Ship-Based Observations of the Diurnal Cycle of Southeast Pacific Marine Stratocumulus Clouds and Precipitation

• DOI: 10.1175/jas-d-13-01.1
• Publication Date: 2013-07-27T05:04:35Z
• Authors: Casey D. Burleyson; Simon P. de Szoeke; Sandra E. Yuter; Matt Wilbanks; W. Alan Brewer
• Keywords: Drizzle; Sunrise; Diurnal cycle; Marine stratocumulus; Diurnal temperature variation; Sunset

Abstract The diurnal cycle of marine stratocumulus in cloud-topped boundary layers is examined using ship-based meteorological data obtained during the 2008 Variability American Monsoon Systems (VAMOS) Ocean–Cloud–Atmosphere–Land Study Regional Experiment (VOCALS-REx). high temporal and spatial continuity ship data, as well 31-day sample size, allows transition degree coupling stratocumulus-topped layer to be resolved. amplitude variation was comparable magnitude longitudinal differences between regions east west 80°W for most cloud, surface, precipitation variables examined. terms areal coverage, number drizzle cells, estimated rain rate. East 80°W, cell frequency area peaks just prior sunrise. West total at 0300 local solar time (LST), 2–3 h before Peak 3 times higher compared 80°W. waning several hours ramp up shortwave fluxes may related peak frequencies west. ensemble effect localized subcloud evaporation make a self-limiting process where density cells sufficiently high. daytime reduction vertical velocity variance less coupled accompanied by enhanced stratification potential temperature buildup moisture near surface.