A Study of the Diurnal Thermal Wave in a Non-Grey Atmosphere

Abstract

The form of the diurnal thermal wave driven by a harmonically oscillating ground temperature into a semi-infinite homogeneous non-grey absorbing atmosphere is studied, neglecting convection and molecular conduction. Results are calculated for the terrestrial atmosphere and, with fair accuracy, for the martian atmosphere. The penetration heights are about 10 m and 200 m, respectively. In both cases the wave amplitude decays at large heights inversely with the height, and the phase lag relative to the ground approaches ?/2. The grey-absorption solution and the solution predicted by the quasi-transparent model of Gierasch and Goody are compared with the non-grey one. The grey solution is qualitatively good if the absorption coefficient is chosen so that the penetration depth equals that of the non-grey solution. The effects of convective heat transport are discussed.