一次南海海雾微物理结构个例分析

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

本文利用2010年3月22～23日广东省湛江市一次海雾过程的雾滴谱和能见度资料,分析了海雾的微物理特征及微物理参量(数浓度、液态含水量和平均直径)之间的相关性,并讨论了影响海雾的主要物理过程。结果表明:湛江地区海雾的平均雾滴谱符合Junge分布;在海雾发展和成熟阶段,雾滴谱拓宽过程以及数浓度与平均直径的正相关关系表明本次海雾过程主要以雾滴活化和凝结增长过程为主;湍流过程的参与使得雾滴混合均匀,雾滴平均直径向3.5μm附近集中,趋向平均化。同时湍流使雾体内部和外部空气交流,外部空气的凝结核核化,数浓度升高,凝结增长造成小雾滴变大。

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 ~am. 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.