Statistical Characteristics of Ionospheric Absorption Spike Events at Zhongshan Station

The total number of 189 ionospheric absorption spike events was identified in the imaging riometer＇s data from 2000 to 2001 at Zhongshan station, Antarctica. All events are divided into two groups, the nightside events （69 samples） and the dayside events （120 samples） according to their occurring time. The whole features are found with regard to their occurrence, duration, intensity, shape, size, movement and the relationship with Kp by using statistical methods. The occurrence peak of the nightside spike event is around magnetic per-midnight and in April, while the occurrence peak of the dayside spike event is around magnetic noon and in August. It is suggested that the nightside spike events are closely related to the aurora substorm activities, while the dayside spike events are affected by the solar wind conditions. The typical duration of the spike events is 2 - 3 minutes. The maximum intensities of absorption are usually less than 1 dB. The shape of the spike is most like elliptic with the major axis along the geomagnetic east-west direction. Comparisons have been made on the occurrence of the spike events between Zhongshan station and arctic stations. The possible mechanisms which cause the spike events are suggested in the paper.