I have developed two single column boundary layer turbulence closure models- One, which runs with mass flux closure and the other which runs with standard turbulence closure following Bougeault. For the mass flux closure method, w'w'w', w'w' , all second order vertical fluxes, and mean quantities are the only prognostic variables. Variances and all other higher order moments are diagnosed in terms of the differences in properties between the updrafts and downdrafts. Results from this model are compared with observations and with those obtained using the standard turbulence closure model. The two models are run with a variety of tropical and sub-tropical cases. These cases include an Atlantic Stratocumulus Transition Experiment (ASTEX) stratocumulus case, a Barbados Oceanographic and Meteorological Experiment (BOMEX) shallow non-precipitating cumulus case, and an Atlantic Tradewind Experiment (ATEX) classical trade wind cumulus case. Results will be shown and conclusions drawn as to the strengths and weaknesses of the two closure methods