Abstract:  Based on the Lband sounding data, automatic weather station data, conventional observation data, NCEP global 1°×1° reanalysis data, the formation mechanism, characteristics of development processes and transmission mechanism of a persistent advection fog occurring over the north of the Yellow Sea during 23-24 April 2012 were analyzed. The results show that this fog belongs to an advection cooling fog. It was a result of interaction between cold sea surface and warmwet air flow. The sustained ridge over the Yellow Sea blocked and weakened the cold air, and it was favorable in establishment of a stable stratification in the lower layer of atmosphere. The sustained and strengthened transport of moisture by the southerly in the lower layer over the Yellow Sea not only provided abundant moisture for formation of the fog but also facilitated northward spreading of the fog areas. The “warm dry layer” above the fog layer and the underlying cold waters in the northern Yellow Sea were the primary factors for development and maintenance of this advection fog. The dense fog area corresponded to the cold advection area and the moisture convergence zone in the nearsurface layer. The area of merging of the cold and warm advections was prone to fog occurence. Under stable synoptic situation, the increase of southerly wind speed in the northern Yellow Sea did not affect maintaining of the advection fog. This unique character can be evidently distinguished from radiation fog.

Key words: northern Yellow Sea, spring advection fog, inversion layer, characteristic

摘要： 采用L波段加密探空资料、自动气象站资料、FY2E卫星观测资料和NCEP全球再分析资料，对2012年4月23—24日黄海北部出现的一次持续性平流雾过程的成因、发展维持及传播特征进行了诊断分析。结果表明:此次平流雾是暖湿气流与其下垫面冷水域相互作用所致，属于平流冷却雾。黄海维持的高压脊阻挡和减弱了冷空气，利于低层建立稳定大气层结；黄海低层偏南水汽输送的持续和加强既为雾的形成提供了丰富水汽供应，又利于雾区的向北传播。黄海北部冷水域和雾层上的“暖干层”是此次平流雾发展和维持的重要原因。浓雾区与近地层的冷平流区和水汽辐合区相对应，冷暖平流交汇之处易发生平流雾。在静稳天气形势下，黄海北部偏南风风速的增大并不影响平流雾的维持，这一特点明显区别于辐射雾。

关键词: 黄海北部, 春季平流雾, 稳定层结, 特征