Transient dayside reconnection processes through imaging and radar measurements

Abstract:

Dayside magnetic reconnection in the Earth’s magnetosphere plays an important role in energy transport from the solar wind to the Earth’s magnetosphere-ionosphere system. Understanding of dayside reconnection is important for plasma dynamics in its ionospheric footprint (cusp), including plasma transport and heating. While in-situ measurements by satellites can determine local behavior of reconnection, it is difficult to address its spatial extent and time evolution. On the other hand, remote-sensing from the ground by imagers and radars provides 2-d measurements of electron precipitation from the reconnection region, allowing to find spatial and temporal evolution of dayside reconnection and its connection to ionospheric phenomena.

This talk presents timing and structure of dayside reconnection using imagers and radars in combination with satellites. Recently a new incoherent scatter radar located at Resolute Bay, Canada, started its science operation. In combination with the existing north-facing radar, the pair of radars provides the highest resolution of data in the cusp region over 10 degree latitudes. We report two modes of reconnection responses including their spatial extent, timing, and duration, and their dependence on upstream solar wind conditions. We also address how dayside reconnection and the outer magnetosphere respond to magnetosheath jets and foreshock activities using THEMIS satellite-imager conjunction events.