The relation between transpolar potential and reconnection rates during sudden enhancement of solar wind dynamic pressure: OpenGGCM‐CTIM results
The relation between transpolar potential and reconnection rates during sudden enhancement of solar wind dynamic pressure: OpenGGCM‐CTIM results
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太阳风动压突然增强过程中跨极电势与重联率的关系：OpenGGCM-CTIM结果
DOI：
10.1002/2013ja019728
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
J. Raeder
中科院分区：
文献类型：
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作者：
H. Connor;E. Zesta;D. Ober;J. Raeder
利用开放地球空间环流模式-耦合电离层热层模式（OpenGGCM-CTIM）三维全球磁层-电离层-热层模型，研究了太阳风动压（Psw）突然增强时太阳风能量如何沉积到磁层-电离层系统中。我们模拟了在负、近零和正行星际磁场（IMF）Bz期间发生的三个独特的太阳风压力增强事件。然后，我们研究的昼侧和夜侧重联率的行为，并量化各自的贡献跨极冠电位（CPCP），电离层等离子体对流强度的代理。在所有三种情况下，模拟的CPCP增加PSW增强后，这与国防气象卫星计划航天器的观测和电离层电动力学同化映射技术的预测一致。在OpenGGCM-CTIM模型中，压力冲击后9-13分钟内，昼侧重连增加，而压力增加后约13-25分钟，夜侧重连加剧。由于强Psw压缩向阳侧磁鞘，随后，磁尾，它们的磁场加强，并激活更强的反平行重联向阳侧磁层顶第一和附近的中央等离子体片第二。对于向南的IMF，昼侧重连对CPCP增强的贡献是夜侧重连的2-4倍。对于北上的IMF，白天的贡献减弱，而夜间的重连对CPCP的增强贡献更大。我们发现，高纬度磁层顶重联期间向北IMF产生向阳电离层等离子体对流，这降低了典型的黎明到黄昏电离层电场。这导致在向北的IMF期间，较弱的向阳面重新连接对CPCP的贡献。
This study investigates how solar wind energy is deposited into the magnetosphere‐ionosphere system during sudden enhancements of solar wind dynamic pressure (Psw), using the coupled Open Geospace General Circulation Model–Coupled Ionosphere Thermosphere Model (OpenGGCM‐CTIM) 3‐D global magnetosphere‐ionosphere‐thermosphere model. We simulate three unique events of solar wind pressure enhancements that occurred during negative, near‐zero, and positive interplanetary magnetic field (IMF) Bz. Then, we examine the behavior of the dayside and nightside reconnection rates and quantify their respective contributions to cross polar cap potential (CPCP), a proxy of ionospheric plasma convection strength. The modeled CPCP increases after a Psw enhancement in all three cases, which agrees well with observations from the Defense Meteorological Satellite Program spacecraft and predictions from the assimilative mapping of ionospheric electrodynamics technique. In the OpenGGCM‐CTIM model, dayside reconnection increases within 9–13 min of the pressure impact, while nightside reconnection intensifies about 13–25 min after the pressure increase. As the strong Psw compresses the dayside magnetosheath and, subsequently, the magnetotail, their magnetic fields intensify and activate stronger antiparallel reconnection on the dayside magnetopause first and near the central plasma sheet second. For southward IMF, dayside reconnection contributes to the CPCP enhancement 2–4 times more than nightside reconnection. For northward IMF, the dayside contribution weakens, and nightside reconnection contributes more to the CPCP enhancement. We find that high‐latitude magnetopause reconnection during northward IMF produces sunward ionospheric plasma convection, which decreases the typical dawn‐to‐dusk ionosphere electric field. This results in a weaker dayside reconnection contribution to the CPCP during northward IMF.