Mesopause temperature perturbations caused by infrasonic waves as a potential indicator for the detection of tsunamis and other geo-hazards

摘要

Many geo-hazards such as earthquakes, tsunamis,\udvolcanic eruptions, severe weather, etc., produce acoustic\udwaves with sub-audible frequency, so called infrasound. This\udsound propagates from the surface to the middle and upper\udatmosphere causing pressure and temperature perturbations.\udTemperature fluctuations connected with the above\udmentioned events usually are very weak at the surface, but the amplitude increases with height because of the exponential\uddecrease of atmospheric pressure with increasing altitude. At\udthe mesopause region (80–100 km height) signal amplitudes\udare about two to three orders of magnitude larger than on the\udground.\ud\udThe GRIPS (GRound-based Infrared P-branch Spectrometer)\udmeasurement system operated by the German Remote\udSensing Data Center of the German Aerospace Center (DLRDFD) derives temperatures of the mesopause region by observing hydroxyl (OH) airglow emissions in the near infrared atmospheric emission spectrum originating from a thin layer at approximately 87 km height.\ud\udThe GRIPS instrument is in principle suited for the detection\udof infrasonic signals generated by e.g. tsunamis and\udother geo-hazards. This is due to the fact that the infrasound\udcaused by such events should induce observable shortperiod\udfluctuations in the OH airglow temperatures. First results\udobtained during a field campaign performed at the Environmental Research Station “Schneefernerhaus”, Zugspitze (47.4 N, 11.0 E) from October to December 2008 are presented regarding potential sources of meteorological and orographical\udorigin.\ud\udAn adequate distinction of the overlapping infrasonic signatures caused by different infrasound sources in the OH\udtemperature record is needed for the ascription to the proper\udsource. The approach presented here could form a contribution to a hazard monitoring and early warning system.