Oppositely to a previous statistical work using a single time resolution of the total ion density measured onboard the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite, this work deals with statistical seismo‐ionospheric influences by comparing different parameters and various time resolutions. The O⁺ density and electron density recorded by the China Seismo‐Electromagnetic Satellite (CSES) for more than one year and by the DEMETER satellite for about 6.5 years have been utilized to globally search ionospheric perturbations with different time resolutions. A comparison is automatically done by software between the occurrence of these ionospheric perturbations determined by different data sets, and the occurrence of earthquakes under the conditions that these perturbations occur at less than 1,500 km and up to 15 days before the earthquakes. Combined with statistical results given by both satellites, it is shown that the detection rate r of earthquakes increases as the data time resolution and the earthquake magnitude increase and as the focal depth decreases. On average, the number of perturbations is higher the day of the earthquake, and then smoothly decreases the days before, which is independent of either ionospheric parameters or time resolutions. The number of right alarms is high near the South Atlantic Magnetic Anomaly area but its relationship with seismic activities is weak. The ion density tends to be more sensitive to seismic activities than the electron density but this needs further investigations. This study shows that the CSES could effectively register ionospheric perturbations due to strong EQs as the DEMETER satellite does.

Driven by the objective of earthquake disaster prevention and mitigation, China launched the Zhangheng mission to build a stereoscopic earthquake monitoring system from the lithosphere to space. This report briefly presents the possible seismic ionospheric disturbances recorded by the first probe of the Zhangheng mission, which is known as the China-Seismo-Electromagnetic Satellite (CSES). The routine data preprocessing and seismo-ionospheric information analysis methods are briefly introduced. The possible seismo-ionospheric disturbances that appeared during the strong shallow earthquakes (with a magnitude over 7 and a depth shallower than 30 km) are analyzed by using CSES and other multi-source data. Investigating seismo-ionospheric mechanisms requires multidisciplinary knowledge involving geophysics, atmosphere/ionosphere physics, geochemistry/atmospheric chemistry, etc. We state that the results from the CSES scientific application center are preliminary, calling for international scientists to contribute to the seismo-ionospheric perturbation phenomena, which is one of the most challenging scientific problems.

This research examines the correlation between seismic activity and variations in ionospheric electron density (Ne) using the data from the Langmuir probe (LAP) onboard the China Seismo-Electromagnetic Satellite (CSES) during nighttime. Statistical analysis of Ms ≥ 6.8 earthquakes that occurred globally between August 2018 and March 2023 is conducted, as well as Ms ≥ 6.0 earthquakes in China during the same period, using the quartile analysis method for fixed revisiting orbits. The main conclusions are that: (1) the larger the magnitude of the earthquake, the more anomalous the phenomena that appear; (2) the anomalies on the east side of the epicenter are significantly higher than those on the west side, and the anomalies in the Northern Hemisphere are mostly distributed southward from the epicenter, while those in the Southern Hemisphere are mostly distributed northward from the epicenter; (3) anomalies appear with a higher frequency on several specific time intervals, including the day of the earthquake (likely co-seismic effect) and 2, 7, and 11 days before the earthquake (possible precursor candidates); and (4) for the 15 earthquakes of Ms ≥ 6.0 in China over the past five years, anomalous Ne mainly occurred southwest of the epicenter, with the highest frequency observed 5 days before the earthquake, and there were continuous anomalous phenomena between 9 days and 5 days before the earthquake. This study concludes that Ne, measured by CSES, can play a fundamental role in studying earthquake-related ionospheric disturbances.

In this paper, in order to investigate the correlation between seismic activity and ionospheric density variation, nighttime ion density (Ni) data from IAP onboard the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite from 2005 to 2010 are used to carry out statistical analysis. Only data with kp ≤ 3 are selected to avoid density perturbations due to magnetic activity. The aftershocks are also carefully removed. The earthquake-related data were further strictly screened, and the apparent position of anomalies were normalized using Dobrovolsky’s radius. Real and pseudorandom earthquakes are compared and analyzed. The statistical results show that the postseismic effect is obvious; the Ni enhancements are more focused 3–5 days, 9–10 days, and 13–14 days before the earthquake; as the magnitude of earthquake increases, the apparent range and intensity of the ion density enhancements is also increased; and for medium–strong earthquakes, the position of disturbance will exceed Dobrovolsky’s radius.