Abstract
It is well known that tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron densities in the E and F regions. These ionospheric disturbances can be studied in detail using ionospheric total electron content (TEC) measurements collected by continuously operating ground-based receivers from the Global Navigation Satellite Systems (GNSS). Here, we present results using a new approach, named VARION (Variometric Approach for Real-Time Ionosphere Observation), and estimate slant TEC (sTEC) variations in a real-time scenario. Using the VARION algorithm we compute TEC variations at 56 GPS receivers in Hawaii as induced by the 2012 Haida Gwaii tsunami event. We observe TEC perturbations with amplitudes of up to 0.25 TEC units and traveling ionospheric perturbations (TIDs) moving away from the earthquake epicenter at an approximate speed of 316 m/s. We perform a wavelet analysis to analyze localized variations of power in the TEC time series and we find perturbation periods consistent with a tsunami typical deep ocean period. Finally, we present comparisons with the real-time tsunami MOST (Method of Splitting Tsunami) model produced by the NOAA Center for Tsunami Research and we observe variations in TEC that correlate in time and space with the tsunami waves.
Highlights
It is well known that tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron densities in the E and F regions
The direct outputs of the VARION algorithm are the slant TEC (sTEC) variations (Equation 3), subsequently integrated over a certain time period; the variometric approach overcomes the problem of estimating the phase initial ambiguity and the Inter-Frequency Biases (IFBs), being ideal for real-time applications
For the satellite PRN 10 the total electron content (TEC) perturbation occurred before the tsunami reached the Hawaiian Islands; this is due to the geometry corresponding to the particular elevation and azimuth angles of satellite PRN 10 as the tsunami-generated traveling ionospheric disturbances (TIDs) were detected when tsunami the wave front was still about 150 km away from the coast
Summary
It is well known that tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron densities in the E and F regions. We are presenting a new GNSS processing algorithm, named VARION (Variometric Approach for Real-Time Ionosphere Observation) that focuses on the real-time detection of the TIDs caused by tsunami atmospheric gravity waves (see Appendix A for the methodology).
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