大连地区辐射雾与平流雾边界层温度场及风场对比

Comparison of ABL Temperature and Wind Features between Radiative and Advective Fogs in Dalian

选取2008年3月和6月出现在大连及其沿海地区的辐射雾和平流雾过程,采用GTS1型数字式探空仪探测资料、能见度仪自动观测资料和常规观测资料,对其边界层温度场及风场结构特征进行了对比分析。结果表明,两种性质不同的大雾(辐射雾和平流雾)具有共同特征:都产生于纬向环流背景,中层东南暖湿气流为大雾的形成提供了充沛的水汽和热力条件。但两者存在明显的差异:底层东北风平流降温是辐射雾生成的重要条件,却造成了平流雾的消亡,底层东南风是平流雾生成的条件,却对应于辐射雾的消亡;辐射雾逆温厚而强,平流雾则为弱的逆温或无逆温;辐射雾生消演变对应于大气层结由稳定发展为不稳定,平流雾则对应于由不稳定趋于稳定。

Two heavy fog processes occurred in March and June 2008 in Dalian and the coastal areas are analyzed by using the sounding data from GTS1 digital radiosondes,conventional observation data,and automatically observed visibility data.The structural features of ABL temperature and wind fields are analyzed.The results show that both radiative fog and advective fog usually form under the conditions of zonal circulation,abundant water vapor and appropriate thermal state supplied by the middle-level southeast wind.However,there is obvious difference between them.The advection cooling near the surface by the north-easterly wind is an important condition for the formation of radiation fog,leading to the dispersion of advection fog.The surface southeast wind is a condition for the generation of advection fog,but it contributes to the disappearance of radiation fogs.The inversion in the radiation fog is thick and strong,but weaker or no inversion in advection fogs.Radiation fogs evolve from occurrence to dispersion while the stratification varies from stable to unstable,but from unstable to stable for advection fogs.