SeaCluse: Numerical simulation of evaporating sea spray droplets

Abstract

The SeaCluse computer code calculates the nonlinear interactions between sea spray droplet concentrations and the scalar fields of water vapor concentration and temperature in the marine atmospheric surface layer. The code simulates most of the dynamics of the evaporating sea spray droplets in the turbulent air flow over a wavy surface, the thermodynamic transformations of the spray droplets, and the influence of the droplets on the structure of the lower marine atmosphere. The main processor computes along the vertical the horizontally averaged budgets of droplet concentration, water vapor concentration, and sensible heat, including the dynamic and thermodynamic air‐droplet interactions. This paper presents the first simulations of evaporating sea spray droplets made with the SeaCluse model. It is shown that common assumptions such as exponential vertical concentration profiles and the evaporation of all droplets to their equilibrium radius do not necessarily hold for droplets with a radius larger than ∼30 μm. The present results also demonstrate the importance of the nonlinear interactions between sea spray droplets and the scalar fields of water vapor and temperature. Most droplets evaporate close to the surface, in a layer of ∼2–3 times the wave height. The impact of evaporating sea spray droplets increases rapidly with increasing wind speed.