基于中国地磁台网数据的太阳静日期间地磁场Z分量日变化幅度分析

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

本文应用中国地磁台网完成数字化改造后自2008年以来的地磁场观测数据,分析了过去12年(2008—2019年)中国地区地磁场Z分量的日变化幅度特征.重点研究了地磁场Z分量在太阳活动高低年的月变化、季节变化情况以及对其在云南地区和中国东南部地区同纬度台站之间进行了对比分析.研究表明,Z分量日变化幅度在同一月份或季节随太阳活动的变化主要来自电离层电导率的影响;但在太阳活动高年,电离层中性风的作用可能会使分点月的Z分量日变化幅度大于或等于夏至月;由于云南地区地下电性结构的复杂性,地下电导率可能在分点月和夏至月对云南地区的Z分量日变化幅度起到了放大作用,使其增加了约12%~41%.研究结果为地磁场日变化及地磁异常提取的背景信息选择提供了新的参考.

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%~41% in Yunnan Province during equinox and summer solstice months.