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

Ionospheric perturbations induced by acoustic-gravity waves generated in the neutral atmosphere are observed in trans-ionospheric global navigation satellite system (GNSS) datasets. Events on the Earth's surface or in the atmosphere, such as earthquakes, tsunamis, meteor ablations, space shuttle launches, and large explosions are potential sources of ionospheric disturbances. In this research, we applied two different approaches to detect ionospheric disturbances in dual frequency GNSS measurements during the Chelyabinsk meteor impact event on February 15, 2013. The data were collected from near-field GNSS networks, GEONET (Japan), and Plate Boundary Observatory (PBO) stations in Alaska and the coterminous U.S. Using a novel wavelet coherence detection technique, we were able to identify three different wave trains in the measurements collected from the nearest GPS station to the meteor impact site, with frequencies of approximately 0.004-0.0078 Hz, 0.001-0.0027 Hz and 0.00098-0.0025 Hz at 03: 30 UTC. We estimated the speed and direction of arrival of the total electron content (TEC) disturbances by cross-correlating every pair of stations in several sub-areas of the GEONET and PBO networks. These may be characterized as three different kinds of traveling ionospheric disturbances (TIDs). First, the higher frequency (0.004-0.0078 Hz) disturbances were observed at the station ARTU (56.43 degrees N, 58.56 degrees E), with propagation speed of about 1180 m/s. Another type of TID disturbance related to the wave trains was identified in the lower frequency band (0.00098-0.0025 Hz), propagating with a speed of 996 m/s. The lower frequency ionospheric perturbations were observed approximately 1500 km away from Chelyabinsk. The third type TID wave train was identified using the GEONET and Alaska stations in the frequency band 0.001-0.0027 Hz having propagation speeds of 336-450 m/s.