The National Center for Atmospheric Research thermosphere general circulation model (TGCM) is utilized to perform a series of controlled experiments aimed at better understanding the interactive coupling between ionospheric plasma densities and thermospheric neutral winds. The experiments are simple and controlled so as to facilitate identification of governing mechanisms. The interaction is accomplished by parameterizing the F layer peak height (hmF2) in an empirical ionosheric model in terms of the meridional wind (vsouth) and forcing hmF2 and vsouth to remain mutually coupled in a dynamical calculation.

Interactive computations are performed where the TGCM is driven by 30-kV and 90-kV cross polar cap potentials are compared with corresponding reference simulations where hmF2 is constrained to a balance height near 280 km with a small (~20 km) diurnal variation. Mutual coupling between hmF2 and vsouth is found to be weak during the daytime when the F layer exhibits a broad vertical structure. At night, when the F2 layer is more localized, the neutral dynamical structure is dependent on whether hmF2 is significantly above or below the altitude (approximately 275--300 km) at which ion drag effectively competes with viscosity in the neutral momentum balance. At Arecibo during both levels of high-latitude forcing, the premidnight elevation (+75 km) of hmF2 relative to a nighttime balance height of approximately 290 km is accompanied by an increase (~50 m s-1) in the zonal wind above 250 km relative to the noninteractive simulation. A much smaller effect, characterized by an 8-hour periodicity spanning 24 hours, is seen in the meridional wind component. At Millstone Hille under the 90-kV forcing, a 40-km ascent of hmF2 to 330 km around midnight due to southward winds is accompanied by a 40--60m s-1 increase in the westward wind above 200 km. Interestingly, the southward wind is diminished in magnitude by about 35 m s-1 compared to the noninteractive simulation, opposite to what one would expect if the ion drag presented to the meridional flow were reduced. We interpret this as a Coriolis effect induced by the increased westward wind. ¿ American Geophysical Union 1990