Magnetosphere - Ionosphere Coupling During Periods of Extreme Solar Wind Driving

太阳风电场驱动着太阳风、磁层和电离层系统的动力学。在正常太阳风条件下，跨极冠电位差与太阳风电场成比例。然而，在极端的太阳风条件下，如磁暴期间发生的情况下，CPCP变得非线性和饱和。这项研究将主要支持弗吉尼亚理工大学和州立大学的博士后学者，他将学习相干和非相干散射电离层雷达的操作，这项研究的目标是调查饱和的原因，并了解为什么北方和南半球的行为不同。对于CPCP饱和有两类解释。在一个昼侧区域1中，场向电流限制了强驱动的磁重联率，而在另一个区域中，建立了阿尔文翼，其中太阳风建立的电场的一部分在电离层被反射，这是由于太阳风的阿尔文电导和电离层的彼得森电导之间的电导失配。研究小组提出了第三种解释，即电离层等离子体的不稳定性导致电离层电流的限制，并反馈到磁层。该研究涉及使用混合模拟代码和观测SuperDARN和ISR雷达在电离层，ACE太阳风观测和THEMIS数据在磁层。

The dynamics of the solar wind, magnetosphere and ionosphere system are driven by the solar wind electric field. Under normal solar wind conditions the cross polar cap potential (CPCP) difference scales with the solar wind electric field. However under extreme solar wind conditions such as those occurring during magnetic storms the CPCP becomes non-linear and saturates. This study will primarily support a post-doctoral scholar at Virginia Polytechnic and State University who will be taught about the operation of both coherent and incoherent scatter ionospheric radars.The goals of this study are to investigate the causes of the saturation and to understand why the northern and southern hemispheres behave differently. There have been two classes of explanations for CPCP saturation. In one dayside region 1 field aligned currents limit the magnetic reconnection rate for strong driving and in the other an Alfvén wing is set up in which a portion of the electric field set up by the solar wind is reflected at the ionosphere as the result of a conductance mismatch between the Alfvénic conductance of the solar wind and the Pedersen conductance of the ionosphere. The team proposes a third explanation that ionospheric plasma instabilities lead to limitations on ionospheric currents and that this feeds back into the magnetosphere. The research involves using a hybrid simulation code and observations from SuperDARN and ISR radar in the ionosphere, ACE solar wind observations and THEMIS data in the magnetosphere.