A New Perspective on Coastally Trapped Disturbances Using Data from the Satellite Era

Coastal marine environments are regions of significant meteorological interest as a result of the direct impact of atmospheric processes on, for example, commerce and trade, naval operations, and civilian activities. Because the coastal topography of California acts as a rigid, lateral boundary for the marine layer, it plays a critical role in the life cycle of various atmospheric processes. This study focuses on the dynamical and microphysical properties of 23 coastally trapped disturbances (CTDs) – spanning the years from 2004 to 2016 – from a climatological perspective using several data products. While it is well known that broad stratiform cloud decks and fogs accompany CTDs, which surge from south to north, very little is known about their cloud microphysical and macrophysical properties because they are difficult to forecast and therefore in situ observations are few and far between. Previous works investigating marine boundary layer clouds off the California coast have generally focused on those that form under the typical northerly flow regime during the boreal warm season. Results shown here suggest that CTD cloud decks may play a unique role in the radiation budget due to a combination of aerosol sources that enhance cloud droplet number concentration and diminish cloud top effective radius. This particular type of cloud regime should therefore be treated differently than that which is more commonly found in the summertime months over the northeast Pacific Ocean.