一次春季黄海海雾和东海层云关系的研究

REMOTE RELATIONSHIP IN ORIGINATION OF SEA FOG IN EAST CHINA SEA TO THE STRATUS IN YELLOW SEA IN SPRING

结合多种观测数据和数值模拟结果对2011年3月12—13日的一次黄海海雾过程进行分析。观测数据分析表明:此次黄海海雾过程与东海层云之间存在密切的联系。地面高低压位置为水汽从层云区向北输送提供了有利的环流条件;黄海上空天气尺度下沉运动,加强了海洋大气边界层(MABL)层结的稳定性,MABL顶自南向北高度降低,有利于水汽在向北输送过程中不断向海面聚集;下沉导致的干层以及逆温层对海雾的发生发展起重要作用。模式结果进一步证明天气尺度下沉运动与MABL内的下沉在29°—30°N附近同位相叠加,使得该海区上空的下沉运动明显增强,边界层高度迅速下降。下沉可能会导致气块温度升高,云滴蒸发,来自层云区的水汽随流场向北向下输送逐渐接近冷海面凝结成雾,近海面水汽的平流输送使海雾进一步向北发展。本研究为海雾预报提供新的参考思路。

A sea fog event in the East China Sea and stratus-fog system over the Yellow Sea on 12—13 March, 2011 were found closely related in this study as shown by observations and numerical modeling. Results indicate that the synoptic high- and low-pressure systems favored the northward moisture transfer in the cloud. Subsidence in 29°—30°N generated by synoptic high stabilized the marine atmospheric boundary layer(MABL). The height of the MABL from south to north is conducive for confining the northward water vapor into the low level. Inversion and dry layer generated by the subsidence played a major role in the formation of the sea fog. In addition, the modeling testified that synoptic scale subsidence superimposed onto that inside the MABL in 29°—30°N zone, which enhanced the subsidence and lowered the height of the MABL. Consequently, the air masses were heated, clouds evaporated, and water vapor condensed; water from the stratus plunged down to the cold sea surface, forming up the sea fog subsequently. This study can provide a new method of fog forcast.