Effects of strong IMF B z southward events on the equatorial and mid-latitude ionosphere
Effects of strong IMF B z southward events on the equatorial and mid-latitude ionosphere
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DOI：
10.5194/angeo-27-1175-2009
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发表时间：
2009-03
影响因子：
1.9
通讯作者：
E. Astafyeva
中科院分区：
文献类型：
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作者：
E. Astafyeva
利用CHAMP、SAC-C、TOPEX/Jason-1卫星同步TEC测量数据，研究了2001- 2005年发生的5次强日侧电离层对Dst< 120nt的响应。由于卫星经过不同的纵向扇区并在不同的高度范围内测量TEC，因此有可能获得有关这些风暴期间的高度和纵向电离层重新分布的信息。在本文分析的5次事件中，有2次（2001年11月6日和2004年11月8日）观测到赤道和中纬度TEC在430 km以上与赤道异常峰同时移动的距离为10-15纬度的强烈增强（高达350%）。这种现象被称为昼侧电离层上升，或“白天超级喷泉效应”，发生在IMF Bz突然下降和随后的电场渗透到低纬度电离层之后。然而，在2003年6月18日、2004年2月11日和2005年8月24日的其他三个事件中，相同量级的Bz负事件导致日侧TEC相对较弱的变化（高达80 TECU）。在这些风暴的主要阶段，主要观察到赤道异常的“典型”双峰结构的形成，而不是喷泉效应和异常本身的加强。本文讨论了极端电离层效应发展的可能原因和因素。
Dayside ionospheric response to five intense ge- omagnetic storms (Dst< 120 nT) that occurred in 2001- 2005 was investigated by use of simultaneous TEC mea- surements by the CHAMP, SAC-C, TOPEX/Jason-1 satel- lites. Since the satellites passed over different longitudinal sectors and measured TEC in different range of altitudes, it was possible to obtain information about altitudinal and longitudinal ionosphere redistribution during these storms. Severe enhancements (up to 350%) of the equatorial and mid-latitude TEC above 430 km with concurrent traveling of the equatorial anomaly crests for a distance of 10-15 of latitude were observed during two of the five events an- alyzed here (6 November 2001 and 8 November 2004). This phenomenon, known as the dayside ionosphere uplift, or the "daytime super-fountain effect", occurred after sudden drop in IMF Bz and consequent penetration of the electric fields to the low-latitude ionosphere. However, the same order Bz negative events caused comparatively weak changes in the dayside TEC (up to 80 TECU) during the other three events of 18 June 2003, 11 February 2004 and 24 August 2005. At the main phase of these storms there were mostly observed formation of the "typical" dual peak structure of the equa- torial anomaly rather than the reinforcement of the fountain effect and the anomaly itself. Possible reasons and factors responsible for the development of the extreme ionosphere effects are discussed in the paper.