SURFACE ATMOSPHERIC HEAT-FLUX ANALYSIS ON THE LETTAU MODEL

Abstract

Determinations of the turbulent flux of heat at the earth's surface are made for the period 24?25 January 1950 at Manor, Texas, with use of mean vertical gradients of air temperature and wind speed, following the Lettau model of non-isotropic turbulence. Simultaneous measurements of net radiation at the surface and of heat interchange in the soil give independent measures of the eddy heat flux, which show reasonable agreement with theory under certain conditions. It is shown that these conditions are apparently such as to require the use of representative values of the potential-temperature difference over a height interval in the surface layer during daylight hours, and of the ratio of mean wind to adiabatic wind at a level in the surface layer at night. It is further observed that the use of the temperature profile in the computation of net heat flux during night hours gives rise to values of negative heat transfer greater in magnitude than theoretical critical limits.