Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Coupling between the Magnetosphere and Upper Atmosphere

Naomi Maruyama

We have developed a self-consistent first-principles model of the inner magnetosphere and thermosphere-ionosphere-plasmasphere, in order to understand the response of the electrodynamic interactions within the coupled system and the role of the electrodynamics in restructuring the ionosphere, plasmasphere and thermosphere, in particular, during geomagnetically active conditions. Modeling of the storm-time ionospheric electrodynamics requires a description of the two disturbance mechanisms: prompt penetration and disturbance dynamo. We have coupled the Rice Convection Model (RCM), used to calculate the region 2 field aligned currents from the inner magnetosphere which control the shielding process of the high latitude convection electric field, and the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) model, used to calculate the time-dependent conductivities and neutral winds that are the key to describe the disturbance dynamo as well as the quiet-time ionospheric wind dynamo.

Self-consistency in the electrodynamic coupling between RCM and CTIPe is accomplished by using a common global electrodynamic solver. As compared to the classical picture of prompt penetration, our model results from the non self-consistent coupling suggest a possibility that penetration effects can have a longer lifetime when the IMF Bz is large and southward, as a consequence of the ineffective shielding resulted from the magnetospheric reconfiguration. Furthermore, our simulations indicate that the arrival of the disturbance dynamo effect in the low latitude ionosphere can possibly be faster than previously believed, as the disturbance dynamo is modified by the changes in the conductivity and neutral wind initiated by the penetration effect. Comparison of the results from the combined models with observations under a variety of conditions demonstrates that our models are capable of reproducing many of the observed features in the ionosphere. In this paper, the electrodynamic interactions will be discussed using the fully self-consistently coupled model, and its impact on the low latitude coupled ionosphere- thermosphere system.