SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase
changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed
etc. There is a sharp difference between the ocean surface and the land surface.
Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been
shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can
increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two
earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed
using SLHF data by STD (standard deviation) threshold method.
It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal
earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then
disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy
change process about earthquake preparation, that is, weak-strong-weak-disappeared.
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<sup>2</sup>, 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.
In this paper mid-term infrared (IR) emission anomalies related to medium or large earthquake using wavelet
time-frequency analysis method have been detected using OLR(Outgoing Longwave Radiation) daily grid data (2.5°)
for Sichuan-Yunnan area. Our analysis of OLR mean value(25 points totally) about Sichuan-Yunnan study area from
2000 to 2008 using wavelet time-frequency analysis shows obvious peaks in the scale of 0-0.2 years. The peaks appeared
in the latter half of 2002 and 2007. It can be found that nine earthquakes (Ms>6.0)had happened in Sichuan-Yunnan
region during this period, and these earthquakes mainly concentrated in 2003 and 2008. The OLR anomalies in 2002 and
2007 can be thought as precursors for earthquakes in 2003 and 2008, respectively. The anomalies are mainly occurred on
half a year to one year before earthquakes. And the anomalous points in twenty-five studied points are near the
epicenters. It indicates that there are relationship between earthquakes and OLR anomalies which can be detected by this
method. It is possible to identify some mid-scale anomalies before occurrences of medium to large earthquakes by using
this method. The result of this study will provide reference to mid-term earthquake prediction.