The second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study is described. The field program consisted of nine flights in marine stratocumulus west-southwest of San Diego, California. The objective of the program was to better understand the physics a n d dynamics of marine stratocumulus. Toward this end special flight strategies, including predominantly nocturnal flights, were employed to optimize estimates of entrainment velocities at cloud-top, large-scale divergence within the boundary layer, drizzle processes in the cloud, cloud microstructure, and aerosol–cloud interactions. Cloud conditions during DYCOMS-II were excellent with almost every flight having uniformly overcast clouds topping a well-mixed boundary layer. Although the emphasis of the manuscript is on the goals and methodologies of DYCOMS-II, some preliminary findings are also presented—the most significant being that the cloud layers appear to entrain less and drizzle more than previous theoretical work led investigators to expect.

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Department of Atmospheric Sciences, University of California, Los Angeles, Los Angeles, California

National Center for Atmospheric Research, Boulder, Colorado

Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming

Gerber Scientific Inc., Reston, Virginia

Department of Chemistry, Drexel University, Philadelphia, Pennsylvania

CNRM Météo-France, Toulouse, France

Department of Atmospheric Sciences, University of Washington, Seattle, Washington

Desert Research Institute, Reno, Nevada

School of Meteorology, University of Oklahoma, Norman, Oklahoma

Joint Office for Science Support, University Corporation for Atmospheric Research, Boulder, Colorado

Institute of Geophysics, Warsaw University, Warsaw, Poland

Princeton University, Princeton, New Jersey

Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado

College of Oceanography and Atmospheric Sciences, Oregon State University, Corvallis, Oregon

A supplement to this article is available online (DOI: 10.1175/BAMS-84-5-Stevens)