中山站电离层尖峰脉冲型吸收统计特性

通过对南极中山站成像式宇宙噪声接收机2000至2001年的观测数据进行分析,得到了189例电离层尖峰脉冲型吸收事件,按其发生时间可分为夜侧吸收事件(69例)和日侧吸收事件(120例)．对这两类吸收事件进行对比统计研究,得到了其吸收发生时间、吸收持续时间、吸收强度、吸收区域形状和空间尺度、运动状况以及吸收事件与地磁Kp指数关系等特性,并对电离层尖峰脉冲型吸收的可能产生机制进行了讨论．

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.