MARINE STRATOCUMULUS CLOUD CLEARING EPISODES OBSERVED DURING FIRE

Data from the First ISCCP (International Satellite Cloud Climatology P roject) Regional Experiment (FIRE) were combined with NOAA synoptic pr oducts, satellite imagery, and boundary-layer model data to document t he existence and causes of periodic clearing of large regions of marin e stratocumulus clouds off the coast of California during the summer s eason. These synoptic-to-mesoscale clearing episodes appear to be corr elated with the ridging of the Pacific subtropical anticyclone into th e United States Pacific Northwest, resulting in offshore flow effects. Furthermore, the subsidence associated with the Pacific subtropical a nticyclone may help cause the clearing episodes, or prevent the redeve lopment of these clouds in the clear regions. Because of the contribut ion of marine stratocumulus clouds to the global albedo, the clearing of large regions of these clouds may impact climate. Therefore, better understanding of these clouds is necessary in order to parameterize t hem in global climate models.