandia specifically for infrasound application evaluation and for supplementary criteria not addressed in the IEEE standards. The objective of this work was to evaluate the overall technical performance of the Inter Mountain Labs (IML) infrasound sensor model SS. The results of this evaluation were only compared to relevant noise models; due to a lack of manufactures documentation notes on the sensors under test prior to testing. The tests selected for this system were chosen to demonstrate different performance aspects of the components under test.

  18. Detectability of Tengchong infrasound array in China

    NASA Astrophysics Data System (ADS)

    Su, Wei; Yuan, Songyong

    2016-04-01

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

  19. 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.

  20. 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.

  1. Deep Chandra Observations of NGC 3115: Properties of Point Sources

    NASA Astrophysics Data System (ADS)

    Lin, Dacheng; Irwin, J.; Wong, K.; Romanowsky, A. J.; Strader, J.; Sivakoff, G. R.

    2013-01-01

    Our recent Chandra X-ray Visionary Project to observe the nearby S0 galaxy NGC3115 for 1 Msec has provided the deepest look to date of the low-mass X-ray binary (LMXB) population of a normal early-type galaxy. Here we report our study of the 450 point sources detected in these long observations, including many supersoft and highly variable sources. We compare the luminosity distribution of the LMXBs with those obtained from other galaxies. We also investigate their possible nature based on the spectral evolution and multiwavelength cross-correlation and matching with globular clusters.

  2. 2013 Russian Fireball Largest Ever Detected by CTBTO Infrasound Sensors (Invited)

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    On 15 February 2013 at 03h20 UT, a large Earth impacting fireball disintegrated over the Ural Mountains near the city of Chelyabinsk. The bolide produced shock waves that blew out windows, injured hundreds of people and damaged buildings in many surrounding cities. Infrasonic waves generated by the explosion propagated over very long distances. The event was globally detected by 20 arrays part of the 44 operating infrasound IMS (International Monitoring System) stations of the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). This fireball event provides a prominent milestone for studying, in detail, infrasound propagation traveling twice around the globe for almost two days at distances larger than 80000 km. Therefore, its analysis offers a unique opportunity to calibrate detection and location methods and evaluate the global performance of the IMS network. The presentation will provide an overview on the global recordings and analyses. Moreover, in order to explain the detection capability of the overall operating IMS network, range-dependent propagation modeling considering both a point-like explosive source and a line source is performed.

  3. Columbia/Einstein observations of galactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Long, K. S.

    1979-01-01

    The imaging observations of galactic clusters are presented. These fall into three categories: pre-main-sequence stars in the Orion nebulae, isolated-main-and-post main-sequence stars, and supernova remnants SNR. In addition to SNR, approximately 30 sources were detected.

  4. Multiwavelength observations of unidentified high energy gamma-ray sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    As was the case for COS B, the majority of high-energy (greater than 100 MeV) gamma-ray sources detected by the EGRET instrument on GRO are not immediately identifiable with catalogued objects at other wavelengths. These persistent gamma-ray sources are, next to the gamma-ray bursts, the least understood objects in the universe. This two year investigation is intended to support the analysis, correlation, and theoretical interpretation of data that we are obtaining at x-ray, optical, and radio wavelengths in order to render the gamma-ray data interpretable. This second year was devoted to studies of unidentified gamma-ray sources from the first EGRET catalog, similar to previous observations. Efforts have concentrated on the sources at low and intermediate Galactic latitudes, which are the most plausible pulsar candidates.

  5. Modeling of Jovian Hectometric Radiation Source Locations: Ulysses Observations

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Reiner, M. J.

    1996-01-01

    The Unified Radio and Plasma Wave (URAP) experiment on Ulysses has provided unique high latitude measurements of Jovian hectometric radiation (HOM) during its encounter with Jupiter in February 1992. URAP was the first radio instrument in the Jovian environment with radio direction-finding capability, which was previously used to determine the HOM source locations in the Jovian magnetosphere. These initial source location determinations were based on several assumptions, including the neglect of refractive effects, which may be tested. We have, for the first time, combined the measured incident ray-direction at the spacecraft with a model magnetosphere to directly trace the rays back to the HOM source. We concentrate on the observations of HOM from high northern latitudes when Ulysses was at distances less than 15 R(sub j). The three- dimensional ray-tracing calculations presented here indicate that the HOM sources probably lie on L shells in the range 3 less than or approximately equal to L less than 7 (tilted dipole magnetic field model) consistent with previous determinations that ignored the effects of refraction. The ray-tracing results, however, indicate that wave refraction due to the Io torus and the magnetic field can significantly influence the precise source location. We show that constraints on the locations imposed by the gyroemission mechanism suggest that the lo torus density may have experienced temporal and/or spatial fluctuations during the Ulysses observations of HOM. Finally, in the cold plasma approximation we demonstrate that even if the emission were nearly linearly polarized near the source region, almost circular polarization will be observed at Ulysses, in agreement with observations.

  6. Long-Term Analysis of Infrasound at Villarrica Volcano and the Eruption of March 3, 2015

    NASA Astrophysics Data System (ADS)

    Palma Lizana, J. L.; Johnson, J. B.; Gonzalez, X. A.; Valderrama, O. A.

    2015-12-01

    For the last 30 years Villarrica volcano has shown persistent degassing and mild strombolian activity taking place at the lava lake located inside its crater. This activity exhibited changes in the magnitud of the strombolian explosions, levels of the lava lake, and gas emission rates. In February 2014, a six-component infrasound array was installed 8 km to the NW of the summit in order to acquire a long-term record of the acoustics associated with the explosive activity originated at Villarrica's crater. Visual observations from the crater rim and acoustic data show that in 2014 the activity at Villarrica was relatively low and began to increase at the beginning of February 2015. Between January and early March of 2015 four complementary three-component infrasound arrays were deployed between 4 and 9 km from the crater. Villarrica volcano erupted on March 3rd, 2015, exhibiting a >1000 m high lava fountain, scoria flows, snow-ice avalanches and lahars, among other phenomena. The eruption was preceded by 25 minutes of strombolian explosions that gradually increased in magnitud and frequency until they turned into the lava fountain. The data collected with the infrasound arrays are used to identify changes in explosive activity as well as the flow of at least three lahars. Analysis of the amplitude, number of events, waveform and frequency content of the acoustic signal show small and/or short (hours to days) variations in the persistent explosive activity of Villarrica's lava lake during 2014. The short (~27 days) increased level of activity and subsequent eruption may be interpreted as the result of a relatively gas-rich magma intruding into the upper plumbing system.

  7. Location of space debris by infrasound

    NASA Astrophysics Data System (ADS)

    Asming, Vladimir; Vinogradov, Yuri

    2013-04-01

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

  8. A likely source of an observation report in Ptolemy's Almagest.

    NASA Astrophysics Data System (ADS)

    Jones, A.

    1999-09-01

    A recently publishes volume of Greek papyri from Oxyrhynchus (modern Bahnasa, Egypt) containing astronomical text, tables, and horoscopes also includes a fragment of a theoretical work on planetary theory. This text, published under the number P.Oxy. LXI 4133, contains the report of an observation of Jupiter's position in AD 104-105 and refers also to another observation of Jupiter made 344 years earlier. The author of the present note has identified tentatively Menelaus of Alexandria as the author of the treatise on planetary theory. Here, he argues that the recovered treatise was very likely Ptolemy's immediate source for the Jupiter observations referred to in the Almagest.

  9. Commercial observation satellites: broadening the sources of geospatial data

    NASA Astrophysics Data System (ADS)

    Baker, John C.; O'Connell, Kevin M.; Venzor, Jose A.

    2002-09-01

    Commercial observation satellites promise to broaden substantially the sources of imagery data available to potential users of geospatial data and related information products. We examine the new trend toward private firms acquiring and operating high-resolution imagery satellites. These commercial observation satellites build on the substantial experience in Earth observation operations provided by government-owned imaging satellites for civilian and military purposes. However, commercial satellites will require governments and companies to reconcile public and private interests in allowing broad public access to high-resolution satellite imagery data without creating national security risks or placing the private firms at a disadvantage compared with other providers of geospatial data.

  10. Isis 1 observations at the source of auroral kilometric radiation

    NASA Technical Reports Server (NTRS)

    Benson, R. F.; Calvert, W.

    1979-01-01

    Observations of auroral kilometric radiation (AKR) were made by Isis 1 in the source region. The radiation is found to be generated in the extraordinary mode just above the local cut-off frequency and to emanate nearly perpendicular to the magnetic field. It occurs within local depletions of electron density, where the ratio of plasma frequency to cyclotron frequency is less than 0.2. The density depletion is restricted to altitudes above about 2000 km, and the upper AKR frequency limit corresponds to the extraordinary cut-off frequency at this altitude. AKR is observed from Isis 1 above the nighttime auroral zone over a wider extent in longitude than in latitude with an intense source region observed most often near 2200 LMT and 70 deg invariant latitude. It is directly related to inverted V electron precipitation events with an electron-to-wave energy conversion efficiency of the order of 0.1 to 1%.

  11. Determination of uncertainty in the estimation of velocity and direction-of-arrival for atmospheric infrasound signals

    NASA Astrophysics Data System (ADS)

    Szuberla, Curt A. L.; Olson, John V.

    2002-11-01

    Upon the detection of an atmospheric infrasound signal, the problem of precisely estimating the signal's velocity (v) and direction-of-arrival (theta) arises. Multiple sources, multipath, medium anisotropies, and other propagation effects can all degrade precision; however, uncertainty in the estimates of v and theta is fundamentally governed by array geometry and the estimation of time delays across the array. Typically, as in the Comprehensive Test Ban Treaty Organzation Provisional Technical Secretariat (CTBTO/PTS) specification for data from infrasound stations, the Cramer-Rao lower bound is invoked to ascertain the uncertainties associated with v and theta. As this theoretical lower limit is often overly conservative, a more general, and useful, approach to calculate these uncertainties is developed. Examples of this uncertainty determination are presented for typical impulsive and continuous atmospheric infrasound signals received at arrays in Windless Bight, Antarctica and Fairbanks, Alaska. Since the determination of v and theta serves as primary input to any propogation model, it is critical that uncertainties in these estimates be addressed. As an extension of this work, an interactive graphical tool is constructed to assist in the analysis of performance bounds for arbitrary array geometries and signal characteristics.

  12. The source of Jovian auroral hiss observed by Voyager 1

    NASA Technical Reports Server (NTRS)

    Morgan, D. D.; Gurnett, D. A.; Kurth, W. S.; Bagenal, F.

    1994-01-01

    Observations of auroral hiss obtained from the Voyager 1 encounter with Jupiter have been reanalyzed. The Jovian auroral hiss was observed near the inner boundary of the warm Io torus and has a low-frequency cutoff caused by propagation near the resonance cone. A simple ray tracing procedure using an offset tilted dipole of the Jovian magnetic field is used to determine possible source locations. The results obtained are consistent with two sources located symmetrically with respect to the centrifugal equator along an L shell (L approximately = 5.59) that is coincident with the boundary between the hot and cold regions of the Io torus and is located just inward of the ribbon feature observed from Earth. The distance of the sources from the centrifugal equator is approximately 0.58 +/- 0.01 R(sub J). Based on the similarity to terrestrial auroral hiss, the Jovian is auroral hiss is believed to be generated by beams of low energy (approximately tens to thousands of eV) electrons. The low-frequency cutoff of the auroral hiss suggests that the electrons are accelerated near the inferred source region, possibly by parallel electric fields similar to those existing in the terrestrial auroral regions. A field-aligned current is inferred to exist at L shells just inward of the plasma ribbon. A possible mechanism for driving this current is discussed.

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

    PubMed

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

    2014-07-01

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

  14. Uncovering the nature of UV sources observed with Swift

    NASA Astrophysics Data System (ADS)

    Luna, G. J. M.; Lopes, de Oliveira, R.; Nuñez, R. N. E.; Montané, B.

    2016-08-01

    We present an ongoing project aiming to reveal the nature and study the variability of UV sources. The project explores emitters in a sample of more than 60 fields covering around symbiotic stars which were observed with the ultraviolet/optical telescope onboard the Swift satellite. Here we detail the procedures developed in order to search for variability in their flux, and the first results from the three fields already investigated. The UV sources identified are likely associated with cataclysmic variables, white dwarfs, and active stars.

  15. Center determination for trailed sources in astronomical observation images

    NASA Astrophysics Data System (ADS)

    Du, Jun Ju; Hu, Shao Ming; Chen, Xu; Guo, Di Fu

    2014-11-01

    Images with trailed sources can be obtained when observing near-Earth objects, such as small astroids, space debris, major planets and their satellites, no matter the telescopes track on sidereal speed or the speed of target. The low centering accuracy of these trailed sources is one of the most important sources of the astrometric uncertainty, but how to determine the central positions of the trailed sources accurately remains a significant challenge to image processing techniques, especially in the study of faint or fast moving objects. According to the conditions of one-meter telescope at Weihai Observatory of Shandong University, moment and point-spread-function (PSF) fitting were chosen to develop the image processing pipeline for space debris. The principles and the implementations of both two methods are introduced in this paper. And some simulated images containing trailed sources are analyzed with each technique. The results show that two methods are comparable to obtain the accurate central positions of trailed sources when the signal to noise (SNR) is high. But moment tends to fail for the objects with low SNR. Compared with moment, PSF fitting seems to be more robust and versatile. However, PSF fitting is quite time-consuming. Therefore, if there are enough bright stars in the field, or the high astronometric accuracy is not necessary, moment is competent. Otherwise, the combination of moment and PSF fitting is recommended.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Large plinian volcanic eruptions can inject a substantial amount of volcanic gas and ash into the stratosphere. This can present a severe hazard to commercial air traffic. A hazardous Icelandic volcanic ash-eruption was reported on April 14, 2010. This resulted in London's aviation authority to issue an alert that an ash plume was moving from an eruption in Iceland towards northwestern Europe. This eruption resulted in the closure of large areas of European airspace. Large plinian volcanic eruptions radiate infrasonic signals that can be detected by a global infrasound array network. To reduce potential hazards for commercial aviation from volcanic ash, these infrasound sensor arrays have been used to detect infrasonic signals released by sustained volcanic eruptions that can inject ash into the stratosphere at aircraft's cruising altitudes, typically in the order of 10km. A system that is capable of near, real-time eruption detection and discrimination of plinian eruptions from other natural phenomena that can produce infrasound with overlapping spectral content (0.01 to 0.1 Hz) is highly desirable to provide ash-monitoring for commercial aviation. In the initial study, cepstral features were extracted from plinian volcanic eruptions and mountain associated wave infrasound signals. These feature vectors were then used to train and test a two-module neural network classifier (radial basis function neural networks were used for each module). One module is dedicated to classifying plinian volcanic eruptions, the other mountain associated waves. Using an independent validation dataset, the classifier's correct classification rate was 91.5%. Then a different two-module neural network classifier was designed to discriminate between plinian volcanic eruptions and a collection of infrasound signals that are not-of-interest but have spectral content that overlaps with the volcano signals. One module is again dedicated to classifying plinian volcanic eruptions, however, in

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Aimed at the absolute calibration of infrasound sensors at very low frequencies, an upgraded and improved infrasonic pistonphone has been developed. The pistonphone was designed such that a very narrow clearance between the piston and its guide was realized based on an automatically-centered clearance-sealing structure, and a large volume rigid-walled chamber was also adopted, which improved the leakage time-constant of the chamber. A composite feedback control system was applied to the electromagnetic vibrator to control the precise motion of the piston. Performance tests and uncertainty analysis show that the leakage time-constant is so large, and the distortion of the sound pressure is so small, that the pistonphone can be used as a standard infrasound source in the frequency range from 0.001 Hz to 20 Hz. The low frequency property of the pistonphone has been verified through calibrating low frequency microphones. Comparison tests with the reciprocity method have shown that the pressure sensitivities from the pistonphone are not only reliable at common frequencies but also have smaller uncertainties at low frequencies.

  18. Direct observation of the CRAND proton radiation belt source

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Hudson, M. K.; Kress, B. T.

    2013-12-01

    Observations of geomagnetically trapped 27-45 MeV protons following the November 2003 magnetic storm show a gradual intensity rise that is interpreted as a direct measurement of the cosmic ray albedo neutron decay (CRAND) source strength. The intensity rise is simulated by combining the detector response function with a model CRAND source, obtained by drift-averaging neutron intensity from Monte Carlo simulation of cosmic ray interactions in the atmosphere. The simulation, for 2.4source was predominant, while radial diffusion and magnetic storm losses effected minor corrections in certain L ranges.

  19. Chandra Observations of Eight Sources Discovered by INTEGRAL

    NASA Astrophysics Data System (ADS)

    Tomsick, John A.; Krivonos, Roman; Wang, Qinan; Bodaghee, Arash; Chaty, Sylvain; Rahoui, Farid; Rodriguez, Jerome; Fornasini, Francesca M.

    2016-01-01

    We report on 0.3-10 keV observations with the Chandra X-ray Observatory of eight hard X-ray sources discovered within 8° of the Galactic plane by the International Gamma-ray Astrophysics Laboratory satellite. The short (˜5 ks) Chandra observations of the IGR source fields have yielded very likely identifications of X-ray counterparts for three of the IGR sources: IGR J14091-6108, IGR J18088-2741, and IGR J18381-0924. The first two have very hard spectra in the Chandra band that can be described by a power law with photon indices of Γ = 0.6 ± 0.4 and -{0.7}-0.3+0.4, respectively (90% confidence errors are given), and both have a unique near-IR counterpart consistent with the Chandra position. IGR J14091-6108 also displays a strong iron line and a relatively low X-ray luminosity, and we argue that the most likely source type is a cataclysmic variable (CV), although we do not completely rule out the possibility of a high mass X-ray binary. IGR J18088-2741 has an optical counterpart with a previously measured 6.84 hr periodicity, which may be the binary orbital period. We also detect five cycles of a possible 800-950 s period in the Chandra light curve, which may be the compact object spin period. We suggest that IGR J18088-2741 is also most likely a CV. For IGR J18381-0924, the spectrum is intrinsically softer with {{Γ }}={1.5}-0.4+0.5, and it is moderately absorbed, NH = (4 ± 1) × 1022 cm-2. There are two near-IR sources consistent with the Chandra position, and they are both classified as galaxies, making it likely that IGR J18381-0924 is an active galactic nucleus. For the other five IGR sources, we provide lists of nearby Chandra sources, which may be used along with further observations to identify the correct counterparts, and we discuss the implications of the low inferred Chandra count rates for these five sources.

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

    NASA Astrophysics Data System (ADS)

    Tuma, Matthias; Igel, Christian; Mialle, Pierrick

    2014-05-01

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  3. Chandra Orion Ultradeep Project: Observations and Source Lists

    NASA Astrophysics Data System (ADS)

    Getman, K. V.; Flaccomio, E.; Broos, P. S.; Feigelson, E. D.; Grosso, N.; Tsujimoto, M.; COUP Collaboration

    2004-08-01

    We present the observations, data analysis methodology, and tabulated results from the Chandra Orion Ultradeep Project (COUP). COUP is based on a single nearly-continuous 850 ks pointing towards the Orion Nebula obtained in January 2003. Over 1600 young stars are detected. Data preparation includes correction for charge transfer inefficiency and subpixel event repositioning. Source detection is based on two wavelet-based search algorithms optimized for maximum reduction of background. For each source, we perform data extraction, pileup correction, spectral and variability analysis, and broad-band luminosity determinations using the sophisticated semi-automated IDL-based ACIS Extract (AE) package. Our treatment of photon pileup using annular extraction regions is effective for both lightly and heavily piledup sources. The AE data products efficiently provide detailed and comprehensive information for point sources in ACIS fields. COUP is supported by Chandra grant SAO GO3-4009A (Feigelson PI). ACIS Extract is available at http://www.astro.psu.edu/xray/docs/TARA/ae_users_guide.html.

  4. Chandra Observations of Dying Radio Sources in Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Murgia, M.; Markevitch, M.; Govoni, F.; Parma, P.; Fanti, R.; de Ruiter, H. R.; Mack, K.-H.

    2012-01-01

    Context. The dying radio sources represent a very interesting and largely unexplored stage of the active galactic nucleus (AGN) evolution. They are considered to be very rare, and almost all of the few known ones were found in galaxy clusters. However, considering the small number detected so far, it has not been possible to draw any firm conclusions about their X-ray environment. Aims. We present X-ray observations performed with the Chandra satellite of the three galaxy clusters Abell 2276, ZwCl 1829.3+6912, and RX J1852.1+5711, which harbor at their center a dying radio source with an ultra-steep spectrum that we recently discovered. Methods. We analyzed the physical properties of the X-ray emitting gas surrounding these elusive radio sources. We determined the global X-ray properties of the clusters, derived the azimuthally averaged profiles of metal abundance, gas temperature, density, and pressure. Furthermore, we estimated the total mass profiles. Results. The large-scale X-ray emission is regular and spherical, suggesting a relaxed state for these systems. Indeed, we found that the three clusters are also characterized by significant enhancements in the metal abundance and declining temperature profiles toward the central region. For all these reasons, we classified RX J1852.1+5711, Abell 2276, and ZwCl 1829.3+6912 as cool-core galaxy clusters. Conclusions. We calculated the non-thermal pressure of the radio lobes assuming that the radio sources are in the minimum energy condition. For all dying sources we found that this is on average about one to two orders of magnitude lower than that of the external gas, as found for many other radio sources at the center of galaxy groups and clusters. We found marginal evidence for the presence of X-ray surface brightness depressions coincident with the fossil radio lobes of the dying sources in A2276 and ZwCl 1829.3+691. We estimated the outburst age and energy output for these two dying sources. The energy power from

  5. 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

    We deployed a 47-node infrasound sensor network around Kilauea’s Halemaumau Vent to image the atmospheric conditions of the near-surface. This active vent is a persistent radiator of energetic infrasound enabling us to probe atmospheric winds and temperatures. This research builds upon a previous experiment that recorded infrasound on a three-node network, to determine relative phase delay and invert for atmospheric wind. The technique developed for this previous analysis assumed the intrinsic sound speed and was able to track the evolution of the average wind field in a large area (around 10 km2) and was largely insensitive to local meteorological effects, caused by topography and vegetation. The results of this previous experiment showed the potential of this technique for atmospheric studies and called for a following experiment with a denser sensor network over a larger area. During the summer 2010, we returned to Kilauea and deployed a 47-sensor network in three different configurations around Kilauea summit and down the volcano’s flanks. Persistent infrasonic tremor was ‘loud’ with excess pressures up to 10 Pa (when scaled to 1 km) and periods of high acoustic emissions that lasted from hours to days. The instrumentation for this experiment was composed of single-channel RefTek RT125A Texan digitizers and InfraNMT infrasound sensors. The Texan digitizers provide high-resolution 24-bit analog to digital conversion and can operate continuously for approximately five days with two D-cell batteries. The InfraNMT sensor is based on a piezo-electric transducer and was developed at the Infrasound Laboratory at New Mexico Tech. This sensor features low power (< 3 mA at 9 V) and flat response between 0.02 to 50 Hz. Three different network topologies were tested during this two-week experiment. For the first and second topologies, the sensors were deployed along established roads on two almost perpendicular sensor lines centered at the Halema’uma’u crater

  6. Towards an enhanced picture of the detection capability of the IMS infrasound network

    NASA Astrophysics Data System (ADS)

    Le Pichon, A.; Vergoz, J.; Ceranna, L.

    2010-12-01

    Previous detection capability studies were based on empirical-yield scaling relations, seasonal description of stratospheric winds (climatological HWM), and median station noise models (e.g. Clauter and Blandford, 1997; Stevens et al., 2002; D. Green, 2008). The most commonly used yield-scaling relation is derived from high explosive dataset (Whitaker, 2003). Limitations of this approach have been found by comparisons with reference events where problems arise either due to a fixed stratospheric wind speed or by an over-estimate of a known yield (Ceranna et al., 2008; Gitterman et al., 2009). More realistic predictions can be achieved using both improved atmospheric specifications and real station noise characterization, and attenuation relations derived from operational propagation tools. The detection capability of the IMS network is assessed using near-real time atmospheric updates and background noise calculations at various times of day for each month. This information is useful in determining global network detection capability and quantifies its spatial and temporal variability (hourly, daily, seasonal and yearly). Improved yield scaling relations are generated using intensively wide angle parabolic equation methods as they provide detailed propagation information with reasonable computation time. A reduced number of parameters describing the source (source altitudes between 0 and 30 km, frequencies between 0.01 and 4 Hz) and the atmosphere (including naturally occurring gravity waves, altitude and strength of the stratospheric wind jet) which have significant impact on infrasound propagation have been identified in order to compute a massive synthetic data set. Comprehensive ground-truth databases provide a statistical approach for evaluating the potential of infrasound monitoring. In order to evaluate this approach, accidental and calibration explosions are analysed and used here as benchmark for validating the calculated threshold maps. Such studies would

  7. Sources of Mass and Energy Observed in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Riofrio, L. M.

    2005-12-01

    EVIDENCE from the laboratory of Saturn's Rings solves riddles of planet formation. Observations by Cassini and other spacecraft show conditions similiar to the birth of our Solar System. These observations lead to new theories of small-body accretion. Applications have benefits for physics and energy on Earth. There have been several open questions regarding the planets. Most puzzling is the formation of mountain-sized planetesimals from protostellar dust, for these objects could not form naturally. Power source of the "dynamo" generating planetary magnetic fields was also unknown. Internal heat generated by planets and even small moons is an additional mystery. These riddles may be explained by presence of primordial singularities in the Solar System's formation. Saturn's Rings are a field of ice in which the tracks of these objects may be seen. The Cassini spacecraft has returned many fascinating images of the Rings. We now know them to be home to massive unseen objects. Satellite objects glimpsed in the Encke and Keeler gaps show behaviour unlike moons of rock or ice. Discrete trails of dirt and molecular oxygen indicate radiation discharge emanating from these objects. Similiar trails photographed in Cassini's Division indicate massive objects where no large object has been sighted visually. We must consider whether the Rings could be a home to singularities. It is generally agreed the primordial singularities were created shortly after the Big Bang, and exist in unknown numbers today. Presence of these objects in the Solar System's formation would have seeded formation of planetesimals and larger bodies. Their hidden presence would explain both planetary magnetic fields and internal heat sources. They would also explain the Ring's presence and longetivity. The most convincing evidence for singularities would be radiation discharge. Observation of a polar "hot spot" on Enceladus can not be explained by old theories of radioactive decay. The only feasible source

  8. Test definitions for the evaluation of infrasound sensors.

    SciTech Connect

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

    2007-07-01

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

  9. Using Seismic and Infrasonic Data to Identify Persistent Sources

    NASA Astrophysics Data System (ADS)

    Nava, S.; Brogan, R.

    2014-12-01

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

  10. Impact of mountain gravity waves on infrasound propagation

    NASA Astrophysics Data System (ADS)

    Damiens, Florentin; Lott, François; Millet, Christophe

    2016-04-01

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

  11. STACEE Observations of Active Galactic Nuclei and Other Sources

    NASA Astrophysics Data System (ADS)

    Ong, R. A.; Boone, L. M.; Bramel, D.; Chae, E.; Covault, C. E.; Fortin, P.; Gingrich, D.; Hanna, D. S.; Hinton, J. A.; Meuller, C.; Mukherjee, R.; Ragan, K.; Scalzo, R. A.; Schuette, D. R.; Theoret, C. G.; Williams, D. A.

    2001-08-01

    We describe recent observations and future plans for the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) located at Sandia National Laboratories in Albuquerque, New Mexico. STACEE is a ground-based experiment for detecting atmospheric Cherenkov light from γrays in the energy range 50 to 500 GeV. We describe recent observations of active galactic nuclei such as Mrk 501, and also outline plans for the observations of other AGN, including Flat Spectrum Radio Quasars (FSRQs) detected by EGRET above 1 GeV and other BL-Lac objects. We summarize plans for observing other sources, including the Crab Nebula, other pulsars, supernova remnants, and unidentified EGRET objects. The up-to-date results from recent source observations by STACEE will be presented at the conference. 1 Intergalactic absorption and the γ-ray horizon The energy range from 50 to 250 GeV is important for understanding many high energy astrophysical objects, especially active galactic nuclei. Great progress has been made during the last decade, but many problems remain. For example, while dozens of AGN at a variety of redshifts were detected by EGRET, only a few of the closest AGN have been detected by ground-based experiments above 250 GeV. These results imply that the power-law spectra of many AGN cut off at energies between 20 and 250 GeV, and the fact that only nearby AGN are seen at very high energies argues that the γrays are attenuated on their long journey to Earth. High energy γ-rays interact with photons at infrared/optical/UV energies via the pair-production process (Stecker and de Jager, 1993; Biller, 1995). The level of such extragalactic background light (EBL) from galaxies is not well known, but measurements of absorption features of AGN should provide constraints on its flux and spectral shape. These constraints in turn could give us valuable information about the epoch of galaxy formation and the composition of dark mat-

  12. Studies of Accreting Neutron Stars with RXTE Cycle 4 Observations: III: TOO Observations of Atoll Sources

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2002-01-01

    NASA Grant NAG 5-9244 provided funds for the research projects 'ASM-Triggered TOO Observations of Kilohertz Oscillations in Five Atoll Sources' and 'Further Measurements of the Kilohertz Oscillations in 4U 1705-44' approved under the Rossi X-ray Timing Explorer (RXTE) Guest Observer Program Cycle 4 and funded under the 1999 NASA Astrophysics Data Program. The principal investigator of the observing time proposals was Dr. E. C. Ford (U. of Amsterdam). The grant was funded for one year beginning 3/15/2000. The original ADP proposal was submitted by Prof. Jan van Paradijs, who passed away in 1999 before the funds were distributed. Prof. Wilham S. Padesas administered the grant during the period of performance. In spite of a wealth of observational data on the kHz QPO in low-mass X-ray binaries (LMXBs), the interpretation of this phenomenon is currently uncertain because the pairs of kHz QPO peaks and the oscillations seen in some Type I X-ray bursts are almost, but not quite, connected by a simple beat frequency relation. Further systematic studies of systems with known QPOs are required in order to better understand the phenomenon. The proposals were intended to contribute to a solution to this confusion by observing the sources as they vary over a wide range of X-ray flux. RXTE target-of-opportunity observations of six transient atoll sources, 4U 0614+09, KS 1732-260, Ser X-1, 4U 1702-42, 4U 1820-30 and 4U 1705-44 were to be performed at various flux levels based on ASM measurements.

  13. Design and Development of a High Impedance Amplifier For Use With Piezoelectric Infrasound Microphones

    NASA Astrophysics Data System (ADS)

    Kleinert, D. E.; Talmadge, C. L.

    2011-12-01

    The National Center for Physical Acoustics (NCPA) has developed a new class of high fidelity low cost piezoelectric infrasound sensors. One of the key electronic issues has been the design and development of the appropriate high impedance amplifiers including material specification as well as circuit layout and fabrication. The high impedance amplifier is required to allow the piezoelectronic sensor to operate over its entire bandwidth as the sensor itself has high impedance at the low frequency end of its operation. The specifications include a flat frequency response from at least .01 Hz to 500 Hz, a dynamic range suitable to feed a 24 bit ADC and reasonably low power (mW levels). There has been extensive field testing of the resulting amplifier in conjunction with the piezoelectric microphone, also developed at NCPA, in a variety of locations and climates using various sources, including hurricanes, tornados and high explosive detonations.

  14. Mapping thunder sources by inverting acoustic and electromagnetic observations

    NASA Astrophysics Data System (ADS)

    Anderson, J. F.; Johnson, J. B.; Arechiga, R. O.; Thomas, R. J.

    2014-12-01

    We present a new method of locating current flow in lightning strikes by inversion of thunder recordings constrained by Lightning Mapping Array observations. First, radio frequency (RF) pulses are connected to reconstruct conductive channels created by leaders. Then, acoustic signals that would be produced by current flow through each channel are forward modeled. The recorded thunder is considered to consist of a weighted superposition of these acoustic signals. We calculate the posterior distribution of acoustic source energy for each channel with a Markov Chain Monte Carlo inversion that fits power envelopes of modeled and recorded thunder; these results show which parts of the flash carry current and produce thunder. We examine the effects of RF pulse location imprecision and atmospheric winds on quality of results and apply this method to several lightning flashes over the Magdalena Mountains in New Mexico, USA. This method will enable more detailed study of lightning phenomena by allowing researchers to map current flow in addition to leader propagation.

  15. 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

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

    PubMed

    He, Renhong; Fan, Jianzhong

    2014-11-01

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

  17. Infrasound Generation from the HH Seismic Hammer.

    SciTech Connect

    Jones, Kyle Richard

    2014-10-01

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

  18. Chandra Observations of Point Sources in Abell 2255

    NASA Technical Reports Server (NTRS)

    Davis, David S.; Miller, Neal A.; Mushotzky, Richard F.

    2003-01-01

    In our search for "hidden" AGN we present results from a Chandra observation of the nearby cluster Abell 2255. Eight cluster galaxies are associated with point-like X-ray emission, and we classify these galaxies based on their X-ray, radio, and optical properties. At least three are associated with active galactic nuclei (AGN) with no optical signatures of nuclear activity, with a further two being potential AGN. Of the potential AGN, one corresponds to a galaxy with a post-starburst optical spectrum. The remaining three X-ray detected cluster galaxies consist of two starbursts and an elliptical with luminous hot gas. Of the eight cluster galaxies five are associated with luminous (massive) galaxies and the remaining three lie in much lower luminosity systems. We note that the use of X-ray to optical flux ratios for classification of X-ray sources is often misleading, and strengthen the claim that the fraction of cluster galaxies hosting an AGN based on optical data is significantly lower than the fraction based on X-ray and radio data.

  19. Source properties of microearthquakes revealed by near-source observation at SAFOD (Invited)

    NASA Astrophysics Data System (ADS)

    Imanishi, K.; Ellsworth, W. L.

    2010-12-01

    Near-source observation of earthquakes in deep boreholes and mines provides significant opportunities to enhance our understanding of the source properties of earthquakes. Short hypocentral distances and a high-Q environment make it possible to observe earthquake processes that cannot be seen in shallow boreholes or at the surface. The SAFOD Main Hole is a 3.2 km-deep inclined borehole that crosses the active traces of the San Andreas Fault. A 3-component 15 Hz GS-20DM geophone was deployed within the fault zone at depths between 2350 and 2750 m. Because of the close proximity to earthquake sources, we routinely observed earthquakes with Mw < 0 with high signal-to-noise ratio. Events were recorded at three different sampling rates (1000, 2000, and 4000 sps) depending on observation period (2005 - 2010). This study focuses on earthquakes with S-P time differences shorter than 0.5s, corresponding to hypocentral distance less than 3 km. Among more than 400 earthquakes, we selected 117 events classified into 35 clusters on the basis of waveform similarity at low frequencies. Selected events range in size from approximately Mw -3 to Mw 2. The dataset includes many events in three clusters that formed the SAFOD drilling target; San Francisco, Los Angeles and Hawaii named as their relative positions with respect to those cities. We determined source parameters by the Multi-Window Spectral Ratio (MWSR) method (Imanishi and Ellsworth, 2006). The key step in the method is to stack the ratios calculated from moving windows taken along the record starting with the direct waves. We confirmed that stacking better suppresses the random noise due to differences in path than single-window methods, producing a better estimate of the source spectral ratio. For Mw>-1, the calculated stress drops range between 0.1 and 100 MPa. These observations indicate that there is no breakdown in stress drop scaling for Mw>-1. The stacked spectral ratios show that corner frequencies of events for

  20. Earthquake Source Parameters Inferred from T-Wave Observations

    NASA Astrophysics Data System (ADS)

    Perrot, J.; Dziak, R.; Lau, T. A.; Matsumoto, H.; Goslin, J.

    2004-12-01

    The seismicity of the North Atlantic Ocean has been recorded by two networks of autonomous hydrophones moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). In February 1999, a consortium of U.S. investigators (NSF and NOAA) deployed a 6-element hydrophone array for long-term monitoring of MAR seismicity between 15o-35oN south of the Azores. In May 2002, an international collaboration of French, Portuguese, and U.S. researchers deployed a 6-element hydrophone array north of the Azores Plateau from 40o-50oN. The northern network (referred to as SIRENA) was recovered in September 2003. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation results in a detection threshold reduction from a magnitude completeness level (Mc) of ˜ 4.7 for MAR events recorded by the land-based seismic networks to Mc=3.0 using hydrophone arrays. Detailed focal depth and mechanism information, however, remain elusive due to the complexities of seismo-acoustic propagation paths. Nonetheless, recent analyses (Dziak, 2001; Park and Odom, 2001) indicate fault parameter information is contained within the T-wave signal packet. We investigate this relationship further by comparing an earthquake's T-wave duration and acoustic energy to seismic magnitude (NEIC) and radiation pattern (for events M>5) from the Harvard moment-tensor catalog. First results show earthquake energy is well represented by the acoustic energy of the T-waves, however T-wave codas are significantly influenced by acoustic propagation effects and do not allow a direct determination of the seismic magnitude of the earthquakes. Second, there appears to be a correlation between T-wave acoustic energy, azimuth from earthquake source to the hydrophone, and the radiation pattern of the earthquake's SH waves. These preliminary results indicate there is a relationship between the T-wave observations and earthquake source parameters, allowing for additional insights into T

  1. Scaling Relationship Among Source Parameters of Microearthquake," From Near Source Observation in a Deep Mine

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Y.; Yoshimura, M.; Furumoto, M.

    2004-12-01

    Scaling relationships among various source parameters are important clues to understand the source process. In particular the relationship between the corner frequency, fC, and the seismic moment, MO, has been investigated by many researchers. Aki(1967) investigated fC and MO using the spectra of seismic waves and reported that these parameters obeyed a relationship of MO ∝ fC-3. For small earthquakes, the breakdown of this relationship was often reported. On the other hand, no breakdown of the relationship for microearthquakes has been reported from high quality observation at deep boreholes and in a deep gold mine. We report here these scaling relationships using waveform of microearthquakes observed at the distance range of 15m to 1km. We installed nine tri-axial borehole accelerometers within 200 m along a haulage tunnel 2650m deep in Mponeng mine in South Africa from February to December in 1996. More than 25 thousand seismic events were recorded with a sampling frequency of 15 kHz and a dynamic range of 120 dB. The recording system has flat response up to 2 KHz. Among those events, we select 378 events with high S/N. We locate hypocenters assuming infinite medium with the P-wave velocity 5.5 km/s and the S-wave velocity 3.2 km/s. We calculate the green function using the discrete wavenumber integral method into account the effect of anelasticity by Takeo (1985) and determine the seismic moment and the mechanism using moment tensor inversion. We apply the omega square model by Brune (1970) to determine the corner frequency and the stress drop. Minimizing L2 norm between the observed spectra of P and S waves and the synthetic ones give the optimum source parameters. The earthquakes analyzed in this study show the constant stress drop of 0.4 ˜8MPa in the ranges of 40

  2. Near Source 2007 Peru Tsunami Runup Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Borrero, J. C.; Fritz, H. M.; Kalligeris, N.; Broncano, P.; Ortega, E.

    2008-12-01

    On 15 August 2007 an earthquake with moment magnitude (Mw) of 8.0 centered off the coast of central Peru, generated a tsunami with locally focused runup heights of up to 10 m. A reconnaissance team was deployed two weeks after the event and investigated the tsunami effects at 51 sites. Three tsunami fatalities were reported south of the Paracas Peninsula in a sparsely populated desert area where the largest tsunami runup heights and massive inundation distances up to 2 km were measured. Numerical modeling of the earthquake source and tsunami suggest that a region of high slip near the coastline was primarily responsible for the extreme runup heights. The town of Pisco was spared by the Paracas Peninsula, which blocked tsunami waves from propagating northward from the high slip region. As with all near field tsunamis, the waves struck within minutes of the massive ground shaking. Spontaneous evacuations coordinated by the Peruvian Coast Guard minimized the fatalities and illustrate the importance of community-based education and awareness programs. The residents of the fishing village Lagunilla were unaware of the tsunami hazard after an earthquake and did not evacuate, which resulted in 3 fatalities. Despite the relatively benign tsunami effects at Pisco from this event, the tsunami hazard for this city (and its liquefied natural gas terminal) cannot be underestimated. Between 1687 and 1868, the city of Pisco was destroyed 4 times by tsunami waves. Since then, two events (1974 and 2007) have resulted in partial inundation and moderate damage. The fact that potentially devastating tsunami runup heights were observed immediately south of the peninsula only serves to underscore this point.

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

    SciTech Connect

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

    1997-11-01

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

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

    PubMed

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

    2011-11-01

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

  5. Ground-coupled air waves and diffracted infrasounds from the Arequipa earthquake of June 23, 2001

    NASA Astrophysics Data System (ADS)

    Lepichon, A.; Guilbert, J.; Van de Walle, M.

    2001-12-01

    On June 23, 2001, a strong earthquake measuring Ms 8.2 occurred along the coast of south-central Peru. This event was detected by the IS08 infrasound station of Bolivia operating for the CTBTO(Comprehensive Test Ban Treaty Organization). Coherent infrasonic waves have been detected over a period of one hour. In the first part of the signals, the analysis of the seismic coupled-air waves shows clearly that the rupture propagates from the northwertern to the southeastern part of the fault. The Doppler effect allows us to fixe the velocity of the rupture equal to 3.4 +/- 0.5 km.s-1. In the second part of the signals, the azimuth variation is interpreted as a distribution of secondary sources along the highest mountain ranges generating distant air-coupled waves in the atmosphere. The predominant source mechanism of the earthquake and two main aftershocks is likely diffracted pressure waves radiated along the Eastern Andean Cordillera from the southwest of the station to the coastline near Pamana. From the wave azimuth and arrival time determination, the horizontal scale size of the distant source regions remote from the epicenters is reconstructed over distances greater than 400 km. The generation of pressure waves associated with offshore source regions is also considered.

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

    NASA Astrophysics Data System (ADS)

    Johnson, J. B.; Palma, J.

    2015-12-01

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

  7. Infrasound analysis using Fisher detector and Hough transform

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. 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.

  9. PTS Infrasound portable array in Tunisia: Deployment and Results

    NASA Astrophysics Data System (ADS)

    Kallel, Mohamed; Khemiri, Lotfi; Mialle, Pierrick; Le Pichon, Alexis; Vergoz, Julien

    2014-05-01

    Within the scope of a scientific collaboration between the Tunisian NDC and the PTS an infrasound portable array (I66TN) were deployed in Tunisia for 6 Months starting from 15th of May 2013 till 15th of November 2013. The 4 sites of the portable array were installed in the mountain ranges surrounding the city of Aïn Draham in northwest of Tunisia with an aperture of about 1KM. The installation was done by Dr. Pierrick Mialle, a representative from the PTS, together with a team from the Tunisian NDC. Data retrieval is performed by the Tunisian NDC team on a periodic basis. The Data recorded by I66TN and the data recorded by the IMS Infrasound Station I48TN during the same period were processed. A bulletin of the fusion of the data of the two stations was created with the support of the French NDC. In this poster, we will present the different steps of the deployment of the station I66TN and show the results of the data processing and data fusion.

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

    PubMed

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

    2011-09-01

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

  11. Multiwavelength observations of unidentified high energy gamma ray sources

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1993-01-01

    As was the case for COS B, the majority of high-energy (greater than 100 MeV) gamma-ray sources detected by the EGRET instrument on GRO are not immediately identifiable with cataloged objects at other wavelengths. These persistent gamma-ray sources are, next to the gamma-ray bursts, the least understood objects in the universe. Even a rudimentary understanding of their nature awaits identifications and follow-up work at other wavelengths to tell us what they are. The as yet unidentified sources are potentially the most interesting, since they may represent unrecognized new classes of astronomical objects, such as radio-quiet pulsars or new types of active galactic nuclei (AGN's). This two-year investigation is intended to support the analysis, correlation, and theoretical interpretation of data that we are obtaining at x ray, optical, and radio wavelengths in order to render the gamma-ray data interpretable. According to plan, in the first year concentration was on the identification and study of Geminga. The second year will be devoted to studies of similar unidentified gamma-ray sources which will become available in the first EGRET catalogs. The results obtained so far are presented in the two papers which are reproduced in the Appendix. In these papers, we discuss the pulse profiles of Geminga, the geometry and efficiency of the magnetospheric accelerator, the distance to Geminga, the implications for theories of polar cap heating, the effect of the magnetic field on the surface emission and environment of the neutron star, and possible interpretations of a radio-quiet Geminga. The implications of the other gamma-ray pulsars which were discovered to have high gamma-ray efficiency are also discussed, and the remaining unidentified COS B sources are attributed to a population of efficient gamma-ray sources, some of which may be radio quiet.

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

    PubMed

    Marsden, O; Bogey, C; Bailly, C

    2014-03-01

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

  13. Multi-wavelength observations of high energy sources

    NASA Astrophysics Data System (ADS)

    Motch, C.; Pineau, F.-X.

    2009-07-01

    Gathering large sets of clean multi-wavelength measurements on specific classes of astrophysical objects or conversely, unveiling rare outliers, both first require a careful handling of the cross-identification process, taking into account positional errors and probabilities of spurious matches. Most high energy telescopes offer significantly lower spatial resolution than those operating at optical or infrared wavelengths. This can lead to confusion issues particularly in regions of high optical and infrared source densities such as in the Galactic plane. We review here the elementary steps leading to a statistically controlled identification and classification of X-ray sources and illustrate these methods and related problems with some examples extracted from the work carried out by the Survey Science Center of the XMM-Newton satellite. We then list some functionality and interoperability requirements on a few basic VO tools which would ease the proper identification and subsequent classification of high energy sources and, in general, facilitate the computation of the reliabilities of the cross-identifications of sources in pairs of catalogues collected at any wavelengths.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

    de Groot-Hedlin, C D

    2016-04-01

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

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

    PubMed

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

    2013-09-01

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

  17. The Ionosphere's Pocket Litter: Exploiting Crowd-Sourced Observations

    NASA Astrophysics Data System (ADS)

    Miller, E. S.; Frissell, N. A.; Kaeppler, S. R.; Demajistre, R.; Knuth, A. A.

    2015-12-01

    One of the biggest challenges faced in developing and testing our understanding of the ionosphere is acquiring data that characterizes the latitudinal and longitudinal variability of the ionosphere. While there are extensive networks of ground sites that sample the vertical distribution, we have rather poor coverage over the oceans and in parts of the southern hemisphere. Our ability to validate the ionospheric models is limited by the lack of point measurements and those measurements that essentially constitute characterization of horizontal gradients. In this talk, we discuss and demonstrate the use of various types of crowd-sourced information that enables us to extend our coverage over these regions. We will discuss new sources of these data, concepts for new experiments and the use of these data in assimilative models. We note that there are new, low cost options for obtaining data that broaden the participation beyond the aeronomy/ionospheric community.

  18. Long-Period Seismicity and Very-Long-Period Infrasound Driven by Shallow Magmatic Degassing at Mount Pagan, Mariana Islands

    NASA Astrophysics Data System (ADS)

    Lyons, J. J.; Haney, M. M.; Werner, C. A.; Kelly, P. J.; Patrick, M. R.; Kern, C.; Trusdell, F.

    2015-12-01

    Mount Pagan is the currently active vent on the north end of Pagan Volcano, Mariana Islands. A persistent degassing plume, LP seismicity, and VLP infrasound (iVLP) have dominated activity since at least 2013, when ground-based geophysical sensors were first installed. Direct gas sampling with a Multi-GAS sensor indicates a plume generated by a shallow magmatic system. Here we present an analysis of coupled LP and iVLP events in order to reveal the details of their source processes and how the signals are related to shallow magmatic degassing. The LP and iVLP waveform characteristics were highly stable from July 2013 - January 2014. Both events have durations of 5-20 s, occur every 1-2 minutes, and have emergent onsets. The LP events have a dominant frequency of 0.54 Hz, while the dominant frequency of the iVLP is 0.32 Hz. The delay times between the LP and iVLP arrivals show little variation during the 7-month study, indicating a stable, shallow, and nearly co-located source. Full waveform inversion of a master LP event reveals a volumetric source 60 m below and 180 m west of the summit vent. Inverting Green's functions of different geometric combinations results in a 2-crack model dominated by a subhorizontal crack intersecting a NW-SE trending dike. The extension of the modeled crack intersects the surface near the vent location. The nearly horizontal orientation of the dominant crack is likely controlled by the orientation of lava flows and pyroclastic deposits that are observed in the western wall of the cone at the LP depth. We propose that the LP seismicity is crack resonance triggered by collapse of the gas-charged upper conduit system following periodic venting. Measured and modeled pressure-velocity (P/Vz) ratios for the seismoacoustic events indicate that elastodynamic processes associated with the seismic LP cannot generate the iVLP. Thus, we model the iVLP as volume resonance of an exponential horn, based on the shape of the crater and the wavelength of

  19. Tropical sources and sinks of carbonyl sulfide observed from space

    NASA Astrophysics Data System (ADS)

    Glatthor, N.; Höpfner, M.; Baker, I. T.; Berry, J.; Campbell, J. E.; Kawa, S. R.; Krysztofiak, G.; Leyser, A.; Sinnhuber, B.-M.; Stiller, G. P.; Stinecipher, J.; Clarmann, T.

    2015-11-01

    According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore, COS has been suggested as cotracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 parts per trillion by volume (pptv) in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large-scale COS depletion, which in austral summer amounts up to -40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications are assumed.

  20. Tropical sources and sinks of carbonyl sulfide observed from space

    NASA Astrophysics Data System (ADS)

    Glatthor, Norbert; Höpfner, Michael; Baker, Ian T.; Berry, Joe; Campbell, Elliott; Kawa, Stephan R.; Krysztofiak, Gisele; Sinnhuber, Björn-Martin; Stiller, Gabriele; Stinecipher, Jim; von Clarmann, Thomas

    2016-04-01

    According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore COS has been suggested as co-tracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 pptv in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large-scale COS depletion, which in austral summer amounts up to -40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications is assumed.

  1. Columbia/Einstein observations of extragalactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Ku, W. H. M.

    1979-01-01

    Results are presented of the analysis of data from observations of extragalactic objects with the imaging proportional counter on board the Einstein Observatory. Surveys of normal galaxies, radio galaxies, active galaxies, quasars and BL Lacs, and clusters of galaxies were studied in order to improve the understanding of the origin of the Milky Way Galaxy.

  2. Observations of collective effects at the Advanced Light Source

    SciTech Connect

    Byrd, J.M.; Barry, W.; Corlett, J.N.; Fox, J.; Teytelman, D.

    1995-10-01

    We present a summary of measurements of single beam collective effects in the Advanced Light Source (ALS). We describe measurements of coupled-bunch instabilities, including some recent results using the newly commissioned feedback systems and the results of an initial search for the fast ion instability. Single bunch effects include bunch lengthening, energy spread increase, HOM loss measurements, head-tail damping rates, current dependent tune shifts, and transverse mode coupling instability threshold. The longitudinal measurements are consistent with a broadband impedance {vert_bar}{Zeta}{sub {parallel}}/{eta}{vert_bar}{sub eff} = 0.22{plus_minus}0.07 {Omega} and transverse measurements indicate broadband impedances of {Zeta}{sub y,eff} = 155 k{Omega}/m and Z{sub x,eff} = 58 k{Omega}/m.

  3. Testing nonlocal observation as a source of intuitive knowledge.

    PubMed

    Radin, Dean

    2008-01-01

    This study explored the hypothesis that in some cases intuitive knowledge arises from perceptions that are not mediated through the ordinary senses. The possibility of detecting such nonlocal observation was investigated in a pilot test based on the effects of observation on a quantum system. Participants were asked to imagine that they could intuitively perceive a low-intensity laser beam in a distant Michelson interferometer. If such observation were possible, it would theoretically perturb the photons' quantum wave functions and change the pattern of light produced by the interferometer. The optical apparatus was located inside a light-tight, double-steel walled, shielded chamber. Participants sat quietly outside the chamber with eyes closed. The light patterns were recorded by a cooled digital camera once per second, and average illumination levels of these images were compared in counterbalanced mental blocking versus nonblocking conditions. By design, perturbation would produce a lower overall level of illumination, which was predicted to occur during the blocking condition. Based on a series of planned experimental sessions, the outcome was in accordance with the prediction (z = -2.82; P = .002). This result was primarily due to nine sessions involving experienced meditators (combined z = -4.28; P = 9.4 x 10(-6)); the other nine sessions with nonmeditators were not significant (combined z = 0.29; P = .61). The same experimental protocol run immediately after 15 of these test sessions, but with no one present, revealed no hardware or protocol artifacts that might have accounted for these results (combined control z = 1.50; P = .93). Conventional explanations for these results were considered and judged to be implausible. This pilot study suggests the presence of a nonlocal perturbation effect that is consistent with traditional concepts of intuition as a direct means of gaining knowledge about the world, and with the predicted effects of observation on a

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Tropical cyclone waves detected with infrasound sensor array

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-02-01

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

  6. 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

  7. Possibility of observable signatures of leptonium from astrophysical sources

    NASA Astrophysics Data System (ADS)

    Ellis, S. C.; Bland-Hawthorn, Joss

    2015-06-01

    The formation of positronium in our Galaxy is well measured, and has led to important and unanswered questions on the origin of the positrons. In principle it should be possible to form analogous systems from μ and τ leptons, viz. true muonium and true tauonium. However the probability of formation for these systems is greatly reduced due to the intrinsically short lifetimes of the μ and τ leptons. Likewise, the decay of the atoms is hastened by the high probability of the constituent particles decaying. Nevertheless, if sufficient numbers of μ and τ pairs are produced in high energy astrophysical environments there may be significant production of true muonium and true tauonium, despite the small probabilities. This paper addresses this possibility. We have calculated the pair production spectra of μ and τ leptons from photon-photon annihilation and electron-positron annihilation in astrophysical environments. We have computed the cross sections for radiative recombination and direct annihilation of the pairs, and the decay constants for the various allowable decays, and the wavelengths and energies of the recombination and annihilation signatures. In this way we have calculated the probabilities for the formation of true muonium and true tauonium, and the branching ratios for the various observable signatures. We have estimated the expected fluxes from accretion disks around microquasars and active galactic nuclei, and from interactions of jets with clouds and stars. We find that accretion disks around stellar mass black holes in our own Galaxy should have observable signatures at x-ray and γ -ray energies that are in principle observable with current observatories.

  8. Riverine source of Arctic Ocean mercury inferred from atmospheric observations

    NASA Astrophysics Data System (ADS)

    Fisher, Jenny A.; Jacob, Daniel J.; Soerensen, Anne L.; Amos, Helen M.; Steffen, Alexandra; Sunderland, Elsie M.

    2012-07-01

    Methylmercury is a potent neurotoxin that accumulates in aquatic food webs. Human activities, including industry and mining, have increased inorganic mercury inputs to terrestrial and aquatic ecosystems. Methylation of this mercury generates methylmercury, and is thus a public health concern. Marine methylmercury is a particular concern in the Arctic, where indigenous peoples rely heavily on marine-based diets. In the summer, atmospheric inorganic mercury concentrations peak in the Arctic, whereas they reach a minimum in the northern mid-latitudes. Here, we use a global three-dimensional ocean-atmosphere model to examine the cause of this Arctic summertime maximum. According to our simulations, circumpolar rivers deliver large quantities of mercury to the Arctic Ocean during summer; the subsequent evasion of this riverine mercury to the atmosphere can explain the summertime peak in atmospheric mercury levels. We infer that rivers are the dominant source of mercury to the Arctic Ocean on an annual basis. Our simulations suggest that Arctic Ocean mercury concentrations could be highly sensitive to climate-induced changes in river flow, and to increases in the mobility of mercury in soils, for example as a result of permafrost thaw and forest fires.

  9. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    SciTech Connect

    Franklyn, C. B.

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  10. Open Source Dataturbine (OSDT) Android Sensorpod in Environmental Observing Systems

    NASA Astrophysics Data System (ADS)

    Fountain, T. R.; Shin, P.; Tilak, S.; Trinh, T.; Smith, J.; Kram, S.

    2014-12-01

    The OSDT Android SensorPod is a custom-designed mobile computing platform for assembling wireless sensor networks for environmental monitoring applications. Funded by an award from the Gordon and Betty Moore Foundation, the OSDT SensorPod represents a significant technological advance in the application of mobile and cloud computing technologies to near-real-time applications in environmental science, natural resources management, and disaster response and recovery. It provides a modular architecture based on open standards and open-source software that allows system developers to align their projects with industry best practices and technology trends, while avoiding commercial vendor lock-in to expensive proprietary software and hardware systems. The integration of mobile and cloud-computing infrastructure represents a disruptive technology in the field of environmental science, since basic assumptions about technology requirements are now open to revision, e.g., the roles of special purpose data loggers and dedicated site infrastructure. The OSDT Android SensorPod was designed with these considerations in mind, and the resulting system exhibits the following characteristics - it is flexible, efficient and robust. The system was developed and tested in the three science applications: 1) a fresh water limnology deployment in Wisconsin, 2) a near coastal marine science deployment at the UCSD Scripps Pier, and 3) a terrestrial ecological deployment in the mountains of Taiwan. As part of a public education and outreach effort, a Facebook page with daily ocean pH measurements from the UCSD Scripps pier was developed. Wireless sensor networks and the virtualization of data and network services is the future of environmental science infrastructure. The OSDT Android SensorPod was designed and developed to harness these new technology developments for environmental monitoring applications.

  11. Observing the Earliest Galaxies: Looking for the Sources of Reionization

    NASA Astrophysics Data System (ADS)

    Illingworth, Garth

    2015-04-01

    Systematic searches for the earliest galaxies in the reionization epoch finally became possible in 2009 when the Hubble Space Telescope was updated with a powerful new infrared camera during the final Shuttle servicing mission SM4 to Hubble. The reionization epoch represents the last major phase transition of the universe and was a major event in cosmic history. The intense ultraviolet radiation from young star-forming galaxies is increasingly considered to be the source of the photons that reionized intergalactic hydrogen in the period between the ``dark ages'' (the time before the first stars and galaxies at about 100-200 million years after the Big Bang) and the end of reionization around 800-900 million years. Yet finding and measuring the earliest galaxies in this era of cosmic dawn has proven to a challenging task, even with Hubble's new infrared camera. I will discuss the deep imaging undertaken by Hubble and the remarkable insights that have accrued from the imaging datasets taken over the last decade on the Hubble Ultra-Deep Field (HUDF, HUDF09/12) and other regions. The HUDF datasets are central to the story and have been assembled into the eXtreme Deep Field (XDF), the deepest image ever from Hubble data. The XDF, when combined with results from shallower wide-area imaging surveys (e.g., GOODS, CANDELS) and with detections of galaxies from the Frontier Fields, has provided significant insights into the role of galaxies in reionization. Yet many questions remain. The puzzle is far from being fully solved and, while much will done over the next few years, the solution likely awaits the launch of JWST. NASA/STScI Grant HST-GO-11563.

  12. Auroral kilometric radiation source region observations from ISIS 1

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1981-01-01

    The ISIS 1 observations of the high-frequency portion of the auroral kilometric radiation (AKR) spectrum are considered, that is, from the minimum frequency encountered for the extraordinary mode cut-off (approximately 450 kHz) to the upper frequency cut-off (approximately 800 kHz). AKR is found to be generated in the extraordinary mode just above the local cutoff frequency and to emanate in a direction that is nearly perpendicular to the magnetic field. It occurs within local depletions of electron density, where the ratio of plasma frequency to cyclotron frequency is below 0.2. The density depletion is restricted to altitudes above approximately 2,000 km, and the upper AKR frequency limit corresponds to the extraordinary cutoff frequency at this altitude.

  13. Funding sources for continuing medical education: An observational study

    PubMed Central

    Venkataraman, Ramesh; Ranganathan, Lakshmi; Ponnish, Arun S.; Abraham, Babu K.; Ramakrishnan, Nagarajan

    2014-01-01

    Aims: Medical accreditation bodies and licensing authorities are increasingly mandating continuing medical education (CME) credits for maintenance of licensure of healthcare providers. However, the costs involved in participating in these CME activities are often substantial and may be a major deterrent in obtaining these mandatory credits. It is assumed that healthcare providers often obtain sponsorship from their institutions or third party payers (i.e. pharmaceutical-industry) to attend these educational activities. Data currently does not exist exploring the funding sources for CME activities in India. In this study, we examine the relative proportion of CME activities sponsored by self, institution and the pharmaceutical-industry. We also wanted to explore the characteristics of courses that have a high proportion of self-sponsorship. Materials and Methods: This is a retrospective audit of the data during the year 2009 conducted at an autonomous clinical training academy. The details of the sponsor of each CME activity were collected from an existing database. Participants were subsequently categorized as sponsored by self, sponsored by institution or sponsored by pharmaceutical-industry. Results: In the year 2009, a total of 2235 participants attended 40 different CME activities at the training academy. Of the total participants, 881 (39.4%) were sponsored by self, 898 (40.2%) were sponsored by institution and 456 (20.3%) by pharmaceutical-industry. About 47.8% participants attended courses that carried an international accreditation. For the courses that offer international accreditation, 63.3% were sponsored by self, 34.9% were sponsored by institution and 1.6% were sponsored by pharmaceutical-industry. There were 126 participants (5.6%) who returned to the academy for another CME activity during the study period. Self-sponsored (SS) candidates were more likely to sponsor themselves again for subsequent CME activity compared with the other two groups (P < 0

  14. Understanding the Solar Sources of In Situ Observations

    NASA Technical Reports Server (NTRS)

    Riley, Pete; Mikic, Zoran; Linker, Jon; Zurbuchen, Thomas H.

    2002-01-01

    The solar wind can, to a good approximation be described as a two component flow with fast, tenuous, quiescent flow emanating from coronal holes, and slow, dense and variable flow associated with the boundary between open and closed magnetic fields. In spite of its simplicity, this picture naturally produces a range of complex heliospheric phenomena, including the presence, location, and orientation of corotating interaction regions and their associated shocks. In this study, we apply a two-step mapping technique, incorporating a magnetohydrodynamic model of the solar corona, to bring in situ observations h m Ulysses, WIND, and ACE back to the solar surface in an effort to determine some intrinsic properties of the quasi-steady solar wind. In particular, we find that a "layer" of approx. 35,000 h n exists between the Coronal Hole Boundary (CHB) and the fast solar wind, where the wind is slow and variable. We also- derive a velocity gradient within large polar coronal boles (that were present during Ulysses rapid latitude scan) as a function of distance from the CHB. We find that nu = 713 km/s + 3.2 d, where d is the angular distance from the CHB boundary in degrees.

  15. Catalog of infrared observations including: Bibliography of infrared astronomy and index of infrared source positions

    NASA Technical Reports Server (NTRS)

    Gezari, D. Y.; Schmitz, M.; Mead, J. M.

    1984-01-01

    The Catalog of Infrared Observations and its Far Infrared Supplement summarize all infrared astronomical observations at infrared wavelengths published in the scientific literature between 1965 and 1982. The Catalog includes as appendices the Bibliography of infrared astronomy which keys observations in the Catalog with the original journal references, and the index of infrared source positions which gives source positions for alphabetically listed sources in the Catalog. The Catalog data base contains over 85,000 observations of about 10,000 infrared sources, of which about 2,000 have no known visible counterpart.

  16. Observations on vapor pressure in SPR caverns : sources.

    SciTech Connect

    Munson, Darrell Eugene

    2010-05-01

    The oil of the Strategic Petroleum Reserve (SPR) represents a national response to any potential emergency or intentional restriction of crude oil supply to this country, and conforms to International Agreements to maintain such a reserve. As assurance this reserve oil will be available in a timely manner should a restriction in supply occur, the oil of the reserve must meet certain transportation criteria. The transportation criteria require that the oil does not evolve dangerous gas, either explosive or toxic, while in the process of transport to, or storage at, the destination facility. This requirement can be a challenge because the stored oil can acquire dissolved gases while in the SPR. There have been a series of reports analyzing in exceptional detail the reasons for the increases, or regains, in gas content; however, there remains some uncertainty in these explanations and an inability to predict why the regains occur. Where the regains are prohibitive and exceed the criteria, the oil must undergo degasification, where excess portions of the volatile gas are removed. There are only two known sources of gas regain, one is the salt dome formation itself which may contain gas inclusions from which gas can be released during oil processing or storage, and the second is increases of the gases release by the volatile components of the crude oil itself during storage, especially if the stored oil undergoes heating or is subject to biological generation processes. In this work, the earlier analyses are reexamined and significant alterations in conclusions are proposed. The alterations are based on how the fluid exchanges of brine and oil uptake gas released from domal salt during solutioning, and thereafter, during further exchanges of fluids. Transparency of the brine/oil interface and the transfer of gas across this interface remains an important unanswered question. The contribution from creep induced damage releasing gas from the salt surrounding the cavern is

  17. Volcanic Lightning: New Global Observations and Constraints on Source Mechanisms

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.; Venzke, E.; Williams, E.

    2012-12-01

    New data on volcanic lightning from the Smithsonian Volcano Reference File are added to an existing database and greatly expand the number of cases available for study. Lightning has now been documented at 154 volcanoes in association with 394 eruptions, a significant increase from the earlier numbers of 89 volcanoes and 240 eruptions. Lightning and electrification at volcanoes are important because they represent a hazard in their own right, they are a component of the global electrical circuit, and because they contribute to ash particle aggregation and modification within ash plumes. The role of water substance (water in all forms) in particular has not been well studied. The Volcanic Explosivity Index (VEI) was determined for 177 eruptions. Eight percent of VEI=3-5 eruptions have reported lightning, and 10 percent of VEI=6, but less than 2 percent of those with VEI=1-2, suggesting consistent reporting for larger eruptions but either less lightning or under-reporting for small eruptions. Ash plume heights (142 observations) show a bimodal distribution with peaks at 7-12 km and 1-4 km. The former are similar to heights of typical thunderstorms and suggest involvement of water substance, whereas the latter suggest other factors contributing to electrical behavior near the vent. The distributions of the latitudes of volcanoes with lightning and eruptions with lightning roughly mimic the distribution of all volcanoes; flat with latitude. Meteorological lightning, on the other hand, is common in the tropics and decreases markedly with increasing latitude as the ability of the atmosphere to hold water decreases poleward. This finding supports the idea that if lightning in large eruptions depends on water substance, then the origin of the water is primarily magma and not entrainment from the surrounding atmosphere.

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

    PubMed

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

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  20. Simultaneous observations of hard X-ray and microwave burst sources in a limb flare

    NASA Technical Reports Server (NTRS)

    Takakura, T.; Kundu, M. R.; Mcconnell, D.; Ohki, K.

    1985-01-01

    Observations of a flare which occurred just behind the west solar limb on 1981 August 3 are reported. A hard X-ray source (20-30 keV) and a microwave source at 5 GHz were observed simultaneously using the Very Large Array and the hard X-ray telescope aboard the Hinotori spacecraft. Both sources were located in the corona, apparently near the tops of two independent coronal arcades or loops. The source may be composed of many thin filaments unresolved by the VLA observations.

  1. Optical Fiber Infrasound Sensor Arrays: An Improved Alternative to Arrays of Rosette Wind Filters

    NASA Astrophysics Data System (ADS)

    Zumberge, M. A.; Walker, K. T.; Dewolf, S.; Berger, J.; Hedlin, M. A.

    2009-12-01

    A key difficulty in infrasound signal detection is the noise created by spatially-incoherent turbulence that is usually present in wind. Increasing wind speeds correlate with increasing noise levels across the entire infrasound band. Spatial separation of sensors with array processing provides only limited signal-to-noise improvement. Mechanical wind filters, like rosette pipe arrays, also help to reduce wind noise, but the rosette infrasound response depends on the apparent speed and frequency of the signal that propagates across the ports as well as the rosette size. This response places an upper limit of about 70 m on the diameter of rosettes; larger rosettes, while better at wind noise reduction, attenuate desirable infrasound signals arriving from all directions. Optical fiber infrasound sensors (OFIS) are line microphones that instantaneously integrate pressure along their lengths with laser interferometry. Although the sensor has a very low noise floor, the promise of the sensor is in its effectiveness at reducing wind noise. We have previously shown that a single 90 m OFIS (line) is just as effective at reducing wind noise as a 70 m diameter rosette (covering a circular area). We have also empirically measured the infrasound response of the OFIS as a function of back azimuth, showing that it is well predicted by an analytical solution; the response is flat for broadside signals and similar to the rosette response for endfire signals. Using that analytical solution, we have developed and tested computationally efficient beamforming techniques that permit the rapid estimation of back azimuth using an array of OFIS arms as well as an array deconvolution technique that accurately stacks weighted versions of the recordings to obtain the original infrasound signal. Recently, several improvements to the instrumentation and methodology have been achieved. We have made an important modification to our interferometric technique that makes the interferometer

  2. 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

  3. 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.

  4. 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

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

    SciTech Connect

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

    1997-11-01

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

  6. 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.

  7. Infrasonic Observations of Thunderstorms at High Latitudes: Time Scales

    NASA Astrophysics Data System (ADS)

    Liszka, L. J.

    2008-12-01

    The present work summarizes some results of infrasonic observations of thunderstorms recorded in the Northern Scandinavia by the Swedish-Finnish Infrasound Network (SIN). A lightning in the atmosphere is a source of cylindrical shock waves. When the distance from the source increases, more and more energy is transferred into the low-frequency range through the same mechanism as for shock waves from supersonic aircraft. Frequently, semi-regular sequences of lightning with similar orientation and nearly constant repetition frequency are observed. For that reason the spectrum of time delays between individual strokes is studied. It has been found that the apparent random occurrence of strokes seems be a result of superposition of several processes with slowly varying time scales.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  9. Chemical Source Inversion using Assimilated Constituent Observations in an Idealized Two-dimensional System

    NASA Technical Reports Server (NTRS)

    Tangborn, Andrew; Cooper, Robert; Pawson, Steven; Sun, Zhibin

    2009-01-01

    We present a source inversion technique for chemical constituents that uses assimilated constituent observations rather than directly using the observations. The method is tested with a simple model problem, which is a two-dimensional Fourier-Galerkin transport model combined with a Kalman filter for data assimilation. Inversion is carried out using a Green's function method and observations are simulated from a true state with added Gaussian noise. The forecast state uses the same spectral spectral model, but differs by an unbiased Gaussian model error, and emissions models with constant errors. The numerical experiments employ both simulated in situ and satellite observation networks. Source inversion was carried out by either direct use of synthetically generated observations with added noise, or by first assimilating the observations and using the analyses to extract observations. We have conducted 20 identical twin experiments for each set of source and observation configurations, and find that in the limiting cases of a very few localized observations, or an extremely large observation network there is little advantage to carrying out assimilation first. However, in intermediate observation densities, there decreases in source inversion error standard deviation using the Kalman filter algorithm followed by Green's function inversion by 50% to 95%.

  10. The Source Structure of 0642+449 Detected from the CONT14 Observations

    NASA Astrophysics Data System (ADS)

    Xu, Ming H.; Heinkelmann, Robert; Anderson, James M.; Mora-Diaz, Julian; Schuh, Harald; Wang, Guang L.

    2016-11-01

    The CONT14 campaign with state-of-the-art very long baseline interferometry (VLBI) data has observed the source 0642+449 with about 1000 observables each day during a continuous observing period of 15 days, providing tens of thousands of closure delays—the sum of the delays around a closed loop of baselines. The closure delay is independent of the instrumental and propagation delays and provides valuable additional information about the source structure. We demonstrate the use of this new “observable” for the determination of the structure in the radio source 0642+449. This source, as one of the defining sources in the second realization of the International Celestial Reference Frame, is found to have two point-like components with a relative position offset of ‑426 microarcseconds (μas) in R.A. and ‑66 μas in decl. The two components are almost equally bright, with a flux-density ratio of 0.92. The standard deviation of closure delays for source 0642+449 was reduced from 139 to 90 ps by using this two-component model. Closure delays larger than 1 ns are found to be related to the source structure, demonstrating that structure effects for a source with this simple structure could be up to tens of nanoseconds. The method described in this paper does not rely on a priori source structure information, such as knowledge of source structure determined from direct (Fourier) imaging of the same observations or observations at other epochs. We anticipate our study to be a starting point for more effective determination of the structure effect in VLBI observations.

  11. Using Generalizability Theory to Examine Sources of Variance in Observed Behaviors within High School Classrooms

    ERIC Educational Resources Information Center

    Abry, Tashia; Cash, Anne H.; Bradshaw, Catherine P.

    2014-01-01

    Generalizability theory (GT) offers a useful framework for estimating the reliability of a measure while accounting for multiple sources of error variance. The purpose of this study was to use GT to examine multiple sources of variance in and the reliability of school-level teacher and high school student behaviors as observed using the tool,…

  12. JVLA observations of IC 348 SW: Compact radio sources and their nature

    SciTech Connect

    Rodríguez, Luis F.; Zapata, Luis A.; Palau, Aina E-mail: l.zapata@crya.unam.mx

    2014-07-20

    We present sensitive 2.1 and 3.3 cm Jansky Very Large Array radio continuum observations of the region IC 348 SW. We detect a total of 10 compact radio sources in the region, 7 of which are first reported here. One of the sources is associated with the remarkable periodic time-variable infrared source LRLL 54361, opening the possibility of monitoring this object at radio wavelengths. Four of the sources appear to be powering outflows in the region, including HH 211 and HH 797. In the case of the rotating outflow HH 797, we detect a double radio source at its center, separated by ∼3''. Two of the sources are associated with infrared stars that possibly have gyrosynchrotron emission produced in active magnetospheres. Finally, three of the sources are interpreted as background objects.

  13. Observation of the X-ray source Sco X-1 from Skylab. [radiant flux density

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1977-01-01

    An attempt to observe the discrete X-ray source Sco X-1 on 20 September 1973 between 0856 and 0920 UT is reported. Data obtained with the ATM/S-056 X-ray event analyzer, in particular the flux observed with the 1.71 to 4.96 KeV counter, is analyzed. No photographic image of the source was obtained because Sco X-1 was outside the field of view of the X-ray telescope.

  14. Swift observations of unidentified radio sources in the revised Third Cambridge Catalogue

    NASA Astrophysics Data System (ADS)

    Maselli, A.; Massaro, F.; Cusumano, G.; La Parola, V.; Harris, D. E.; Paggi, A.; Liuzzo, E.; Tremblay, G. R.; Baum, S. A.; O'Dea, C. P.

    2016-08-01

    We have investigated a group of unassociated radio sources included in the Third Cambridge Catalogue (3CR) to increase the multifrequency information on them and possibly obtain an identification. We have carried out an observational campaign with the Swift satellite to observe with the Ultraviolet/Optical Telescope (UVOT) and the X-Ray Telescope (XRT) the field of view of 21 bright NRAO VLA Sky Survey (NVSS) sources within the positional uncertainty region of the 3CR sources. Furthermore, we have searched in the recent AllWISE Source Catalogue for infrared sources matching the position of these NVSS sources. We have detected significant emission in the soft X-ray band for nine of the investigated NVSS sources. To all of them, and in four cases with no soft X-ray association, we have associated a Wide-field Infrared Survey Explorer infrared counterpart. Eight of these infrared candidates have not been proposed earlier in the literature. In the five remaining cases our candidate matches one among a few optical candidates suggested for the same 3CR source in previous studies. No source has been detected in the UVOT filters at the position of the NVSS objects, confirming the scenario that all of them are heavily obscured. With this in mind, a spectroscopic campaign, preferably in the infrared band, will be necessary to establish the nature of the sources that we have finally identified.

  15. MAMBO observations at 240GHz of optically obscured Spitzer sources: source clumps and radio activity at high redshift

    NASA Astrophysics Data System (ADS)

    Andreani, P.; Magliocchetti, M.; de Zotti, G.

    2010-01-01

    Optically very faint (R > 25.5) sources detected by the Spitzer Space Telescope at 24μm represent a very interesting population at redshift z ~ (1.5-3). They exhibit strong clustering properties, implying that they are hosted by very massive haloes, and their mid-infrared emission could be powered by either dust-enshrouded star formation and/or by an obscured active galactic nucleus (AGN). We report observations carried out with the Max Planck Millimetre Bolometer (MAMBO) array at the IRAM 30-m antenna on Pico Veleta of a candidate protocluster with five optically obscured sources selected from the 24-μm Spitzer sample of the First-Look Survey. Interestingly, these sources appear to lie on a high-density filament aligned with the two radio jets of an AGN. Four out of five of the observed sources were detected. We combine these measurements with optical, infrared and radio observations to probe the nature of the candidate protocluster members. Our preliminary conclusions can be summarized as follows: the spectral energy distributions (SEDs) of all sources include both AGN and starburst contributions; the AGN contribution to the bolometric luminosities ranges between 14 and 26 per cent of the total. Such a contribution is enough for the AGN to dominate the emission at 5.8, 8 and 24μm, while the stellar component, inferred from SED fitting, prevails at 1.25mm and at λ < 4.5μm. The present analysis suggests a coherent interplay at high z between extended radio activity and the development of filamentary large-scale structures.

  16. [Flow of high-voltage current in coal electrodes of arc furnaces as a source of noise of special nature].

    PubMed

    Polanowska, R

    1984-01-01

    The noise level for working arc furnace has been measured. Arc furnaces were found to be the source of infrasounds and acoustic field. The sound pressure levels for infrasounds range from 55 to 77 dB. It has been showed that particular noise level includes the onethird-octave band with middle frequency 100 Hz. The sound pressure levels in this band range from 105 to 110 dB.

  17. Observations of discrete gamma ray sources with SAS-2. [compact sources centered on Crab nebula and Vela X supernova remnant

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Bignami, G. F.

    1974-01-01

    Compact gamma ray sources centered on the Crab nebula and the Vela X supernova remnant are considered. An excess in the galactic radiation was observed in both regions. Data indicate that a large fraction of this flux is pulsed. The excess from the Vela region could reflect either a large-scale galactic feature, such as a superposition of spiral arm segments, or it could be associated with the Vela supernova remnant. Low-energy gamma ray bursts were observed in the SAS-2 anticoincidence shielding.

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

    PubMed

    Ziaran, Stanislav

    2014-01-01

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

  19. Constraints on galactic distributions of gamma-ray burst sources from BATSE observations

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Meegan, Charles A.; Pendleton, Geoffrey N.; Fishman, Gerald J.; Wilson, Robert B.; Paciesas, William S.; Brock, Martin N.; Horack, John M.

    1994-01-01

    The paradigm that gamma-ray bursts originate from Galactic sources is studied in detail using the angular and intensity distributions observed by the Burst and Transient Source Experiment (BATSE) on NASA's Compton Gamma Ray Observatory (CGRO). Monte Carlo models of gamma-ray burst spatial distributions and luminosity functions are used to simulate bursts, which are then folded through mathematical models of BATSE selection effects. The observed and computed angular intensity distributions are analyzed using modifications of standard statistical homogeneity and isotropy studies. Analysis of the BATSE angular and intensity distributions greatly constrains the origins and luminosities of burst sources. In particular, it appears that no single population of sources confined to a Galactic disk, halo, or localized spiral arm satisfactorily explains BATSE observations and that effects of the burst luminosity function are secondary when considering such models. One family of models that still satisfies BATSE observations comprises sources located in an extended spherical Galactic corona. Coronal models are limited to small ranges of burst luminosity and core radius, and the allowed parameter space for such models shrinks with each new burst BATSE observes. Multiple-population models of bursts are found to work only if (1) the primary population accounts for the general isotropy and inhomogeneity seen in the BATSE observations and (2) secondary populations either have characteristics similar to the primary population or contain numbers that are small relative to the primary population.

  20. 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.

  1. Observations of IPS radio sources at 140 MHz with the Mexican Array Radio Telescope (MEXART)

    NASA Astrophysics Data System (ADS)

    Mejia-Ambriz, Julio-Cesar; Villanueva-Hernandez, Pablo; Gonzalez-Esparza, Americo; Aguilar-Rodriguez, Ernesto; Mendoza-Torrez, Jose Eduardo; Carrillo-Vargas, Armando; Andrade-Mascote, Ernesto

    The MEXART is a dedicated transit station to perform Interplanetary Scintillation (IPS) ob-servations. The array of 4096 full wavelenght dipoles has a collecting area of 9600 square meters, the operation frequency is 140 MHz with a bandwidth of 2 MHz. Recently we began the IPS observations with the instrument. We report a list of IPS radio sources observed at 140 MHz. We perform an analysis of the scintillation index (m) versus the elongation angle to obtain the first g values given by the instrument for some radio sources. We report the single station solar wind velocity fitting model adapted at 140 MHz based on Manoharan and Ananthakrishnan (1990).

  2. Chandra Observations of the X-Ray Point Source Population in NGC 4636

    NASA Astrophysics Data System (ADS)

    Posson-Brown, Jennifer; Raychaudhury, Somak; Forman, William; Donnelly, R. Hank; Jones, Christine

    2009-04-01

    We present the X-ray point-source population in the nearby Virgo elliptical galaxy NGC 4636 from three Chandra X-ray observations. These observations, totaling ~193 ks after time filtering, were taken with the Advanced CCD Imaging Camera (ACIS) over a three-year period. Using a wavelet decomposition detection algorithm, we detect 318 individual point sources. For our analysis, we use a subset of 277 detections with >= net 10 counts (a limiting luminosity of approximately 1.2 × 1037 erg s-1 in the 0.5-2 keV band, outside the central 1farcm5 bright galaxy core). We present a radial distribution of the point sources. Between 1farcm5 and 6' from the center, 25% of our sources are likely to be background sources (active galactic nuclei (AGNs)) and 75% are low-mass X-ray binaries (LMXBs) within the galaxy, while at radial distances greater than 6', background sources (AGN) will dominate the point sources. We explore short and long-term variability (over timescales of 1 day to three years) for X-ray point sources in this elliptical galaxy. 54 sources (24%) in the common ACIS fields of view show significant variability between observations. Of these, 37 are detected with at least 10 net counts in only one observation and thus may be "transient." In addition, ~10% of the sources in each observation show significant short-term variability; we present an example light curve for a variable bright source. The cumulative luminosity function (LF) for the point sources in NGC 4636 can be represented as a power law of slope α = 1.14 ± 0.03. We do not detect, but estimate an upper limit of ~4.5 × 1037 erg s-1 to the current X-ray luminosity of the historical supernova SN1939A. We find 77 matches between X-ray point sources and globular cluster (GC) candidates found in deep optical images of NGC 4636. In the annulus from 1farcm5 to 6' of the galaxy center, 48 of the 129 X-ray point sources (37%) with >=10 net counts are matched with GC candidates. Since we expect 25% of these

  3. Source identification and apportionment of halogenated compounds observed at a remote site in East Asia.

    PubMed

    Li, Shanlan; Kim, Jooil; Park, Sunyoung; Kim, Seung-Kyu; Park, Mi-Kyung; Mühle, Jens; Lee, Gangwoong; Lee, Meehye; Jo, Chun Ok; Kim, Kyung-Ryul

    2014-01-01

    The sources of halogenated compounds in East Asia associated with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 halogenated compounds and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from November 2007 to December 2011 were analyzed by a positive matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concentrations of halogenated compounds observed at Gosan and corresponding concentration-based source contributions were also suggested: primary aluminum production explaining 37% of total concentration enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC production with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory analysis was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum production, solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF analysis results. The industry-based emission sources of halogenated compounds identified in this study help improve our understanding of the East Asian countries' industrial contributions to halogenated compound emissions. PMID:24298975

  4. DEEP CHANDRA MONITORING OBSERVATIONS OF NGC 4649. I. CATALOG OF SOURCE PROPERTIES

    SciTech Connect

    Luo, B.; Fabbiano, G.; Strader, J.; Kim, D.-W.; Fragos, T.; Brodie, J. P.; King, A.; Zezas, A.

    2013-02-15

    We present the X-ray source catalog for the Chandra monitoring observations of the elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501 X-ray sources detected in the 0.3-8.0 keV band in the merged observation or in one of the six individual observations; 399 sources are located within the D{sub 25} ellipse. The observed 0.3-8.0 keV luminosities of these 501 sources range from 9.3 Multiplication-Sign 10{sup 36} erg s{sup -1} to 5.4 Multiplication-Sign 10{sup 39} erg s{sup -1}. The 90% detection completeness limit within the D{sub 25} ellipse is 5.5 Multiplication-Sign 10{sup 37} erg s{sup -1}. Based on the surface density of background active galactic nuclei (AGNs) and detection completeness, we expect Almost-Equal-To 45 background AGNs among the catalog sources ( Almost-Equal-To 15 within the D{sub 25} ellipse). There are nine sources with luminosities greater than 10{sup 39} erg s{sup -1}, which are candidates for ultraluminous X-ray sources. The nuclear source of NGC 4649 is a low-luminosity AGN, with an intrinsic 2.0-8.0 keV X-ray luminosity of 1.5 Multiplication-Sign 10{sup 38} erg s{sup -1}. The X-ray colors suggest that the majority of the catalog sources are low-mass X-ray binaries (LMXBs). We find that 164 of the 501 X-ray sources show long-term variability, indicating that they are accreting compact objects. We discover four transient candidates and another four potential transients. We also identify 173 X-ray sources (141 within the D{sub 25} ellipse) that are associated with globular clusters (GCs) based on Hubble Space Telescope and ground-based data; these LMXBs tend to be hosted by red GCs. Although NGC 4649 has a much larger population of X-ray sources than the structurally similar early-type galaxies, NGC 3379 and NGC 4278, the X-ray source properties are comparable in all three systems.

  5. NaCo/SAM observations of sources at the Galactic Center

    NASA Astrophysics Data System (ADS)

    Sanchez-Bermudez, J.; Schödel, R.; Alberdi, A.; Pott, J. U.

    2012-07-01

    Sparse aperture masking (SAM) interferometry combined with Adaptive Optics (AO) is a technique that is uniquely suited to investigate structures near the diffraction limit of large telescopes. The strengths of the technique are a robust calibration of the Point Spread Function (PSF) while maintaining a relatively high dynamic range. We used SAM+AO observations to investigate the circumstellar environment of several bright sources with infrared excess in the central parsec of the Galaxy. For our observations, unstable atmospheric conditions as well as significant residuals after the background subtraction presented serious problems for the standard approach of calibrating SAM data via interspersed observations of reference stars. We circumvented these difficulties by constructing a synthesized calibrator directly from sources within the field-of-view. When observing crowded fields, this novel method can boost the efficiency of SAM observations because it renders interspersed calibrator observations unnecessary. Here, we presented the first NaCo/SAM images reconstructed using this method.

  6. ASCA Observation of Bright X-Ray Sources in the Nearby Spiral Galaxy IC 342

    NASA Astrophysics Data System (ADS)

    Okada, Kyoko; Dotani, Tadayasu; Makishima, Kazuo; Mitsuda, Kazuhisa; Mihara, Tatehiro

    1998-02-01

    X-ray observations of the nearby starburst galaxy IC 342 with ASCA led to the detection of three bright X-ray sources, whose positions are consistent with those from the Einstein and ROSAT observations. The X-ray luminosities of the two sources exceed the Eddington limit of a 1.4MO object by two orders of magnitude for an assumed distance of 4.5 Mpc. The brightest one (source 1) among the three exhibited significant time variations on a time scale of a few hours during the ASCA observation. Thus, the size of the emission region must be smaller than about 10(14) cm. The energy spectrum of the source can be represented either by a power-law with an exponential roll-over, or by an optically thick accretion disk model with a maximum color temperature of 1.77 keV. Although the large luminosity of source 1 may be explained by a ~ 100MO black hole at 4.5 Mpc, the observed energy spectrum is too hard to be accounted for by an optically thick accretion disk around the black hole. Ifsource1 is a relativistic jet source with strong X-ray beaming, both the large luminosity and the hard X-ray spectrum can be explained.

  7. 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

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

    PubMed

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

    2013-01-01

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

  9. Ionosonde tracking of infrasound wavefronts in the thermosphere launched by seismic waves after the 2010 M8.8 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Maruyama, Takashi; Yusupov, Kamil; Akchurin, Adel

    2016-03-01

    Ionospheric disturbances associated with the M8.8 Chile earthquake (35.91°S, 72.73°W) on 27 February 2010 were observed at Kazan, Russia (55.85°N, 48.81°E). Rapid-run ionograms at 1 min intervals exhibited multiple-cusp signatures (MCSs) for more than 30 min, which have been observed several times after large earthquakes. The ionospheric disturbances were caused by infrasound propagating upward in the atmosphere, which modified the electron density distribution through ion-neutral collisions. The anomaly of the vertical electron density distribution responsible for the MCSs was analyzed by converting the ionogram traces into real height profiles. The density profiles at 1 min intervals allowed the tracking of the vertical propagation of infrasound and provided information on parameters of acoustic waves, which was not possible from the previous measurements such as standard ionograms at 5-15 min intervals, HF Doppler soundings, and total electron content using satellite beacon signals. The speed of acoustic waves in the thermosphere was evaluated from the consecutive ionograms with MCSs, and it was found that the thermospheric temperature was slightly higher than that calculated using the Mass Spectrometer and Incoherent Scatter Radar empirical model (NRLMSISE-00).

  10. Observations of the frequency tuning effect in the 14 GHz CAPRICE ion source

    SciTech Connect

    Celona, L.; Ciavola, G.; Consoli, F.; Gammino, S.; Maimone, F.; Mascali, D.; Spaedtke, P.; Tinschert, K.; Lang, R.; Maeder, J.; Rossbach, J.; Barbarino, S.; Catalano, R. S.

    2008-02-15

    A set of measurements with the CAPRICE ion source at the GSI test bench has been carried out to investigate its behavior in terms of intensity and shape of the extracted beam when the microwaves generating the plasma sweep in a narrow range of frequency ({+-}40 MHz) around the klystron center frequency (14.5 GHz). Remarkable variations have been observed depending on the source and the beamline operating parameters, confirming that a frequency dependent electromagnetic distribution is preserved even in the presence of plasma inside the source. Moreover, these observations confirm that the frequency tuning is a powerful method to optimize the electron cyclotron resonance ion source performances. A description of the experimental setup and of the obtained results is given in the following.

  11. Full-Sun observations for identifying the source of the slow solar wind.

    PubMed

    Brooks, David H; Ugarte-Urra, Ignacio; Warren, Harry P

    2015-01-01

    Fast (>700 km s(-1)) and slow (~400 km s(-1)) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705

  12. Full-Sun observations for identifying the source of the slow solar wind.

    PubMed

    Brooks, David H; Ugarte-Urra, Ignacio; Warren, Harry P

    2015-01-01

    Fast (>700 km s(-1)) and slow (~400 km s(-1)) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind.

  13. Full-Sun observations for identifying the source of the slow solar wind

    PubMed Central

    Brooks, David H.; Ugarte-Urra, Ignacio; Warren, Harry P.

    2015-01-01

    Fast (>700 km s−1) and slow (~400 km s−1) winds stream from the Sun, permeate the heliosphere and influence the near-Earth environment. While the fast wind is known to emanate primarily from polar coronal holes, the source of the slow wind remains unknown. Here we identify possible sites of origin using a slow solar wind source map of the entire Sun, which we construct from specially designed, full-disk observations from the Hinode satellite, and a magnetic field model. Our map provides a full-Sun observation that combines three key ingredients for identifying the sources: velocity, plasma composition and magnetic topology and shows them as solar wind composition plasma outflowing on open magnetic field lines. The area coverage of the identified sources is large enough that the sum of their mass contributions can explain a significant fraction of the mass loss rate of the solar wind. PMID:25562705

  14. MULTIBAND DIAGNOSTICS OF UNIDENTIFIED 1FGL SOURCES WITH SUZAKU AND SWIFT X-RAY OBSERVATIONS

    SciTech Connect

    Takeuchi, Y.; Kataoka, J.; Maeda, K.; Takahashi, Y.; Tahara, M.; Nakamori, T.

    2013-10-01

    We have analyzed all the archival X-ray data of 134 unidentified (unID) gamma-ray sources listed in the first Fermi/LAT (1FGL) catalog and subsequently followed up by the Swift/XRT. We constructed the spectral energy distributions (SEDs) from radio to gamma-rays for each X-ray source detected, and tried to pick up unique objects that display anomalous spectral signatures. In these analyses, we target all the 1FGL unID sources, using updated data from the second Fermi/LAT (2FGL) catalog on the Large Area Telescope (LAT) position and spectra. We found several potentially interesting objects, particularly three sources, 1FGL J0022.2–1850, 1FGL J0038.0+1236, and 1FGL J0157.0–5259, which were then more deeply observed with Suzaku as a part of an AO-7 program in 2012. We successfully detected an X-ray counterpart for each source whose X-ray spectra were well fitted by a single power-law function. The positional coincidence with a bright radio counterpart (currently identified as an active galactic nucleus, AGN) in the 2FGL error circles suggests these sources are definitely the X-ray emission from the same AGN, but their SEDs show a wide variety of behavior. In particular, the SED of 1FGL J0038.0+1236 is not easily explained by conventional emission models of blazars. The source 1FGL J0022.2–1850 may be in a transition state between a low-frequency peaked and a high-frequency peaked BL Lac object, and 1FGL J0157.0–5259 could be a rare kind of extreme blazar. We discuss the possible nature of these three sources observed with Suzaku, together with the X-ray identification results and SEDs of all 134 sources observed with the Swift/XRT.

  15. On the possibility of observing cosmic ray sources in high energy gamma rays

    NASA Technical Reports Server (NTRS)

    Ormes, J. F.

    1987-01-01

    If cosmic rays are accelerated by strong shocks, then cosmic ray sources should be characterized by spectra, dN/dE alpha E exp -(2.0-2.2), reflecting the strength of those shocks. This is expected from the 'standard leaky box' model of cosmic ray propagation in which the source spectra are harder than the observed spectra because higher energy particles have shorter residence times in the galactic magnetic fields. Furthermore, data on cosmic ray nucleons suggest that these sources might be surrounded by material. If the latter is true, such sources should be observable in gamma rays at energies beyond 1 GeV where the angular resolution of gamma-ray telescopes is optimized and the background is significantly reduced. For identified sources, the source location accuracy can be shown to improve with increasing energy in spite of the decreasing statistics, as long as the gamma-ray spectrum is harder than dN/dE alpha E exp -gamma. A Monte Carlo model is used to predict the photon spectra which would be expected from cosmic ray sources under varying assumptions about the strength of the shocks in the acceleration region.

  16. The impact of compact radio sources on their host galaxies: observations

    NASA Astrophysics Data System (ADS)

    Tadhunter, C.

    2016-02-01

    I review the observational evidence that CSS/GPS radio sources have a significant impact on the evolution of their host galaxies, particularly on the kpc-scales of the galaxy bulges. Starting with an overview of the observational evidence for jet-cloud interactions and warm ionised outflows in CSS/GPS sources, I then consider the challenges involved in quantifying the feedback effect of the warm outflows in terms of their mass outflow rates and kinetic powers. For the best-observed cases it is shown that the warm outflows may have a major negative feedback effect in the very central regions, but probably lack the power to heat and eject the full cool ISM contents of the host galaxies. In contrast, the recently-discovered neutral and molecular outflows are more massive and powerful and therefore carry more destructive potential. However, the feedback effect of such outflows is not necessarily negative: there is now clear observational evidence that the molecular outflows are formed as the hot, compressed gas cools behind fast shocks driven into the ISM by the relativistic jets. The natural endpoint of this process is the formation of stars. Therefore, jet-induced star formation may be a significant process in CSS/GPS radio galaxies. Finally, I discuss whether CSS/GPS sources are ``imposters'' in flux-limited radio samples, due the flux boosting of the radio sources by strong jet-cloud interactions in the early stages of radio source evolution.

  17. Observational manifestations and intrinsic properties of the RCR sources in terms of a unified model

    NASA Astrophysics Data System (ADS)

    Zhelenkova, O. P.; Majorova, E. K.

    2016-04-01

    We present a summary results of the study of radio sources showing significant variations of integral flux density using the data from the RATAN-600 surveys of 1980-1994 at a frequency of 7.6 cm. The majority of the detected variable sources have flat radio spectra, although there are also all other spectrum types found. Point and compact sources predominate, although all known morphological structures are found in the sample. Variability is detected both in quasars and galaxies. Using the catalog data, we found brightness variations in the optical and/or infrared ranges for a half of host objects of radio sources. We analyzed the properties of nonvariable and variable RCR sources. We compared the ratio of absolute magnitude to radio luminosity for sources with the active nucleus types determined from the optical data. It is found that this parameter is approximately the same for quasars with different radio luminosity. It isminimum for the strongest radio galaxies and grows up to the level characteristic of quasars with the decrease of radio luminosity. Considering that the ratio depends on obscuring properties of a dust torus, such behavior can be explained if we assume that the torus geometry and its optical depth depend on the source long. This parameter is slightly higher among variable sources than among nonvariable ones which counts in favor of the nucleus more open to an observer.

  18. Chandra Observations of Unresolved X-Ray Sources Around Two Clusters of Galaxies

    NASA Technical Reports Server (NTRS)

    Molnar, Sandor M.; Hughes, John P.; Donahue, Megan; Joy, Marshall; Six, N. Frank (Technical Monitor)

    2002-01-01

    We have searched for unresolved X-ray sources in the vicinity of two rich clusters of galaxies: Abell 1995 (A1995) and MS 0451.6-0305 (MS0451), using the Chandra X-ray observatory. We detected significantly more unresolved sources around A1995 than expected based on the number of X-ray sources to the same flux limit detected in deep Chandra observations of blank fields. Previous studies have also found excess X-ray sources in the vicinity of several nearby clusters of galaxies using ROSAT (Roentgen Satellite), and recently in more distant (z is approximately 0.5) clusters (RXJ0030 and 3C295) using Chandra. In contrast, we detect only 14 unresolved X-ray sources near MS0451, which is consistent with the number expected from a cluster-free background. We determine the luminosity functions of the extra sources under the assumption that they are at the distance of their respective clusters. The characteristic luminosity of the extra sources around A1995 must be an order of magnitude fainter than that of the extra sources around RXJ0030 and 3C295. The apparent lack of extra sources around MS0451 is consistent with its greater distance and the same characteristic luminosity as the A1995 sources. Hardness ratios suggest that, on average, the extra sources in A1995 may have harder spectra than those of RXJ0030 and 3C295. These results indicate that different classes of objects may dominate in different clusters, perhaps depending on the formation history and/or dynamical state of the accompanying cluster.

  19. VLBA observations of radio faint Fermi-LAT sources above 10 GeV

    NASA Astrophysics Data System (ADS)

    Lico, R.; Giroletti, M.; Orienti, M.; D'Ammando, F.

    2016-10-01

    Context. The first Fermi-LAT high-energy source catalog (1FHL), containing γ-ray sources detected above 10 GeV, is an ideal sample for characterizing the physical properties of the most extreme γ-ray sources. Aims: We investigate the pc scale properties of a subsample of radio faint 1FHL sources with the aim of confirming the proposed blazar associations by revealing a compact high brightness temperature radio core, and we propose new low-frequency counterparts for the unassociated γ-ray sources (UGS). Moreover, we increase the number of 1FHL sources with high-resolution observations to explore the possible connection between radio and γ rays at E> 10 GeV. Methods: We observed 84 1FHL sources, mostly blazars of high synchrotron peaked (HSP) type, in the northern sky with the Very Long Baseline Array (VLBA) at 5 GHz. These sources lack high-resolution radio observations and have at least one NRAO VLA sky survey counterpart within the 95% confidence radius. For those sources without a well-identified radio counterpart we exploit the VLBA multiple phase-center correlation capability to identify the possible low-frequency candidates. Results: For ~93% of the sources in our sample we reveal a compact high brightness temperature radio core, which supports their proposed blazar association. The vast majority of the detected sources are radio weak, with a median VLBI flux density value of 16.3 mJy. For the detected sources we obtain an average brightness temperature on the order of 2 × 1010 K. We find a compact component for 16 UGS, for which we propose a new low-frequency association. Conclusions: We find brightness temperature values that do not require high Doppler factors, and are in agreement with the expected values for the equipartition of energy between particles and magnetic field. We find strong indications for the blazar nature of all of the detected UGS, for which we propose new low-frequency associations. The characterization of the physical properties of

  20. Very Long Baseline Array observations of the intraday variable source J1128+592

    NASA Astrophysics Data System (ADS)

    Gabányi, K. É.; Marchili, N.; Krichbaum, T. P.; Fuhrmann, L.; Müller, P.; Zensus, J. A.; Liu, X.; Song, H. G.

    2009-12-01

    Context: Short timescale flux density variations in flat spectrum radio sources are often explained by the scattering of radio waves in the turbulent ionized interstellar medium of the Milky Way. One of the most convincing observational arguments in favor of this is the annual modulation of the variability timescale caused by the orbital motion of Earth around the Sun. J1128+5925 is a recently discovered IDV source with a possible annual modulation in its variability timescale. New observations suggest a change in its variability characteristics. Aims: We search for changes either in source structure or in the interstellar medium that can explain the variations in the IDV pattern of J1128+5925. Using Very Long Baseline Interferometry (VLBI), we study a possible relation between source orientation on the sky and anisotropy angle seen in the annual modulation. Additionally, obtaining a source size estimate from VLBI data enables us to calculate the distance to the screen causing the variations in J1128+5925. Methods: We observed the source in six consecutive epochs with the Very Long Baseline Array (VLBA) at three frequencies, 5 GHz, 8 GHz, and 15 GHz in total intensity and polarization. This data are combined with our densely time-sampled flux-density monitoring performed with the radio telescopes at Effelsberg (Germany) and at Urumqi (China). Results: The VLBA observations detected an east-west oriented core-jet structure with no significant motion in its jet. The expansion of the VLBI core leads to an estimate of mild relativistic speed (2.5{ c} ± 1.4 c). The position angle of the VLBI jet agrees with the angle of anisotropy derived from the annual modulation model. No significant long-term structural changes were observed with VLBI on mas-scales, although, the VLBI core-size expansion offers a possible explanation of the observed decrease in the strength of IDV. VLBI polarimetry measured significant changes in the electric vector position angle (EVPA) and

  1. Fusion of chemical, biological, and meteorological observations for agent source term estimation and hazard refinement

    NASA Astrophysics Data System (ADS)

    Bieringer, Paul E.; Rodriguez, Luna M.; Sykes, Ian; Hurst, Jonathan; Vandenberghe, Francois; Weil, Jeffrey; Bieberbach, George, Jr.; Parker, Steve; Cabell, Ryan

    2011-05-01

    Chemical and biological (CB) agent detection and effective use of these observations in hazard assessment models are key elements of our nation's CB defense program that seeks to ensure that Department of Defense (DoD) operations are minimally affected by a CB attack. Accurate hazard assessments rely heavily on the source term parameters necessary to characterize the release in the transport and dispersion (T&D) simulation. Unfortunately, these source parameters are often not known and based on rudimentary assumptions. In this presentation we describe an algorithm that utilizes variational data assimilation techniques to fuse CB and meteorological observations to characterize agent release source parameters and provide a refined hazard assessment. The underlying algorithm consists of a combination of modeling systems, including the Second order Closure Integrated PUFF model (SCIPUFF), its corresponding Source Term Estimation (STE) model, a hybrid Lagrangian-Eulerian Plume Model (LEPM), its formal adjoint, and the software infrastructure necessary to link them. SCIPUFF and its STE model are used to calculate a "first guess" source estimate. The LEPM and corresponding adjoint are then used to iteratively refine this release source estimate using variational data assimilation techniques. This algorithm has undergone preliminary testing using virtual "single realization" plume release data sets from the Virtual THreat Response Emulation and Analysis Testbed (VTHREAT) and data from the FUSION Field Trials 2007 (FFT07). The end-to-end prototype of this system that has been developed to illustrate its use within the United States (US) Joint Effects Model (JEM) will be demonstrated.

  2. ROSAT observations of clusters with wide-angle tailed radio sources

    NASA Technical Reports Server (NTRS)

    Burns, Jack O.

    1993-01-01

    The goal of these ROSAT PSPC pointed observations was to understand the nature of X-ray emission associated clusters that contain luminous wide-angle tailed (WAT) radio sources identified with the centrally dominant cluster galaxies. These 500 kpc diameter radio sources are strongly affected by confinement and interaction with the intracluster medium. So, a complete picture of the origin and evolution of these radio sources is not possible without detailed X-ray observations which sample the distribution and temperature of the surrounding hot gas. Two WAT clusters have been observed with the ROSAT PSPC to date. The first is Abell 2634 which contains the WAT 3C 465 and was approved for observations in AO-1. Unfortunately, these observations were broken into two widely separated pieces in time. The first data set containing about 9000 sec of integration arrived in mid-March, 1992. The second data set containing about 10,500 sec arrived just recently in early April (after a first tape was destroyed in the mail). The second cluster is 1919+479 which was approved for observations in AO-2. These ROSAT data arrived in October 1992.

  3. Generalization of the Van Cittert-Zernike theorem: observers moving with respect to sources

    NASA Astrophysics Data System (ADS)

    Braun, Daniel; Monjid, Younes; Rougé, Bernard; Kerr, Yann

    2016-01-01

    The use of the Van Cittert-Zernike theorem for the formulation of the visibility function in satellite-based Earth observation with passive radiometers does not take into account the relative motion of the observer (the satellite antenna) with respect to sources of the electro-magnetic fields at the surface of the Earth. The motion of the observer leads on the one hand to a more complex signal due to a pixel-dependent Doppler shift that is neglected in the standard derivation of the Van Cittert-Zernike theorem, but on the other hand one may hope that it could be employed for a temporal aperture synthesis, where virtual baselines are created through the motion of the satellite. Here, we generalize the formulation of the aperture synthesis concept to the case of observers moving with respect to the sources, and to the correlation of fields measured at times that differ by the travel time of the observer along a virtual baseline. Our derivation is based on first principles, starting with the wave propagation in the Earth reference frame of electro-magnetic fields arising from incoherent current sources, and Lorentz transforming the fields into the reference frame of the satellite. Our detailed study leads to the remarkable conclusion that the delay time due to observer motion cancels exactly the Doppler effect. This justifies the neglect of the Doppler effect in existing imaging systems based on the standard Van Cittert-Zernike theorem.

  4. Observations of the X-ray burst source MXB 1636-53

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.; Lewin, W. H. G.; Doty, J.

    1977-01-01

    X-ray bursts have been observed from MXB 1636-53, almost certainly associated with the strong steady X-ray source 2S 1636-536 (Norma X-1, 3U 1636-53). The steady source was observed in January 1977 at roughly half the intensity reported in the 3U catalog and showed about 15% variability on a time scale of hours. The spectra of the X-ray bursts are well fitted by blackbody radiation whose temperature rises rapidly to a maximum of approximately 28 million K and then cools slowly. If the source is at a distance of 10 kpc, the radius of the projected burst emission region is about 10 km, similar to the size of a neutron star.

  5. Einstein observations of the 1978 November 19 gamma ray burst source field

    NASA Technical Reports Server (NTRS)

    Pizzichini, G.; Cline, T. L.; Desai, U. D.; Mushotzky, R.; Teegarden, B. J.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.

    1982-01-01

    It is pointed out that several years after the discovery of cosmic gamma ray bursts (GRB) their sources have not yet been identified, although searches have been conducted in optical, X-ray, and radio wavelengths. The three smallest error boxes are now related to the events of Mar. 5, 1979, Apr. 6, 1979, and Nov. 19, 1978. X-ray observations, with the Imaging Proportional Counter (IPC) of the Einstein Observatory, were made for all three locations. A description is presented of the results of the 8200 second IPC observation of the Nov. 19, 1978 GRB, made on July 1 and 2, 1980. Three sources were detected. However, two of them were outside the GRB error box. The third source is located well inside the burst error box.

  6. Constraining the Sources and Sinks of Atmospheric Methane Using Stable Isotope Observations and Chemistry Climate Modeling

    NASA Astrophysics Data System (ADS)

    Feinberg, A.; Coulon, A.; Stenke, A.; Peter, T.

    2015-12-01

    Methane acts as both a greenhouse gas and a driver of atmospheric chemistry. There is a lack of consensus for the explanation behind the atmospheric methane trend in recent years (1980-2010). High uncertainties are associated with the magnitudes of individual methane source and sink processes. Methane isotopes have the potential to distinguish between the different methane fluxes, as each flux is characterized by an isotopic signature. Methane emissions from each source category are expressed explicitly in a chemistry climate model SOCOL, including wetlands, rice paddies, biomass burning, industry, etc. The model includes 48 methane tracers based on source type and geographical origin in order to track methane after it has been emitted. SOCOL simulations for the years 1980-2010 are performed in "nudged mode", so that model dynamics reflect observed meteorology. Available database estimates of the various surface emission fluxes are inputted into SOCOL. The model diagnostic methane tracers are compared to methane isotope observations from measurement networks. Inconsistencies between the model results and observations point to deficiencies in the available emission estimates or model sink processes. Because of their dependence on the OH sink, deuterated methane observations and methyl chloroform tracers are used to investigate the variability of OH mixing ratios in the model and the real world. The analysis examines the validity of the methane source and sink category estimates over the last 30 years.

  7. Is the Source of Reinforcement for Naming Multiple Conditioned Reinforcers for Observing Responses?

    ERIC Educational Resources Information Center

    Longano, Jennifer M.; Greer, R. Douglas

    2015-01-01

    Naming refers to the incidental acquisition of word-object relations as listener and speaker without explicit reinforcement. To investigate possible sources of reinforcement for naming, we examined the effects of a procedure for conditioning reinforcement for observing responses on the emergence of naming in children who previously lacked it. The…

  8. Determination of Source Hemisphere of Auroral Kilometric Radiation (AKR) observed by KAGUYA

    NASA Astrophysics Data System (ADS)

    Goto, Y.; Uda, K.; Kasahara, Y.; Hashimoto, K.

    2013-12-01

    The auroral kilometric radiation (AKR) were observed with a plasma wave receiver called WFC (waveform capture) [1] onboard the lunar orbiter KAGUYA during the whole mission period (2007-2009). It is well-known that the AKR is dominated by right-handed mode wave with small contribution of left-handed one. Investigation of observation conditions of each mode wave is still an interesting subject associated with AKR generation and propagation characteristics. A problem in the AKR polarization analysis is that the relation between the source polarization and the observed polarization depends on the source hemisphere. Because the WFC measured only two orthogonal electric field components, wave normal vectors of the AKR cannot be determined from the measurements. A simple way to determine the source hemisphere is to examine whether AKR is observed when the polar region of one hemisphere is seen and that of the other is shadowed by the Moon. However, its usable conditions are limited. In this study, we used a new technique to determine the source hemisphere of the observed AKR. Because the KAGUYA orbits around the moon in two-hour periods, the log-ratio of the two measured electric fields of the AKR has a clear sinusoidal time variation with the two-hour periodicity. The phase of the variation depends on the source location. For example, the times when the log-ratio becomes zero are several minutes different in two cases: the AKR sources exist in the north and south polar regions, respectively. Since the time resolution of the WFC measurements were 0.5 - 8 seconds, it is not difficult to determine the phase of the sinusoidal variations. Using the technique, the source hemispheres of the AKR were determined even when the AKR from the both hemispheres had been simultaneously observed. The statistical characteristic of the AKR polarization will be discussed. [1] Y. Kasahara, Y. Goto, K. Hashimoto, T. Imachi, A. Kumamoto, T. Ono, and H. Matsumoto, Plasma Wave Observation Using

  9. Structure and sources of the sporadic meteor background from video observations

    NASA Astrophysics Data System (ADS)

    Jakšová, Ivana; Porubčan, Vladimír; Klačka, Jozef

    2015-10-01

    We investigate and discuss the structure of the sporadic meteor background population in the near-Earth space based on video meteor orbits from the SonotaCo database (SonotaCo 2009, WGN, 37, 55). The selection of the shower meteors was done by the Southworth-Hawkins streams-search criterion (Southworth & Hawkins 1963, Smithson. Contr. Astrophys., 7, 261). Of a total of 117786 orbits, 69.34% were assigned to sporadic background meteors. Our analysis revealed all the known sporadic sources, such as the dominant apex source which is splitting into the northern and southern branch. Part of a denser ring structure about the apex source connecting the antihelion and north toroidal sources is also evident. We showed that the annual activity of the apex source is similar to the annual variation in activity of the whole sporadic background. The antihelion source exhibits a very broad maximum from July until January and the north toroidal source shows three maxima similar to the radar observations by the Canadian Meteor Orbit Radar (CMOR). Potential parent bodies of the sporadic population were searched for by comparison of the distributions of the orbital elements of sporadic meteors, minor planets and comets.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  11. Ragweed pollen observed in Turkey: detection of sources using back trajectory models.

    PubMed

    Zemmer, Franziska; Karaca, Ferhat; Ozkaragoz, Fatih

    2012-07-15

    This paper discusses the pollen season and the source apportionment of ragweed (Ambrosia) grains detected in the atmosphere of Istanbul, Turkey. The dynamic migration of this invasive taxon is a serious environmental issue. Ragweed pollen is highly allergenic and causes sensitization in patients at low concentrations. At present, there is no floristic evidence of this taxon in the region. Aerobiological records presented here, though, indicate a local source. Moreover, we argue that ragweed pollen comes from distant sources through air mass movements. The analysis concerns the ragweed season 2007. Pollens were sampled with a Burkard trap and identified at a magnification of 400 ×. Grains were counted on 12 transverse traverses to estimate bi-hourly changes in concentrations. The peak day was on August 28 with 20 grainsm(-3). Ragweed was observed on 22 days during August and September 2007. On all days, except one, the daily average concentration was below 10 grainsm(-3). Diurnal bi-hourly ragweed concentrations reached a maximum at 11:00 EET. Relatively high concentrations were observed between 21:00 and 01:00 EET. This allowed for the assumption of a local and a remote ragweed pollen source. We used HYSPLIT backward trajectory ensembles to identify possible sources on peak day. A frequency analysis of back trajectories covering the entire ragweed season followed. Firstly, possible local sources were the Istanbul Province and Turkish Thrace; secondly, a likely over-regional source was Bulgaria; and lastly, remote sources of ragweed pollen were the Ukraine, the Russian coastal region of the Black Sea and Moldova. This study provides evidence that pollens detected on our receptor site stem from combined local and remote origins.

  12. 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

  13. Ray tracing of Jovian decametric radiation from Southern and Northern Hemisphere sources - Comparison with Voyager observations

    NASA Technical Reports Server (NTRS)

    Menietti, J. Douglas; Green, James L.; Six, N. Frank; Gulkis, S.

    1987-01-01

    The Voyager 1 and 2 Planetary Radio Astronomy observations of Io-dependent decametric (DAM) radiation originating from the Southern Hemisphere of Jupiter were compared with the results of three-dimensional model ray tracing calculations of the DAM radiation. The ray trajectories for sources located at constant sub-Io longitudes of 260 and 300 deg were computed for both the Northern and the Southern Jovian Hemisphere sources. The model results of wave propagation agree with the Voyager observations obtained with Io located at 260 and 300 deg in Jovian system III longitude. The agreement between the Voyager observations and the model ray tracings allows identification of the origin of several of the emission components.

  14. Suzaku Observation of Two Ultraluminous X-Ray Sources in NGC1313

    NASA Astrophysics Data System (ADS)

    Mizuno, T.; Miyawaki, R.; Ebisawa, K.; Kubota, A.; Miyamoto, M.; Winter, L.; Ueda, Y.; Isobe, N.; Makishima, K.; Ngc 1313 Team

    We report about the Suzaku observation oftwo ultraluminous X-ray sources (ULXs), X-1 and X-2, in NGC1313, together with their spectra by XMM-Newton. During the observation, both showed intensity-correlated spectral changes. The brighter source, X-1, exhibited the highest luminosity (˜ 3 × 1040 erg s-1) ever recorded from this source. Its spectral variation is ascribed to a strong power-law like component with a mild high energy curvature, while about 10 modeled by a cool disk emission. These properties suggest that the source was in the ``very high'' state, wherein the disk emission is strongly Comptonized and the optically-thick disk is truncated at a large radii or cooled off. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor disk model with the innermost disk temperature of 1.2-1.3 keV, and becomes flatter as the source gets brighter. Hence X-2 is interpreted to be in a slim disk state. These results suggest that the two ULXs host black holes of a few tens to a few hundreds solar masses.

  15. 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

  16. The Lockman Hole project: LOFAR observations and spectral index properties of low-frequency radio sources

    NASA Astrophysics Data System (ADS)

    Mahony, E. K.; Morganti, R.; Prandoni, I.; van Bemmel, I. M.; Shimwell, T. W.; Brienza, M.; Best, P. N.; Brüggen, M.; Rivera, G. Calistro; de Gasperin, F.; Hardcastle, M. J.; Harwood, J. J.; Heald, G.; Jarvis, M. J.; Mandal, S.; Miley, G. K.; Retana-Montenegro, E.; Röttgering, H. J. A.; Sabater, J.; Tasse, C.; van Velzen, S.; van Weeren, R. J.; Williams, W. L.; White, G. J.

    2016-09-01

    The Lockman Hole is a well-studied extragalactic field with extensive multi-band ancillary data covering a wide range in frequency, essential for characterising the physical and evolutionary properties of the various source populations detected in deep radio fields (mainly star-forming galaxies and AGNs). In this paper we present new 150-MHz observations carried out with the LOw Frequency ARray (LOFAR), allowing us to explore a new spectral window for the faint radio source population. This 150-MHz image covers an area of 34.7 square degrees with a resolution of 18.6×14.7 arcsec and reaches an rms of 160 μJy beam-1 at the centre of the field. As expected for a low-frequency selected sample, the vast majority of sources exhibit steep spectra, with a median spectral index of α _{150}^{1400}=-0.78± 0.015. The median spectral index becomes slightly flatter (increasing from α _{150}^{1400}=-0.84 to α _{150}^{1400}=-0.75) with decreasing flux density down to S150 ˜10 mJy before flattening out and remaining constant below this flux level. For a bright subset of the 150-MHz selected sample we can trace the spectral properties down to lower frequencies using 60-MHz LOFAR observations, finding tentative evidence for sources to become flatter in spectrum between 60 and 150 MHz. Using the deep, multi-frequency data available in the Lockman Hole, we identify a sample of 100 Ultra-steep spectrum (USS) sources and 13 peaked spectrum sources. We estimate that up to 21 per cent of these could have z > 4 and are candidate high-z radio galaxies, but further follow-up observations are required to confirm the physical nature of these objects.

  17. HerMES: point source catalogues from Herschel-SPIRE observations II

    NASA Astrophysics Data System (ADS)

    Wang, L.; Viero, M.; Clarke, C.; Bock, J.; Buat, V.; Conley, A.; Farrah, D.; Guo, K.; Heinis, S.; Magdis, G.; Marchetti, L.; Marsden, G.; Norberg, P.; Oliver, S. J.; Page, M. J.; Roehlly, Y.; Roseboom, I. G.; Schulz, B.; Smith, A. J.; Vaccari, M.; Zemcov, M.

    2014-11-01

    The Herschel Multi-tiered Extragalactic Survey (HerMES) is the largest Guaranteed Time Key Programme on the Herschel Space Observatory. With a wedding cake survey strategy, it consists of nested fields with varying depth and area totalling ˜380 deg2. In this paper, we present deep point source catalogues extracted from Herschel-Spectral and Photometric Imaging Receiver (SPIRE) observations of all HerMES fields, except for the later addition of the 270 deg2 HerMES Large-Mode Survey (HeLMS) field. These catalogues constitute the second Data Release (DR2) made in 2013 October. A sub-set of these catalogues, which consists of bright sources extracted from Herschel-SPIRE observations completed by 2010 May 1 (covering ˜74 deg2) were released earlier in the first extensive data release in 2012 March. Two different methods are used to generate the point source catalogues, the SUSSEXTRACTOR point source extractor used in two earlier data releases (EDR and EDR2) and a new source detection and photometry method. The latter combines an iterative source detection algorithm, STARFINDER, and a De-blended SPIRE Photometry algorithm. We use end-to-end Herschel-SPIRE simulations with realistic number counts and clustering properties to characterize basic properties of the point source catalogues, such as the completeness, reliability, photometric and positional accuracy. Over 500 000 catalogue entries in HerMES fields (except HeLMS) are released to the public through the HeDAM (Herschel Database in Marseille) website (http://hedam.lam.fr/HerMES).

  18. Copernicus observations of a number of galactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Culhane, J. L.; Mason, K. O.; Sanford, P. W.; White, N. E.

    1976-01-01

    The Copernicus satellite was launched on 21 August 1972. The main experiment on board is the University of Princeton UV telescope. In addition a cosmic X-ray package of somewhat modest aperture was provided by the Mullard Space Science Laboratory (MSSL) of University College London. Following a brief description of the instrument, a list of galactic sources observed during the year is presented. Although the X-ray detection aperture is small, the ability to point the satellite for long periods of time with high accuracy makes Copernicus an ideal vehicle for the study of variable sources.

  19. Waveform analysis of Scholte waves observed in San Diego Trough using a seafloor source and OBS

    NASA Astrophysics Data System (ADS)

    Dorman, L. M.

    2013-12-01

    A seafloor sound source has the fundamental advantage over a surface source of releasing its energy much closer to its sub-sea target. It can produce abundant shear-wave energy. Since marine mammals spend most of their time near the surface, a seafloor source reduces their exposure to damaging acoustical signals. Dorman and Sauter, 2006, Geophysics, designed and built an implosive source for deep/seafloor use. Our existing device is designed to operate down to a depth of 2000 meters. It uses a two-stage valve that allows rapid flooding of a 20-liter cylinder. This volume is has the same moment as 1/4 kg of explosive fired at 800 meters depth, although the source signature is longer. This source is effective in exciting interface (Scholte) waves whose dispersion is diagnostic of the shear wave structure of the seafloor sediments. We earlier analyzed data from the San Diego Trough (SDT) by matching observed and calculated group velocity dispersion, and now extend that analysis to waveform analysis as done earlier for explosive-generated waves by Nolet and Dorman, 1996, GJI. The surficial shear velociy is quite low, about 16 m/s and the velocities we are obtaining from waveform analysis are slightly higher.

  20. Chandra Observation of the X-ray Source Population of NGC 6946

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Schlegel, E. M.; Hwang, U.; Petre, R.

    2003-01-01

    We present the results of a study of discrete X-ray sources in NGC 6946 using a deep Chandra ACIS observation. Based on the slope of the log N-log S distribution and the general correlation of sources with the spiral arms, we infer that the overall discrete source sample in NGC 6946 is dominated by high mass X-ray binaries, in contrast to the source distributions in M31 and the Milky Way. This is consistent with the higher star formation rate in NGC 6946 than in those galaxies. We find that the strong X-ray sources in the region of the galactic center do not correlate in detail with images of the region in the near-IR, although one of them may be coincident with the galactic center. The non-central ultra-luminous X-ray source in NGC 6946, previously identified with a supernova remnant, has an X-ray spectrum and luminosity that is inconsistent with either a traditional pulsar wind nebula or a blast wave remnant.

  1. Multifrequency VLA observations of PKS 0745 - 191 - The archetypal 'cooling flow' radio source?

    NASA Technical Reports Server (NTRS)

    Baum, S. A.; O'Dea, C. P.

    1991-01-01

    Ninety-, 20-, 6- and 2-cm VLA observations of the high-radio-luminosity cooling-flow radio source PKS 0745 - 191 are presented. The radio source was found to have a core with a very steep spectrum (alpha is approximately -1.5) and diffuse emission with an even steeper spectrum (alpha is approximately -1.5 to -2.3) without clear indications of the jets, hotspots, or double lobes found in the other radio sources of comparable luminosity. It is inferred that the energy to power the radio source comes from the central engine, but the source's structure may be heavily influenced by the past history of the galaxy and the inflowing intracluster medium. It is shown that, while the radio source is energetically unimportant for the cluster as a whole, it is important on the scale of the cooling flow. The mere existence of cosmic rays and magnetic fields within a substantial fraction of the volume inside the cooling radius has important consequences for cooling-flow models.

  2. Quantitative Assessment of Upstream Source Influences on TGM Observations at Three CAMNet Sites

    NASA Astrophysics Data System (ADS)

    Wen, D.; Lin, J. C.; Meng, F.; Gbor, P. K.; He, Z.; Sloan, J. J.

    2009-05-01

    Mercury is a persistent and toxic substance in the environment. Exposure to high levels of mercury can cause a range of adverse health effects, including damage to the nervous system, reproduction system and childhood development. Proper recognition and prediction of atmospheric levels of mercury can effectively avoid the adverse affect of Hg, however they cannot be achieved without accurate and quantitative identification of source influences, which is a great challenge due to the complexity of Hg in the air. The objective of this study is to present a new method to simulate Hg concentrations at the location of a monitoring site and quantitatively assess its upstream source influences. Hourly total gaseous mercury (TGM) concentrations at three CAMNet monitoring sites (receptors) in Ontario were predicted for four selected periods using the Stochastic Time-Inverted Lagrangian Transport (STILT) model, which is capable of representing near-field influences that are not resolved by typical grid sizes in transport models. The model was modified to deal with Hg depositions and point source Hg emissions. The model-predicted Hg concentrations were compared with observations, as well as with the results from a CMAQ-Hg simulation in which the same emission and meteorology inputs were used. The comparisons show that STILT-predicted Hg concentrations agree well with observations, and are generally closer to the observations than those predicted by CMAQ-Hg. The better performance of the STILT simulation can be attributed to its ability to account for near-field influences. STILT was also applied to assess quantitatively the relative importance of different upstream source regions for the selected episodes. The assessment was made based on emission fluxes and STILT footprints, i.e., sensitivities of atmospheric concentrations to upstream surface fluxes. The results indicated that the main source regions of observed low Hg concentrations were in Northeastern Ontario, whereas

  3. Cross-Matching Source Observations from the Palomar Transient Factory (PTF)

    NASA Astrophysics Data System (ADS)

    Laher, Russ; Grillmair, C.; Surace, J.; Monkewitz, S.; Jackson, E.

    2009-01-01

    Over the four-year lifetime of the PTF project, approximately 40 billion instances of astronomical-source observations will be extracted from the image data. The instances will correspond to the same astronomical objects being observed at roughly 25-50 different times, and so a very large catalog containing important object-variability information will be the chief PTF product. Organizing astronomical-source catalogs is conventionally done by dividing the catalog into declination zones and sorting by right ascension within each zone (e.g., the USNOA star catalog), in order to facilitate catalog searches. This method was reincarnated as the "zones" algorithm in a SQL-Server database implementation (Szalay et al., MSR-TR-2004-32), with corrections given by Gray et al. (MSR-TR-2006-52). The primary advantage of this implementation is that all of the work is done entirely on the database server and client/server communication is eliminated. We implemented the methods outlined in Gray et al. for a PostgreSQL database. We programmed the methods as database functions in PL/pgSQL procedural language. The cross-matching is currently based on source positions, but we intend to extend it to use both positions and positional uncertainties to form a chi-square statistic for optimal thresholding. The database design includes three main tables, plus a handful of internal tables. The Sources table stores the SExtractor source extractions taken at various times; the MergedSources table stores statistics about the astronomical objects, which are the result of cross-matching records in the Sources table; and the Merges table, which associates cross-matched primary keys in the Sources table with primary keys in the MergedSoures table. Besides judicious database indexing, we have also internally partitioned the Sources table by declination zone, in order to speed up the population of Sources records and make the database more manageable. The catalog will be accessible to the public

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

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Palma, Jose L.

    2015-08-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

  7. Local Group dSph radio survey with ATCA (I): observations and background sources

    NASA Astrophysics Data System (ADS)

    Regis, Marco; Richter, Laura; Colafrancesco, Sergio; Massardi, Marcella; de Blok, W. J. G.; Profumo, Stefano; Orford, Nicola

    2015-04-01

    Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology, especially in connection to the study of galaxy formation and evolution at small scales. In addition, dSphs are optimal targets to investigate the nature of dark matter. However, while we begin to have deep optical photometric observations of the stellar population in these objects, little is known so far about their diffuse emission at any observing frequency, and hence on thermal and non-thermal plasma possibly residing within dSphs. In this paper, we present deep radio observations of six local dSphs performed with the Australia Telescope Compact Array (ATCA) at 16 cm wavelength. We mosaicked a region of radius of about 1 deg around three `classical' dSphs, Carina, Fornax, and Sculptor, and of about half of degree around three `ultrafaint' dSphs, BootesII, Segue2, and Hercules. The rms noise level is below 0.05 mJy for all the maps. The restoring beams full width at half-maximum ranged from 4.2 arcsec × 2.5 arcsec to 30.0 arcsec × 2.1 arcsec in the most elongated case. A catalogue including the 1392 sources detected in the six dSph fields is reported. The main properties of the background sources are discussed, with positions and fluxes of brightest objects compared with the FIRST, NVSS, and SUMSS observations of the same fields. The observed population of radio emitters in these fields is dominated by synchrotron sources. We compute the associated source number counts at 2 GHz down to fluxes of 0.25 mJy, which prove to be in agreement with AGN count models.

  8. OOSTethys - Open Source Software for the Global Earth Observing Systems of Systems

    NASA Astrophysics Data System (ADS)

    Bridger, E.; Bermudez, L. E.; Maskey, M.; Rueda, C.; Babin, B. L.; Blair, R.

    2009-12-01

    An open source software project is much more than just picking the right license, hosting modular code and providing effective documentation. Success in advancing in an open collaborative way requires that the process match the expected code functionality to the developer's personal expertise and organizational needs as well as having an enthusiastic and responsive core lead group. We will present the lessons learned fromOOSTethys , which is a community of software developers and marine scientists who develop open source tools, in multiple languages, to integrate ocean observing systems into an Integrated Ocean Observing System (IOOS). OOSTethys' goal is to dramatically reduce the time it takes to install, adopt and update standards-compliant web services. OOSTethys has developed servers, clients and a registry. Open source PERL, PYTHON, JAVA and ASP tool kits and reference implementations are helping the marine community publish near real-time observation data in interoperable standard formats. In some cases publishing an OpenGeospatial Consortium (OGC), Sensor Observation Service (SOS) from NetCDF files or a database or even CSV text files could take only minutes depending on the skills of the developer. OOSTethys is also developing an OGC standard registry, Catalog Service for Web (CSW). This open source CSW registry was implemented to easily register and discover SOSs using ISO 19139 service metadata. A web interface layer over the CSW registry simplifies the registration process by harvesting metadata describing the observations and sensors from the “GetCapabilities” response of SOS. OPENIOOS is the web client, developed in PERL to visualize the sensors in the SOS services. While the number of OOSTethys software developers is small, currently about 10 around the world, the number of OOSTethys toolkit implementers is larger and growing and the ease of use has played a large role in spreading the use of interoperable standards compliant web services widely

  9. Source and Propagation Characteristics of Kilometric Continuum Observed with Multiple Satellites

    NASA Technical Reports Server (NTRS)

    Hashimoto, K.; Anderson, R. R.; Green, J. L.; Matsumoto, H.

    2004-01-01

    Kilometric continuum radiation was first identified with the GEOTAIL Plasma Wave Instrument (PWI) as the high frequency extension of escaping continuum emissions in the frequency range from 100 kHz to 800 kHz. It consists of from a few to many narrow-band emissions. It was observed mainly near the magnetic equator, and its source was expected to be inside of the plasmapause and the topside equatorial region. Recently, data from the IMAGE Radio Plasma Imager (RPI) and Extreme ultraviolet (EUV) experiments have been used to show that kilometric continuum is generated at the plasmapause, in or near the magnetic equator, within a notch region, and have confirmed the expectation. Data from the CRRES PWI have also identified other sources from the equatorial density irregularities. An example of CRRES observations reveals a possibility that kilometric continuum has been radiated as a wide beam emission. The IMAGE and GEOTAIL simultaneous observations are not like the previous observations since they show it has been observed to have a very broad emission cone. It could also be the highest frequency continuum enhancement so far observed since it is associated with a high energy electron injection event.

  10. Seismic and infrasonic source processes in volcanic fluid systems

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.

    Volcanoes exhibit a spectacular diversity in fluid oscillation processes, which lead to distinct seismic and acoustic signals in the solid earth and atmosphere. Volcano seismic waveforms contain rich information on the geometry of fluid migration, resonance effects, and transient and sustained pressure oscillations resulting from unsteady flow through subsurface cracks, fissures and conduits. Volcanic sounds contain information on shallow fluid flow, resonance in near-surface cavities, and degassing dynamics into the atmosphere. Since volcanoes have large spatial scales, the vast majority of their radiated atmospheric acoustic energy is infrasonic (<20 Hz). This dissertation presents observations from joint broadband seismic and infrasound array deployments at Mount St. Helens (MSH, Washington State, USA), Tungurahua (Ecuador), and Kilauea Volcano (Hawaii, USA), each providing data for several years. These volcanoes represent a broad spectrum of eruption styles ranging from hawaiian to plinian in nature. The catalogue of recorded infrasonic signals includes continuous broadband and harmonic tremor from persistent degassing at basaltic lava vents and tubes at Pu'u O'o (Kilauea), thousands of repetitive impulsive signals associated with seismic longperiod (0.5-5 Hz) events and the dynamics of the shallow hydrothermal system at MSH, rockfall signals from the unstable dacite dome at MSH, energetic explosion blast waves and gliding infrasonic harmonic tremor at Tungurahua volcano, and large-amplitude and long-duration broadband signals associated with jetting during vulcanian, subplinian and plinian eruptions at MSH and Tungurahua. We develop models for a selection of these infrasonic signals. For infrasonic long-period (LP) events at MSH, we investigate seismic-acoustic coupling from various buried source configurations as a means to excite infrasound waves in the atmosphere. We find that linear elastic seismic-acoustic transmission from the ground to atmosphere is

  11. Spectral observations of active region sources with RATAN-600 and WSRT. [Westerbork Synthesis Radio Telescope

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Gel'frejkh, G. B.; Borovik, V. N.; Korzhavin, A. N.; Bogod, V. M.; Nindos, A.; Kundu, M. R.

    1993-01-01

    We present spectral observations of neutral line and sunspot associated sources obtained with the RATAN-600 radio telescope and the WSRT in the wavelength range of 2 to 6 cm. Sources associated with large sunspots have flat spectra, while neutral line sources have very steep spectra. In the case of a large spot we estimated the magnetic field to be at least 2700 G at the base of the transition region and 1800 G in the low corona. We consider possible interpretations of the radio emission above the neutral lines. Gyroresonance emission at the fourth harmonic is inadequate, whereas emission from a small population of nonthermal electrons (total number 10 exp 30 to 10 exp 31) with a delta = 3 power law distribution seems to be sufficient.

  12. Rapid estimation of tsunami source centroid location using a dense offshore observation network

    NASA Astrophysics Data System (ADS)

    Yamamoto, N.; Hirata, K.; Aoi, S.; Suzuki, W.; Nakamura, H.; Kunugi, T.

    2016-05-01

    This paper proposes a rapid method of estimating tsunami source locations using real-time ocean-bottom hydrostatic pressure data from a dense offshore observation network. We defined two characteristic locations representing the real-time tsunami disturbance and the initial sea surface height distribution. First, we defined the tsunami centroid location (TCL), which is the centroid location of the maximum absolute amplitude of the real-time ocean-bottom hydrostatic pressure changes. Second, we defined the centroid location of the absolute values of the initial sea surface height displacements. To determine whether the TCL can approximate the centroid location of the tsunami source, we examined approximately 1000 near-field synthetic tsunami scenarios and a realistic tsunami scenario of the 2011 Tohoku earthquake in the Japan Trench. From these examinations, it was confirmed that in most scenarios, the TCLs obtained within a few minutes after the occurrence of an earthquake were close to the actual corresponding tsunami source locations.

  13. Swift/XRT follow-up observations of unidentified INTEGRAL sources

    NASA Astrophysics Data System (ADS)

    Maiorano, E.; Landi, R.; Parisi, P.; Masetti, N.; Bassani, L.; Malizia, A.; Bazzano, A.; Ubertini, P.; Bird, A. J.; Jimenez-Bailon, E.; Chavushyan, V.; Galaz, G.; Minniti, D.; Morelli, L.

    2010-10-01

    We report on X-ray follow-up observations performed with Swift/XRT of 3 unidentified INTEGRAL sources listed in the fourth IBIS Survey Catalogue (Bird et al. 2010, ApJS, 186, 1). IGR J08190-3835 Within the IBIS uncertainty XRT detects one source with a statistical significance of 5.8 sigma in the energy range 0.3-10 keV and 5.6 sigma above 3 keV. This object, located at RA(J2000) = 08h 19m 11.3s and Dec(J2000) = -38d 33m 09s (5 arcsec uncertainty), is associated with a 2MASS extended object (2MASX J08191136-3833104) classified as a galaxy in the NED archive and is positionally coincident with radio source NVSS J081910-383307.

  14. Investigating the value of passive microwave observations for monitoring volcanic eruption source parameters

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Cimini, Domenico; Marzano, Frank

    2016-04-01

    Volcanic eruptions inject both gas and solid particles into the Atmosphere. Solid particles are made by mineral fragments of different sizes (from few microns to meters), generally referred as tephra. Tephra from volcanic eruptions has enormous impacts on social and economical activities through the effects on the environment, climate, public health, and air traffic. The size, density and shape of a particle determine its fall velocity and thus residence time in the Atmosphere. Larger particles tend to fall quickly in the proximity of the volcano, while smaller particles may remain suspended for several days and thus may be transported by winds for thousands of km. Thus, the impact of such hazards involves local as well as large scales effects. Local effects involve mostly the large sized particles, while large scale effects are caused by the transport of the finest ejected tephra (ash) through the atmosphere. Forecasts of ash paths in the atmosphere are routinely run after eruptions using dispersion models. These models make use of meteorological and volcanic source parameters. The former are usually available as output of numerical weather prediction models or large scale reanalysis. Source parameters characterize the volcanic eruption near the vent; these are mainly the ash mass concentration along the vertical column and the top altitude of the volcanic plume, which is strictly related to the flux of the mass ejected at the emission source. These parameters should be known accurately and continuously; otherwise, strong hypothesis are usually needed, leading to large uncertainty in the dispersion forecasts. However, direct observations during an eruption are typically dangerous and impractical. Thus, satellite remote sensing is often exploited to monitor volcanic emissions, using visible (VIS) and infrared (IR) channels available on both Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO) satellites. VIS and IR satellite imagery are very useful to monitor

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

    PubMed

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

    2016-07-01

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

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

    DOE PAGESBeta

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

    2016-07-14

    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 seasonablymore » variable ocean wave contributions. On the basis of the adaptive F-detector quantification of time variable environmental effects, the time-dependent scaling variable is shown to be dependent on both weather conditions and local site effects. Significant seasonal variations in 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. As a result, this suggests that commonly available atmospheric specifications can be used to predict both station and network detection performance, and an appropriate forward model improves location capabilities as a function of time.« less

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

    PubMed

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

    2013-07-01

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

  18. 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.

  19. Observation of Kilohertz Quasiperiodic Oscillations from the Atoll Source 4U 1702-429 by RXTE

    NASA Technical Reports Server (NTRS)

    Markwardt, C. B.; Strohmayer, Tod E.; Swank, Jean H.

    1998-01-01

    We present results of Rossi X-Ray Timing Explorer (RXTE) observations of the atoll source 4U 1702-429 in the middle of its luminosity range. Kilohertz-range quasiperiodic oscillations (QPOS) were observed first as a narrow (FWHM approximately 7 Hz) peak near 900 Hz, and later as a pair consisting of a narrow peak in the range 625 825 Hz and a faint broad (FWHM 91 Hz) peak. When the two peaks appeared simultaneously the separation was 333 +/- 5 Hz. Six type I thermonuclear bursts were detected, of which five exhibited almost coherent oscillations near 330 Hz, which makes 4U 1702-429 only the second source to show burst oscillations very close to the kilohertz QPO separation frequency. The energy spectrum and color-color diagram indicate that the source executed variations in the range between the "island" and "lower banana" atoll states. In addition to the kilohertz variability, oscillations at approximately 10, approximately 35, and 80 Hz were also detected at various times, superimposed on a red noise continuum. The centroid of the approximately 35 Hz QPO tracks the frequency of the kilohertz oscillation when they were both present. A Lense-Thirring gravitomagnetic precession interpretation appears more plausible in this case, compared to other atoll sources with low frequency QPOs.

  20. Chandra and XMM Observations of the ADC Source 0921-630

    NASA Technical Reports Server (NTRS)

    Kallman, T. R.; Angelini, L.; Boroson, B.; Cottam, J.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We analyze observations of the low mass X-ray binary 2S0921-63 obtained with the gratings and CCDs on Chandra and XMM. This object is a high inclination system showing evidence for an accretion disk corona (ADC). Such a corona has the potential to constrain the properties of the heated accretion disk in this system, and other LMXBs by extension. We find evidence for line emission which is generally consistent with that found by previous experiments, although we are able to detect more lines. For the first time in this source, we find that the iron K line has multiple components. We set limits on the line widths and velocity offsets, and we fit the spectra to photoionization models and discuss the implications for accretion disk corona models. For the first time in any ADC source we use these fits, together with density constraints based on the O VII line ratio, in order to constrain the flux in the medium-ionization region of the ADC. Under various assumptions about the source luminosity this constrains the location of the emitting region. These estimates, together with estimates for the emission measure, favor a scenario in which the intrinsic luminosity of the source is comparable to what we observe.

  1. Task complexity and sources of task-related information during the observational learning process.

    PubMed

    Laguna, Patricia L

    2008-08-01

    Although research has examined the influence of various sources of task information for skill acquisition during observational learning, the results have been ambiguous. The purpose of this study was to examine sources of information in relation to the type of task. One hundred and twenty participants were randomly assigned to one of two sets of six treatment strategies: (1) all model demonstrations; (2) model demonstrations with physical practice with knowledge of performance; (3) model demonstrations with physical practice without knowledge of performance; (4) physical practice without knowledge of performance; (5) physical practice with knowledge of performance; or (6) verbal instructions only. One set learned a simple version of the task while the other set learned a more complex version. Cognitive representation and performance accuracy (spatial and temporal) were assessed. Results indicate that task type does influence the source of information to facilitate skill acquisition. The simple task benefited from model demonstrations, physical practice with knowledge of performance, or a combination of model demonstrations and practice both with and without knowledge of performance, while the complex version benefited more from a combination of model demonstrations and knowledge of performance practice. The results of this study provide an insight into the ambiguity that exists within the observational learning and motor learning literature regarding the effectiveness of information sources for motor skill acquisition.

  2. SAS-2 observations of high energy gamma rays from discrete sources

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.; Hartman, R. C.; Lamb, R. C.; Thompson, D. J.

    1977-01-01

    The SAS-2 identified six localized high energy (greater than 35 MeV) gamma ray sources. Four of these are the radio pulsars, PSR 0531+21, PSR 0833-45, PSR 1818-04, and PSR 1717-46 discovered in a search of 75 radio pulsars. The fact that only one of these is observed in X-rays, and the significant differences in pulse profiles in the gamma ray and radio observations, leads to the speculation that different mechanisms are involved.

  3. Compton Observatory observations of clusters of galaxies and extragalactic radio sources

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This task involved the investigation of the emission of clusters of galaxies, particularly those which contain extended radio emission, in the gamma-ray region of the spectrum. Observations were made of several clusters using the Compton Observatory EGRET instrument. For each cluster a measured flux or upper limit on the gamma-ray flux was obtained. In only one case, Abell 2199, was there a significant measured flux. This source is spatially confused with a know blazar in the field of view. The observation is consistent with all emissions being from the blazar.

  4. Bulgarian - Serbian collaboration: CCD observations of visual double and multiple stars and extragalactic radio sources

    NASA Astrophysics Data System (ADS)

    Cvetković, Zorica; Pavlović, Rade; Damljanović, Goran; Boeva, Svetlana; Latev, Georgi

    The Serbian-Bulgarian cooperation concerning the study of visual double and multiple stars started in 2004 with CCD observations of such objects, and in 2011 was extended to observations of extragalactic radio sources visible at optical wavelengths. Here we present a brief overview of the most interesting results obtained during our collaboration. Begun as a regional Balkan project, this cooperation in 2012 was continued in the form of a bilateral cooperation between the Bulgarian Academy of Sciences and Serbian Academy of Sciences and Arts.

  5. Stereoscopic observations of hard x ray sources in solar flares made with GRO and other spacecraft

    NASA Technical Reports Server (NTRS)

    Kane, S. R.; Hurley, K.; Mctiernan, J. M.; Laros, J. G.

    1992-01-01

    Since the launch of the Gamma Ray Observatory (GRO) in Apr. 1991, the Burst and Transient Source Experiment (BATSE) instrument on GRO has recorded a large number of solar flares. Some of these flares have also been observed by the Gamma-Ray Burst Detector on the Pioneer Venus Orbiter (PVO) and/or by the Solar X-Ray/Cosmic Gamma-Ray Burst Experiment on the Ulysses spacecraft. A preliminary list of common flares observed during the period May-Jun. 1991 is presented and the possible joint studies are indicated.

  6. Observation of soft X-rays from extended sources. [such as Perseus star cluster

    NASA Technical Reports Server (NTRS)

    Catura, R. C.; Acton, L. W.

    1974-01-01

    Efforts were directed toward surveying several supernova remnants for the emission of soft X-rays. Rather than attempt to detect such faint X-ray emission, the program was redirected to observe the spectrum and angular structure of the extended X-ray source in the Perseus cluster of galaxies and the super-nova remnant Puppis A. An attempt was made to detect X-ray line emission from Puppis A with a Bragg crystal spectrometer. Observations provide evidence for the presence of X-ray line emission in the spectrum of Puppis A near .65 keV.

  7. Surface photometry of celestial sources from a space vehicle: introduction and observational procedures.

    PubMed

    Roach, F E; Carroll, B; Aller, L H; Smith, L

    1972-03-01

    Diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein (or contre lumière) can be studied most reliably from above the earth's atmosphere with equipment flown in artificial satellites. We review the techniques used and some of the difficulties encountered in day-time observations from satellites by the use of a special photometer and polarimeter flown in the orbiting skylab observatory, OSO-6.

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

    NASA Astrophysics Data System (ADS)

    Brown, P.

    2014-07-01

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

  9. XMM-Newton Observations of NGC 507: Over-Density of Peripheral Sources and Metal Abundances

    NASA Astrophysics Data System (ADS)

    Fabbiano, G.; Kim, D.-W.; Brickhouse, N.

    2002-12-01

    We report the results of XMM-Newton X-ray observations of NGC 507. We have confirmed the existence of over-density of X-ray sources at the periphery of the X-ray halo in NGC 507, which was first suggested by the ROSAT PSPC data (Kim and Fabbiano 1995). Some of them appear to be extended, although this needs to be confirmed. Among the bright sources, some are extremely hard while others are very soft, possibly indicating that they consist of mixed populations. The possibly nature of these sources will be discussed. We have also confirmed the off-center 2nd peak, possibly interacting with the radio lobe and discovered a sharp discontinuity at 2' southeast from the center. We note that most of the Chandra sources are within the X-ray bright, extended halo and therefore are not individually detected in the XMM-Newton data. Also we discuss metal abundances (Fe and alpha-element separately) in the X-ray halo obtained by applying various emission models (taking into account those Chandra sources within the X-ray halo) and their implications in terms of type I/II SN rates. We acknowledge the financial support of NASA Grant NAG5-9965.

  10. Observation of X-ray sources with XRS onboard HAYABUSA spacecraft

    NASA Astrophysics Data System (ADS)

    Arai, T.; Yamamoto, Y.; Okada, T.; Shirai, K.; Kato, M.

    The HAYABUSA (MUSES-C) spacecraft was launched in Japan by the fifth M-V launch vehicle on May 9, 2003 will carry out rendezvous with near-Earth asteroid Itokawa (1998SF36), and return the samples to the Earth. An X-ray fluorescence spectrometer (XRS) onboard HAYABUSA has high-energy resolution (FWHM: 160eV@5.9keV) by using X-ray CCD, will allow for quantitative measurement of the surface elementals of asteroid, such as Mg, Al, Si, S, Ca, Ti, and Fe. Addition, the XRS has large effective area (25cm2) and suitable field of view for asteroid observation (3.5x3.5degrees). During the transfer and return phase, the HAYABUSA spacecraft will turn off the Ion propulsion thruster and point a high-gain antenna to the Earth station every week. Then, the XRS will observe X-ray sources such as super nova remnant, X-ray binaries and cosmic X-ray back ground for in-flight calibration and scientific observation. In this study, we report results of resent observations. The XRS observed Scorpius X-1 (May 28-30, 2003), Kepler's SNR (Jun. 16-18, 2003), Crab Nebula (Jan. 11-12, 2004), IC443 (Jan. 26, 2004). The XRS separated line X-ray spectra from Kepler's SNR and IC443 such as Si and S, clearly. These X-ray sources have been observed the X-ray astronomy satellite ASCA. We fitted power-law model or non-equilibrium ionization model (Borkowski, 2000) to the XRS observed spectra. However, the intensities were inconsistent with the best-fit models to ASCA observed spectra. Charge traps due to the space radiation may cause characteristic changes of the XRS. We will monitor the performance of the XRS and update the response function by in-flight calibration.

  11. A new approach for tsunami early warning using tsunami observations in a source region

    NASA Astrophysics Data System (ADS)

    Tanioka, Y.

    2015-12-01

    After the 2011 devastating Tohoku tsunami, improvement of tsunami early warning system is one of key issues in Japan. Japanese government was decided to install 125 ocean bottom pressure sensors and seismometers with a cable system along the Japan and Kurile trench. Each sensor is separated by 30km. We should develop a new approach for real-time tsunami forecast using those newly available data combined with GNSS data or seismic data. A well-recognized problem to use tsunami data at pressure sensors on the top of tsunami source area is a fact that a large vertical coseismic deformation due to a large earthquake cannot be observed at those sensors. The sensors observe a tsunami wave when it starts to propagate. Because of that problem, GSNN data or seismic data are typically used to estimate the coseismic deformation for the tsunami numerical simulation. In this paper, we develop a new technique, which solve the problem. Our technique uses the observations at pressure sensors on the tsunami source area as an input to compute the tsunami directly. Actual tsunami heights at the sensors on the source area is unknown because the cosismic vertical deformation is unknown. However, we can observe directly the time derivative of tsunami heights at those sensors. Time derivatives of tsunami heights at each point are used as inputs to compute the tsunami height distribution in the calculated area. Then we can numerically compute a tsunami using a traditional finite difference technique from the tsunami height distribution computed. For numerical test, first, we compute the synthetic tsunamis using the fault model with 1 minute grid system. The computed tsunami waveforms at 15 minutes x 15 minutes grid points are used as the observed data for this new technique. Each observed point is separated by 15 minutes, about 30km. The result show that the accuracy of tsunami computation is good enough for tsunami forecast. Tsunami generation with a long duration, such as tsunami

  12. DEEP GALEX OBSERVATIONS OF THE COMA CLUSTER: SOURCE CATALOG AND GALAXY COUNTS

    SciTech Connect

    Hammer, D.; Hornschemeier, A. E.; Miller, N.; Jenkins, L.; Mobasher, B.; Smith, R.; Arnouts, S.; Milliard, B.

    2010-09-15

    We present a source catalog from a deep 26 ks Galaxy Evolution Explorer (GALEX) observation of the Coma cluster in the far-UV (FUV; 1530 A) and near-UV (NUV; 2310 A) wavebands. The observed field is centered {approx}0.{sup 0}9 (1.6 Mpc) southwest of the Coma core in a well-studied region of the cluster known as 'Coma-3'. The entire field is located within the apparent virial radius of the Coma cluster, and has optical photometric coverage with Sloan Digital Sky Survey (SDSS) and deep spectroscopic coverage to r {approx} 21. We detect GALEX sources to NUV = 24.5 and FUV = 25.0, which corresponds to a star formation rate of {approx}10{sup -3} M {sub sun} yr{sup -1} for galaxies at the distance of Coma. We have assembled a catalog of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically confirmed Coma member galaxies that span a large range of galaxy types from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is {approx}80% complete to NUV = 23 and FUV = 23.5. The GALEX images presented here are very deep and include detections of many resolved cluster members superposed on a dense field of unresolved background galaxies. This required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as position prior), and used the GALEX pipeline catalog for bright and/or extended objects. We performed simulations to assess the importance of systematic effects (e.g., object blends, source confusion, Eddington Bias) that influence the source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is free from source confusion over the UV magnitude range studied here; we estimate that

  13. Characterization of dust emission from alluvial sources using aircraft observations and high-resolution modeling

    NASA Astrophysics Data System (ADS)

    Schepanski, Kerstin; Flamant, Cyrille; Chaboureau, Jean-Pierre; Kocha, Cecile; Banks, Jamie; Brindley, Helen; Lavaysse, Christophe; Marnas, Fabien; Pelon, Jacques; Tulet, Pierre

    2013-04-01

    We investigate mineral dust emission from alluvial sediments within the upland region in northern Mauritania in the vicinity of a decaying nocturnal low-level jet (LLJ). For the first time, the impact of valleys that are embedded in a rather homogeneous surrounding is investigated with regard to their role as dust source. Measures for local atmospheric dust burden were retrieved from airborne observations, satellite observations, and model simulations and analyzed in order to provide complementary information at different horizontal scales. Observations by the LNG backscatter lidar system flying aboard the SAFIRE Falcon 20 aircraft were taken along five parallel flight legs perpendicular to the orientation of the main valley system dominating the topography of the study area. Results from a comparison of lidar-derived extinction coefficients with topography and aerial photographs confirm the relevance of (1) alluvial sediments at the valley bottoms as a dust source, and (2) the break-down of the nocturnal LLJ as a trigger for dust emission in this region. An evaluation of the AROME regional model, forecasting dust at high resolution (5 km grid), points towards an underrepresentation of alluvial dust sources in this region. This is also evident from simulations by the MesoNH research model. Although MesoNH simulations show higher dust loadings than AROME which are more comparable to the observations, both models understimate the dust concentrations within the boundary layer compared to lidar observations. A sensitivity study on the impact of horizontal grid spacing (5 km versus 1 km) highlights the importance of spatial resolution on simulated dust loadings.

  14. Estimation of methane sources and sinks by inverse modelling using GOSAT observations

    NASA Astrophysics Data System (ADS)

    Locatelli, Robin; Bousquet, Philippe; Saunois, Marielle

    2015-04-01

    Since the nineties, inverse modeling by assimilating measurements into a chemical transport model (CTM) has been used to derive sources and sinks of atmospheric trace gases. More recently, the high global warming potential of methane (CH4) caught the attention of several research groups. Indeed, the diversity and the variability of methane sources induce high uncertainty on the present and the future evolution of CH4 budget. Historically, inverse problems have been limited by the lack of observations but, the increasing of available measurement data (satellite data, high frequency measurement, FTIR spectrometry,...) gradually supplements this issue. However, the use of different types of observations is a challenge for current inversions. Do these different datasets derive consistent methane fluxes using inverse modelling ? Moreover, recent studies have highlighted the need for improvements in the accuracy of the atmospheric circulations in chemical transport model: a bad representation of the atmospheric transport may derive wrong methane fluxes. Consequently, we investigate here these two main issues (consistency between inversions using different datasets and transport model errors) by comparing an ensemble of methane inversions using : - different versions of the transport model used in the inverse system - different observation data sets (GOSAT observations and surface measurements) Moreover, these different inversions have been run for recent years, which allow us to investigate the inter-annual variability of methane sources and sinks. In particular, two years of strong methane emissions have been highlighted in 2007 and in 2010. These anomalies have been mainly attributed to anomalies in the Tropics and in China, where major climate events have been observed and where economic development is carrying on with a fast pace, even if emissions reported in inventories are overestimated.

  15. Constraints for the 2004 Sumatra Earthquake Source Process From Coseismic Ionospheric Disturbances Observed by GPS

    NASA Astrophysics Data System (ADS)

    Heki, K.; Otsuka, Y.; Choosakul, N.; Hemmakorn, N.; Komolmis, T.; Maruyama, T.

    2005-12-01

    Coseismic ionospheric total electron content (TEC) perturbations, observable with Global Positioning System (GPS), are caused by the three kinds of atmospheric waves, i.e. (1) direct acoustic wave from the focal area, (2) gravity wave propagating obliquely upward, and (3) secondary acoustic wave excited by the Rayleigh surface wave. They have been detected for the 2003 Tokachi-oki, Japan (Heki and Ping, 2005), the 2001 Peru (Artru et al., 2005), and the 2002 Denali (Ducic et al., 2003) earthquakes, respectively, all with dense GPS arrays. They have different apparent propagation speeds, and the first one has a latitude-dependent directivity due to the Lorentz force. Here we demonstrate that observed coseismic ionospheric disturbances could constrain the source rupture process of the 2004 December Great Sumatra earthquake. After that earthquake, we observed two kinds of ionospheric perturbations, i.e. the surface wave induced perturbation detected by the Japanese GEONET, and those by direct acoustic waves detected by nine continuous GPS stations in Indonesia and Thailand. The latter disturbances amounted to a few TEC units, an order of magnitude larger than the 2003 Tokachi-oki case, and propagated by about 1 km/sec. Their apparent periods were 4-5 minutes or longer. We assumed linear distribution of point sources for acoustic wave generation along the fault from NW Sumatra to the Andaman Islands, and calculated TEC variation waveforms by simulating the acoustic wave propagation from individual sources to the intersections of line-of-sights and ionosphere through the atmosphere with height-dependent sound velocities, by ray-tracing. Then, we tried to reproduce the combined TEC perturbations similar to the observed ones, for several different satellite-receiver pairs, by optimizing the relative strengths of the linearly distributed point sources. The strongest sources were found near G. Nicobar Island, which is consistent with seismological studies and displacements

  16. Mapping Air Pollution Concentrations and Sources in China from Ground-Level Observations

    NASA Astrophysics Data System (ADS)

    Rohde, R. A.; Muller, R. A.

    2014-12-01

    China has recently established an extensive air quality monitoring system with over 1500 sites providing hourly data on airborne particulate matter (PM2.5 / PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO). Based on Kriging interpolation of these surface data, we derive a detailed map of air pollution across the eastern half of China. In northern and central China, the pollution is widespread; contrary to popular belief, pollution is not simply localized to major cities such as Beijing, Shanghai, or Chongqing, or in geologic basins. Pollution levels are lower in southern China, in part due to frequent rains. By incorporating wind measurements and estimating pollution transport, we also infer source distributions for key pollutants. Sources are widespread, but many of the largest sources are often situated in or near major population centers. A northeast corridor extending from near Shanghai to north of Beijing includes many of the most significant pollution sources in China. Roughly 5% of the study region accounts for 25% of observed particulate matter emissions. During the analysis period, roughly half of the population of China was subjected to a long-term average pollution level in the unhealthy range, according to standards used by the US Environmental Protection Agency. In addition, nearly all of China's population (>90%) was exposed to unhealthy levels of air pollution at least some of the time. Based on health impact estimates from the Huai River Study, we estimate that the observed levels of particulate matter pollution contribute to about 1.4 million deaths every year in China, about 3500 per day, in agreement with prior estimates. Identification of sources from pollution data was facilitated by the reporting of hourly measurements, and we encourage other nations around the world to follow China's example and provide such time-resolved data.

  17. High Resolution Rapid Response Observations of Compact Radio Sources with the Ceduna Hobart Interferometer (CHI)

    NASA Technical Reports Server (NTRS)

    Blanchard, Jay M.; Lovell, James E. J.; Ojha, Roopesh; Kadler, Matthias; Dickey, John M.; Edwards, Philip G.

    2011-01-01

    Context. Frequent, simultaneous observations across the electromagnetic spectrum are essential to the study of a range of astrophysical phenomena including Active Galactic Nuclei. A key tool of such studies is the ability to observe an object when it flares i.e. exhibits a rapid and significant increase in its flux density. Aims. We describe the specific observational procedures and the calibration techniques that have been developed and tested to create a single baseline radio interferometer. that can rapidly observe a flaring object. This is the only facility that is dedicated to rapid high resolution radio observations of an object south of -30 degrees declination. An immediate application is to provide rapid contemporaneous radio coverage of AGN flaring at y-ray frequencies detected by the Fermi Gamma-ray Space Telescope. Methods. A single baseline interferometer was formed with radio telescopes in Hobart, Tasmania and Ceduna, South Australia. A software correlator was set up at the University of Tasmania to correlate these data. Results. Measurements of the flux densities of flaring objects can be made using our observing strategy within half an hour of a triggering event. These observations can be calibrated with amplitude errors better than 20%. Lower limits to the brightness temperatures of the sources can also be calculated using CHI. Key words. instrumentation:interferometers - galaxies:active - galaxies:jets - galaxies:nuclei quasars:general gamma rays:galaxies- 1.

  18. Review on recent progress in observations, source identifications and countermeasures of PM2.5.

    PubMed

    Liang, Chun-Sheng; Duan, Feng-Kui; He, Ke-Bin; Ma, Yong-Liang

    2016-01-01

    Recently, PM2.5 (atmospheric fine particulate matter with aerodynamic diameter ≤ 2.5 μm) have received so much attention that the observations, source appointment and countermeasures of it have been widely studied due to its harmful impacts on visibility, mood (mental health), physical health, traffic safety, construction, economy and nature, as well as its complex interaction with climate. A review on the PM2.5 related research is necessary. We start with summary of chemical composition and characteristics of PM2.5 that contains both macro and micro observation results and analysis, wherein the temporal variability of concentrations of PM2.5 and major components in many recent reports is embraced. This is closely followed by an overview of source appointment, including the composition and sources of PM2.5 in different countries in the six inhabitable continents based on the best available results. Besides summarizing PM2.5 pollution countermeasures by policy, planning, technology and ideology, the World Air Day is proposed to be established to inspire and promote the crucial social action in energy-saving and emission-reduction. Some updated knowledge of the important topics (such as formation and evolution mechanisms of hazes, secondary aerosols, aerosol mass spectrometer, organic tracers, radiocarbon, emissions, solutions for air pollution problems, etc.) is also included in the present review by logically synthesizing the studies. In addition, the key research challenges and future directions are put forward. Despite our efforts, our understanding of the recent reported observations, source identifications and countermeasures of PM2.5 is limited, and subsequent efforts both of the authors and readers are needed. PMID:26595670

  19. Deep source model for Nevado del Ruiz Volcano, Colombia, constrained by interferometric synthetic aperture radar observations

    NASA Astrophysics Data System (ADS)

    Lundgren, P.; Samsonov, S. V.; López, C. M.; Ordoñez, M.

    2015-12-01

    Nevado del Ruiz (NRV) is part of a large volcano complex in the northern Andes of Colombia with a large glacier that erupted in 1985, generating a lahar killing over 23,000 people in the city of Armero and 2,000 people in the town of Chinchina. NRV is the most active volcano in Colombia and since 2012 has generated small eruptions, with no casualties, and constant gas and ash emissions. Interferometric synthetic aperture radar (InSAR) observations from ascending and descending track RADARSAT-2 data show a large (>20 km) wide inflation pattern apparently starting in late 2011 to early 2012 and continuing to the time of this study in early 2015 at a LOS rate of over 3-4 cm/yr (Fig. 1). Volcano pressure volume models for both a point source (Mogi) and a spheroidal (Yang) source find solutions over 14 km beneath the surface, or 10 km below sea level, and centered 10 km to the SW of Nevado del Ruiz volcano. The spheroidal source has a roughly horizontal long axis oriented parallel to the Santa Isabel - Nevado del Ruiz volcanic line and perpendicular to the ambient compressive stress direction. Its solution provides a statistically significant improvement in fit compared to the point source, though consideration of spatially correlated noise sources may diminish this significance. Stress change computations do not favor one model over the other but show that propagating dikes would become trapped in sills, leading to a more complex pathway to the surface and possibly explaining the significant lateral distance between the modeled sources and Nevado del Ruiz volcano.

  20. Lessons Learned from OMI Observations of Point Source SO2 Pollution

    NASA Technical Reports Server (NTRS)

    Krotkov, N.; Fioletov, V.; McLinden, Chris

    2011-01-01

    The Ozone Monitoring Instrument (OMI) on NASA Aura satellite makes global daily measurements of the total column of sulfur dioxide (SO2), a short-lived trace gas produced by fossil fuel combustion, smelting, and volcanoes. Although anthropogenic SO2 signals may not be detectable in a single OMI pixel, it is possible to see the source and determine its exact location by averaging a large number of individual measurements. We describe new techniques for spatial and temporal averaging that have been applied to the OMI SO2 data to determine the spatial distributions or "fingerprints" of SO2 burdens from top 100 pollution sources in North America. The technique requires averaging of several years of OMI daily measurements to observe SO2 pollution from typical anthropogenic sources. We found that the largest point sources of SO2 in the U.S. produce elevated SO2 values over a relatively small area - within 20-30 km radius. Therefore, one needs higher than OMI spatial resolution to monitor typical SO2 sources. TROPOMI instrument on the ESA Sentinel 5 precursor mission will have improved ground resolution (approximately 7 km at nadir), but is limited to once a day measurement. A pointable geostationary UVB spectrometer with variable spatial resolution and flexible sampling frequency could potentially achieve the goal of daily monitoring of SO2 point sources and resolve downwind plumes. This concept of taking the measurements at high frequency to enhance weak signals needs to be demonstrated with a GEOCAPE precursor mission before 2020, which will help formulating GEOCAPE measurement requirements.

  1. Preseismic Velocity Changes Observed from Active Source Monitoringat the Parkfield SAFOD Drill Site

    SciTech Connect

    Daley, Thomas; Niu, Fenglin; Silver, Paul G.; Daley, Thomas M.; Cheng, Xin; Majer, Ernest L.

    2008-06-10

    Measuring stress changes within seismically active fault zones has been a long-sought goal of seismology. Here we show that such stress changes are measurable by exploiting the stress dependence of seismic wave speed from an active source cross-well experiment conducted at the SAFOD drill site. Over a two-month period we observed an excellent anti-correlation between changes in the time required for an S wave to travel through the rock along a fixed pathway--a few microseconds--and variations in barometric pressure. We also observed two large excursions in the traveltime data that are coincident with two earthquakes that are among those predicted to produce the largest coseismic stress changes at SAFOD. Interestingly, the two excursions started approximately 10 and 2 hours before the events, respectively, suggesting that they may be related to pre-rupture stress induced changes in crack properties, as observed in early laboratory studies.

  2. In situ calibration of atmospheric-infrasound sensors including the effects of wind-noise-reduction pipe systems.

    PubMed

    Gabrielson, Thomas B

    2011-09-01

    A worldwide network of more than 40 infrasound monitoring stations has been established as part of the effort to ensure compliance with the Comprehensive Nuclear Test Ban Treaty. Each station has four to eight individual infrasound elements in a kilometer-scale array for detection and bearing determination of acoustic events. The frequency range of interest covers a three-decade range-roughly from 0.01 to 10 Hz. A typical infrasound array element consists of a receiving transducer connected to a multiple-inlet pipe network to average spatially over the short-wavelength turbulence-associated "wind noise." Although the frequency response of the transducer itself may be known, the wind-noise reduction system modifies that response. In order to understand the system's impact on detection and identification of acoustical events, the overall frequency response must be determined. This paper describes a technique for measuring the absolute magnitude and phase of the frequency response of an infrasound element including the wind-noise-reduction piping by comparison calibration using ambient noise and a reference-microphone system. Measured coherence between the reference and the infrasound element and the consistency between the magnitude and the phase provide quality checks on the process. PMID:21895058

  3. 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.

  4. Deep Galex Observations of the Coma Cluster: Source Catalog and Galaxy Counts

    NASA Technical Reports Server (NTRS)

    Hammer, D.; Hornschemeier, A. E.; Mobasher, B.; Miller, N.; Smith, R.; Arnouts, S.; Milliard, B.; Jenkins, L.

    2010-01-01

    We present a source catalog from deep 26 ks GALEX observations of the Coma cluster in the far-UV (FUV; 1530 Angstroms) and near-UV (NUV; 2310 Angstroms) wavebands. The observed field is centered 0.9 deg. (1.6 Mpc) south-west of the Coma core, and has full optical photometric coverage by SDSS and spectroscopic coverage to r-21. The catalog consists of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically-confirmed Coma member galaxies that range from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is 80% complete to NUV=23 and FUV=23.5, and has a limiting depth at NUV=24.5 and FUV=25.0 which corresponds to a star formation rate of 10(exp -3) solar mass yr(sup -1) at the distance of Coma. The GALEX images presented here are very deep and include detections of many resolved cluster members superposed on a dense field of unresolved background galaxies. This required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as a position prior), and used the GALEX pipeline catalog for bright and/or extended objects. We performed simulations to assess the importance of systematic effects (e.g. object blends, source confusion, Eddington Bias) that influence source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is also free from source confusion over the UV magnitude range studied here: conversely, we estimate that the GALEX pipeline catalogs are confusion limited at NUV approximately 23 and FUV approximately 24. We have measured the total UV galaxy counts using our catalog and report a 50% excess of counts across FUV=22-23.5 and NUV=21.5-23 relative to previous GALEX

  5. Sources of Information and Behavioral Patterns in Online Health Forums: Observational Study

    PubMed Central

    Friede, Tim; Grabowski, Jens; Koschack, Janka; Makedonski, Philip; Himmel, Wolfgang

    2014-01-01

    Background Increasing numbers of patients are raising their voice in online forums. This shift is welcome as an act of patient autonomy, reflected in the term “expert patient”. At the same time, there is considerable concern that patients can be easily misguided by pseudoscientific research and debate. Little is known about the sources of information used in health-related online forums, how users apply this information, and how they behave in such forums. Objective The intent of the study was to identify (1) the sources of information used in online health-related forums, and (2) the roles and behavior of active forum visitors in introducing and disseminating this information. Methods This observational study used the largest German multiple sclerosis (MS) online forum as a database, analyzing the user debate about the recently proposed and controversial Chronic Cerebrospinal Venous Insufficiency (CCSVI) hypothesis. After extracting all posts and then filtering relevant CCSVI posts between 01 January 2008 and 17 August 2012, we first identified hyperlinks to scientific publications and other information sources used or referenced in the posts. Employing k-means clustering, we then analyzed the users’ preference for sources of information and their general posting habits. Results Of 139,912 posts from 11,997 threads, 8628 posts discussed or at least mentioned CCSVI. We detected hyperlinks pointing to CCSVI-related scientific publications in 31 posts. In contrast, 2829 different URLs were posted to the forum, most frequently referring to social media, such as YouTube or Facebook. We identified a total of 6 different roles of hyperlink posters including Social Media Fans, Organization Followers, and Balanced Source Users. Apart from the large and nonspecific residual category of the “average user”, several specific behavior patterns were identified, such as the small but relevant groups of CCSVI-Focused Responders or CCSVI Activators. Conclusions The bulk

  6. SPITZER OBSERVATIONS OF GX17+2: CONFIRMATION OF A PERIODIC SYNCHROTRON SOURCE

    SciTech Connect

    Harrison, Thomas E.; McNamara, Bernard J.; Bornak, Jillian; Gelino, Dawn M.; Wachter, Stefanie; Gelino, Christopher R. E-mail: bmcnamar@nmsu.edu E-mail: dawn@ipac.caltech.edu E-mail: mrupen@aoc.nrao.edu

    2011-07-20

    GX17+2 is a low-mass X-ray binary (LMXB) that is also a member of a small family of LMXBs known as 'Z-sources' that are believed to have persistent X-ray luminosities that are very close to the Eddington limit. GX17+2 is highly variable at both radio and X-ray frequencies, a feature common to Z-sources. What sets GX17+2 apart is its dramatic variability in the near-infrared, where it changes by {Delta}K {approx} 3 mag. Previous investigations have shown that these brightenings are periodic, recurring every 3.01 days. Given its high extinction (A{sub V} {>=} 9 mag), it has not been possible to ascertain the nature of these events with ground-based observations. We report mid-infrared Spitzer observations of GX17+2 which indicate a synchrotron spectrum for the infrared brightenings. In addition, GX17+2 is highly variable in the mid-infrared during these events. The combination of the large-scale outbursts, the presence of a synchrotron spectrum, and the dramatic variability in the mid-infrared suggest that the infrared brightening events are due to the periodic transit of a synchrotron jet across our line of sight. An analysis of both new, and archival, infrared observations has led us to revise the period for these events to 3.0367 days. We also present new Rossi X-Ray Timing Explorer (RXTE) data for GX17+2 obtained during two predicted infrared brightening events. Analysis of these new data, and data from the RXTE archive, indicates that there is no correlation between the X-ray behavior of this source and the observed infrared brightenings. We examine various scenarios that might produce periodic jet emission.

  7. A XMM-Newton Observation of Nova LMC 1995, a Bright Supersoft X-ray Source

    NASA Technical Reports Server (NTRS)

    Orio, Marina; Hartmann, Wouter; Still, Martin; Greiner, Jochen

    2003-01-01

    Nova LMC 1995, previously detected during 1995-1998 with ROSAT, was observed again as a luminous supersoft X-ray source with XMM-Newton in December of 2000. This nova offers the possibility to observe the spectrum of a hot white dwarf, burning hydrogen in a shell and not obscured by a wind or by nebular emission like in other supersoft X-ray sources. Notwithstanding uncertainties in the calibration of the EPIC instruments at energy E<0.5 keV, using atmospheric models in Non Local Thermonuclear Equilibrium we derived an effective temperature in the range 400,000-450,000 K, a bolometric luminosity Lbolabout equal to 2.3 times 10 sup37 erg s sup-l, and we verified that the abundance of carbon is not significantly enhanced in the X-rays emitting shell. The RGS grating spectra do not show emission lines (originated in a nebula or a wind) observed for some other supersoft X-ray sources. The crowded atmospheric absorption lines of the white dwarf cannot be not resolved. There is no hard component (expected from a wind, a surrounding nebula or an accretion disk), with no counts above the background at E>0.6 keV, and an upper limit Fx,hard = 10 sup-14 erg s sup-l cm sup-2 to the X-ray flux above this energy. The background corrected count rate measured by the EPIC instruments was variable on time scales of minutes and hours, but without the flares or sudden obscuration observed for other novae. The power spectrum shows a peak at 5.25 hours, possibly due to a modulation with the orbital period. We also briefly discuss the scenarios in which this nova may become a type Ia supernova progenitor.

  8. Submillimeter array observations of NGC 2264-C: molecular outflows and driving sources

    NASA Astrophysics Data System (ADS)

    Cunningham, Nichol; Lumsden, Stuart L.; Cyganowski, Claudia J.; Maud, Luke T.; Purcell, Cormac

    2016-05-01

    We present 1.3 mm Submillimeter Array (SMA) observations at ˜3 arcsec resolution towards the brightest section of the intermediate/massive star-forming cluster NGC 2264-C. The millimetre continuum emission reveals ten 1.3 mm continuum peaks, of which four are new detections. The observed frequency range includes the known molecular jet/outflow tracer SiO (5-4), thus providing the first high-resolution observations of SiO towards NGC 2264-C. We also detect molecular lines of 12 additional species towards this region, including CH3CN, CH3OH, SO, H2CO, DCN, HC3N, and 12CO. The SiO (5-4) emission reveals the presence of two collimated, high-velocity (up to 30 km s-1 with respect to the systemic velocity) bipolar outflows in NGC 2264-C. In addition, the outflows are traced by emission from 12CO, SO, H2CO, and CH3OH. We find an evolutionary spread between cores residing in the same parent cloud. The two unambiguous outflows are driven by the brightest mm continuum cores, which are IR-dark, molecular line weak, and likely the youngest cores in the region. Furthermore, towards the Red MSX Source AFGL 989-IRS1, the IR-bright and most evolved source in NGC 2264-C, we observe no molecular outflow emission. A molecular line rich ridge feature, with no obvious directly associated continuum source, lies on the edge of a low-density cavity and may be formed from a wind driven by AFGL 989-IRS1. In addition, 229 GHz class I maser emission is detected towards this feature.

  9. Observation of image pair creation and annihilation from superluminal scattering sources

    PubMed Central

    Clerici, Matteo; Spalding, Gabriel C.; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M.; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-01-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena. PMID:27152347

  10. High energy X-ray observations of Sco-like sources with Ariel V

    NASA Technical Reports Server (NTRS)

    Greenhill, J. G.; Coe, M. J.; Burnell, S. J. B.; Strong, K. T.; Carpenter, G. F.

    1979-01-01

    Results are reported for observations of Sco X-1 and the similar sources 4U 1702-36 (GX 349+2, Sco X-2), 4U 1813-14 (GX 17+2), and 4U 1758-25 (GX 5-1) by several of the X-ray telescopes aboard the Ariel 5 satellite over the energy range from 2 to approximately 100 keV. The results confirm the existence of a high-energy tail in the spectrum of Sco X-1, demonstrate that 4U 1702-36 has a similar spectrum, and provide evidence for a variation of the 26-56-keV flux from 4U 1702-36 by more than a factor of four with no related change in the 2.9-7.6-keV flux. The high-energy emission from Sco X-1 is found to be one to two orders of magnitude above the extrapolated low-energy emission. Observed X-ray, radio, and optical properties of these four sources, as well as two additional Sco-like sources, are summarized.

  11. ON THE NATURE OF HARD X-RAY EXTRAGALACTIC SOURCES OBSERVED WITH XMM-NEWTON

    SciTech Connect

    Jimenez-Bailon, E.; Huerta, E. M.; Krongold, Y.; Chavushyan, V.; Schartel, N.; Santos-Lleo, M.

    2012-03-15

    Over the last decade, X-ray surveys have provided outstanding new results due to the lack of the common selection effects present at other wavelengths. Here, we have selected a sample of unidentified sources from the XMM-Newton Slew Survey Catalog, likely to be extragalactic. Five of them were observed with the XMM-Newton observatory. In this work, we present the results of the spectral analysis of these objects in the X-ray and optical bands. Only three of them had useful spectroscopic X-ray data, and follow up observations were carried out in the optical range to determine their coordinates, classification, and redshift. The sources are different types of active galactic nuclei (AGNs) with redshifts ranging from 0.059 to 0.386. The properties at both spectral ranges (X-rays and optical) are compatible with the common properties of their types of AGNs. Although the sources were selected by their hard X-ray properties, none of the three detected objects turned out to be an obscured AGN.

  12. OT1_rpaladin_1: PACS and SPIRE observations of Galactic anomalous emission sources.

    NASA Astrophysics Data System (ADS)

    Paladini, R.

    2010-07-01

    Despite the increasing evidence that the anomalous emission is a new physical mechanism acting in the diffuse interstellar medium, the nature and distribution of this component remains elusive. The currently most favored models attribute the observed microwave excess to rotating very small dust grains (PAHs and VSGs). Nonetheless, the infrared properties of the sources which, to date, are known to exhibit this type of emission are very poorly known mostly due to the limited angular resolution and frequency coverage of DIRBE and IRAS data. We propose HERSCHEL PACS and SPIRE mapping of three Galactic anomalous emission sources (LDN 1780, LDN 675 and LDN 1111). This data, when combined with ancillary NIR and mid-IR data of comparable angular resolution (mainly from Spitzer), and coupled with available dust models, will allow to set tight constraints on the radiation field in the emitting sources as well as in their immediate surroundings. Such constraints, in turn, will allow to estimate the abundances of PAHs, VSGs and BGs, hence to shed light on the potential link between these dust populations and the observed microwave excess.

  13. Observation of image pair creation and annihilation from superluminal scattering sources.

    PubMed

    Clerici, Matteo; Spalding, Gabriel C; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-04-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena. PMID:27152347

  14. Source apportionment of PM10 in the Western Mediterranean based on observations from a cruise ship

    NASA Astrophysics Data System (ADS)

    Schembari, C.; Bove, M. C.; Cuccia, E.; Cavalli, F.; Hjorth, J.; Massabò, D.; Nava, S.; Udisti, R.; Prati, P.

    2014-12-01

    Two intensive PM10 sampling campaigns were performed in the summers of 2009 and 2010 on the ship Costa Pacifica during cruises in the Western Mediterranean. Samples, mainly collected on an hourly basis, were analysed with different techniques (Particle Induced X-Ray Emission, PIXE; Energy Dispersive - X Ray Fluorescence, ED-XRF; Ion Chromatography, IC; Thermo-optical analysis) to retrieve the PM10 composition and its time pattern. The data were used for obtaining information about the sources of aerosol, with a focus on ship emissions, through apportionment using chemical marker compounds, correlation analysis and Positive Matrix Factorization (PMF) receptor modelling. For the campaign in 2010, 66% of the aerosol sulphate was found to be anthropogenic, only minor contributions of dust and sea salt sulphate were observed while the biogenic contribution, estimated based on the measurements of MSA, was found to be more important (26%), but influenced by large uncertainties. V and Ni were found to be suitable tracers of ship emissions during the campaigns. Four sources of aerosol were resolved by the PMF analysis; the source having the largest impact on PM10, BC and sulphate was identified as a mixed source, comprising emissions from ships. The correlations between sulphate and V and Ni showed the influence of ship emissions on sulphate in marine air masses. For the leg Palma-Tunis crossing a main ship route, the correlations between aerosol sulphate and V and Ni were particularly strong (r2 = 0.9 for both elements).

  15. Infrared observations of eight X-ray sources from Galactic plane surveys

    NASA Astrophysics Data System (ADS)

    Revnivtsev, M. G.; Kniazev, A.; Karasev, D. I.; Berdnikov, L.; Barway, S.

    2013-08-01

    Increasing the identification completeness of sources from new X-ray sky surveys is a necessary condition for further works on analyzing the formation and long-term evolution of star systems in our Galaxy. Infrared observations of several sources selected from Galactic plane surveys as candidates for low-mass X-ray binaries with the IRSF telescope at the South African Astronomical Observatory are presented. The infrared fluxes have been reliably measured from five of the eight sources (4U 1556-60, 4U 1708-40, AX J165901-4208, IGR J16287-5021, IGR J17350-2045, AX J171922-3703, SAX J1712.6-3739, 4U 1705-32). One of the objects (AX J165901-4208) may be a candidate for symbiotic X-ray binaries, i.e., binaries in which the companion of a relativistic object is a giant star. The distances have been estimated for three sources and the orbital periods have been estimated for two.

  16. Suzaku Observation of the Unidentified Gamma-ray Source HESS J1841-055

    NASA Astrophysics Data System (ADS)

    Nobukawa, Kumiko

    HESS J1841-055 is an unidentified Gamma-ray source and spread across 1 degree. There is not yet a conclusive counterpart in any other wave length. We observed HESS J1841-055 with Suzaku. Several sources were found in the region. (1) High mass X-ray binary AX J1841.0-0536 exhibited many short flares with the time-scales of a few hundred seconds and a large flare with the peak flux (1.0-10 keV) of ≤2×10(-10) erg s(-1) cm(-2) . The source had a high dynamical range (ratio of the peak luminosity in the large flare to the quiescent emission), which spanned 3 orders of magnitudes. (2) Soft (0.5-2.0 keV) diffuse X-ray emission is a supernova remnant candidate, since its spectrum was fit by an optically thin thermal plasma model. (3) 2 arcminutes extended source in the hard band (2.0-8.0 keV) had a high column density of N_mathrm{H}˜10(23) cm(-2) and a red-shifted iron line. It can be a new candidate of a cluster of galaxy.

  17. Is the Source of Reinforcement for Naming Multiple Conditioned Reinforcers for Observing Responses?

    PubMed

    Longano, Jennifer M; Greer, R Douglas

    2015-06-01

    Naming refers to the incidental acquisition of word-object relations as listener and speaker without explicit reinforcement. To investigate possible sources of reinforcement for naming, we examined the effects of a procedure for conditioning reinforcement for observing responses on the emergence of naming in children who previously lacked it. The participants were three 5- to 7-year-old children with and without diagnoses of autism spectrum disorder. During the intervention, either visual or auditory stimuli were first conditioned as reinforcers for observing responses. Then, neutral visual or auditory stimuli were paired with the conditioned visual or auditory stimuli until both visual and auditory stimuli acquired reinforcing properties for observing. Following this intervention, the participants demonstrated naming of stimuli that had been used in pretests for naming, as well as on a novel set of stimuli. We observed increases in echoic responding in conjunction with the emergence of naming and conditioned reinforcement for both observing responses. We interpret the data as suggesting that listener and speaker repertoires are joined for naming only when both visual and auditory stimuli reinforce the observing responses of looking and listening simultaneously. PMID:27606200

  18. Using the EXIST Active Shields for Earth Occultation Observations of X-Ray Sources

    NASA Technical Reports Server (NTRS)

    Wilson, Colleen A.; Fishman, Gerald; Hong, Jae-Sub; Gridlay, Jonathan; Krawczynski, Henric

    2005-01-01

    The EXIST active shields, now being planned for the main detectors of the coded aperture telescope, will have approximately 15 times the area of the BATSE detectors; and they will have a good geometry on the spacecraft for viewing both the leading and training Earth's limb for occultation observations. These occultation observations will complement the imaging observations of EXIST and can extend them to higher energies. Earth occultatio observations of the hard X-ray sky with BATSE on the Compton Gamma Ray Observatory developed and demonstrated the capabilities of large, flat, uncollimated detectors for this method. With BATSE, a catalog of 179 X-ray sources was monitored twice every spacecraft orbit for 9 years at energies above about 25 keV, resulting in 83 definite detections and 36 possible detections with 5-sigma detection sensitivities of 3.5-20 mcrab (20-430 keV) depending on the sky location. This catalog included four transients discovered with this technique and many variable objects (galactic and extragalactic). This poster will describe the Earth occultation technique, summarize the BATSE occultation observations, and compare the basic observational parameters of the occultation detector elements of BATSE and EXIST.

  19. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

    NASA Astrophysics Data System (ADS)

    Zavala, M.; Lei, W.; Molina, M. J.; Molina, L. T.

    2009-01-01

    The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx) suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio. This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM) and the standard Brute Force Method (BFM) in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with NOx emission reductions and decrease linearly with VOC emission reductions only up to 30% from the

  20. Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

    NASA Astrophysics Data System (ADS)

    Zavala, M.; Lei, W. F.; Molina, M. J.; Molina, L. T.

    2008-08-01

    The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx) suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio. This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM) and the standard Brute Force Method (BFM) in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with NOx emission reductions and decrease linearly with VOC emission reductions only up to 30% from the

  1. Neurodevelopmental Deceleration by Urban Fine Particles from Different Emission Sources: A Longitudinal Observational Study

    PubMed Central

    Basagaña, Xavier; Esnaola, Mikel; Rivas, Ioar; Amato, Fulvio; Alvarez-Pedrerol, Mar; Forns, Joan; López-Vicente, Mònica; Pujol, Jesús; Nieuwenhuijsen, Mark; Querol, Xavier; Sunyer, Jordi

    2016-01-01

    Background: A few studies have reported associations between traffic-related air pollution exposure at schools and cognitive development. The role of PM components or sources other than traffic on cognitive development has been little explored. Objectives: We aimed to explore the role of PM sources in school air on cognitive development. Methods: A cohort of 2,618 schoolchildren (average age, 8.5 years) belonging to 39 schools in Barcelona (Spain) was followed up for a year. Children completed computerized tests assessing working memory, superior working memory, and inattentiveness during four visits. Particulate matter ≤ 2.5 μm (PM2.5) was measured during two 1-week campaigns in each school, both outdoors and in the classroom. Source apportionment resulted in nine sources: mineral, organic/textile/chalk, traffic, secondary sulfate and organics, secondary nitrate, road dust, metallurgy, sea spray, and heavy oil combustion. Differences in cognitive growth trajectories were assessed with mixed models with age-by-source interaction terms. Results: An interquartile range increase in indoor traffic-related PM2.5 was associated with reductions in cognitive growth equivalent to 22% (95% CI: 2%, 42%) of the annual change in working memory, 30% (95% CI: 6%, 54%) of the annual change in superior working memory, and 11% (95% CI: 0%, 22%) of the annual change in the inattentiveness scale. None of the other PM2.5 sources was associated with adverse effects on cognitive development. Conclusions: Traffic was the only source of fine particles associated with a reduction in cognitive development. Reducing air pollution from traffic at primary schools may result in beneficial effects on cognition. Citation: Basagaña X, Esnaola M, Rivas I, Amato F, Alvarez-Pedrerol M, Forns J, López-Vicente M, Pujol J, Nieuwenhuijsen M, Querol X, Sunyer J. 2016. Neurodevelopmental deceleration by urban fine particles from different emission sources: a longitudinal observational study. Environ

  2. VLA observations of a complete sample of extragalactic X-ray sources. II

    NASA Technical Reports Server (NTRS)

    Schild, R.; Zamorani, G.; Gioia, I. M.; Feigelson, E. D.; Maccacaro, T.

    1983-01-01

    A complete sample of 35 X-ray selected sources found with the Einstein Observatory has been observed with the Very Large Array at 6 cm to investigate the relationship between radio and X-ray emission in extragalactic objects. Detections include three active galactic nuclei (AGNs), two clusters or groups of galaxies, two individual galaxies, and two BL Lac objects. The frequency of radio emission in X-ray selected AGNs is compared with that of optically selected quasars using the integral radio-optical luminosity function. The result suggests that the probability for X-ray selected quasars to be radio sources is higher than for those optically selected. No obvious correlation is found in the sample between the richness of X-ray luminosity of the cluster and the presence of a galaxy with radio luminosity at 5 GHz larger than 10 to the 30th ergs/s/Hz.

  3. 2 Millimeter Observations of Bright-rimmed Clouds with IRAS Point Sources

    NASA Astrophysics Data System (ADS)

    Sugitani, K.; Matsuo, H.; Nakano, M.; Tamura, M.; Ogura, K.

    2000-01-01

    We have made 2 mm continuum observations of 15 bright-rimmed clouds (BRCs) associated with IRAS point sources and S140 with the Nobeyama Bolometer Array (NOBA) mounted on the 45 m telescope of Nobeyama Radio Observatory. Continuum emission was detected in five BRCs and in S140. These five BRCs are known to be associated with near-infrared YSO clusters, mostly on the side facing toward the exciting star(s) and, therefore, are likely the sites of small-scale sequential star formation. The detected emission peaks of these five sources correspond to the IRAS positions within the positional errors, and the IRAS sources are considered to be protostars (Class 0/I-like sources) that were formed most recently in the BRCs. Four of them are clearly extended more than the telescope beam, suggesting the presence of circumstellar structures. The circumstellar masses derived from the 2 mm continuum are ~5-90 Msolar, which are more massive than those of the nearby Class 0/I objects (<~1 Msolar). This fact and the relatively large bolometric luminosities of these objects suggest that the mass of the cluster or star(s) most recently formed in these BRCs could be higher than those of the previously formed stars found in the near-infrared cluster. The comparisons with previous observations of Bok globules unassociated with bright rims and other objects are discussed. Most noteworthy is that the ratios of the bolometric luminosity to the circumstellar mass are significantly higher for these BRCs than for Bok globules.

  4. CHANDRA OBSERVATION OF THE TeV SOURCE HESS J1834-087

    SciTech Connect

    Misanovic, Zdenka; Kargaltsev, Oleg; Pavlov, George G. E-mail: oyk100@astro.ufl.edu

    2011-07-01

    Chandra ACIS observed the field of the extended TeV source HESS J1834-087 for 47 ks. A previous XMM-Newton EPIC observation of the same field revealed a point-like source (XMMU J183435.3-084443) and an offset region of faint extended emission. In the low-resolution, binned EPIC images the two appear to be connected. However, the high-resolution Chandra ACIS images do not support the alleged connection. In these images, XMMU J183435.3-084443 is resolved into a point source, CXOU J183434.9-084443 (L{sub 0.5-8keV} {approx_equal} 2.3 x 10{sup 33} erg s{sup -1}, for a distance of 4 kpc; photon index {Gamma} {approx_equal} 1.1), and a compact ({approx}< 20'') nebula with an isotropic morphology and a softer spectrum (L{sub 0.5-8keV} {approx_equal} 4.1 x 10{sup 33} erg s{sup -1}, {Gamma} {approx_equal} 2.7). The nature of the nebula is uncertain. We discuss a dust scattering halo and a pulsar-wind nebula as possible interpretations. Based on our analysis of the X-ray data, we re-evaluate the previously suggested interpretations of HESS J1834-087 and discuss a possible connection to the Fermi Large Area Telescope source 1FGL J1834.3-0842c. We also obtained an upper limit of 3 x 10{sup -14} erg cm{sup -2} s{sup -1} on the unabsorbed flux of the SGR J1833-0832 (in quiescence), which happened to be in the ACIS field of view.

  5. Gamma-ray observations of Ophiuchus with EGRET: The diffuse emission and point sources

    NASA Technical Reports Server (NTRS)

    Hunter, S. D.; Digel, S. W.; De Geus, E. J.; Kanbach, G.

    1994-01-01

    Observations of the Ophiuchus region made with the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) during the first 2 1/2 years of operation show the diffuse emission from the interstellar gas in Ophiuchus as well as variable emission from two point sources. The gamma-ray emission is modeled in terms of cosmic-ray interactions with atomic and molecular hydrogen in Ophiuchus and with low-energy photons along the line of sight. The model also includes the flux from the two point sources and an isotropic diffuse contribution. The cosmic-ray density is assumed to be uniform. The derived ratio of molecular hydrogen column density to integrated CO intensity is (1.1 +/- 0.2) x 10(exp 20) H-mols/sq cm (K km/s)(exp -1). At the sensitivity and resolution of the gamma-ray data, no variation of this ratio over the modeled region is discernible, nor are any regions of enhanced cosmic-ray density apparent. The model was fitted to seven narrow energy bands to obtain the energy depedence of the gamma-ray production function and the spectra of the point sources. The derived production function is in good agreement with theoretical calculations and the local cosmic-ray electron and proton spectra. The positions of the point sources were determined from maximum likelihood analysis of the gamma-ray emission observed in excess of the diffuse model. We identify one point source with the quasar PKS 1622-253, which has an average flux, E greater than 100 MeV, of (2.5 +/- 0.5) x 10(exp -7) photons/sq cm/s and photon spectral index -1.9 +/- 0.3. The other source, denoted GRO J1631-27, has not yet been identified at other wavelengths. Its average flux, E greater than 100 MeV, is (1.1 +/- 0.4) x 10(exp -7) photons/sq cm/s; however, its spectral index is poorly determined. The spectral index and intensity of the isotropic contribution to the model agree well with the extragalactic diffuse emission derived from the SAS 2 data.

  6. Observational constraints on earthquake source scaling: Understanding the limits in resolution

    USGS Publications Warehouse

    Hough, S.E.

    1996-01-01

    I examine the resolution of the type of stress drop estimates that have been used to place observational constraints on the scaling of earthquake source processes. I first show that apparent stress and Brune stress drop are equivalent to within a constant given any source spectral decay between ??1.5 and ??3 (i.e., any plausible value) and so consistent scaling is expected for the two estimates. I then discuss the resolution and scaling of Brune stress drop estimates, in the context of empirical Green's function results from recent earthquake sequences, including the 1992 Joshua Tree, California, mainshock and its aftershocks. I show that no definitive scaling of stress drop with moment is revealed over the moment range 1019-1025; within this sequence, however, there is a tendency for moderate-sized (M 4-5) events to be characterized by high stress drops. However, well-resolved results for recent M > 6 events are inconsistent with any extrapolated stress increase with moment for the aftershocks. Focusing on comer frequency estimates for smaller (M < 3.5) events, I show that resolution is extremely limited even after empirical Green's function deconvolutions. A fundamental limitation to resolution is the paucity of good signal-to-noise at frequencies above 60 Hz, a limitation that will affect nearly all surficial recordings of ground motion in California and many other regions. Thus, while the best available observational results support a constant stress drop for moderate-to large-sized events, very little robust observational evidence exists to constrain the quantities that bear most critically on our understanding of source processes: stress drop values and stress drop scaling for small events.

  7. SEVEN-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE (WMAP ) OBSERVATIONS: PLANETS AND CELESTIAL CALIBRATION SOURCES

    SciTech Connect

    Weiland, J. L.; Odegard, N.; Hill, R. S.; Greason, M. R.; Wollack, E.; Hinshaw, G.; Kogut, A.; Bennett, C. L.; Gold, B.; Larson, D.; Dunkley, J.; Halpern, M.; Komatsu, E.; Limon, M.; Meyer, S. S.; Nolta, M. R.; Smith, K. M.; Spergel, D. N.

    2011-02-01

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1{sigma} of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% {+-} 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 {mu}m, reproduce WMAP seasonally averaged observations of Mars within {approx}2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at {approx}30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with uncertainties of a

  8. A discussion of observation model, error sources and signal size for spaceborne gravitational gradiometry

    NASA Technical Reports Server (NTRS)

    Rummel, R.; Koop, R.; Schrama, E. J. O.

    1989-01-01

    Various space concepts were discussed during the past 20 years for a global improvement of the knowledge of the earth's gravity field. The concepts reach from high-low and low-low satellite-to-satellite tracking via tethered satellite gradiometers to sophisticated superconducting gradiometers. The purpose is to show that starting from one basic equation three criteria are sufficient to typify the various concepts and define the underlying observation model. Furthermore the different error sources, in particular, the time varying part of self-gravitation, and the expected signal size of all six gravity gradient components shall be discussed.

  9. Seven-year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Planets and Celestial Calibration Sources

    NASA Astrophysics Data System (ADS)

    Weiland, J. L.; Odegard, N.; Hill, R. S.; Wollack, E.; Hinshaw, G.; Greason, M. R.; Jarosik, N.; Page, L.; Bennett, C. L.; Dunkley, J.; Gold, B.; Halpern, M.; Kogut, A.; Komatsu, E.; Larson, D.; Limon, M.; Meyer, S. S.; Nolta, M. R.; Smith, K. M.; Spergel, D. N.; Tucker, G. S.; Wright, E. L.

    2011-02-01

    We present WMAP seven-year observations of bright sources which are often used as calibrators at microwave frequencies. Ten objects are studied in five frequency bands (23-94 GHz): the outer planets (Mars, Jupiter, Saturn, Uranus, and Neptune) and five fixed celestial sources (Cas A, Tau A, Cyg A, 3C274, and 3C58). The seven-year analysis of Jupiter provides temperatures which are within 1σ of the previously published WMAP five-year values, with slightly tighter constraints on variability with orbital phase (0.2% ± 0.4%), and limits (but no detections) on linear polarization. Observed temperatures for both Mars and Saturn vary significantly with viewing geometry. Scaling factors are provided which, when multiplied by the Wright Mars thermal model predictions at 350 μm, reproduce WMAP seasonally averaged observations of Mars within ~2%. An empirical model is described which fits brightness variations of Saturn due to geometrical effects and can be used to predict the WMAP observations to within 3%. Seven-year mean temperatures for Uranus and Neptune are also tabulated. Uncertainties in Uranus temperatures are 3%-4% in the 41, 61, and 94 GHz bands; the smallest uncertainty for Neptune is 8% for the 94 GHz band. Intriguingly, the spectrum of Uranus appears to show a dip at ~30 GHz of unidentified origin, although the feature is not of high statistical significance. Flux densities for the five selected fixed celestial sources are derived from the seven-year WMAP sky maps and are tabulated for Stokes I, Q, and U, along with polarization fraction and position angle. Fractional uncertainties for the Stokes I fluxes are typically 1% to 3%. Source variability over the seven-year baseline is also estimated. Significant secular decrease is seen for Cas A and Tau A: our results are consistent with a frequency-independent decrease of about 0.53% per year for Cas A and 0.22% per year for Tau A. We present WMAP polarization data with uncertainties of a few percent for Tau A

  10. JPL 1990-3: A 5-nrad extragalactic source catalog based on combined radio interferometric observations

    NASA Technical Reports Server (NTRS)

    Sovers, O. J.

    1991-01-01

    A combined analysis merges 17,000 Deep Space Network (DSN) Very Long Baseline Interferometric (VLBI) observations with 303,000 observations from the Crustal Dynamics Project (CDP) and the International Radio Interferometric Surveying (IRIS) project. Observations from the Radio Reference Frame Development (RRFD) and Time and Earth Motion Precision Observations (TEMPO) programs through late 1990 form the DSN VLBI data set. The combined analysis yields angular coordinates of extragalactic radio sources with a precision of a few nanoradians, as compared with 5 to 10 nrad precision for coordinates derived in the past solely from DSN data. The improvement in the combined analysis is due to the new Mark III DSN data, as well as to increased statistical strength from the large volume of observations from non-DSN experiments. Such a unified analysis is made possible by recent improvements in parameter estimation software efficiency. The terrestrial reference frame is based on joint VLBI experiments using both DSN and CDP antennas, and on specifying the coordinates of VLBI antennas in a proper geocentric coordinate system by means of Global Positioning System (GPS) collocation of VLBI, LLR, and SLR (Laser Ranging) sites.

  11. ALMA OBSERVATIONS OF THE OUTFLOW FROM SOURCE I IN THE ORION-KL REGION

    SciTech Connect

    Zapata, Luis A.; Rodriguez, Luis F.; Loinard, Laurent; Schmid-Burgk, Johannes; Menten, Karl M.; Curiel, Salvador

    2012-07-20

    In this Letter, we present sensitive millimeter SiO (J = 5-4; {nu} = 0) line observations of the outflow arising from the enigmatic object Orion Source I made with the Atacama Large Millimeter/Submillimeter Array (ALMA). The observations reveal that at scales of a few thousand AU, the outflow has a marked 'butterfly' morphology along a northeast-southwest axis. However, contrary to what is found in the SiO and H{sub 2}O maser observations at scales of tens of AU, the blueshifted radial velocities of the moving gas are found to the northwest, while the redshifted velocities are in the southeast. The ALMA observations are complemented with SiO (J = 8-7; {nu} = 0) maps (with a similar spatial resolution) obtained with the Submillimeter Array. These observations also show a similar morphology and velocity structure in this outflow. We discuss some possibilities to explain these differences at small and large scales across the flow.

  12. Uhuru observations of 4U 1608-52 - The 'steady' X-ray source associated with the X-ray burst source in Norma

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.; Chaisson, L. J.; Forman, W.; Jones, C.; Matilsky, T. A.

    1976-01-01

    Data are presented for the X-ray source 4U 1608-52, summarizing its light curve, location, and spectral parameters. Evidence is presented showing that this source is the 'steady' X-ray counterpart of the X-ray burst source in Norma. The spectrum of the 'steady' source is compared with the spectrum observed during two bursts, and it is noted that there is substantially more low-energy absorption during the bursts. The 'steady' source spectral data are used to examine the optical data, and it is concluded that if the X-ray spectrum is thermal, then a globular-cluster counterpart probably would have been detected (whereas none has been). Further X-ray and optical observations are suggested for this source, since an optical identification may be central in determining whether all X-ray bursts have a common origin and if this origin requires a globular-cluster environment.

  13. Clumpy Langmuir waves in type III radio sources - Comparison of stochastic-growth theory with observations

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.; Cairns, I. H.; Gurnett, D. A.

    1993-01-01

    Detailed comparisons are made between the Langmuir-wave properties predicted by the recently developed stochastic-growth theory of type III sources and those observed by the plasma wave experiment on ISEE 3, after correcting for the main instrumental and selection effects. Analysis of the observed field-strength distribution confirms the theoretically predicted form and implies that wave growth fluctuates both spatially and temporally in sign and magnitude, leading to an extremely clumpy distribution of fields. A cutoff in the field-strength distribution is seen at a few mV/m, corresponding to saturation via nonlinear effects. Analysis of the size distribution of Langmuir clumps yields results in accord with those obtained in earlier work and with the size distribution of ambient density fluctuations in the solar wind. This confirms that the inhomogeneities in the Langmuir growth rate are determined by the density fluctuations and that these fluctuations persist during type III events.

  14. Sources of Tropospheric Ozone along the Asian Pacific Rim: An Analysis of Ozonesonde Observations

    NASA Technical Reports Server (NTRS)

    Liu, Hong-Yu; Jacob, Daniel J.; Chan, Lo Yin; Oltmans, Samuel J.; Bey, Isabelle; Yantosca, Robert M.; Harris, Joyce M.; Duncan, Bryan N.; Martin, Randall V.

    2002-01-01

    The sources contributing to tropospheric ozone over the Asian Pacific Rim in different seasons are quantified by analysis of Hong Kong and Japanese ozonesonde observations with a global three-dimensional (3-D) chemical transport model (GEOS-CHEM) driven by assimilated meteorological observations. Particular focus is placed on the extensive observations available from Hong Kong in 1996. In the middle-upper troposphere (MT- UT), maximum Asian pollution influence along the Pacific Rim occurs in summer, reflecting rapid convective transport of surface pollution. In the lower troposphere (LT) the season of maximum Asian pollution influence shifts to summer at midlatitudes from fall at low latitudes due to monsoonal influence. The UT ozone minimum and high variability observed over Hong Kong in winter reflects frequent tropical intrusions alternating with stratospheric intrusions. Asian biomass burning makes a major contribution to ozone at less than 32 deg.N in spring. Maximum European pollution influence (less than 5 ppbv) occurs in spring in the LT. North American pollution influence exceeds European influence in the UT-MT, reflecting the uplift from convection and the warm conveyor belts over the eastern seaboard of North America. African outflow makes a major contribution to ozone in the low-latitude MT-UT over the Pacific Rim during November- April. Lightning influence over the Pacific Rim is minimum in summer due to westward UT transport at low latitudes associated with the Tibetan anticyclone. The Asian outflow flux of ozone to the Pacific is maximum in spring and fall and includes a major contribution from Asian anthropogenic sources year-round.

  15. Observation of helicon wave with m = 0 antenna in a weakly magnetized inductively coupled plasma source

    NASA Astrophysics Data System (ADS)

    Ellingboe, Bert; Sirse, Nishant; Moloney, Rachel; McCarthy, John

    2015-09-01

    Bounded whistler wave, called ``helicon wave,'' is known to produce high-density plasmas and has been exploited as a high density plasma source for many applications, including electric propulsion for spacecraft. In a helicon plasma source, an antenna wrapped around the magnetized plasma column launches a low frequency wave, ωce/2 >ωhelicon >ωce/100, in the plasma which is responsible for maintaining high density plasma. Several antenna designs have been proposed in order to match efficiently the wave modes. In our experiment, helicon wave mode is observed using an m = 0 antenna. A floating B dot probe, compensated to the capacitively coupled E field, is employed to measure axial-wave-field-profiles (z, r, and θ components) in the plasma at multiple radial positions as a function of rf power and pressure. The Bθ component of the rf-field is observed to be unaffected as the wave propagates in the axial direction. Power coupling between the antenna and the plasma column is identified and agrees with the E, H, and wave coupling regimes previously seen in M =1 antenna systems. That is, the Bz component of the rf-field is observed at low plasma density as the Bz component from the antenna penetrates the plasma. The Bz component becomes very small at medium density due to shielding at the centre of the plasma column; however, with increasing density, a sudden ``jump'' occurs in the Bz component above which a standing wave under the antenna with a propagating wave away from the antenna are observed.

  16. Observation-based source terms in the third-generation wave model WAVEWATCH

    NASA Astrophysics Data System (ADS)

    Zieger, Stefan; Babanin, Alexander V.; Erick Rogers, W.; Young, Ian R.

    2015-12-01

    Measurements collected during the AUSWEX field campaign, at Lake George (Australia), resulted in new insights into the processes of wind wave interaction and whitecapping dissipation, and consequently new parameterizations of the input and dissipation source terms. The new nonlinear wind input term developed accounts for dependence of the growth on wave steepness, airflow separation, and for negative growth rate under adverse winds. The new dissipation terms feature the inherent breaking term, a cumulative dissipation term and a term due to production of turbulence by waves, which is particularly relevant for decaying seas and for swell. The latter is consistent with the observed decay rate of ocean swell. This paper describes these source terms implemented in WAVEWATCH III ®and evaluates the performance against existing source terms in academic duration-limited tests, against buoy measurements for windsea-dominated conditions, under conditions of extreme wind forcing (Hurricane Katrina), and against altimeter data in global hindcasts. Results show agreement by means of growth curves as well as integral and spectral parameters in the simulations and hindcast.

  17. An Optical Streak Diagnostic for Observing Anode-Cathode Plasmas for Radiographic Source Development

    SciTech Connect

    Droemer, Darryl W.; Crain, Marlon D.; Lare, Gregory A.; Bennett, Nichelle L.; Johnston, Mark D.

    2013-06-13

    National Security Technologies, LLC, and Sandia National Laboratories are collaborating in the development of pulsed power–driven flash x-ray radiographic sources that utilize high-intensity electron beam diodes. The RITS 6 (Radiographic Integrated Test Stand) accelerator at Sandia is used to drive a self magnetic pinch diode to produce a Bremsstrahlung x-ray source. The high electric fields and current densities associated with these short A-K gap pinch beam diodes present many challenges in diode development. Plasmas generated at both the anode and cathode affect the diode performance, which is manifested in varying spot (source) sizes, total dose output, and impedance profiles. Understanding the nature of these plasmas including closure rates and densities is important in modeling their behavior and providing insight into their mitigation. In this paper we describe a streak camera–based optical diagnostic that is capable of observing and measuring plasma evolution within the A-K gap. By imaging a region of interest onto the input slit of a streak camera, we are able to produce a time-resolved one-dimensional image of the evolving plasma. Typical data are presented.

  18. LENSED: a code for the forward reconstruction of lenses and sources from strong lensing observations

    NASA Astrophysics Data System (ADS)

    Tessore, Nicolas; Bellagamba, Fabio; Metcalf, R. Benton

    2016-09-01

    Robust modelling of strong lensing systems is fundamental to exploit the information they contain about the distribution of matter in galaxies and clusters. In this work, we present LENSED, a new code which performs forward parametric modelling of strong lenses. LENSED takes advantage of a massively parallel ray-tracing kernel to perform the necessary calculations on a modern graphics processing unit (GPU). This makes the precise rendering of the background lensed sources much faster, and allows the simultaneous optimisation of tens of parameters for the selected model. With a single run, the code is able to obtain the full posterior probability distribution for the lens light, the mass distribution and the background source at the same time. LENSED is first tested on mock images which reproduce realistic space-based observations of lensing systems. In this way, we show that it is able to recover unbiased estimates of the lens parameters, even when the sources do not follow exactly the assumed model. Then, we apply it to a subsample of the SLACS lenses, in order to demonstrate its use on real data. The results generally agree with the literature, and highlight the flexibility and robustness of the algorithm.

  19. LOFAR 150-MHz observations of the Boötes field: catalogue and source counts

    NASA Astrophysics Data System (ADS)

    Williams, W. L.; van Weeren, R. J.; Röttgering, H. J. A.; Best, P.; Dijkema, T. J.; de Gasperin, F.; Hardcastle, M. J.; Heald, G.; Prandoni, I.; Sabater, J.; Shimwell, T. W.; Tasse, C.; van Bemmel, I. M.; Brüggen, M.; Brunetti, G.; Conway, J. E.; Enßlin, T.; Engels, D.; Falcke, H.; Ferrari, C.; Haverkorn, M.; Jackson, N.; Jarvis, M. J.; Kapińska, A. D.; Mahony, E. K.; Miley, G. K.; Morabito, L. K.; Morganti, R.; Orrú, E.; Retana-Montenegro, E.; Sridhar, S. S.; Toribio, M. C.; White, G. J.; Wise, M. W.; Zwart, J. T. L.

    2016-08-01

    We present the first wide area (19 deg2), deep (≈120-150 μJy beam-1), high-resolution (5.6 × 7.4 arcsec) LOFAR High Band Antenna image of the Boötes field made at 130-169 MHz. This image is at least an order of magnitude deeper and 3-5 times higher in angular resolution than previously achieved for this field at low frequencies. The observations and data reduction, which includes full direction-dependent calibration, are described here. We present a radio source catalogue containing 6 276 sources detected over an area of 19 deg2, with a peak flux density threshold of 5σ. As the first thorough test of the facet calibration strategy, introduced by van Weeren et al., we investigate the flux and positional accuracy of the catalogue. We present differential source counts that reach an order of magnitude deeper in flux density than previously achieved at these low frequencies, and show flattening at 150-MHz flux densities below 10 mJy associated with the rise of the low flux density star-forming galaxies and radio-quiet AGN.

  20. X-ray follow-up observations of unidentified VHE {gamma}-ray sources

    SciTech Connect

    Puehlhofer, Gerd

    2008-12-24

    A large fraction of the recently discovered Galactic Very High Energy (VHE) source population remains unidentified to date. VHE {gamma}-ray emission traces high energy particles in these sources, but for example in case of hadronic processes also the gas density at the emission site. Moreover, the particles have sufficiently long lifetimes to be able to escape from their acceleration sites. Therefore, the {gamma}-ray sources or at least the areas of maximum surface brightness are in many cases spatially offset from the actual accelerators. A promising way to identify the objects in which the particles are accelerated seems to be to search for emission signatures of the acceleration process (like emission from shock-heated plasma). Also the particles themselves (through primary or secondary synchrotron emission) can be traced in lower wavebands. Those signatures are best visible in the X-ray band, and current X-ray observatories are well suited to conduct such follow-up observations. Some aspects of the current status of these investigations are reviewed.

  1. Tundra ecosystems observed to be CO2 sources due to differential amplification of the carbon cycle.

    PubMed

    Belshe, E F; Schuur, E A G; Bolker, B M

    2013-10-01

    Are tundra ecosystems currently a carbon source or sink? What is the future trajectory of tundra carbon fluxes in response to climate change? These questions are of global importance because of the vast quantities of organic carbon stored in permafrost soils. In this meta-analysis, we compile 40 years of CO2 flux observations from 54 studies spanning 32 sites across northern high latitudes. Using time-series analysis, we investigated if seasonal or annual CO2 fluxes have changed over time, and whether spatial differences in mean annual temperature could help explain temporal changes in CO2 flux. Growing season net CO2 uptake has definitely increased since the 1990s; the data also suggest (albeit less definitively) an increase in winter CO2 emissions, especially in the last decade. In spite of the uncertainty in the winter trend, we estimate that tundra sites were annual CO2 sources from the mid-1980s until the 2000s, and data from the last 7 years show that tundra continue to emit CO2 annually. CO2 emissions exceed CO2 uptake across the range of temperatures that occur in the tundra biome. Taken together, these data suggest that despite increases in growing season uptake, tundra ecosystems are currently CO2 sources on an annual basis.

  2. Infrared-excess Source DSO/G2 Near the Galactic Center: Theory vs. Observations

    NASA Astrophysics Data System (ADS)

    Zajacek, Michal; Eckart, Andreas; Peissker, Florian; Karssen, Grischa D.; Karas, Vladimir

    2015-12-01

    Based on the monitoring of the Dusty S-cluster Object (DSO/G2) during its closest approach to the Galactic Center supermassive black hole in 2014 and 2015 with ESO VLT/SINFONI, we further explore the model of a young, accreting star to explain observed spectral and morphological features. The stellar scenario is supported by our findings, i.e., ionized-hydrogen emission from the DSO that remains spatially compact before and after the peribothron passage. The detection of DSO/G2 object as a compact single-peak emission-line source is not consistent with the original hypothesis of a core-less cloud that is necessarily tidally stretched, hence producing a double-peak emission line profile around the pericentre passage. This strengthens the evidence that the DSO/G2 source is a dust-enshrouded young star that appears to be in an accretion phase. The infall of material from the circumstellar disc onto the stellar surface can contribute significantly to the emission of Brγ line as well as the observed large line width of the order of 10 angstrom.

  3. Nonlinear wave fronts and ionospheric irregularities observed by HF sounding over a powerful acoustic source

    SciTech Connect

    Blanc, E.; Rickel, D.; Los Alamos National Laboratory, NM )

    1989-06-01

    Different wave fronts affected by significant nonlinearities have been observed in the ionosphere by a pulsed HF sounding experiment at a distance of 38 km from the source point of a 4800-kg ammonium nitrate and fuel oil (ANFO) explosion on the ground. These wave fronts are revealed by partial reflections of the radio sounding waves. A small-scale irregular structure has been generated by a first wave front at the level of a sporadic E layer which characterized the ionosphere at the time of the experiment. The time scale of these fluctuations is about 1 to 2 s; its lifetime is about 2 min. Similar irregularities were also observed at the level of a second wave front in the F region. This structure appears also as diffusion on a continuous wave sounding at horizontal distances of the order of 200 km from the source. In contrast, a third front unaffected by irregularities may originate from the lowest layers of the ionosphere or from a supersonic wave front propagating at the base of the thermosphere. The origin of these structures is discussed. 14 refs.

  4. Nonlinear wave fronts and ionospheric irregularities observed by HF sounding over a powerful acoustic source

    NASA Astrophysics Data System (ADS)

    Blanc, Elisabeth; Rickel, Dwight

    1989-06-01

    Different wave fronts affected by significant nonlinearities have been observed in the ionosphere by a pulsed HF sounding experiment at a distance of 38 km from the source point of a 4800-kg ammonium nitrate and fuel oil (ANFO) explosion on the ground. These wave fronts are revealed by partial reflections of the radio sounding waves. A small-scale irregular structure has been generated by a first wave front at the level of a sporadic E layer which characterized the ionosphere at the time of the experiment. The time scale of these fluctuations is about 1 to 2 s; its lifetime is about 2 min. Similar irregularities were also observed at the level of a second wave front in the F region. This structure appears also as diffusion on a continuous wave sounding at horizontal distances of the order of 200 km from the source. In contrast, a third front unaffected by irregularities may originate from the lowest layers of the ionosphere or from a supersonic wave front propagating at the base of the thermosphere. The origin of these structures is discussed.

  5. Near Real-Time Determination of Earthquake Source Parameters for Tsunami Early Warning from Geodetic Observations

    NASA Astrophysics Data System (ADS)

    Manneela, Sunanda; Srinivasa Kumar, T.; Nayak, Shailesh R.

    2016-06-01

    Exemplifying the tsunami source immediately after an earthquake is the most critical component of tsunami early warning, as not every earthquake generates a tsunami. After a major under sea earthquake, it is very important to determine whether or not it has actually triggered the deadly wave. The near real-time observations from near field networks such as strong motion and Global Positioning System (GPS) allows rapid determination of fault geometry. Here we present a complete processing chain of Indian Tsunami Early Warning System (ITEWS), starting from acquisition of geodetic raw data, processing, inversion and simulating the situation as it would be at warning center during any major earthquake. We determine the earthquake moment magnitude and generate the centroid moment tensor solution using a novel approach which are the key elements for tsunami early warning. Though the well established seismic monitoring network, numerical modeling and dissemination system are currently capable to provide tsunami warnings to most of the countries in and around the Indian Ocean, the study highlights the critical role of geodetic observations in determination of tsunami source for high-quality forecasting.

  6. Constraining GRB as Source for UHE Cosmic Rays through Neutrino Observations

    NASA Astrophysics Data System (ADS)

    Chen, P.

    2013-07-01

    The origin of ultra-high energy cosmic rays (UHECR) has been widely regarded as one of the major questions in the frontiers of particle astrophysics. Gamma ray bursts (GRB), the most violent explosions in the universe second only to the Big Bang, have been a popular candidate site for UHECR productions. The recent IceCube report on the non-observation of GRB induced neutrinos therefore attracts wide attention. This dilemma requires a resolution: either the assumption of GRB as UHECR accelerator is to be abandoned or the expected GRB induced neutrino yield was wrong. It has been pointed out that IceCube has overestimated the neutrino flux at GRB site by a factor of ~5. In this paper we point out that, in addition to the issue of neutrino production at source, the neutrino oscillation and the possible neutrino decay during their flight from GRB to Earth should further reduce the detectability of IceCube, which is most sensitive to the muon-neutrino flavor as far as point-source identification is concerned. Specifically, neutrino oscillation will reduce the muon-neutrino flavor ratio from 2/3 per neutrino at GRB source to 1/3 on Earth, while neutrino decay, if exists and under the assumption of normal hierarchy of mass eigenstates, would result in a further reduction of muon-neutrino ratio to 1/8. With these in mind, we note that there have been efforts in recent years in pursuing other type of neutrino telescopes based on Askaryan effect, which can in principle observe and distinguish all three flavors with comparable sensitivities. Such new approach may therefore be complementary to IceCube in shedding more lights on this cosmic accelerator question.

  7. Detectability of electrostatic decay products in Ulysses and Galileo observations of type 3 solar radio sources

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.

    1995-01-01

    Recent in situ Ulysses and Galileo observations of the source regions of type 3 solar radio bursts appear to show an absence of ion acoustic waves S produced by nonlinear Langmuir wave processes such as the electrostatic (ES) decay, in contradiction with earlier ISEE 3 observations and analytic theory. This letter resolves these apparent contradictions. Refined analyses of the maximum S-wave electric fields produced by ES decay and of the characteristics of the Ulysses Wave Form Analyzer (WFA) instrument show that the bursty S waves observed by the ISEE 3 should be essentially undetectable by the Ulysses WFA. It is also shown that the maximum S-wave levels predicted for the Galileo event are approximately less than the instrumental noise level, thereby confirming an earlier suggestion. Thus, no contradictions exist between the ISEE 3 and Ulysses/Galileo observation, and no evidence exists against ES decay in the published Ulysses and Galileo data. All available data are consistent with, or at worst not inconsistent with, the ES decay proceeding and being the dominant nonlinear process in type 3 bursts.

  8. Near-source observations from single and multiple cylindrical explosions in a coal mine

    SciTech Connect

    Stump, B.W.; Pearson, D.C.; Yang, Xiaoning

    1994-06-01

    An experimental study of ground motion from explosions designed to remove overburden in an open pit coal mine is reported. The purpose of this study is a characterization of these ground motions in the distance range of several tens of meters to several kilometers. The investigation has focused upon both single cylindrical sources with different explosive configurations as well as arrays of charges in the production mode. Critical to this study of source configuration and coupling is experimental control of the individual explosions, the timing of the explosions and the geological properties. The height of the explosive I charges, their depth and charge distribution were monitored in the field. High speed photography as well as velocity of detonation measurements were made on the multiple explosion source so that detonation of individual charges could be documented. Different yields of both ANFO and Emulsion explosives were used. Two tests were detonated with an air column or deck directly above the explosive while the remaining six, single shots were backfilled with stemming and drill cuttings. The air decks were designed to investigate proposed enhanced motions from such configurations. Observations were made as close as 50 m and as far as 10 km. This range of measurements allows the coupling of the explosive energy into the body and surface wave component of motion to be quantified and characterized as a function of range. The location of these tests was an active coal mine and so there was the opportunity to recover near-source data from three normal production shots of the mine. These explosions range in total explosive size from 43,500 to 87,077 lbs.

  9. Distinct sources of injections in the polar cusp observed by Cluster

    NASA Astrophysics Data System (ADS)

    Escoubet, C. Philippe; Reme, Henri; Dunlop, Malcolm; Daly, Patrick; Laakso, Harri; Berchem, Jean; Richard, Robert; Taylor, Matthew; Trattner, Karlheinz; Grison, Benjamin; Dandouras, Iannis; Fazakerley, Andrew; Pitout, Frederic; Masson, Arnaud

    The main process that injects solar wind plasma into the polar cusp is now generally accepted to be magnetic reconnection. Depending on the IMF direction, this process takes place equatorward (for IMF southward), poleward (for IMF northward) or on the dusk or dawn sides (for IMF azimuthal) of the cusp. We report a Cluster crossing on 5 January 2002 near the exterior cusp on the southern dusk side. The IMF was mainly azimuthal (IMF-By around -5 nT), the solar wind speed lower than usual around 280 km/s and the density around 5 cm-3. The four Cluster spacecraft had an elongated configuration near the magnetopause. C4 was the first spacecraft to enter the cusp around 19:52:04 UT, followed by C2 at 19:52:35 UT, C1 at 19:54:24 UT and C3 at 20:13:15 UT. C4 and C1 observed two ion energy dispersions at 20:10 UT and 20:40 UT and C3 at 20:35 UT and 21:15 UT. Using the time of flight technique on the upgoing and downgoing ions in the dispersions, we obtain an altitude of the sources of these ions between 14 and 20 RE. Using Tsyganenko model, these sources are located on the dusk flank, past the terminator. The first injection by C3 is seen at approximately the same time as the 2nd injection on C1 but their sources at the magnetopause were separated by more than 10 RE. This would imply that two distinct sources were active at the same time on the dusk flank of the magnetosphere.

  10. Coastal Ocean Observing Network - Open Source Architecture for Data Management and Web-Based Data Services

    NASA Astrophysics Data System (ADS)

    Pattabhi Rama Rao, E.; Venkat Shesu, R.; Udaya Bhaskar, T. V. S.

    2012-07-01

    The observations from the oceans are the backbone for any kind of operational services, viz. potential fishing zone advisory services, ocean state forecast, storm surges, cyclones, monsoon variability, tsunami, etc. Though it is important to monitor open Ocean, it is equally important to acquire sufficient data in the coastal ocean through coastal ocean observing systems for re-analysis, analysis and forecast of coastal ocean by assimilating different ocean variables, especially sub-surface information; validation of remote sensing data, ocean and atmosphere model/analysis and to understand the processes related to air-sea interaction and ocean physics. Accurate information and forecast of the state of the coastal ocean at different time scales is vital for the wellbeing of the coastal population as well as for the socio-economic development of the country through shipping, offshore oil and energy etc. Considering the importance of ocean observations in terms of understanding our ocean environment and utilize them for operational oceanography, a large number of platforms were deployed in the Indian Ocean including coastal observatories, to acquire data on ocean variables in and around Indian Seas. The coastal observation network includes HF Radars, wave rider buoys, sea level gauges, etc. The surface meteorological and oceanographic data generated by these observing networks are being translated into ocean information services through analysis and modelling. Centralized data management system is a critical component in providing timely delivery of Ocean information and advisory services. In this paper, we describe about the development of open-source architecture for real-time data reception from the coastal observation network, processing, quality control, database generation and web-based data services that includes on-line data visualization and data downloads by various means.

  11. A review of tropical cyclone-generated storm surges: Global data sources, observations, and impacts

    NASA Astrophysics Data System (ADS)

    Needham, Hal F.; Keim, Barry D.; Sathiaraj, David

    2015-06-01

    Tropical cyclone-generated storm surges are among the world's most deadly and destructive natural hazards. This paper provides the first comprehensive global review of tropical storm surge data sources, observations, and impacts while archiving data in SURGEDAT, a global database. Available literature has provided data for more than 700 surge events since 1880, the majority of which are found in the western North Atlantic (WNA), followed by Australia/Oceania, the western North Pacific (WNP), and the northern Indian Ocean (NIO). The Bay of Bengal (BOB) in the NIO consistently observes the world's highest surges, as this subbasin averages five surges ≥5 m per decade and has observed credible storm tide levels reaching 13.7 m. The WNP observes the highest rate of low-magnitude surges, as the coast of China averages 54 surges ≥1 m per decade, and rates are likely higher in the Philippines. The U.S. Gulf Coast observes the second highest frequency of both high-magnitude (≥5 m) and low-magnitude (≥1 m) surges. The BOB observes the most catastrophic surge impacts, as 59% of global tropical cyclones that have killed at least 5000 people occurred in this basin. The six deadliest cyclones in this region have each killed at least 140,000 people, and two events have killed 300,000. Storm surge impacts transportation, agriculture, and energy sectors in the WNA. Oceania experiences long-term impacts, including contamination of fresh water and loss of food supplies, although the highest surges in this region are lower than most other basins.

  12. Apices of maxillary premolars observed by swept source optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ebihara, Arata; Iino, Yoshiko; Yoshioka, Toshihiko; Hanada, Takahiro; Sunakawa, Mitsuhiro; Sumi, Yasunori; Suda, Hideaki

    2015-02-01

    Apicoectomy is performed for the management of apical periodontitis when orthograde root canal treatment is not possible or is ineffective. Prior to the surgery, cone beam computed tomography (CBCT) examination is often performed to evaluate the lesion and the adjacent tissues. During the surgical procedure, the root apex is resected and the resected surface is usually observed under dental operating microscope (DOM). However, it is difficult to evaluate the details and the subsurface structure of the root using CBCT and DOM. A new diagnostic system, swept source optical coherence tomography (SS-OCT), has been developed to observe the subsurface anatomical structure. The aim of this study was to observe resected apical root canals of human maxillary premolars using SS-OCT and compare the findings with those observed using CBCT and DOM. Six extracted human maxillary premolars were used. After microfocus computed tomography (Micro CT; for gold standard) and CBCT scanning of the root, 1 mm of the apex was cut perpendicular to the long axis of the tooth. Each resected surface was treated with EDTA, irrigated with saline solution, and stained with methylene blue dye. The resected surface was observed with DOM and SS-OCT. This sequence was repeated three times. The number of root canals was counted and statistically evaluated. There was no significant difference in the accuracy of detecting root canals among CBCT, DOM and SS-OCT (p > 0.05, Wilcoxon test). Because SS-OCT can be used in real time during surgery, it would be a useful tool for observing resected apical root canals.

  13. ASCA Observations of "Type 2" LINERs Evidence for a Stellar Source of Ionization

    NASA Technical Reports Server (NTRS)

    Terashima, Yuichi; Ho, Luis C.; Ptak, Andrew F.; Mushotzky, Richard F.; Serlemitsos, Peter J.; Yaqoob, Tahir; Kunieda, Hideyo

    1999-01-01

    We present ASCA observations of LINERs without broad H.alpha emission in their optical spectra. The sample of "type 2" LINERs consists of NGC 404, 4111, 4192, 4457, and 4569. We have detected X-ray emission from all the objects except for NGC 404; among the detected objects are two so-called transition objects (NGC 4192 and NGC 4569), which have been postulated to be composite nuclei having both an H II region and a LINER component. The images of NGC 4111 and NGC 4569 in the soft (0.5-2 keV) and hard (2-7 keV) X-ray bands are extended on scales of several kpc. The X-ray spectra of NGC 4111, NGC 4457 and NGC 4569 are well fitted by a two-component model that consists of soft thermal emission with kT approximately 0.65 keV and a hard component represented by a power law (photon index approximately 2) or by thermal bremsstrahlung emission (kT approximately several keV). The extended hard X-rays probably come from discrete sources, while the soft emission most likely originates from hot gas produced by active star formation in the host galaxy. We have found no clear evidence for the presence of active galactic nuclei (AGNs) in the sample. Using black hole masses estimated from host galaxy bulge luminosities, we obtain an upper limit on the implied Eddington ratios less than 5 x 10(exp -5). If an AGN component is the primary ionization source of the optical emission lines, then it must be heavily obscured with a column density significantly larger than 10(exp 23)/sq cm, since the observed X-ray luminosity is insufficient to drive the luminosities of the optical emission lines. Alternatively, the optical emission could be ionized by a population of exceptionally hot stars. This interpretation is consistent with the small [O I] lambda6300/H.alpha ratios observed in these sources, the ultraviolet spectral characteristics in the cases where such information exists, and the X-ray results reported here. We also analyze the X-ray properties of NGC 4117, a low

  14. 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