Tidal Winds at Ionospheric Heights

Publisher Website
Google Scholar
Abstract
Tidal winds excited by thermal or gravitational forces propagate into ionospheric altitudes and generate currents by dynamo action. The vertical and horizontal structure of these winds is altered by various dissipative forces which gain importance at these altitudes. In this paper, the dissipative effects of the Lorentz force, molecular viscosity, and molecular heat conductivity are considered in terms of a perturbation treatment. Both the rotation and the sphericity of the earth are explicitly taken into account. For propagating tidal modes, the dissipative effects are found to reduce and reverse the amplitude growth with height predicted by dissipationless tidal theory. Quantitative differences are obtained between the behavior of tides on a rotating earth and of internal gravity waves of comparable frequencies and vertical wavelengths on a non‐rotating earth.