A simple parameterization of longwave radiative cooling with application to the atmospheric boundary layer for clear sky conditions

A simple parameterization is proposed to obtain longwave radiative cooling rates, which can be used for atmospheric boundary-layer simulations on clear days in mid-latitudes. The net flux difference which is set to zero at the surface, can be parameterized with the use of three variables: the surface temperature, the lowest level (1.5 m) air temperature, and the total amount of water vapor. If these three elements, along with the water vapor profile are known, it is possible to estimate the cooling rate due to longwave radiation. The results of this parameterization are in good agreement with those of a precise scheme (Roach and Slingo, 1979), within a range of ± 1°C/day of diurnal change for boundary-layer simulations.