HR: 11:50h
AN: S42B-07    [Abstracts]
TI: Statistical studies of ionospheric parameters recorded by the satellite DEMETER during seismic activity
AU: Li, F
EM: fengli@cnrs-orleans.fr
AF: LPCE/CNRS, 3A Avenue de la Recherche, Orleans, 45071, France
AU: * PARROT, M
EM: mparrot@cnrs-orleans.fr
AF: LPCE/CNRS, 3A Avenue de la Recherche, Orleans, 45071, France
AB: DEMETER is an ionospheric micro-satellite launched on a polar orbit at an altitude of 710 km. Its main scientific objective is to study the ionospheric perturbations in relation with seismic activity, and then, its scientific payload allows to measure electromagnetic waves and plasma parameters all around the Earth except in the auroral zones. Two specific parameters are taken into account in this paper: the electron density and the electrostatic turbulence. First the paper will show specific events where the electron density and the electrostatic turbulence are perturbed prior to large earthquakes above the future epicentre. Although, these examples have been carefully selected (close in time and space to the earthquakes, abnormal variations relative to the background level for the same location, the same local time and the same magnetic activity) it is always possible that the perturbations are due to other natural mechanisms because the ionosphere is highly variable and mainly under the control of the sun. Only a statistical analysis of the data is able to remove this ambiguity. The statistic is done as functions of the geographic position, the local time, and the magnetic activity. Geographical maps with average data are obtained to be used as background levels, and the superposed epoch method is applied to merge the data recorded during seismic activity. In relation to previous presentations the data set has been increased because we have now more than three years of data and a comparison is done when we remove the aftershocks from the statistics because pre- and post-seismic effects can be mixed.
DE: 2411 Electric fields (2712)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2435 Ionospheric disturbances
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting