Idealized Simulations of the Marine Atmospheric Boundary Layer Response to Varying Coastal Land Surface Properties

Land surface properties are widely known to influence weather in coastal environments, primarily through their effects on surface drag, albedo, and the partitioning between surface latent and sensible heat fluxes. Although the local impacts of varying land surface properties on the overlying atmosphere have been studied extensively, considerably less research has explored how the land surface influences weather in the adjacent offshore environment. In this study, we conduct a set of idealized, cloud-resolving simulations with the Navy’s Coupled Ocean Atmospheric Prediction System (COAMPS) for a domain bisected by a north-south oriented coastline. We vary latitude, coastal soil moisture, and the large-scale atmospheric winds among these simulations in order to understand how properties of the marine atmospheric boundary layer respond to these changes at different distances away from the coast. We find that at low latitudes, sea breeze circulations extend up to 200 km offshore and result in a 10-15% reduction in the height of the marine atmospheric boundary layer. Decreasing soil moisture expectedly strengthens the diurnal sea breeze circulation by increasing land-sea temperature contrasts, but does not noticeably change the diurnal evolution of the boundary layer height offshore. At higher latitudes, the Coriolis force increasingly limits the offshore extent of land surface influences unless there is significant synoptic-scale flow to transport land-modified air masses offshore. We discuss the implications of these results in terms of how the land surface impacts mesoscale atmospheric predictability in the littoral environment under different flow regimes.