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  • 1
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    Comparison of co-located independent ground-based middle-atmospheric wind and temperature measurements with Numerical Weather Prediction models (2015)
    Wiley
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    Publication Date: 2015-07-25
    Description: High-resolution, ground-based and independent observations including co-located wind radiometer, lidar stations, and infrasound instruments are used to evaluate the accuracy of general circulation models and data constrained assimilation systems in the middle atmosphere at northern hemisphere mid-latitudes. Systematic comparisons between observations, the Medium-Range Weather Forecasts (ECMWF) operational analyses including the recent Integrated Forecast System (IFS) cycles 38r1 and 38r2, the NASA's Modern Era Retrospective analysis for Research and Applications (MERRA) re-analyses and the free running climate Max Planck Institute Earth System Model (MPI-ESM-LR) are carried out in both temporal and spectral domains. We find that ECMWF and MERRA are broadly consistent with lidar and wind radiometer measurements up to ~40 km. For both temperature and horizontal wind components, deviations increase with altitude as the assimilated observations become sparser. Between 40 and 60 km altitude, the standard deviation of the mean difference exceeds 5 K for the temperature and 20 m/s for the zonal wind. The largest deviations are observed in winter when the variability from large-scale planetary waves dominates. Between lidar data and MPI-ESM-LR, there is an overall agreement in spectral amplitude down to 15-20 days. At shorter time-scales, the variability is lacking in the model by ~10 dB. Infrasound observations indicate a general good agreement with ECWMF wind and temperature products. As such, this study demonstrates the potential of the infrastructure of the Atmospheric Dynamics Research Infrastructure in Europe project (ARISE) that integrates various measurements and provides a quantitative understanding of stratosphere-troposphere dynamical coupling for numerical weather prediction applications.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
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    Geophysical investigation across the Peel boundary fault (The Netherlands) for a paleoseismological study (2001)
    In:  Netherlands Journal of Geosciences / Geologie en Mijnbouw, London, Army Corps of Engineers, Woodward-Clyde Consultants, vol. 80, no. 3-4, pp. 119-127, pp. L18607, (ISBN: 0-12-018847-3)
    Details
    Publication Date: 2001
    Keywords: Earthquake hazard ; paleo ; Seismicity ; Fault zone ; Belgium ; The ; Netherlands ; Germany ; Refraction seismics ; Reflection seismics ; GPR ; Geoelectrics ; Electromagnetic methods/phenomena ; Tomography ; paleoseismology, ; Roer ; graben, ; geophysical ; prospecting
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    On the infrasound detected from the 2013 and 2016 DPRK's underground nuclear tests (2016)
    Wiley
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    Publication Date: 2016-03-23
    Description: 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 shows 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.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
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    Evanescent wave coupling in a geophysical system: Airborne acoustic signals from the Mw 8.1 Macquarie Ridge earthquake (2014)
    Wiley
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    Publication Date: 2014-01-15
    Description: [1]  Atmospheric low frequency sound, i.e., infrasound, from underwater events has not been considered thus far, due to the high impedance contrast of the water-air interface making it almost fully reflective. Here, we report for the first time on atmospheric infrasound from a large underwater earthquake (Mw 8.1) near the Macquarie Ridge, which was recorded at 1,325 km from the epicenter. Seismic waves coupled to hydro-acoustic waves at the ocean floor, after which the energy entered the SOund Fixing And Ranging (SOFAR) channel and was detected on a hydrophone array. The energy was diffracted by a sea mount and an oceanic ridge, which acted as a secondary source, into the water column followed by coupling into the atmosphere. The latter results from evanescent wave coupling and the attendant anomalous transparency of the sea surface for very low frequency acoustic waves.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
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  • 5
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    Bi-directional Infrasonic Ducts Associated with Sudden Stratospheric Warming Events (2014)
    Wiley
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    Publication Date: 2014-01-11
    Description: [1]  In January 2011, the state of the polar vortex in the midlatitudes changed significantly due to a minor Sudden Stratospheric Warming event. As a result, a bi-directional duct for infrasound propagation developed in the middle atmosphere that persistedfor two weeks. The ducts were due to two zonal wind jets, one between 30-50 km and the other around 70 km altitude. In this paper, using microbarom source modeling, a previously unidentified source region in the eastern Mediterranean is identified,besides the more well known microbarom source regions in the Atlantic Ocean. Infrasound data is then presented in which the above mentioned bi-directional duct is observed in microbarom signals recorded at the IMS station I48TN in Tunisia from the Mediterranean region to the east and from the Atlantic Ocean to the west. While the frequency bands of the two sources overlap, the Mediterranean signal is coherent up to about 0.6 Hz. This observation is consistent with the microbarom source modeling; the discrepancy in the frequency band is related to differences in the ocean wave spectra for the two basins considered. This work demonstrates the sensitivity of infrasound to stratospheric dynamics and illustrates that the classic paradigm of a unidirectional stratospheric duct for infrasound propagation can be broken during a Sudden Stratospheric Warming event.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
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  • 6
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    Anomalous infrasound propagation in a hot stratosphere and the existence of extremely small shadow zones (2012)
    Wiley
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    Publication Date: 2012-03-31
    Description: Long-range infrasound propagation strongly depends on the state of the stratosphere. Infrasound can be efficiently ducted between the Earth's surface and the stratopause under a favorable wind and temperature structure between 40 and 50 km altitude. Understanding infrasound propagation under variable stratospheric conditions is of importance for a successful verification of the Comprehensive Nuclear-Test Ban Treaty, in which infrasound is used as a verification technique. Inversely, infrasound observations can be used in acoustic remote sensing of the upper atmosphere. In previous studies, attention has been paid to the strength and direction of the circumpolar vortex wind. In this study, an analysis is made of the temperature effect in the stratosphere on infrasound propagation. A case study is presented from an explosion during a sudden stratospheric warming. During such conditions, the size of the classical stratospheric shadow zone (∼200 km) appeared to be reduced by a factor of 2. The occurrence of such conditions is quantified by evaluating 10 years of atmospheric specifications. It unexpectedly appeared that the size of the shadow zone can become smaller than 100 km, which is confirmed by evaluating infrasound detections from mining blasts in southwestern Siberia, Russia. These results are valid over a latitudinal range of 20°N to 60°N, which is determined by the stratospheric surf zone.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
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  • 7
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    The Life Cycle of a Sudden Stratospheric Warming from Infrasonic Ambient Noise Observations (2014)
    Wiley
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    Publication Date: 2014-10-18
    Description: A method is presented to study the life cycle of a SSW using infrasonic ambient noise observations. The potential of infrasound is shown to provide the missing observations required by numerical weather prediction to better resolve the upper atmosphere. The 2009 major SSW is re-analyzed using the Evers and Siegmund (2009) dataset. Microbarom observations are evaluated to identify detections that cannot be explained by the analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF). Identified differences can be related to either the altitude limit of the analysis, not resolving thermospheric ducts, or to an actual error in the analysis. Therefore, a first-order model is used to relate observations with the analysis, existing of the Waxler et al. (2007) microbarom source model, including bathymetry to allow column resonances, and an atmospheric propagation model using 3-D ray tracing. Daily normalized spectral powers are proposed to distinguish stratospheric from thermospheric return height, based on the different signature of solar tidal amplitude fluctuations. It is shown, that a SSW is not a smooth event as following from the analysis, but a series of abrupt changes with a period of 10 to 16 days, increasing in intensity and duration. This is in agreement with the wave period of Rossby waves, interacting with the stratospheric circumpolar vortex. The type of vortex disturbance, split or reversal, can be deduced from the combined effect of the change in back-azimuth direction, solar tidal signature type and or phase variation of the amplitude variation of the observed microbaroms.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
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  • 8
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    Infrasonic interferometry applied to microbaroms observed at the Large Aperture Infrasound Array in the Netherlands (2014)
    Wiley
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    Publication Date: 2014-08-05
    Description: We present the results of infrasonic interferometry applied to microbaroms, obtained from ambient noise. For this purpose the ’Large Aperture Infrasound Array’ (LAIA) was used, which has been installed in the Netherlands. Pre-processing appeared to be an essential step in enhancing the microbarom signals from ambient noise that strongly influences the results of the interferometry. Both the state of the atmosphere and the noise characteristics are taken into account to assess the strength of the cross correlation. The delay time of the microbaroms between two stations is determined through cross correlating the recordings. By calculating the cross correlations between all 55 station pairs of LAIA we are able to find the delay time of microbaroms up to a inter-station distance of 40.6 km. Using the strength of the cross correlations we are able to show that the coherence of the microbaroms along the direction of arrival is higher than orthogonal to it. A comparison of the atmospheric state, with a cross correlation, over a period of 10 days, reveals that the infrasound propagation over the array is correlated with the tropospheric temperature and wind. Based on the cross correlations between the three closest stations, we are able to passively estimate the effective sound speed and the wind speed as a function of time.
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    Topics: Geosciences , Physics
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  • 9
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    Chelyabinsk airburst, damage assessment, meteorite recovery, and characterization (2013)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2013-11-10
    Description: The asteroid impact near the Russian city of Chelyabinsk on 15 February 2013 was the largest airburst on Earth since the 1908 Tunguska event, causing a natural disaster in an area with a population exceeding one million. Because it occurred in an era with modern consumer electronics, field sensors, and laboratory techniques, unprecedented measurements were made of the impact event and the meteoroid that caused it. Here, we document the account of what happened, as understood now, using comprehensive data obtained from astronomy, planetary science, geophysics, meteorology, meteoritics, and cosmochemistry and from social science surveys. A good understanding of the Chelyabinsk incident provides an opportunity to calibrate the event, with implications for the study of near-Earth objects and developing hazard mitigation strategies for planetary protection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Popova, Olga P -- Jenniskens, Peter -- Emel'yanenko, Vacheslav -- Kartashova, Anna -- Biryukov, Eugeny -- Khaibrakhmanov, Sergey -- Shuvalov, Valery -- Rybnov, Yurij -- Dudorov, Alexandr -- Grokhovsky, Victor I -- Badyukov, Dmitry D -- Yin, Qing-Zhu -- Gural, Peter S -- Albers, Jim -- Granvik, Mikael -- Evers, Laslo G -- Kuiper, Jacob -- Kharlamov, Vladimir -- Solovyov, Andrey -- Rusakov, Yuri S -- Korotkiy, Stanislav -- Serdyuk, Ilya -- Korochantsev, Alexander V -- Larionov, Michail Yu -- Glazachev, Dmitry -- Mayer, Alexander E -- Gisler, Galen -- Gladkovsky, Sergei V -- Wimpenny, Josh -- Sanborn, Matthew E -- Yamakawa, Akane -- Verosub, Kenneth L -- Rowland, Douglas J -- Roeske, Sarah -- Botto, Nicholas W -- Friedrich, Jon M -- Zolensky, Michael E -- Le, Loan -- Ross, Daniel -- Ziegler, Karen -- Nakamura, Tomoki -- Ahn, Insu -- Lee, Jong Ik -- Zhou, Qin -- Li, Xian-Hua -- Li, Qiu-Li -- Liu, Yu -- Tang, Guo-Qiang -- Hiroi, Takahiro -- Sears, Derek -- Weinstein, Ilya A -- Vokhmintsev, Alexander S -- Ishchenko, Alexei V -- Schmitt-Kopplin, Phillipe -- Hertkorn, Norbert -- Nagao, Keisuke -- Haba, Makiko K -- Komatsu, Mutsumi -- Mikouchi, Takashi -- Chelyabinsk Airburst Consortium -- New York, N.Y. -- Science. 2013 Nov 29;342(6162):1069-73. doi: 10.1126/science.1242642. Epub 2013 Nov 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute for Dynamics of Geospheres of the Russian Academy of Sciences, Leninsky Prospect 38, Building 1, Moscow, 119334, Russia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24200813" target="_blank"〉PubMed〈/a〉
    Keywords: *Accidents ; *Air ; *Explosions ; *Meteoroids ; Russia
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 10
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    ECMWF SSW forecast evaluation using infrasound (2016)
    Wiley
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    Publication Date: 2016-04-23
    Description: Accurate prediction of Sudden Stratospheric Warming (SSW) events is important for the performance of numerical weather prediction due to significant stratosphere–troposphere coupling. In this study, for the first time middle atmospheric numerical weather forecasts are evaluated using infrasound. A year of near continuous infrasound from the volcano Mt. Tolbachik (Kamchatka, Russian Federation) is compared with simulations using high resolution deterministic forecasts of the European Centre for Medium-range Weather Forecasts (ECMWF). For the entire timespan the nowcast generally performs best, indicated by a higher continuity of the predicted wavefront characteristics with a minimal back azimuth difference. Best performance for all forecasts is obtained in summer. The difference between the infrasound observations and the predictions based on the forecasts is significantly larger during the 2013 SSW period for all forecasts. Simulations show that the SSW onset is better captured by the ten day forecast while the recovery is better captured by the nowcast.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
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