The anomalous characteristics of Ti and Ni recorded by IAP on DEMETER Satellite before strong earthquakes

摘要

Based on the data of DEMETER Satellite, the ion temperature(Ti) and ion density (Ni) detected by IAP were analyzed before four strong earthquakes, including the Wenchuan Earthquake occurring in Sichuan Province, China, on May 12, 2008. Similar anomalous characteristics of Ti and Ni were concluded as follows: (1) From half month to the earthquake occurrence, Ti decreased more than 100K above the epicentral area in the daytime of local time and repeated many times; (2) Synchronizing with or after the Ti variation, Ni especially density of Hydrogen ion, exhibited increasing changes, with the amplitude of more than 1000cm-3, while sometimes O+ exhibiting similar feature with much larger amplitude; (3) This type of anomaly affected a much broader range in the ionosphere, even to the equatorial region and higher latitudes, which may be related to the fast propagating velocity of ion in daytime.