Possible ionosphere and atmosphere precursory analysis related to Mw > 6.0 earthquakes in Japan

The attention towards possible link of earthquakes (EQs) and ionosphere in the form of seismo ionosphere anomalies (SIAs) has increased exponentially by utilizing new data and more accurate observations. The integrated atmosphere and ionosphere monitoring satellites has played a decisive role in this development and provided detection and analysis of anomalies attributed to seismic processes. In this paper, we study EQ anomalies in ionosphere from IGS permanent Global Navigation Satellite Systems (GNSS) based Total Electron Content (TEC) and foF2 parameter (highest frequency reflected from the main ionospheric F2 layer on a vertical propagation path), retrieved from stations operating within the seismogenic zone in Japan for EQs of magnitude Mw > 6.0. Furthermore, spatial composite maps of geopotential height, air temperature, and Outgoing Long-wave Radiation (OLR) from National Oceanic and Atmospheric Administration/National Center for Environmental Prediction (NOAA/NCEP) are analyzed to support the hypothesis of diffusion of SIAs through the atmosphere over the epicenter during the seismic preparation zone. We find evidences of TEC and foF2 anomalies in the analysis of nearby IGS permanent stations within seismogenic zone on main shock day, when geomagnetic activities remain quiet. In addition, atmospheric composite indices manifest anomalies attributed to the EQ on the same day as TEC and foF2 perturbations. Similarly, differential ionosphere and atmosphere values indicate that EQ abnormalities are significant on main shock day during UT = 10–12. Our results show that atmospheric and ionospheric measurements may play a role for the analysis and prediction of EQs.