The great disturbances of the horizontal component of the geomagnetic field in mid-low latitudes caused by the ring current in the Earth's magnetosphere can be characterized by the Disturbance Storm Time (Dst) index and the symmetric H component (SYM-H) index. The Dst index and SYM-H index are important indicators for measuring geomagnetic activity, which can clearly reflect the commencement and intensity of geomagnetic storms. Due to the asymmetry of ring current during geomagnetic storms, there are significant differences in the geomagnetic disturbance intensity in different regions. As global geomagnetic index, Dst index and SYM-H index may not accurately describe the geomagnetic disturbance situation in China. We uses geomagnetic data from four stations in Lhasa, Chengdu, Wuhan, and Hangzhou of the Chinese Meridian Project from 2010 to 2024 to calculate the Chinese geomagnetic index (cDst index, cSYM-H index), and compares and analyzes them with the global geomagnetic index (Dst index, SYM-H index). The results indicate that the two types of Chinese geomagnetic index can more accurately describe the characteristics of geomagnetic disturbances in China, and their differences from the global geomagnetic index show a dawn-dusk dependence: The absolute value of the Chinese geomagnetic index is greater than the global geomagnetic index when China is located on the dusk side, and is less when China is on the dawn side. Correspondingly, the number of Chinese geomagnetic disturbances is more than geomagnetic storms when China is located on the dusk side, and is less when China is on the dawn side. The physical mechanism of these phenomena is closely related to the dawn-dusk asymmetry of the ring current. Meanwhile, based on the Chinese geomagnetic index, the global geomagnetic index can be effectively obtained, and the results are in good agreement. Therefore, when the global geomagnetic index cannot be obtained, high-quality supplementary data can be provided.
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