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|Title:||Average auroral configuration parameterized by geomagnetic activity and solar wind conditions|
Evans, T. A.
|Publisher:||European Geosciences Union (EGU)|
|Citation:||Annales Geophysicae, 2010, 28 (4), pp. 1003-1012|
|Abstract:||Abstract. Average proton and electron auroral images are compiled from three years of observations by the IMAGE spacecraft, binned according to concurrent K[subscript: P] 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 K[subscript: P], 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 K[subscript: P] 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 K[subscript: P], 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.|
|Rights:||© Author(s) 2010. This work is distributed under the Creative Commons Attribution 3.0 License ( http://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.|
|Appears in Collections:||Published Articles, Dept. of Physics and Astronomy|
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