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Testing the Hill model of transpolar potential with Super Dual Auroral Radar Network observations
Author(s) -
Shepherd S. G.,
Ruohoniemi J. M.,
Greenwald R. A.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl015426
Subject(s) - interplanetary spaceflight , ionosphere , solar wind , interplanetary magnetic field , geophysics , physics , computational physics , electric field , radar , magnetosphere , geodesy , geology , magnetic field , computer science , quantum mechanics , telecommunications
We use a data set consisting of periods for which the transpolar ionospheric potential (Φ) is well‐determined by Super Dual Auroral Radar Network (SuperDARN) data to test the Hill model. The Hill model, as formulated by Siscoe et al. [2002], specifies Φ as a function of solar wind speed and ram pressure, the interplanetary magnetic field, the reconnection electric field ( E ), and the ionospheric conductance (Σ). The periods used in our study were identified as times when the interplanetary electric field was quasi‐stable for and SuperDARN coverage was sufficient to determine Φ. SuperDARN‐determined Φ (Φ) is compared to Φ determined using the Hill model (Φ) for 1317 10‐min periods. A minimum in the root‐mean‐square difference between (Φ)( E ) and (Φ)( E ) is achieved when Σ = 23 S and a constant potential, Φ 0 = 17 kV, are used. Some aspects of the data agree very well for these values of Σ and Φ 0 , including the mean value of Φ( E ) and that both data sets clearly indicate saturation at higher values of E . The ram pressure dependence of (Φ), however, is inconsistent with that of (Φ) and suggests that Σ should be lower than 23 S. There is also significantly more variability in (Φ) for all values of E than the Hill model predicts.