Equatorial ionosphere responses to two magnetic storms of moderate intensity from conjugate point observations in Brazil

M. A. Abdu; I. S. Batista; F. BertoniB. W. ReinischE . A. KheraniJ. H. A. Sobral

摘要

Equatorial ionospheric responses during two magnetic storms of moderate intensity are investigated, for the first time, by conjugate point observations in Brazil. The study focuses on storm-induced changes in the evening prereversal vertical drift, thermospheric trans-equatorial winds, spread F/plasma bubble irregularity development, electron density/plasma frequency heights, the EIA strength, and zonal plasma drifts. It is based on data obtained from five Digisondes operated in Brazil, three of them being part of a conjugate point equatorial experiment (COPEX) involving a dip equatorial and two magnetic conjugate sites at ±12°. The other two were operated at the equatorial ionization anomaly (EIA) trough and crest locations at nearby magnetic meridians. The results bring out, and clarify, many outstanding aspects of the strong influence of storm time electric fields on the equatorial ionosphere at different phases of the two long lasting storm sequences. During both storms prompt penetration electric fields dominated the ionospheric response features as compared to the disturbance wind dynamo effects that were not very conspicuous. An under-shielding (over-shielding) electric field occurring in the evening hours causes enhancement (suppression) of the prereversal vertical drift and post sunset spread F/plasma bubble generation. The same electric fields cause post sunset EIA enhancement and suppression, respectively. Post sunset (post midnight) spread F can develop from under-shielding (over-shielding) electric fields, while it can be disrupted by over-shielding (under-shielding) electric field. Trans-equatorial winds are found to be ineffective to stabilize the post sunset F region against the destabilizing effect of strong prereversal vertical drift. Storm time westward plasma drifts are found to be driven by prompt penetration eastward electric fields (through their effect of inducing vertical Hall electric fields), rather than by a disturbance westward thennospheric wind during these storms.

机译：在两个赤道电离层响应中等强度的磁场风暴调查,首次通过共轭在巴西点观测。在晚上storm-induced变化thermospheric prereversal垂直漂移trans-equatorial风,传播F /等离子体泡沫不规则性发展,电子密度/等离子体频率高,EIA强度和纬向等离子体漂移。五Digisondes操作在巴西,他们三个赤道的共轭点实验(COPEX)涉及赤道和两个磁共轭网站12°±。两人在赤道电离异常(EIA)波谷和波峰位置附近的磁子午线。和澄清,很多优秀的方面强烈的风暴时间电场的影响在不同阶段的赤道电离层两个长久的风暴序列。风暴迅速渗透电场占据了电离层响应特性干扰相比风力发电机的影响不是很明显的。under-shielding (over-shielding)电场发生在晚上时间会导致增强(抑制)prereversal垂直漂移和日落传播F /等离子体后泡沫的一代。日落环评增强和抑制,分别。从under-shielding F可以开发(over-shielding)电场,同时它可以打乱了over-shielding (under-shielding)电场。没有稳定后日落F地区的不稳定效应强prereversal垂直漂移。发现等离子体漂移的提示东电场(通过渗透诱导垂直霍尔电的效果字段),而不是干扰向西在这些风暴thennospheric风。

Equatorial ionosphere responses to two magnetic storms of moderate intensity from conjugate point observations in Brazil

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