PARAMETERIZATIONS OF MARINE STRATUS MICROPHYSICS BASED ON IN-SITU OBSERVATIONS - IMPLICATIONS FOR GCMS

Airborne observations conducted in marine stratus over the east coast of Canada during the North Atlantic Regional Experiment in the summer of 1993 are used to develop cloud microphysical parameterization schem es for general circulation models. Observations of cloud droplet numbe r concentration (N-d), interstitial aerosol number concentration, temp erature, vertical air velocity (w), and liquid water content (LWC) are considered, as well as determination of the effective radius (r(eff)) and total particle concentration (interstitial aerosol + cloud drople t). Statistical techniques are used to obtain regression equations amo ng the above parameters. For individual clouds, an inverse relationshi p between the interstitial aerosol concentration and droplet concentra tion is always observed. In general, variations in r(eff) are determin ed by N-d as much as by LWC. The regression equations are compared wit h current parameterizations fdr GCMs. Results showed that multiple rel ationships are present among N-d, N-t, and w; and r(eff), LWC, and N-d .