Synoptic-scale forcing of marine stratocumulus cloud dissipation during ASTEX

Data gathered during ASTEX will be used to intensively study the synoptic-scale and mesoscale dynamic and thermodynamic structure of the marine stratocumulus environment during an intense stratocumulus cloud clearing episode occurring from June 14--16, 1992 in the eastern North Atlantic Ocean. Previous studies have attempted to explain the cause(s) of marine-stratocumulus cloud clearing episodes. However, a great deal of debate remains. Explanations derived from other studies include prefrontal convergence and upward vertical motion associated with the passage of cold fronts; cloud top entrainment instability, which causes evaporation of the cloud by the entrainment of dry air from above the cloud; warm, dry, offshore flow from continental regions caused by ridging of the subtropical anticyclone onshore; and enhanced synoptic-scale subsidence within the subtropical anticyclone. This particular clearing event appeared to be related to the ridging of the Atlantic subtropical anticyclone into the British Isles, resulting in offshore flow effects from the European continent.