Investigation on pre-seismic equatorial ionospheric anomaly and its possible association with the gravity wave using satellite measurements
Abstract
Some examples of the equatorial plasma density measured by DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) increased before some large earthquakes are introduced. Previous examples of the pre-seismic equatorial ionization anomalies (EIA) associated with the northern Sumatra earthquake of 2005, Wenchuan earthquake of 2008, Pisco earthquake of 2007, and Kuril Island earthquake of 2007, commonly accompanied conspicuous precursory EIA enhancements distinct from the longitudinal asymmetric variation which is known as a result of ionospheric interaction with the thermospheric tidal modulation generating wave structure in the global ionospheric density profile in the dayside local time. The physical mechanisms of the seismo-ionospheric coupling manifested as the enhanced EIA intensity can be ascribed either to the gravity wave or static electric field generated by the lithosphere-atmosphere-ionosphere coupling, which is still in debate because of lack in confident observational evidences. Molucca sea earthquake of 2007 which accompanied dominant-ever precursory EIA enhancement was selected as a case study to investigate whether the seismo-ionospheric coupling was originated from the gravity wave propagating from the mesosphere to the thermosphere using the SABER satellite data. The gravity wave intensity according to the frequency was derived by applying the s-transform to the atmospheric neutral temperature profile measured by SABER limb-scanning method. The initial analysis results of the ionospheric plasma condition and thermospheric gravity wave derived from DEMETER, CHAMP, and SABER are introduced and the possible association between the physical conditions are discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNH51C1971R
- Keywords:
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- 0619 Electromagnetic theory;
- ELECTROMAGNETICSDE: 2427 Ionosphere/atmosphere interactions;
- IONOSPHEREDE: 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDSDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGY