Development of an Analytical Profile for Vertical Concentration of Sea Spray Aerosols in the Marine Atmospheric Boundary Layer

Sea spray and sea salt particles contribute to a significant fraction of atmospheric aerosols. The aerosols can directly and indirectly impact the long-term weather patterns and climate in local to global scales. They influence the net radiation, air quality, cloud formation and precipitation, electromagnetic wave propagation, and bio-geochemical processes in the atmosphere. Thus, information about the sea spray aerosol transport and their vertical distribution in Marine Atmospheric Boundary Layer (MABL) are important for accurate marine meteorological forecasting and atmospheric bio-geochemical models. However, due to the difficulties in field observations, sea spray aerosol concentrations are typically limited to a single height measurements and extending those to obtain the vertical concentration profiles is quite challenging. Beyond point measurements, obtaining the size-resolved concentration profiles is far more challenging or even impossible. Hence, numerical and analytical studies are vital in modeling the transport of aerosols in the atmospheric boundary layer and beyond. Since most of the meso-scale and global aerosol models do not accurately resolve the sea spray and aerosol concentrations in the MABL, particularly in the surface layer, because of their coarse resolution, the objective of the present study is to develop a relatively simple analytical model relating the surface flux to vertical concentration profile of aerosols in the MABL. The new analytical model was developed by extending conventional similarity theories and recent developments of surface layer models into the full atmospheric boundary layer. The model takes into account atmospheric stability and particle settling due to gravity. The model is validated against simulation results from large eddy simulations model and compares well with the simulated concentration profiles for both neutral and unstable atmospheric stability conditions for a wide range of particle sizes.