Investigating Natural Hazards Using GNSS Measurements: The Chelyabinsk Meteor Ionospheric Impact

摘要

Ionospheric perturbations induced by acoustic-gravitywaves generated in the neutral atmosphere are observed intrans-ionospheric global navigation satellite system(GNSS) datasets. Events on the Earth’s surface or in theatmosphere, such as earthquakes, tsunamis, meteorablations, space shuttle launches, and large explosions arepotential sources of ionospheric disturbances. In thisresearch, we applied two different approaches to detectionospheric disturbances in dual frequency GNSSmeasurements during the Chelyabinsk meteor impactevent on February 15, 2013. The data were collected fromnear-field GNSS networks, GEONET (Japan), and PlateBoundary Observatory (PBO) stations in Alaska and thecoterminous U.S. Using a novel wavelet coherencedetection technique, we were able to identify threedifferent wave trains in the measurements collected fromthe nearest GPS station to the meteor impact site, withfrequencies of approximately 0.004-0.0078 Hz, 0.001-0.0027 Hz and 0.00098-0.0025 Hz at 03:30 UTC. Weestimated the speed and direction of arrival of the totalelectron content (TEC) disturbances by cross-correlatingevery pair of stations in several sub-areas of the GEONETand PBO networks. These may be characterized as threedifferent kinds of traveling ionospheric disturbances(TIDs). First, the higher frequency (0.004-0.0078 Hz)disturbances were observed at the station ARTU (56.43ºN, 58.56º E), with propagation speed of about 1180 m/s.Another type of TID disturbance related to the wavetrains was identified in the lower frequency band(0.00098-0.0025 Hz), propagating with a speed of 996m/s. The lower frequency ionospheric perturbations wereobserved approximately 1500 km away fromChelyabinsk. The third type TID wave train wasidentified using the GEONET and Alaska stations in thefrequency band 0.001-0.0027 Hz having propagationspeeds of 336-450 m/s.