The Dependence of the Strength and Thickness of Field-Aligned Currents on Solar Wind and Ionospheric Parameters
Authors: Jay R. Johnson and Simon Wing
Abstract: Sheared plasma flows at the low-latitude boundary layer correlate well with early afternoon auroral arcs and eld-aligned currents [Sonnerup, 1980; Lundin and Evans, 1985]. We present a simple analytic model that relates solar wind and ionospheric parameters to the strength and thickness of field-aligned currents in a region of sheared velocity, such as the low latitude boundary layer. We compare the predictions of the model with DMSP observations and nd remarkably good scaling of the currents with solar wind and ionospheric parameters. The sheared boundary layer thickness is inferred to be around 3000km consistent with observational studies. The analytic model provides a simple way to organize data and to infer boundary layer structures from ionospheric data.
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Submitted to: Journal of Geophysical Research
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