Analysis of possible seismo-ionosphere perturbations before the strong Sichuan earthquake on May 12, 2008 using DEMETER Data

There have been a large number of experimental studies concerning the ionoshperic perturbations before earthquakes. These perturbations include variations in electron and ion densities, anomalous electromagnetic emissions at various frequencies and so on. The real physical process of seismo- ionospheric couping is not well known up to now, though many research results have been published [1]. It is an effective way to monitor the ionospheric variations related to seismic activity by satellite observations, and this is the main scientific objective of the French micro-satellite DEMETER, which was launched on June 29, 2004. Its orbit is polar and circular with an altitude of 710 km (changed to 665 km later). The electromagnetic emission in a frequency range from DC to 3.3 MHz can be detected by the scientific payload IMSC (search-coil magnetometer instrument) and ICE (electric field instrument). The electron density and ion density variations are studied by the ISL (Langmuir probe instrument) and IAP (plasma analysis instrument). There are two operation modes: the survey mode which record low bit rate data all around the Earth at invariant latitudes less than ~ 65deg and burst mode which record high bit rate data above seismic regions. Data and plots are available on the web server according to the user´s authorization. All data and plots are organized by half-orbits. Some ionospheric variations during earthquakes using DEMETER data have been published in the past few years.