Temporal-spatial characteristics of seismo-ionospheric influence observed by the CSES satellite

As a continuity of our previous work with an emphasis mainly on temporal variations, this research aims to statistically investigate the temporal-spatial characteristics on seismo-ionospheric influence associated with strong earthquakes. Firstly, the latest electron density and ion density data measured by the CSES satellite for more than three years have been utilized to globally search ionospheric disturbances by limiting spatial scale 140-2,100 km (in-situ measurement time t = 20-300 s if the satellite velocity 7 km/s is considered) and without limit on amplitude (A). At the same time, 3,577 strong earthquakes with a magnitude equal to or > 5.0 occurring during this period and three-hourly averaged Kp index have also been collected. It has shown that ionospheric variations with large scale (t > 200 s) and large amplitude (|A| > 100%) majorly reveal the major large-scale ionosphere structures, such as EIA, WN3/4, WSA, MIT, and so on, as well as strengthened varieties globally induced by strong solar activities especially on daytime, although electron density and ion density vary with different properties. Secondly, by large ionospheric perturbations eliminated, the sensitivity of nighttime plasma variations (here, |A| < 100% and t < 200 s) to different group strong earthquakes with respect to several aspects has been tentatively testified. Kp index is kept < 3 during this period to avoid its global effect from solar activities. The results have demonstrated that the seismic activities are more sensitive to ionospheric anomalies predominantly appearing 7 days before and with the spatial size < 120 s. Finally, nighttime plasma perturbations with various sizes and amplitudes have been further applied to a worldwide correlation in space and time with total 3,577 strong earthquakes happening within 1,500 km and 15 day's delay. The statistical results show that seismo-electron influence subtracted by an averaged variation significantly occurs 5 days prior to events and shifts 500-700 km away instead of right above the epicenters, which highly complies theoretically with the physical seismoionospheric model based on zonal electric field propagating along magnetic lines. While seismo-ion effect shows a specified temporal feature but without a confirmed spatial distribution and further work on validation and reliability of ion data is needed. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.