Seasonal-Latitudinal Structure of the Diurnal Thermospheric Tide

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Abstract
The seasonal-latitudinal structure of the diurnal thermospheric tide is investigated for minimum and maximum levels of solar activity by numerically solving the linearized inseparable tidal equations for a spherical, rotating, viscous atmosphere with anisotropic ion drag. Variations in F-region ionospheric structure and the solar zenith angle dependence of the EUV heat source are major factors controlling the seasonal-latitudinal structure of the diurnal thermospheric tide. The combined interaction of the solar-cycle dependent background temperature profile (which controls the altitude of diffusion dominance) and variations in the seasonal structure of the ionospheric plasma with sunspot activity leads to a solar-cycle variation of the seasonal-latitudinal morphology of the diurnal tide. For instance, summer-winter differences in tidal winds at a given height are more pronounced during SSMAX as opposed to SSMIN. At a given level of solar activity, westerly winds, vertical winds and temperatures a... Abstract The seasonal-latitudinal structure of the diurnal thermospheric tide is investigated for minimum and maximum levels of solar activity by numerically solving the linearized inseparable tidal equations for a spherical, rotating, viscous atmosphere with anisotropic ion drag. Variations in F-region ionospheric structure and the solar zenith angle dependence of the EUV heat source are major factors controlling the seasonal-latitudinal structure of the diurnal thermospheric tide. The combined interaction of the solar-cycle dependent background temperature profile (which controls the altitude of diffusion dominance) and variations in the seasonal structure of the ionospheric plasma with sunspot activity leads to a solar-cycle variation of the seasonal-latitudinal morphology of the diurnal tide. For instance, summer-winter differences in tidal winds at a given height are more pronounced during SSMAX as opposed to SSMIN. At a given level of solar activity, westerly winds, vertical winds and temperatures a...

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