Paper#: 55
Poster #:
Session Name: Workshop 3A: M/I Coupling
Room: West Ballroom
Day: Tuesday
Time: 1:30-1:55 p.m.
Abstract Title: Response of Ionospheric Electric Fields, Currents, and Conductances to the Substorm Expansion Phase
PresentSurname: Greenwald, R.A.
All Authors: R.A. Greenwald
Abstract : Many of the ionospheric consequences of magnetospheric substorms have been well documented for many years. The most significant are enhanced magnetosphere-ionosphere coupling currents (the substorm current wedge), substorm-associated magnetic disturbances (most significantly the onset of negative magnetic bays), and the intensification and expansion of nightside auroral precipitation (the auroral bulge). Nightside current systems, magnetic disturbances and conductances are often enhanced by factors of 5-50 during the expansion and early recovery phases of the substorm. In contrast to these dramatic increases in conductance and current, the ionospheric electric field displays only modest changes during substorm expansion and may even be depressed. In this paper, we review past observations of currents, conductances, and electric fields that illustrate these differences. It appears that enhancements in ionospheric current are entirely due to enhancements in nightside ionospheric conductance caused by substorm-associated particle precipitation, an idea originally suggested by Kamide and Kokobun. However, the concept of an additional substorm-associated convection cell as predicted by several magnetic inversion analyses does not appear to exist and my have resulted from incorrect assessment of the magnitude of the nightside conductance enhancements. Possible reasons for the modest response of ionospheric electric fields will be discussed.