TitleSolar activity dependence of nightside aurora in winter conditions
Publication TypeJournal Article
Year of Publication2016
AuthorsZhou, S, Luan, X, Dou, X
JournalJournal of Geophysical Research: Space Physics
Paginationn/a - n/a
Date Published02/2016
Keywordsauroral conjugate effects; auroral geomagnetic activity variation; auroral imaging scaling; auroral solar cycle variation

The dependence of the nightside (21:00–03:00 MLT; magnetic local time) auroral energy flux on solar activity was quantitatively studied for winter/dark and geomagnetically quiet conditions. Using data combined from Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics/Global Ultraviolet Imager and Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager observations, we separated the effects of geomagnetic activity from those of solar flux on the nightside auroral precipitation. The results showed that the nightside auroral power was reduced by ~42% in solar maximum (F10.7 = 200 sfu; solar flux unit 1 sfu = 10−22 W m−2 Hz−1) with respect to that under solar minimum (F10.7 = 70 sfu) for the Kp = 1 condition, and this change rate became less (~21%) for the Kp = 3 condition. In addition, the solar cycle dependence of nightside auroral power was similar with that from both the premidnight (21:00–23:00 MLT) and postmidnight (01:00–03:00 MLT) sectors. These results indicated that as the ionospheric ionization increases with the enhanced auroral and geomagnetic activities, the solar activity dependences of nightside auroral power become weaker, at least under geomagnetically quiet conditions.

Short TitleJ. Geophys. Res. Space Physics

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