Auroral Energy Flux Distribution Over the Nightside Auroral Oval Observed by the DMSP F16/SSUSI:Seasonal, Geomagnetic, and Solar Activity Dependences

摘要

The present work investigates variations in the relative strengths of average premidnight and postmidnight aurorae. The average auroral energy flux data for the southern hemisphere in 2004-2015 are taken from the Special Sensor Ultraviolet Spectrographic Imager onboard the Defense Meteorological Satellite Program F16 satellite. The main findings are as follows: (1) In local winter, the maximum auroral energy flux over the oval is located in the premidnight sector (18:00-00:00 magnetic local time) under geomagnetically quiet condition (Kp = 1) and moves toward the postmidnight sector (00:00-06:00 magnetic local time) as the Kp index increases. (2) In local summer, the maximum energy flux occurs in the postmidnight for higher solar activities (F10.7 > 100 sfu). (3) The premidnight bulge of the auroral energy flux is most prominent under winter, solar minimum and geomagnetically quiet (Kp = 1) conditions. (4) Relatively more auroral energy tends to be deposited in the postmidnight sector than in the premidnight sector as Kp increases. These results show that the auroral energy over the nightside oval is redistributed on average as the season, solar flux, and geomagnetic activity change. This would substantially affect the thermosphere and ionosphere at high latitudes.