GEM: Modeling of Magnetosphere-Ionsophere Coupling (MIC) at High and Mid-Latitudes

University Of Minnesota-Twin Cities, Minneapolis MN

Investigators

Abstract

The coupling of the magnetosphere and ionosphere is a critical problem to the dynamics of the magnetosphere at both high and mid-latitudes. Much of the information that is available about this dynamics comes from arrays of ground magnetometers and ionospheric radars that can give multi-point observations of these processes. This project will model the propagation of electromagnetic energy through this system to better understand the relationship between magnetospheric and ionospheric processes and the observed signatures on the ground. The main tool to be used in this investigation is a linear three-dimensional Magneto-HydroDynamics (MHD) wave modeling code that has been cast in non-orthogonal dipole coordinates in order to better model the lower altitude parts of magnetospheric field lines. This code has been successfully used to model of the propagation of Pc1 pulsations through the ionospheric waveguide and the formation of Pc3 field line resonances in the dayside magnetosphere. This code is complementary to both global MHD models that describe convection in the outer magnetosphere and to the Rice Convection Model (RCM) that models hot particle convection in the inner magnetosphere. As such, it will be useful as a means to better understand the electrodynamic magnetosphere-ionosphere coupling processes at low altitudes that are not well covered by either of these other two models. The wave modeling code is well suited to comparing observations at various points in the magnetosphere and ionosphere. Thus, the project will compare date from satellites, ionospheric radars, and ground magnetometers with the results from the model. The research will focus on three specific topics: (1) The propagation of ULF waves in the plasmasphere, (2) the coupling between electric fields at high and mid-latitudes during magnetic storms, and (3) The feedback dynamics of the ionosphere in response to field-aligned currents. The first of these problems will involve the extension of currently available code to include the dynamics of the ionosphere. These extensions have already been included in simpler versions of the code. The second and third problems will benefit from model improvements in which the ionospheric density and conductivity are varied in all three dimensions, including day-night asymmetry and the variation of plasmasphere density with local time. This work will largely be done by graduate students, who will be trained in the art of scientific computation as well as the physics understanding necessary to interpret the results of not only the numerical results but also the data obtained by satellites, radars, and ground magnetometers. In addition, the work will serve the purposes of the Geospace Environment Modeling (GEM) program by developing a magnetosphere-ionosphere coupling model that can be integrated into a Geospace General Circulation Model (GGCM).