Extreme changes in the equatorial electrojet under the influence of interplanetary electric field and the associated modification in the low‐latitude F region plasma distribution
Extreme changes in the equatorial electrojet under the influence of interplanetary electric field and the associated modification in the low‐latitude F region plasma distribution
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行星际电场影响下赤道电射流的极端变化及低纬F区等离子体分布的改变
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
T. Pant
中科院分区：
文献类型：
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作者：
K. Simi;S. Thampi;D. Chakrabarty;B. M. Pathan;S. Nayar;T. Pant
[1]本文介绍了2001年11月24日发生的空间天气事件期间，一个向东的瞬时穿透和一个向西的过屏蔽电场相继影响白天赤道电离层的剧烈效应的一个实例。在印度标准时间（IST）11：25开始的强东移瞬穿电场的影响下，赤道电急流（EEJ）强度在IST 12：42达到最大值225 nT，几乎是同期月平静时间均值的7倍。这一峰值EEJ值超过了11月期间观测到的整个太阳活动周期的最大值超过100 nT，无论是安静还是干扰条件。此外，由于随后的过度屏蔽事件发生在风暴的主要阶段，而不是结束的主要阶段，这个异常大的EEJ显示了同样强烈的极性反转沿着与减弱的零星E层赤道。EEJ的强度在13：45 IST从+225 nT降低到−120 nT，导致了强烈的反电射流条件。从CHAMP卫星的F区电子密度数据的纬度变化揭示了一个不发达的赤道电离异常在17：00 IST（11：24 UT）在印度部门由于这一显着减弱的纬向电场。这些观测结果表明，低纬度电离层可能受到行星际电场的影响。
[1] A case of the drastic effects of an eastward prompt penetration and a westward overshielding electric field successively affecting the daytime equatorial ionosphere during the space weather event that occurred on 24 November 2001 is presented. Under the influence of the strong eastward prompt penetration electric field starting from 11:25 Indian standard time (IST), the equatorial electrojet (EEJ) strength reached the maximum value of 225 nT at 12:42 IST, almost 7 times greater than the monthly quiet time mean at the same time. This peak EEJ value exceeds the maximum observed values during the month of November for the entire solar cycle by more than 100 nT, irrespective of quiet or disturbed conditions. Further, owing to an ensuing overshielding event that occurred during the main phase of the storm rather than the end of the main phase, this unusually large EEJ showed an equally strong polarity reversal along with a weakening of the sporadic E layer over the equator. The EEJ strength was reduced from +225 to −120 nT at ∼13:45 IST, resulting in a strong counter electrojet condition. The latitudinal variation of the F region electron density data from the CHAMP satellite reveal an ill-developed equatorial ionization anomaly at 17:00 IST (11:24 UT) over the Indian sector due to this significant weakening of the zonal electric field. These observations showcase the significant degree to which the low-latitude ionosphere can be affected by the interplanetary electric field.