How well are interhemispheric asymmetries in ionospheric potential reproduced in global MHD models?
Abstract
Differences in the Sun-Earth coupling for the North and South (magnetic) poles cause big and prevalent effects in the configuration and dynamics of the magnetosphere and ionosphere. In fact, asymmetries are ubiquitous and play an important role in forming the «normal» state, prompting a need to study the magnetosphere and ionosphere as a coupled bi-polar system in its entirety. Global MHD models constitute a unique tool for understanding the morphology and dynamics of the coupled solar wind-magnetosphere-ionosphere system, including the asymmetries caused, for example, by dipole tilt and a significant east-west component in the interplanetary magnetic field. Both effects create complex potential patterns in the ionosphere with large differences and asymmetries between the northern and southern hemispheres. The degree to which these are reproduced correctly in the models is an important open question. One condition that model simulations should meet, in the absence of parallel electric fields, is that ionospheric footprints of closed field-lines are at the same potential in the two hemispheres. In order to understand how well models represent the ionospheric potential and symmetries or asymmetries thereof, it is of great interest to investigate how well the equal potential-condition is met by global MHD models. We report here on an investigation of the extent and comparison of this condition between four different global MHD models available for runs-on-request at the CCMC. We shall also discuss the implication for the use of the models in interpreting conjugate observations, e.g. of flows, currents, and particle precipitation, between the magnetosphere and ionosphere and between hemispheres.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSM41A..03J
- Keywords:
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- 3369 Thermospheric dynamics;
- ATMOSPHERIC PROCESSESDE: 2431 Ionosphere/magnetosphere interactions;
- IONOSPHEREDE: 2704 Auroral phenomena;
- MAGNETOSPHERIC PHYSICSDE: 2776 Polar cap phenomena;
- MAGNETOSPHERIC PHYSICS