EPP

The China Seismo-Electromagnetic Satellite, launched into orbit from Jiuquan Satellite Launch Centre on February 2^nd, 2018 , is China’s first space satellite dedicated to geophysical exporation. The satellite carries eight scientific payloads including high-precision magnetometers to detect electromagnetic changes in space, in particular changes associated with global earthquake disasters. In order to encourage and facilitate use by geophysical scientists of data from the satellite’s payloads, this paper introduces the application systems developed for the China Seismo-Electromagnetic Satellite by the Institute of Crustal Dynamics, China Earthquake Administration; these include platform construction, data classification, data storage, data format, and data access and acquisition.

The CSES (China seismic electromagnetic satellite) was launched on February 2, 2018 in a circular polar orbit at an altitude of ~507 km. One of the main objectives of CSES is to search for and characterize ionospheric perturbations that can be associated with seismic activities, to better understand the generation mechanism of such perturbations. Its scientific payload can measure a broad frequency range of electromagnetic waves and some important plasma parameters. This paper is a first-hand study of unusual observations recorded by the CSES over seismic regions prior to four earthquakes with M >7.0 since the satellite's launch. CSES detectors measured irregularities near the epicenter of these four earthquakes. It is already clear that data from instruments onboard the CSES will be of significant help in studies of characteristics of ionospheric perturbations related to earthquakes and their generation mechanisms.

The high energetic particle package (HEPP) on-board the China Seismo-Electromagnetic Satellite (CSES) was launched on February 2, 2018. This package includes three independent detectors: HEPP-H, HEPP-L, and HEPP-X. HEPP-H and HEPP-L can detect energetic electrons from 100 keV to approximately 50 MeV and protons from 2 MeV to approximately 200 MeV. HEPP-X can measure solar X-rays in the energy range from 1 keV to approximately 20 keV. The objective of the HEPP payload was to provide a survey of energetic particles with high energy, pitch angle, and time resolutions in order to gain new insight into the space radiation environments of the near-Earth system. Particularly, the HEPP can provide new measurements of the magnetic storm related precipitation of electrons in the slot region, and the dynamics of radiation belts. In this paper, the HEPP scientific data sets are described and initial results are provided. The scientific data can show variations in the flux of energetic particles during magnetic storms.

This study presents signatures of seismo-ionospheric perturbations possibly related to the 14 July 2019 $ {M}_{w} $7.2 Laiwui earthquake, detected by a cross-validation analysis of total electron content (TEC) data of the global ionospheric map (GIM) from GPS and plasma parameter data recorded by the China Seismo-Electromagnetic Satellite (CSES). After separating pre-seismic ionospheric phenomena from the ionospheric disturbances due to the magnetospheric and solar activities, we have identified three positive temporal anomalies, around the epicenter, at 1 day, 3 days and 8 days before the earthquake (14 July 2019), along with a negative anomaly 6 days after the earthquake. These results agree well with the TEC spatial variations in latitude–longitude–time (LLT) maps. To confirm these anomalies further, we employed the moving mean method (MMM) to analyze ionospheric plasma parameters (electron, $ {\mathrm{O}}^{+} $and $ {\mathrm{H}\mathrm{e}}^{+} $densities) recorded by the Langmuir probe (LAP) and Plasma Analyzer Package (PAP) onboard the CSES. The analysis detected on, on Day Two, Day Four, and Day Seven before the earthquake, remarkable enhancements along the orbits around when in proximity to the epicenter. To make the investigations still more convincing, we compared the orbits on which anomalous readings were recorded to their corresponding four nearest revisiting orbits; the comparison did indeed indicate the existence of plasma parameter anomalies that appear to be associated with the Laiwui earthquake. All these results illustrate that the unusual ionospheric perturbations detected through GPS and CSES data are possibly associated with the $ {M}_{w}7.2 $ Laiwui earthquake, which suggests that at least some earthquakes may be predicted by alertness to pre-seismic ionospheric anomalies over regions known to be at seismic risk. This case study also contributes additional information of value to our understanding of lithosphere–atmosphere–ionosphere coupling.

Four levels of the data from the search coil magnetometer (SCM) onboard the China Seismo-Electromagnetic Satellite (CSES) are defined and described. The data in different levels all contain three components of the waveform and/or spectrum of the induced magnetic field around the orbit in the frequency range of 10 Hz to 20 kHz; these are divided into an ultra-low-frequency band (ULF, 10–200 Hz), an extremely low frequency band (ELF, 200–2200 Hz), and a very low frequency band (VLF, 1.8–20 kHz). Examples of data products for Level-2, Level-3, and Level-4 are presented. The initial results obtained in the commission test phase demonstrated that the SCM was in a normal operational status and that the data are of high enough quality to reliably capture most space weather events related to low-frequency geomagnetic disturbances.

The Langmuir Probe (LAP), onboard the China Seismo-Electromagnetic Satellite (CSES), has been designed for in situ measurements of bulk parameters of the ionosphere plasma, the first Chinese application of in-situ measurement technology in the field of space exploration. The two main parameters measured by LAP are electron density and temperature. In this paper, a brief description of the LAP and its work mode are provided. Based on characteristics of the LAP, and assuming an ideal plasma environment, we introduce in detail a method used to invert the I-V curve; the data products that can be accessed by users are shown. Based on the LAP data available, this paper reports that events such as earthquakes and magnetic storms are preceded and followed by obvious abnormal changes. We suggest that LAP could provide a valuable data set for studies of space weather, seismic events, and the ionospheric environment.

The electromagnetic satellite Zhangheng 01 (ZH-01) was successfully launched on February 2, 2018. The GNSS Radio Occultation (GRO) receiver on board the satellite is able to observe the occultation events of GPS and BeiDou navigation satellites. We analyzed the data acquired during the in-orbit testing period. We concludes that the GRO ionosphere inversion results are reasonable, the trend is correct, the satellite can observe about 600 ionosphere occultation events each day. The global coverage of more than 30000 consecutive GRO events in more than two months were analyzed and compared with COSMIC observations: both the GRO and COSMIC occultation can realize global coverage: the N_mF₂ and H_mF₂ global distributions are similar and change obviously with latitude. We used three digisondes at different latitudes to analyze and compare the spatio-temporally consistent GRO data: the RMSE of GRO N_mF₂ relative to digisonde is better than 9.41%, the correlation coefficient is better than 0.8682: the relative RMSE of H_mF₂ is better than 7.80% and the correlation coefficient is better than 0.7066.

High energy particles are the main target of satellite space exploration; particle storm events are closely related to solar activity, cosmic ray distribution, and magnetic storms. The commonly seen energetic particle (electron) precipitation anomalies include mainly the inner and outer Van Allen radiation belts, the South Atlantic Anomaly, and the anomalous stripes excited by artificial electromagnetic waves. The China Seismo-Electromagnetic Satellite (CSES), launched in February of 2018, provides a platform for studying ionospheric particle disturbances. This paper reports the first studies of electron precipitation phenomenon based on high energy particle data from the CSES. We find that the global distribution of electron fluxes in the low energy band (0.1–3 MeV) can relatively well reflect the anomalous precipitation belt, which is consistent with results based on the DEMETER satellite, indicating that the quality of the low-energy band payload of the CSES is good. In addition, this paper makes an in-depth study of the electron precipitation belt excited by the NWC artificial VLF electromagnetic transmitter located in Australia, which appears as a typical wisp structure on the energy spectrum. The magnetic shell parameter L corresponding to the precipitation belt ranges from 1.44 to 1.74, which is close to the L value (~1.45) of the NWC transmitter; the energy of the precipitation electrons is between 100 keV and 361.57 keV, among which the precipitation of 213.73 keV electrons is most conspicuous.