Generation of Field Aligned Currents during IMF By; mechanisms and theory

Paul Tenfjord1, Nikolai Ostgaard2, Kristian Snekvik1, Karl Laundal3 and Jone Peter Reistad4, (1)University of Bergen, Birkeland Centre for Space Science, Bergen, Norway, (2)University of Bergen, Department of Physics and Technology, Bergen, Norway, (3)DTU Space, Kongens Lyngby, Denmark, (4)University of Bergen, Bergen, Norway
Abstract:
Studies have revealed that the aurora is not always symmetric between the two hemispheres. Based on concurrent observations of the IMF orientation, it has been proposed that one explanation is asymmetries in magnetic field aligned currents, that arise due to non-uniform penetration of IMF By to the closed magnetosphere. According to the theory, the asymmetries in Birkeland currents are a manifestation of the hemispheric asymmetries in the curl of the magnetic field associated with such a penetration. We study By penetration theoretically, using MHD modelling, and investigate the associated currents. We address the validity of the proposed mechanisms using models and theory, and show how IMF By influences the coupling between the two hemispheres.
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