PARMETRIZATION OF THE DEPTH OF THE ENTRAINMENT ZONE ABOVE THE DAYTIMEMIXED-LAYER

A new parametrization for the depth of the daytime entrainment zone is presented. It is derived from a simple energy budget, in which the ed dy velocity in the mixed layer penetrating the overlying stable entrai nment zone is taken to be proportional to the characteristic top-down velocity scale. It gives a better ordering of the data of two earlier studies by Deardorff et al. and Boers and Eloranta as compared with tr aditional parcel theory based on the bottom-up velocity scale. Further more, it can be seen that the data from the two studies belong to diff erent regimes of the characteristic scaling parameter.