AN APPLIED-MODEL FOR THE HEIGHT OF THE DAYTIME MIXED-LAYER AND THE ENTRAINMENT ZONE

A model is presented for the height of the mixed layer and the depth o f the entrainment zone under near-neutral and unstable atmospheric con ditions. It is based on the zero-order mixed layer height model of Bat chvarova and Gryning (1991) and the parameterization of the entrainmen t zone depth proposed by Gryning and Batchvarova (1994). However, mast zero-order slab type models of mixed-layer height may be applied. The use of the model requires only information on those meteorological pa rameters that are needed in operational applications of ordinary zero- order slab type models of mixed-layer height: friction velocity, kinem atic heat flux near the ground and potential temperature gradient in t he free atmosphere above the entrainment zone. When information is ava ilable on the horizontal divergence of the large-scale flow field, the model also takes into account the effect of subsidence, although this is usually neglected in operational models of mixed-layer height owin g to lack of data. Model performance is tested using data from the CIR CE experiment.