parameterizations of Marine Stratus Microphysics Based on In Situ Observations: Implications for GCMS

Abstract

Airborne observations conducted in marine stratus over the cast coast of Canada during the North Atlantic Regional Experiment in the summer of 1993 are used to develop cloud microphysical parameterization schemes for general circulation models. Observations of cloud droplet number concentration (Nd), interstitial aerosol number concentration, temperature, vertical air velocity (w), and liquid water content (LWC) are considered, as well as determination of the effective radius (reff) and total particle concentration (interstitial aerosol + cloud droplet). Statistical techniques are used to obtain regression equations among the above parameters. For individual clouds, an inverse relationship between the interstitial aerosol concentration and droplet concentration is always observed. In general, variations in reff are determined by Nd as much as by LWC. The regression equations are compared with current parameterizations for GCMS. Results showed that multiple relationships are present among Nd, Nt, and w; and reff, LWC, and Nd.