Analysis of the geomagnetic component Z daily variation amplitude based on the Geomagnetic Network of China during solar quiet days

The daily variation amplitude of geomagnetic component Z from Geomagnetic Network of China is analyzed in the past twelve years (2008-2019) , including variation for each month in high and low solar activity years, seasonal variations and comparisons between the stations in Yunnan Province and in southeast China. The study indicates that the ionospheric conductivity mainly contributes to the Z daily variations amplitude in the same month or season changing with solar activity. But the neutral wind in ionosphere may make the Z daily variations amplitude in equinox months equal to or greater than that in summer solstice months during some solar high activity years. Due to the complicated underground electrical structures in Yunnan province, the conductivity underground seems to act as an amplifier to make the Z daily variations amplitude increase by about 12%similar to 41% in Yunnan Province during equinox and summer solstice months.

Automated summary

The daily variation amplitude of the geomagnetic component Z from the Geomagnetic Network of China was analyzed for the past twelve years. The study found that the ionospheric conductivity primarily contributes to the daily variations of Z, with the same month or season changing with solar activity. However, the neutral wind in the ionosphere may also affect the daily variation amplitude of Z in certain scenarios. In Yunnan Province, the complex underground electrical structures act as an amplifier, increasing the daily variations amplitude of Z.