Wavelet filtering of GPS network data for identification of ionospheric disturbances associated with tsunamis

Acoustic-Gravity Waves (AGWs) in the neutral atmosphere can induce disturbances in the ionosphere that are subsequently observable in trans-ionospheric Global Navigation Satellite System (GNSS) measurements. Disruptive events on the Earths surface, such as earthquakes, tsunamis and large explosions are one source of these disturbances. In this presentation, we applied wavelet decomposition to detect the presence of ionospheric disturbances in dual frequency GNSS time series collected from the GEONET (Japan) and SCIGN (Southern California) networks during the Peru tsunami on June 23 2001 and the Chile Tsunami on February 27 2010. Through use of the wavelet decomposition, we are able to find two wave trains, present in the data collected from both networks, with frequencies of approximately 0.0005-0.0011 Hz and 0.0016-0.0167 Hz. The speed and direction of arrival of the disturbances are found through cross-correlating every pair of stations in several sub-areas of each network. These were found to be compatible with the arrival direction and speed of a disturbance created from the Tsunami, with propagation speeds of 101-265 m/s and 559-1195 m/s, respectively.