Shiptracks in the Californian stratus region: dependency on marine atmospheric boundary layer depth

Abstract

Analysis of AVHRR (Advanced Very High Resolution Radiometer) satellite image/atmospheric sounding pairs reveals that the development and persistence of shiptracks is dependent on Marine Atmospheric Boundary Layer Depth (MABL). 65 image/sounding pairs were analyzed with eight cases featured. The data was collected from the SEAHUNT (July 1991) and MAST (June 1994) field experiments off the western coast of the United States. A distribution of cloud-topped MABLs for the dataset reveals that shiptracks developed in boundary layers of depth less than 750 meters. A mean number of shiptracks versus MABL depth reveals that shiptracks decrease in number with increasing boundary layer depth, supporting MAST hypotheses. Several mechanisms are proposed to explain the decrease in track development with increasing MABL depth and these present several avenues for future data analyses. Additionally, a composite track environment is also presented to document other environmental variables encountered during the analysis deemed pertinent to shiptrack formation.