Observations and numerical simulations of the diurnal cycle of the EUROCS stratocumulus case

• DOI: 10.1256/qj.03.139
• Publication Date: 2005-02-22T23:38:04Z
• Authors: Peter G. Duynkerke; Stephan R. de Roode; Margreet C. van Z...; Javier Calvo; Joan Cuxart; Sylvain Cheinet; Andreas Chlond; Hervé Grenier; Piet J. Jonker; Martin Köhler; Geert Lenderink; David Lewellen; Cara‐lyn Lappen; Adrian P. Lock; Chin‐hoh Moeng; Frank Müller; Dolores Olmeda; Jean‐marcel Piriou; Enrique Sánchez; Igor Sednev
• Keywords: Liquid water path; Diurnal cycle; Entrainment (biomusicology); Marine stratocumulus; Cloud albedo

Abstract As part of the European Project on Cloud Systems in Climate Models, diurnal cycle stratocumulus has been simulated with Large‐Eddy Simulation (LES) models and Single Column Models (SCMs). The were initialized compared observations collected marine July 1987 during First International Satellite Climatology Regional Experiment. results six LES are found to be a fair agreement observations. They all capture distinct variation cloud liquid‐water path, turbulence profiles clearly show decoupled boundary layer daytime vertically well‐mixed night. Entrainment relatively dry warm air from just above inversion into is major process modifying thermodynamic structure differences that arise path evolution can therefore attributed mainly entrainment rate. mean rates computed model 0.58±0.08 cm s −1 0.36±0.03 for night‐time periods, respectively. If horizontal domain size enlarged, mesoscale fluctuations develop. This leads broader distribution reduction albedo. To assess quality representation general‐circulation models, ten SCMs results. SCM latent sensible heat fluxes at surface agree fairly well Many predict which much too low, cover smaller than unity, tops lower larger amount downwelling short‐wave radiation absorbed sea surface. Improvement parametrizations needed better SCMs. Observations different cases compared. observed Atlantic clouds Stratocumulus Transition Experiment (ASTEX) ones over Pacific Ocean off coast California. Results corroborate these findings. rate likely jumps potential temperature ASTEX cases. © Royal Meteorological Society, 2004. A. P. Lock's contribution Crown copyright