Research on the Distribution of Geomagnetic Daily Variation Along Some Station Chains in China

The temporal and spatial distribution of SqH in China was analyzed based on geomagnetic digitized data from the geomagnetic observation network. It was found that; 1) there was obvious prenoon-postnoon asymmetry of SqH in summer and equinox; 2) in summer, equinox, and winter, the averaged foci of Sq were located at 27° N, 29° N, and 35° N, respectively. However, in a single quiet day, the Sq foci might reach a latitude north of 50° N and south of 19° N; 3). There were some inconsistencies in the behavior of the SqH distributions in two longitudinal chains, such as the reverse of SqH variations in the same latitudinal chain and the increase (decrease) of the daily ranges from east to west. All these demonstrated that there might be latitudinal migration of the Sq focus or changes in current intensity during the longitudinal migration of the Sq focus from east to west.