Quasi-synchronous ionospheric and surface latent heat flux anomalies before the 2007 Pu'er earthquake in China

Pre-earthquake ionospheric and thermal anomalies are two widely-reported short-term earthquake precursors. This paper attempts to examine the possible relationship between the ionospheric anomaly and the thermal anomaly related to the 2007 Ms =6.4 Pu'er earthquake. The spatio-temporal statistical analyses of multi-years SLHF data from USA NCEP/NCAR Reanalysis Project reveal that local SLHF enhancements appeared 11, 10 and 7 days before the Pu'er earthquake, respectively. As contrasted to the formerly reported local ionospheric Ne enhancement 9 days before the shocking observed by DEMETER satellite, it is discovered that the SLHF and Ne anomalies are quasi-synchronous and have nice spatial correspondence with the epicentre and the local active faults. Based on current physical models presented, we suggest that the air ionization in Pu'er seismogenic process, possible resulted from radon leaking out and subsequent alpha particles emitting, and/or positive holes activating and recombining, is the common cause of the observed ionospheric and SLHF anomalies before the Pu'er earthquake. This is valuable for understanding the seismogenic coupling processes and for recognizing earthquake anomaly with multiple parameters from integrated Earth observation system.