Study on Outgoing Longwave Radiation Variations Associated with Strong Earthquake

In this paper, OLR (Outgoing Longwave Radiation) data monthly vorticity variations related to three earthquakes in Sichuan-Yunnan area have been analyzed so as to seek short-term (within three months) seismic anomalies. In order to obtain a reference field without any seismic information, OLR data of three years (2004, 2005, and 2006) without earthquakes are selected as the data source for normal field, then the monthly reference fields(from January to December) of this region are generated using it. The results indicate that OLR anomalies are possible to be detected in earthquakes of greater magnitude (Ms>6.0), the anomalies appeared 1-3 months prior to earthquakes and disappeared after the events, the affected area can reach million square kilometers, and the anomalous values are about 17-25W/m(2), that is to say, the OLR vorticity values near the epicenter area can be increased by about 10%. It should be noted that the epicenter of the impending earthquake is not just in the high value area of OLR anomalies, but located at a short distance away from it. And the relationship between anomalous amplitude and seismic magnitude is not a simple direct proportion.