与地磁急始相伴的电离层暂态振荡

分析了从１９８５年９月至１９９２年１２月共１１５次急始型磁暴期间武昌多普勒台阵观测到的电离层暂态振荡（ＳＩＯ）．这种与地磁ＳＣ相伴的ＳＩＯ可分成ＳＣＦ（＋，－），ＳＣＦ（－，＋），ＳＣＦ（＋）与ＳＣＦ（－）几种类型．分析发现，伴随地磁急始在Ｆ区总是存在突发电离层暂态振荡，除非电波被吸收、穿透、被Ｅ５屏蔽，以致Ｆ区无反射回波或在反射区电离密度的高度梯度特别大，使多普勒频率很小在多普勒图上显示不出来．通常ＳＣＦ（＋，－）发生在白天，而ＳＣＦ（－，＋）发生在晚上．ＳＩＯ与地磁急始有很好的对应关系．

SUDDEN IONOSPHERIC OSCILLATIONS ACCOMPANIED WITH SUDDEN COMMENCEMENT OF GEOMAGNETIC STORM

This paper investigated Sudden Ionospheric Oscillations(SIO)observed atWuhan which occurred simultaneously with the corresponding 116 events of SuddenCommencements(SC)of Geomagnetic storms,during the period from September 1985 to December 1992.It was noticed that SIO accompanied with SC can be distinguished.as SCF( ,-),SCF(-, ),SCF( ),and SCF(-).It was found that if the waves reflect from F-layer,almost all SC cause observable SIO,unless the ionospheric conditions disallow the F-layer reflected wave to be received,such as absorption,Es reflection,or that in reflection region is so large that the Doppler frequency shift is small.It was also noticed that SCF( ,-)appears inthe daytime, while SCF(-, )in the nighttime.