The seasonal variation of the geomagnetic solar daily variation field in China

Yingyan Wu

Published August 2, 2019, SCEC Contribution #9324, 2019 SCEC Annual Meeting Poster #040 (PDF)

The geomagnetic field shows a regular diunal variation at the middle and low latitudes during geomagnetic quiet time, which is called as solar quiet daily variation (Sq). It is mainly generated from the ionosphere dynamic current system in the E-region of ionosphere, which is controlled by the ionospheric diunal and semi-diunal tidal wind field. The variation of the Sq field is greatly related to the latitude and the local time, and its amplitude and the phase vary very slowly in the whole year. Furthermore, a significant day-to-day (DTD) variation is usually seen in the amplitude and the phase of the Sq. It is greatly related to many factors such as the conductivity and the wind field in the ionosphere, and states of the magnetosphere.

This paper is primarily to study the seasonal variation of the amplitude and the phase of the Sq field on both north-and-south sides of the Sq current, by using of the hourly data of the geomagnetic field X, Y and Z components from the Beijing Ming Tombs(BMT) and Guangzhou(GZH) observatories in China. The result shows that the seasonal variations of the amplitude and the phase on both north-and-south sides of the Sq are distinctly different. For the amplitude of Sq(X), it is stronger in autumn than in spring at BMT observatories, but stronger in spring than in autumn at GZH observatory. The amplitude of Sq(Y) shows an enhancement in summer at both of the observatories, but displays some decreasing on July at GZH. The amplitude of Sq (Z) increases in spring and autumn at all observatories, but also enhances in the summer at BMT observatories. For the phase of Sq(X), it shows a slightly moving forenoon at BMT observatories in summer, but on the contrary, it presents a delaying to the afternoon at GZH observatory.

Key Words
seasonal variation; Sq; both north-and-south sides

Citation
Wu, Y. (2019, 08). The seasonal variation of the geomagnetic solar daily variation field in China. Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Forecasting and Predictability (EFP)