Simultaneous observations of the auroral ovals in both hemispheres under 
varying conditions 

T.J. Stubbs, R. R. Vondrak, N. Ostgaard, J.B. Sigwarth, and L.A. Frank

This is the first analysis to use simultaneous observations of the entire
auroral ovals in both hemispheres to track their location. Data was used from
the Polar VIS and IMAGE FUV imagers on 23 October 2002 and plotted in AACGM
coordinates. Results showed the expected IMF By-dependent asymmetry along the
dawndusk meridian; however, there was an unexpected offset of both ovals toward
dawn. Evidence is also shown for an asymmetry along the noon-midnight meridian
dependent on both dipole tilt angle and the sense of IMF Bx. During a brief
period of weak IMF Bz > 0 and IMF Bx >0,the southern oval is observed to move
equatorward relative to the northern oval, consistent with tail lobe
reconnection occurring only in the southern hemisphere. This has important
implications for the global response of the magnetosphere to different
interplanetary conditions. 

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Geophysical Research Letters, 32, L03103, doi:10.1029/2004GL021199, 2005