ORGANIZATION AND REPRESENTATION OF BOUNDARY-LAYER CLOUDS

This study is intended to summarize and to simplify the complicated pr ocesses in boundary layer cloud regimes using a single parameter, Q(1) , the normalized saturation deficit. With the aid of large eddy simula tion (LES) data from different boundary layer cloud regimes it is illu strated i) that the in-cloud buoyancy flux is maximized when the fract ional cloudiness approaches zero; ii) that the ensemble average buoyan cy flux possesses two maxima, one for the trade wind cumulus case and one for the stratocumulus case; and iii! that the preferred mode for b oundary layer clouds is either small cumuli or high values of cloudine ss, and that cloudiness transitions from one regime to the other are d ifficult to represent numerically as in the transition regime the clou d-water-related variables are very parameter sensitive. In addition, t he importance of the contribution of the liquid water flux to the in-c loud and total buoyancy flux is outlined, and simple analytical and em pirical methods are presented to compute the liquid water Bur as a fun ction of the fluxes of conserved variables for different boundary laye r cloud regimes.