TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 64 (No. 12), pp. 1287-1294, 2012

Detecting ionospheric TEC perturbations caused by natural hazards using a global network of GPS receivers: The Tohoku case study

A. Komjathy1, D. A. Galvan2, P. Stephens1, M. D. Butala1, V. Akopian1, B. Wilson1, O. Verkhoglyadova1, A. J. Mannucci1, and M. Hickey3

1NASA Jet Propulsion Laboratory, California Institute of Technology Pasadena, CA 91109, U.S.A.
2RAND Corporation, Santa Monica, CA 90401, U.S.A.
3Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, U.S.A.

(Received December 21, 2011; Revised August 16, 2012; Accepted August 17, 2012; Online published January 28, 2013)

Abstract: Recent advances in GPS data processing have demonstrated that ground-based GPS receivers are capable of detecting ionospheric TEC perturbations caused by surface-generated Rayleigh, acoustic and gravity waves. There have been a number of publications discussing TEC perturbations immediately following the M 9.0 Tohoku earthquake in Japan on March 11, 2011. Most investigators have focused on the ionospheric responses up to a few hours following the earthquake and tsunami. In our research, in addition to March 11, 2011 we investigate global ionospheric TEC perturbations a day before and after the event. We also compare indices of geomagnetic activity on all three days with perturbations in TEC, revealing strong geomagnetic storm conditions that are also apparent in processed GEONET TEC observations. In addition to the traveling ionospheric disturbances (TIDs) produced by the earthquake and tsunami, we also detect "regular" TIDs across Japan about 5 hours following the Tohoku event, concluding these are likely due to geomagnetic activity. The variety of observed TEC perturbations are consistent with tsunami-generated gravity waves, auroral activity, regular TIDs and equatorial fluctuations induced by increased geomagnetic activity. We demonstrate our capabilities to monitor TEC fluctuations using JPL's real-time Global Assimilative Ionospheric Model (GAIM) system. We show that a real-time global TEC monitoring network is able to detect the acoustic and gravity waves generated by the earthquake and tsunami. With additional real-time stations deployed, this new capability has the potential to provide real-time monitoring of TEC perturbations that could potentially serve as a plug-in to enhance existing early warning systems.
Key words: Ionosphere, GPS, TEC, tsunami detection, acoustic and gravity waves, data assimilation, real-time monitoring, early warning systems.

Corresponding author E-mail: attila.komjathy@jpl.nasa.gov

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