A Compendium of Theoretical Atmospheric Tidal Structures. Part I. Model Description and Explicit Structures Due to Realistic Thermal and Gravitational Excitation

摘要

This report documents the equations, coefficient parameterizations, method of numerical solution, and results from a theoretical (numerical) model of atmospheric tidal oscillations from the surface to 400 km. The westerly, northerly, and vertical winds and temperature are governed by four second order partial differential equations derived from the perturbation fluid equations for momentum, continuity, thermal energy, and the ideal gas law applied to a spherical, rotating, viscous atmosphere with anisotropic ion drag. The equations represent perturbations about a basic atmospheric state with latitude- and height-dependent mean winds, temperature, and composition. Model parameterizations described include mean winds and temperatures, molecular and eddy viscosity and thermal conductivity, ion-neutral collision frequency for momentum transfer, and solar thermal and lunar gravitational forcing. Thermal excitation occurs via absorption of EUV and UV radiation in the thermosphere, H2O insolation absorption in the troposphere and lower stratosphere, and O3 insolation absorption in the mesosphere. Ion-neutral coupling provides an important semidiurnal momentum source in the F-region. In addition, extensive tabulations and figures representing numerical solutions of diurnal and semidiurnal temperatures and winds every 6 deg of latitude from the surface to 400 km are presented for equinox and solstice conditions.