一次重度霾后的平流雾过程微物理特征及其对颗粒物浓度的影响

Microphysical Characteristics of Advection Fog Process after a Severe Haze Event and Its Effect on Particulate Matter Concentration

摘要: 2016/2017年冬季在天津开展平流雾微物理结构特征观测试验，结合距地66 m高度处雾滴谱和255 m气象塔大气边界层资料，对重度霾后的一次平流雾过程雾体内部的微物理特征展开分析，讨论其生消演变特征，并对重度霾背景下大气颗粒物浓度与雾微物理量的相互作用进行讨论。结果表明：高空脊前的负涡度平流维持地面均压场，低层反气旋环流外围偏南气流促使暖湿空气向天津地区输送；66 m高度数浓度高值出现在雾过程成熟阶段初期，而含水量、特征直径高值出现在成熟阶段后期，对应成熟阶段后期雾滴数浓度减少、地面能见度小幅跃升；重度污染造成高颗粒物浓度导致雾滴数浓度增多，雾滴尺度偏小，平流雾对颗粒物具有明显的湿清除效应，通过不同站点污染物浓度随时间变化趋势，可以判断雾在水平方向有西南向东北方向的发展进程。

Abstract: The microphysical characteristics observation test of advection fog was carried out in Tianjin in the winter of 2016/2017. Combined with the droplet spectrum at a height of 66 m above the ground and the atmospheric boundary layer data 0f 255m meteorological tower, this paper analyzes the microphysical characteristics inside the fog in an advective fog process after a severe haze event, discusses its evolution characteristics, the interaction between atmospheric particle concentration and fog microphysical quantities under the background of severe haze event. The result shows that the negative vorticity advection in front of the high-altitude ridge maintains the ground’s uniform pressure field, and the southerly airflow at the periphery of the low-level anticyclonic circulation promotes the transport of warm and humid air to the Tianjin area; The high value of the characteristic diameter appears in the late stage of maturity, corresponding to the decrease in the number of droplets and the slight increase in ground visibility in the latter stage of the maturity stage; the high particle concentration caused by heavy pollution leads to an increase in the number of drop-lets, the size of the droplets is small, and the advection fog has obvious effects on particulate matter. The high concentration of particulate matter caused by heavy pollution will lead to an increase in the fog droplets concentration, and the size of droplets will be smaller, at the same time, the advection fog has a significant wet removal effect on the particulate matter. With the change of concen-tration of the ground particulate matter at different sites, it can be judged that the horizontal development of the fog moves from southwest to northeast.