Closure scheme for stably stratified turbulence without critical Richardson number

Abstract This paper presents a new modification of the second order turbulence closure that removes critical gradient Richardson number limitation typically found in Mellor-Yamada style models. The mean wind speed and potential temperature profiles are derived for newly modified model terms similarity structure functions depending on number. derivation is based boundary layer approximation neutral to very stable stratification conditions. Some recent assumptions pressure-temperature heat flux considered. Variances covariances turbulent fluctuations also investigated with respect predictions confronted some well known