Analysis of Ionospheric Anomalous Disturbance During a Heavy Rainfall

摘要

The global navigation satellite system (GNSS) has the advantages of high precision, high temporal resolution and low cost. The total electronic content (TEC) can be calculated by GNSS observations. The TEC sequence can be used to reflect the disturbances of the ionosphere, and it can detect the ionospheric anomalies caused by strong convective weather which plays an important role in studying the coupling mechanism between the ionosphere and the troposphere. In this paper, the GNSS observations during a heavy rainfall at July 9, 2013 in Sichuan Province were selected, and the de-trend TEC sequence was obtained. It can be seen from the dTEC sequence that there are obvious anomalies in the ionosphere when the rainfall occurred, and the abnormal times between the different stations are slightly different which show the abnormal propagation process. In this paper, we argue that the ionospheric anomalies are related to the acoustic gravity waves (AGWs). Due to the special terrain of Sichuan, when the waves encountered the mountain, they would spread upward, and then reach the ionosphere and cause ionospheric anomalies. According to its propagation velocity, Sichuan Province is divided into uniform grid and the approximate location of the excitation AGWs can be found. Finally, based on the analysis of the heavy rainfall event, the coupling mechanism between ionosphere and troposphere is discussed.