C. B. Boyle, P. H. Reiff, A. L. Urquhart
(All at Space Physics and Astronomy Department, Rice University,
Houston,TX, 77251-1892)
M. R. Hairston
(Hanson Center for Space Sciences, University of Texas at Dallas,
01731)
Empirically based estimates of the total cross polar cap potential drop (F) are shown for the 18-20 October 1995 magnetic cloud event. For this event, we compare determinations of F from direct measurements of ionospheric convection (using DMSP satellites) with recent empirical models using WIND IMF and plasma data. Models of the asymptotic steady state F(IMF) are contrasted with methods using several hours of high time resolution IMF history to represent F during this event. Several activity index driven estimates of F are also included, illustrating the level of accuracy that can be achieved depending on the availability of satellite data.
The long history/high time resolution IMF driven estimates significantly out perform the other methods, particularly in characterizing the peak in F on day 292. We discuss the estimates from several techniques for modeling F during the steep step-like changes in the IMF which occurred during the event. Also, although the results are noticeably inferior to the (WIND based) IMF driven estimates, it is possible to usefully model F, even for an extraordinary event such as this, using a relatively low time resolution global input such as Kp.
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