Global modeling of the mesoscale buildup of the ring current and its role in magnetosphere-ionosphere coupling

During geomagnetically active periods plasma is transported from the magnetotail into the inner magnetosphere to become the ring current. The transpot of plasma into the ring current occurs at different spatial and temporal scales, from global quasi-steady convection to bursty bulk flows (BBFs), with typical cross-tail extents of 1-3 Earth radii. During its enhancement, the ring current plays a critical role in magnetosphere-ionosphere coupling. Ring current ions build up plasma pressure in the inner magnetosphere and will drive field-aligned currents which must close in the ionosphere, while electrons will lead to diffuse precipitation and enhanced ionospheric conductance which shape the ionospheric path of current closure. Current closure in the ionosphere will couple to the thermospheric neutral population, via Joule heating, and alter the dynamics of the plasmasphere, via the penetration electric field in the inner magnetosphere. 

Understanding the relative role of convection at different spatial scales in both the buildup of the ring current and its broader effects on geospace coupling is an area of active interest and one of the core science questions of the Center for Geospace Storms. In this talk I will describe how addressing this question has informed the development of the Multiscale Atmosphere Geospace Environment (MAGE) model and highlight several recent modeling studies which illustrate the central role of mesoscale processes.