Sea Spray Effects on Marine and Coastal Boundary Layer

Abstract

The air-water exchange processes are considered as complicated but very important for the boundary layer structure. The complex physical procedures related to momentum, moisture and thermal exchanges, render their numerical description into a quite challenging task. Ocean surface roughness and spray droplets have an impact on the lower atmospheric layers with profound effects. These involve alterations in the atmospheric stability profiles and microphysical processes such as the formation of sea salt particles. Water vapor produced by sea spray can alter humidity and temperature profiles close to the ocean surface, leading to modified stability conditions. This cascade of effects can be further extended to wind profiles. Sea salt particles derived from water droplet evaporation are a major source of CCN and GCCN that may lead in low cloud formation over the sea and/or the coastal boundary layer. To describe these processes numerically, an atmospheric-wave-spray coupled system is introduced. The RAMS/ICLAMS atmospheric and the WAM wave spectral model are interfaced, including schemes for ocean drag, water droplet thermodynamics and salt particles considered as predictive quantity. Model simulations performed in the Atlantic shoreline showed that droplet evaporation near the surface modifies the atmospheric stability and affects sea salt dispersion.