[P-EM11] Dynamics of Magnetosphere and Ionosphere

[PEM11-05] Aspects of simulating magnetosphere-ionosphere coupling via field-aligned current

*Astrid I Maute¹、Arthur D Richmond¹、Gang Lu¹ (1.High Altitude Observatory, National Center for Atmospheric Research, Boulder CO, 80301, USA)

キーワード：Magnetosphere-ionosphere coupling via field-aligned current, Interhemispheric assymetries, Middle and low latitude effects

Magnetosphere-ionosphere (MI) coupling is crucial in modeling the thermosphere-ionosphere (TI) response to geomagnetic activity. In general circulation models (GCMs) the MI coupling is frequently realized by specifying the ion convection and auroral particle precipitation patterns from, e.g., empirical models or assimilative models. Using assimilative models, such as the Assimilative Model of Ionospheric Electrodynamics (AMIE), has the advantage that the ion convection and auroral particle precipitation patterns are self-consistent and based on available observations. However, assimilating data can be time consuming and requires expert knowledge, and therefore it is so far not the standard way of MI coupling in GCMs. With the availability of AMPERE data, there is an increased interest of employing field-aligned currents (FAC) in GCMs to represent the MI coupling. The FAC from AMPERE captures interhemispheric differences in the MI coupling not represented by empirical ion convection models. However, since GCMs mostly employ prescribed high latitude ion convection patterns little is known about differences in the TI response to high latitude forcing by prescribed FACs.

In this study, we will compare with the help of a simulated geomagnetic storm the different MI coupling methods, i.e., AMIE, empirical ion convection and AMPERE field-aligned current. We illustrate the sensitivity of the Joule heating and low latitude electric field with respect of the spatial distribution of the aurora and ion convection for the different cases. The influence of interhemispheric differences in the MI coupling on the middle and low latitude thermosphere-ionosphere system will be examined.