Study on the geoelectric index (GEI): taking the geoelectric field observation in mainland China as an example

Abstract

This paper reports three methods of researching the geoelectric index (GEI) based on the ratio between the variation amplitude of geoelectric field on an index calculation day and that on a magnetically quiet day, and uses the three methods to process the observation data of 18 geoelectric stations in China in September 2017. Results showed that, each method has obtained 4096 single-station geoelectric indices D and 240 multi-station average geoelectric indices Ds, all 3-hour indices. Comparing the geoelectric indices with the geomagnetic indices of the 18 stations, it can be understood that: 87.35%–88.26% of indices D are the same with the single-station geomagnetic indices K or have only a difference of 1 from the indices K, and 97.08%–97.50% of indices Ds are the same with the multi-station average geomagnetic indices $\overline{\mathrm{K}}$ or have only a difference of 1 from the indices $\overline{\mathrm{K}}.$ The high consistency between two kinds of indices shows that the methods of calculating geoelectric index are practicable, and that the calculated indices D and Ds are reliable. The geoelectric field, as an independent observation, should have a criterion to judge the interference.

Keywords:

• geoelectric field
• geoelectric index (GEI)
• geoelectric disturbance
• geomagnetic field
• geomagnetic index
• geomagnetic disturbance

Acknowledgments

We would like to thank the China’s Geoelectric Observation Network for providing observation data of the geoelectric fields, the China’s Geomagnetic Network Center for providing the geomagnetic indices and the World Data Center for providing geomagnetic activity data.Thanks for the hard work of editors and anonymous experts.

Data availability statement

The data that support the findings of this study are available from the first author, Junsong Sun, upon reasonable request.

Disclosure statement

The authors report no conflict of interest.

Additional information

Funding

This work has been supported by the Seismological Science and Technology Spark Project of China Earthquake Administration (No. XH22001YC), the National Natural Science Foundation of China (grant no. 41374080), the Beijing Natural Science Foundation of China (grant no. 8211045) and the Director fund of Jiangsu Earthquake Agency (202201).