Observations and model predictions of substorm auroral asymmetries in the 
conjugate hemispheres
 
N. Ostgaard, N. A. Tsyganenko, S. B. Mende, H. U. Frey, T. J. Immel, 
M. Fillingim, L. A. Frank, and J. B. Sigwarth


Based on imaging data from the Polar VIS Earth camera and the IMAGE-FUV 
instruments we have documented how the IMF orientation and the dipole tilt 
angle act as the main and the secondary controlling factors of the relative 
displacement of the aurora in the conjugate hemispheres. Comparing our results 
with the asymmetries predicted by recent empirical magnetospheric models, we 
show that the assumed partial penetration of the IMF into the magnetosphere is 
clearly supported by observations, but the modeled conjugate shifts were found 
to be an order of magnitude smaller than the observed ones. 

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Geophysical Research Letters, 32, L05111, doi:10.1029/2004GL022166, 2005