Switching between First-Order Closure Schemes in a Numerical Mesoscale Model

Abstract

Within the numerical mesoscale model described by McNider and Pielke (1981) the eddy exchange coefficients are estimated from either a local or nonlocal scheme. Switching between these is dependent on the sign of the surface heat flux. In inhomogeneous regions this switching is shown to be sensitive to the height of the stable planetary boundary layer. By defining the boundary layer height as the height to which turbulence generated by the wind shear falls to zero, a more realistic estimate can be obtained and the model is able to simulate observed potential temperature fields.