A Model of the Formation of the Low‐Latitude Boundary Layer for Northward IMF by Reconnection: A Summary and Review

A model of formation of the low-latitude boundary layer (LLBL) by reconnection for northward interplanetary magnetic field is reviewed. In this model, the solar wind enters the magnetosphere by reconnection poleward of the cusp in both hemispheres. The entered plasma then flows along the magnetopause, with increasing speed and thickness and decreasing density, from local noon to the nightside driven by the thermal pressure. Further on the nightside, the LLBL becomes the magnetotail. Reconnection that brings the solar wind flux into the magnetosphere disconnects the tail flux from the magnetosphere and makes it back to the solar wind. Globally, the LLBL/magnetotail region maps to the sunward convection cells and north-Bz currents in the polar ionosphere. In this model, most of the solar wind particles gain access to the dayside cusps of the ionosphere and some within the rest of polar caps. Although much of the solar wind energy returns back to the solar wind, a portion of the energy is directly dissipated in the polar ionosphere through Joule heating and another portion is coupled to the low-latitude ionosphere through ionospheric current system. The latter portion drives the magnetospheric convection and eventually dissipates in the low-latitude ionosphere.