海雾生成过程中平流、湍流和辐射效应的数值试验

Numerical Experiments With the Advection,Turbulence and Radiation Effects in the Seafog Formation Process

利用相对湿度方程,结合数值模式研究了在海雾生成过程中平流、湍流和辐射的效应。结果表明,海雾生成的主要“推动力”是长波辐射冷却,湍流冷却在低层主要发生在平流的初始阶段。随着时间的推移,湍流对低层大气很快变为起加热作用,不利于海雾的生成。湍流和辐射效应在低层大气中符号相反(仅在海雾生成的初始阶段符号相同),量级相同,在高层大气中湍流和辐射效应符号相同,但辐射效应占优势。湍流效应和辐射效应是影响海雾生成的主要因素,平流直接作用似乎不大。平流、湍流和辐射效应及其总效应均随时间推移而减小。另外,还初步研究了风速大小和海温高低对平流、湍流和辐射效应及海雾生成的影响。

In this paper, the relative humidity equation and numerical model are used to study the advection, turbulence and radiation effects in the seafog formation process. It is shown from the study results that the main driving force of seafog formation is the longwave radiation cooling, the turbulence cooling of the lower layer atmosphere occurs only at the initial stage of advection process, and the turbulence effect on the lower layer atmosphere quickly turns to heating effect with the elapse of time so as to be unfavorable to the seafog formation. The turbulence and radiation effects in the lower layer atmosphere have signs opposite to each other （have the same sign only at the initial stage of seafog formation process）, and are of the same order; the turbulence and radiation effects in the upper layer atmosphere have the same sign, but the radiation effect is predominant. The turbulence and radiation effects are the main factors affecting the seafog formation, and the direct effect of advection is relatively small. The effects of advection, turbulece, radiation and sum of them all decrease with the elapse of time. In addition, the actions of wind speed and sea surface temperature on the advection, turbulence and radiation effects and the seafog formation are also studied.