Analysis of Signals from an Unique Ground-Truth Infrasound Source Observed at IMS Station IS26 in Southern Germany
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Quantitative modeling of infrasound signals and development and verification of the corresponding atmospheric propagation models requires the use of well-calibrated sources. Numerous sources have been detected by the currently installed network of about 40 of the final 60 IMS infrasound stations. Besides non-nuclear explosions such as mining and quarry blasts and atmospheric phenomena like auroras, these sources include meteorites, volcanic eruptions and supersonic aircraft including re-entering spacecraft and rocket launches. All these sources of infrasound have one feature in common, in that their source parameters are not precisely known and the quantitative interpretation of the corresponding signals is therefore somewhat ambiguous. A source considered well-calibrated has been identified producing repeated infrasound signals at the IMS infrasound station IS26 in the Bavarian forest. The source results from propulsion tests of the ARIANE-5 rocket’s main engine at a testing facility near Heilbronn, southern Germany. The test facility is at a range of 320 km and a backazimuth of ~280° from IS26. Ground-truth information was obtained for nearly 100 tests conducted in a 5-year period. Review of the available data for IS26 revealed that at least 28 of these tests show signals above the background noise level. These signals are verified based on the consistency of various signal parameters, e.g., arrival times, durations, and estimates of propagation characteristics (backazimuth, apparent velocity). Signal levels observed are a factor of 2–8 above the noise and reach values of up to 250 mPa for peak amplitudes, and a factor of 2–3 less for RMS measurements. Furthermore, only tests conducted during the months from October to April produce observable signals, indicating a significant change in infrasound propagation conditions between summer and winter months.
KeywordsInfrasound atmospheric propagation sound source ground-truth explosion monitoring
This research was triggered by a family visit and an embedded coffee afternoon. Only by a factual report fortuitously received from my sister D. Sahm was this study initiated. I am deeply indebted to the Institute for Propulsion Studies of DLR (German Aerospace Agency) at Lampoldshausen for providing me with ground-truth information of the ARIANE-5 engine tests for the years 2000–2004. In particular, I gratefully acknowledge the support by Prof. W. Koschel and Dipl.-Ing. R. Hupertz through stimulating discussions and a guided tour to the testing facility. The data used for this study are openly available from the Federal Institute for Geosciences and Natural Resources (Bundesanstalt für Geowissenschaften und Rohstoffe-BGR, Hannover) by AutoDRM.
- Brown, D.J., Katz, C.N., LeBras, R., Flanagan, M.P., Wang, J., and Gault, A.K. (2002), Infrasonic signal detection and source location at the Prototype International Data Centre, Pure Appl. Geophys. 159, 1081–1125.Google Scholar
- Campus, P. (2004), The IMS infrasound network and its potential for detecting events: Examples of a variety of signals recorded around the World, Inframatics Newsletter 06(Jun), 13–22 (http://www.inframatics.org/newsletter.html).
- DLR (2004), http://www.la.dlr.de/ra/.
- Donn, J.W. and Ewing, M. (1962), Atmospheric waves from nuclear explosions, J. Geophys. Res. 67, 1855–1866.Google Scholar
- Donn, J.W. and Rind, D. (1971), Natural infrasound as atmospheric probe, Geophys. J. R. astr. Soc. 26, 111–133.Google Scholar
- Donn, J.W. and Shaw, D.M. (1967), Exploring the atmosphere with nuclear explosions, Rev. Geophys. 5, 53–82.Google Scholar
- Drob, D. P., Picone, J. M., and Garcés, M. A. (2003), The global morphology of infrasound propagation, J. Geophys. Res. 108(D21), 4680, doi: 10.1029/2002JD003307.
- Garces, M.A, Hansen, R.A., and Lindquist, K.G. (1998), Traveltimes for infrasonic waves propagating in a stratified atmosphere, Geophys. J. Int. 135, 255–263.Google Scholar
- Koch, K. (2005), Data analysis of infrasound recordings at IS26 from ARIANE-5 engine tests (abstract), 65th Annual Meeting of the German Geophysical Society, Graz, Austria, 21–25 February, 2005.Google Scholar
- Le Pichon, A. and Cansi, Y. (2003), PMCC for infrasound data processing, Inframatics Newsletter 02(Jun), 1–9 (http://www.inframatics.org/newsletter.html).
- Le Pichon, A. and Drob, D.P. (2004), Probing high-altitude winds using infrasound from volcanoes, Inframatics Newsletter 08(Dec), 1–17 (http://www.inframatics.org/newsletter.html).
- Le Pichon, A., Vergoz, J., Herry, P., and Ceranna, L. (2008), Analyzing the detection capability of infrasound arrays in Central Europe, J. Geophys. Res. 113, D12115, doi: 10.1029/2007JD009509.
- Liszka, L. (1974), Long-distance propagation of infrasound from artificial sources, J. Acoust. Soc. Am. 56, 1383–1388.Google Scholar
- Pierce, A.D. and Posey, J.W. (1971), Theory of the excitation and propagation of Lamb’s atmospheric edge mode from nuclear explosions, Geophys. J. R. astr. Soc. 26, 341–368.Google Scholar
- Quaschning, V. (2000), Systemtechnik einer klimaverträglichen Elektrizitätsversorgung in Deutschland für das 21. Jahrhundert, Fortschr.-Ber. VDI Reihe 6 437, Düsseldorf, VDI Verlag.Google Scholar
- Stammler, K. (1993), SeismicHandler—Programmable multichannel data handler for interactive and automatic processing of seismological analyses, Computers and Geosci. 19, 135–140.Google Scholar
- Wexler, H. and Hass, W.A. (1962), Global atmospheric pressure effects of the October 30, 1961 explosion, J. Geophys. Res. 67, 3875–3887.Google Scholar