ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-28-1003-2010 Average auroral configuration parameterized by geomagnetic activity and solar wind conditions Milan S. E. 1 Evans T. A. 1 Hubert B. 2 Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK Laboratory of Planetary and Atmospheric Physics, University of Liége, Liége, 4000 Belgium 22 04 2010 28 4 1003 1012 Copyright: © 2010 S. E. Milan et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/28/1003/2010/angeo-28-1003-2010.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/28/1003/2010/angeo-28-1003-2010.pdf

Average proton and electron auroral images are compiled from three years of observations by the IMAGE spacecraft, binned according to concurrent <I>K<sub>P</sub></I> and upstream solar wind conditions measured by the ACE spacecraft. The solar wind parameters include solar wind velocity, density, and pressure, interplanetary magnetic field (IMF) magnitude and orientation, and an estimate of the magnetopause reconnection rate. We use both (a) the overall variation in brightness in the images and (b) the variation in location of the aurorae with respect to the binning parameters to determine which parameters best order the auroral response. We find that the brightness varies by a factor of ~50 with <I>K<sub>P</sub></I>, a similar amount with estimated dayside reconnection voltage, ~15 with the IMF, ~3 with solar wind density, ~2 with solar wind velocity, and ~5 with pressure. Clearly, geomagnetic activity as measured by <I>K<sub>P</sub></I> and auroral dynamics are closely associated. In terms of the solar wind-magnetosphere coupling that drives auroral dynamics, the IMF is of paramount importance in modulating this, with solar wind speed and density playing a lesser role. Dayside reconnection voltage, derived from the solar wind velocity and IMF magnitude and orientation, orders the data almost as well as <I>K<sub>P</sub></I>, though we find a plateau in the auroral response between voltages of 100 and 150 kV. We also discuss changes in configuration and overall size of the average auroral oval with upstream conditions.

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