American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article    Cited by

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 102, NO. D12, PAGES 13,527–13,534, 1997

A modeling study of the effect of drizzle on cloud optical depth and susceptibility

Graham Feingold

Cooperative Institute for Research in the Atmosphere and NOAA Environmental Technology Laboratory Boulder, Colorado


Reinout Boers

Division of Atmospheric Research, CSIRO, Aspendale, Victoria, Australia


Bjorn Stevens

Department of Atmospheric Science, Colorado State University, Fort Collins


William R. Cotton

Department of Atmospheric Science, Colorado State University, Fort Collins


Abstract

This paper examines the impact of drop spectral broadening, generated by the collection process, on the optical depth, cloud albedo, and susceptibility of marine stratocumulus clouds. The results are arrived at using (1) the output from a simple box model calculation of collection and (2) the output from an eddy-resolving model of stratocumulus clouds that explicitly represents the size distribution of the drops. It is shown that commonly used relationships for cloud optical properties developed for narrow spectra do not generally apply to spectra undergoing spectral broadening. The optical depth dependence on the drop number concentration to the one-third power is shown to be an overestimate of the optical depth when spectra broaden through collection. In addition, the cloud susceptibility dependence on drop number is shown to be larger for spectra experiencing broadening than for narrow spectra.

Received 20 November 1996; accepted 26 March 1997.

Read Full Article    Cited by

Citation: Feingold, G., R. Boers, B. Stevens, and W. R. Cotton (1997), A modeling study of the effect of drizzle on cloud optical depth and susceptibility, J. Geophys. Res., 102(D12), 13,527–13,534.