Radiative and turbulent fluxes in the nocturnal boundary layer

Abstract

This study examines the relative contributions of turbulent and radiative flux divergences to nocturnalcooling by analyzing data from the 60-m flux tower in CASES99 and using an offline model of theradiative flux. The sensitivity of radiative cooling to structure of the atmosphere near the surface is firstexamined in terms of artificial profiles. In general, the radiative cooling is proportional to the negativecurvature of the temperature profile, magnitude of the specific humidity and the deficit of the groundsurface temperature. For the days examined, the radiative flux divergence appears to control the initialformation of the surface inversion at the beginning of the night when the turbulence collapses.