环渤海近海岸雾产生的天气条件及边界层特征分析

利用渤海沿岸微波辐射计、风廓线雷达、四分量辐射仪和超声风速仪等多种观测反演资料，并结合常规站点气象资料，卫星云图，浮标气象水文观测和FNL（Final）再分析资料研究了2016年12月17~19日一次环渤海大雾个例产生的天气水文条件以及边界层垂直分层的辐射和湍流特征。研究发现:（1）此次大雾出现在大陆低压前部、入海高压后部的西南低空急流控制区域，与强急流相伴的暖湿平流输送为雾区提供了稳定的逆温和持续的水汽积累，非常有利于大雾天气的形成；（2）水汽通量的分布与低空急流的移动密切相关，近地面比湿的增速与低空急流的强度成正比；（3）由于低空急流的水汽输送增湿了环渤海低层大气，从而增强了大气辐射的衰减效应，导致雾形成前向下短波辐射逐渐减小，向下长波辐射不断增加，净辐射在大雾形成后趋近于零；（4）逆温有效抑制了湍流的发展，近地层湍流动能和摩擦速度微弱。

The Synoptic Condition and Boundary Layer Characteristics of Coastal Fog around the Bohai Sea

In this study, a heavy fog that occurred around the Bohai Sea on 17 December 2016, was investigated based on measurement data from microwave radiometer, wind profiler radar, four-component radiometer, sonic anemometer-thermometer, satellite images, buoys, conventional surface observation, and FNL (Final) reanalysis. The synoptic system for fog formation and vertical characteristics of radiation and turbulence were studied as key analysis points. The results show the following: (1) The fog appeared in the front of a low-pressure area and the back of a high-pressure area, and the warm-wet advection accompanied by strong low-level jet provided stable inversion and continuous water vapor accumulation in the fog area, which was very helpful to the fog formation. (2) The water vapor flux was closely related to the movement of the low-level jet. The growth rate of near-surface specific humidity was proportional to the intensity of the low-level jet. (3) Water vapor transport humidified the lower-boundary layer atmosphere around the Bohai Sea, which enhanced the attenuation effect of atmospheric radiation, leading to a decrease in short-wave radiation and an increase in long-wave radiation. When the fog formed, the net radiation was approaching zero. (4) Inversion effectively inhibited the development of turbulence. The kinetic energy and friction velocity of the turbulence were weak in the near-surface layer.