Seasonal and hemispheric variations of the total auroral precipitation energy flux from TIMED/GUVI

The hemispheric power, which is the total auroral electron precipitation energy flux over the auroral oval area in one hemisphere, is calculated from the averaged energy flux derived from Far-ultraviolet emissions of the Global Ultraviolet Imager (GUVI) instrument on board the TIMED satellite. Using observations from 2002 to 2007, the seasonal variation in the hemispheric power are separated from its hemispheric dependence. The results show that there is almost no June/Southern-winter to December/Northern-winter difference under all conditions (Kp=1-5). On the other hand, under geomagnetically quiet conditions (Kp<=3), the hemispheric power shows significant summer-winter and June/Northern-summer to December/Southern-summer differences, which vary between 5%-35% and decrease with an increase in the Kp index. These seasonal variations in hemispheric power disappear under geomagnetically disturbed conditions (Kp=4, 5).