CLOUDINESS AND MARINE BOUNDARY-LAYER DYNAMICS IN THE ASTEX LAGRANGIANEXPERIMENTS .2. CLOUDINESS, DRIZZLE, SURFACE FLUXES, AND ENTRAINMENT

The Analysis of the Atlantic Stratocumulus Transition Experiment (ASTE X) Lagrangians started in Part I is continued, presenting measurements of sea surface temperature, surface latent and sensible heat fluxes f rom bulk aerodynamic formulas, cloud fraction, and drizzle rate for th e two Lagrangians, mainly using data from horizontal legs down by the Electra and C130. Substantial drizzle, averaging 1 mm day(-1) at the s urface, was measured during the first Lagrangian. The surface fluxes i ncreased rapidly as the air mass advected over rapidly increasing SST. Cloud fraction remained high throughout. During the second Lagrangian , drizzle formed in the stratocumulus layer but mainly evaporated in t he deep, dry cumulus layer and the subcloud layer before reaching the surface. Stratocumulus cloud cover was thickest when moist air lay abo ve the inversion and then it dissipated to leave only cumuli once dry air advected over the inversion. Three methods are compared for determ ining entrainment rate (European Centre for Medium-Range Weather Forec asts analyses of mean vertical motion, calculation of a water budget, and the ozone flux-jump method). While all three methods have signific ant uncertainties, their predictions are all consistent with an entrai nment rate of 0.7 +/- 0.3 cm s(-1) for the first Lagrangian and 0.6 +/ - 0.3 cm s(-1) for the second Lagrangian. Corresponding estimates of t he time-dependent horizontal divergence are also presented. Estimates of the cumulus mass flux, internal mixing time, and entrainment diluti on time for the boundary layers observed during the two Lagrangians ar e also presented.