The Microphysical Structure of Fog Droplets in a Sea Fog Event in the South China Sea

On the basis of the fog droplet spectrum and visibility observations in Zhanjiang during a sea fog event in the spring of 2010, the microphysical characteristics and the correlations among microphysical properties, such as the fog droplet number concentration, the liquid water content, and the fog droplet mean diameter, were analyzed, and the dominant physical processes that govern the sea fog event were discussed. The result showed that the average fog droplet size distribution was in good agreement with the Junge distribution. In the development and mature stages of the sea fog, the broadening process of the fog droplet spectrum and the positive correlation between and showed that activation and condensational growth were the main processes. Turbulent mixing tends to make the droplets homogeneous, with a central diameter of approximately 3.5 μm. Simultaneously, turbulence causes an exchange between the inside and outside air, concentrations from outside air nucleation resulting in higher number concentration, and the condensational growth results in larger droplets.