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