【摘要】 利用时序叠加法对１９８４年４月至１９８７年２月的日侧极隙纬度ＶＬＦ波活动指数与磁暴活动作了统计分析．结果表明若以磁暴开始日为第０天，则ＶＬＦ波活动指数在０至一２天内相对于平均值都有下降的效应，而在第２天或第４天则有明显的上升效应，并且存在着季节不对称性，其中急始型的暴始下降和缓始型的暴后上升效应均显冬大夏小的特征，冬季值约为夏季值的３倍．更多还原

【Abstract】 A statistical has been carried out for the relationship between the VLF activities at dayside cleft latitudes and geomagnetic storms from Apr. 1984 to Feb. 1987. It is shown that: 1. There is an obvious effect of geomagnetic storm on the VLF emissions. 2. The VLF emission activities are affected by geomagnetic storms in a way that .there are an obvious VLF activity decrease before or during storm onset day anda large increase of the activities after geomagnetic storm. 3. The influence of Sc storm on VLF activity is different from that of Gc storm. 4. There is a characteristic seasonnal asymmetry of the effects. In local winter the VLF decrease during Sc storm onset day and the VLF increase after G. storm reaches mazimum, while in summer the decrease and the increase are small. The amplitude of the decrease and the increase in winter is 3 times as large as in summer.更多还原