Local temperature changes in the mesosphere due to a “horizontally propagating” turbulent patch

Abstract

In this study, we model thermal changes in the background atmosphere due to a horizontally” moving” turbulent patch. We divide the process of mutual adjustment of the turbulent patch and the background atmosphere into the two stages: (i) Fast high-to-low transition of the atmospheric stability within the turbulent patch induced by strong adiabatic mixing within the “moving” turbulent patch. (ii) Slow adjustment of the ambient background atmosphere to a quasi-stabilized, near-adiabatic thermal stratification within the turbulent patch. Within the framework of the first stage, assuming the existence of a background downward heat flux, we developed a boundary value problem for a non-homogeneous heat equation that accounts for turbulent dissipative heating and mixing. This two-point boundary value problem was solved analytically by applying the Fourier method (separation of variables) to the thickness of the turbulent patch. The solution obtained tends towards equilibrium as the distance from the front border of the “moving” turbulent patch increases. Within the scope of the second stage, we solved the problem of thermal coupling of the two heat-transfer domains, one of which is characterized by a high coefficient of heat transfer. Solving this problem is the basis of our proposing that the thermal structure of a turbulent patch does not change under the influence of an ambient atmosphere, while the ambient atmosphere is cooled slowly above the turbulent patch and warmed slowly below it. Consequently, it is shown that the model temperature profiles demonstrate the same features as those observed in mesospheric inversion layers (MILs): temperature inversions and a near-adiabatic lapse rate between them.