Paper#: 73
Poster #: 22
Session Name: Poster Session 1
Room: East Ballroom
Day: Tuesday
Time: 10:10 a.m.-Noon
Abstract Title: Ionospheric Influence on the Global Characteristics of Electron Precipitation during Substorms
PresentSurname: Chua, D.
All Authors: D. Chua, G. Parks, M. Brittnacher, G. Germany, C. Carlson
Abstract : A comparison of coordinated optical and in situ observations of the aurora during substorms occurring in different seasons is presented to provide further evidence for the emerging view that the ionospheric boundary conditions at the foot of auroral field lines play a significant role in determining the synoptic scale structure of the aurora. Previous statistical studies of the seasonal dependence of auroral structure have focused on contrasting the characteristics of the aurora near winter and summer solstice when the nightside auroral oval is either in complete darkness or sunlit. We generalize our seasonal analysis of the aurora to include events occurring near the equinoxes in addition to periods near winter and summer solstice. Moreover, we extend the results of previous studies of ionospheric effects on the aurora by examining how seasonality affects shorter time scale variations in auroral structure associated with substorms. It is shown that the characteristic time for substorm activity is roughly a factor of three longer for events occurring in darkness than for those when the ionosphere is sunlit. From our combined analysis of Polar UVI remote sensing and FAST particle measurements, we find that intense, discrete aurora associated with substorms persist longer during events that occur in a dark ionosphere by roughly a factor of three over those that happen in sunlit conditions. Our results suggest that the ionosphere plays a significant role in setting the time scale of auroral phenomena.