Magnetosphere - Ionosphere Coupling During Periods of Extreme Solar Wind Driving

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

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.