Role of Mesoscale Convection in the Inner Magnetosphere

Abstract:

Transport through the Earth’s plasma sheet and inner magnetosphere is a combination of global-scale convection and mesoscale processes such as flux-tube interchange associated with propagation of bursty bulk flows and dipolarization fronts. It is now clear that mesoscale processes play a significant role in plasma sheet transport on closed magnetic field lines; however, it is not clear if they play a dominant role. In this paper, we will describe initial steps in attempting quantitative modeling of flux-tube interchange processes using a high-resolution version of the Rice Convection Model (RCM) that includes effects of inertial drifts. In our approach, we make three simplifying assumptions: (i) the communication between the equatorial plane and ionosphere occurs either instantaneously or with a given time lag, (ii) the pressure is isotropic and therefore constant along field lines, and (iii) for purposes of calculating the effect of inertia, all of a flux tube's mass is assumed to be concentrated in the equatorial plane. We will present idealized numerical simulations of a depleted flux tube propagation in the magnetosphere and its particle signature as well as auroral consequences. We will also describe the sensitivity of the results to the assumptions made in the inclusion of the inertia effects. Finally, we address the minimum required spatial resolution needed to include the physics of flux-tube interchange processes while describing the global magnetospheric convection on closed field lines.