Solar concept of flux transport by interchange reconnection applied to the magnetosphere

Abstract

The traditional concept of steady state convection of magnetic field‐line foot points in Earth's ionosphere driven by reconnection between the interplanetary and geomagnetic fields implies that those foot points follow closed contours of circulation. Remote reconnection that occurs when the foot points cross the polar cap boundary controls whether the field lines are open or closed, but the foot points remain firmly rooted to their paths around the closed circulation cells. In steady state MHD models, however, this concept of convection breaks down owing to interchange reconnection between open and closed field lines. In the solar heliospheric community, interchange reconnection has long been understood as a means of flux transport. In the magnetosphere, flux transport by interchange reconnection causes field‐line foot points to jump, or saltate, from one side of the polar cap to the other as part of the steady state circulation. We develop a definitive method for identifying interchange reconnection in an MHD model and illustrate the resultant foot point saltation.