Time-frequency analysis of the influence of Japan M_W9.1 earthquake on regional thermal radiation background field

A major earthquake has a greater impact on the thermal radiation background field in and around the epicenter. The black body temperature （TBB） data in the region of （30°N—45°N, 135°E—150°E） from 2007 to 2016 which is from the Chinese stationary weather satellite series （FY-2C/2E/2F/2G） was processed using time-frequency relative power spectrum （T-F RPS for short） with full-time and full-band, and we got the thermal radiation anomalies. The result shows that the characteristics of thermal radiation anomalies are obvious and well corresponding to the seismogenic structure of the Japan M_W9.1 earthquake on March 11, 2011. In addition, we used the time-frequency analysis method to analyze the influence of the M_W9.1 earthquake on the thermal radiation background in the above region. It was found that a long-term thermal radiation anomaly in the region in 2011, which was inconsistent with other years, displayed as three phases from appearance to maximum and then to disappearance. Meanwhile, we compared the similarities and differences of seismic thermal radiation anomalies processed by multi-scale relative power spectrum. It is indicated that the relative Fourier power spectrum with the 6th-order wavelet transform is more effectively with different window lengths to extract and recognize the thermal radiation anomalies. A total of six thermal radiation anomalies occurred in ten years, among which twice occurred in 2011 and three anomalies corresponded to the earthquakes in other years of this area, and the remaining one anomaly had no earthquake to correspond to.