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Dusk-Dawn Asymmetries in SuperDARN Convection Maps
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  • Maria-Theresia Walach,
  • Adrian Grocott,
  • Evan G. Thomas,
  • Frances A Staples
Maria-Theresia Walach
Lancaster University

Corresponding Author:m.walach@lancaster.ac.uk

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Adrian Grocott
Lancaster University
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Evan G. Thomas
Dartmouth College
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Frances A Staples
University of California Los Angeles
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Abstract

The Super Dual Auroral Radar Network (SuperDARN) is a collection of radars built to study ionospheric convection. We use a 7-year archive of SuperDARN convection maps, processed in 3 different ways, to build a statistical understanding of dusk-dawn asymmetries in the convection patterns. We find that the dataset processing alone can introduce a bias which manifests itself in dusk-dawn asymmetries. We find that the solar wind clock angle affects the balance in the strength of the convection cells. We further find that the location of the positive potential foci is most likely observed at latitudes of 78◦ for long periods (>300 minutes) of southward IMF, as opposed to 74◦ for short periods (<20 minutes) of steady IMF. For long steady dawnward IMF the median is also at 78◦. For long steady periods of duskward IMF, the positive potential foci tends to be at lower latitudes than the negative potential and vice versa during dawnward IMF. For long periods of steady Northward IMF, the positive and negative cells can swap sides in the convection pattern.We find that they move from ~0-9 MLT to 15 MLT or ~15-23 MLT to 10 MLT, which reduces asymmetry in the average convection cell locations for Northward IMF. We also investigate the width of the region in which the convection returns to the dayside, the return flow width. Asymmetries in this are not obvious, until we select by solar wind conditions, when the return flow region is widest for the negative convection cell during Southward IMF.