京津冀区域典型重污染过程与反馈效应研究

以京津冀地区2014年10月5~12日一次重污染过程为例，采用飞机AMDAR数据和WRF-Chem模式，分析了大气边界层垂直结构与PM_2.5的时空演变规律，定量研究了气溶胶直接反馈效应对多种气象要素的影响.结果表明：此次重污染过程地域范围广、持续时间长、影响强度大，PM_2.5污染呈带状分布，主要受地面均压场和高空纬向环流形成稳定的大气环流背景场、垂直层风场及逆温共同影响.气溶胶直接反馈效应导致京津冀地区整个时段太阳辐射量降低39.80W/m²，气温下降0.34℃，边界层高度降低36.64m，相对湿度升高0.90%.反馈效应南部地区较北部更显著，污染日强于平均时段和清洁天，气溶胶的辐射反馈作用使得各气象要素均呈现不利于污染物扩散的趋势，造成气溶胶聚集区PM_2.5浓度进一步增加.

Study on typical heavy pollution process and feedback effect in Beijing-Tianjin-Hebei region

Taking the heavy pollution episode in Beijing-Tianjin-Hebei region from October 5th to 12th, 2014 as an example, the aircraft AMDAR data and WRF-Chem model were applied to the evolution analysis of atmospheric boundary layer vertical structure and PM_2.5 temporal and spatial characteristic. The aerosol direct feedback effect on multiple meteorological factors was simulated and quantitatively estimated. The results indicated that the heavy pollution process presented the characteristics including long duration, wide influencing region, large intensity and a tape-shape distribution of PM_2.5 pollution, which was mainly affected by the uniform pressure field of ground, stable atmospheric background formed by latitudinal circulation in upper air, the vertical structure distribution of wind field and inversion structure. Aerosol direct feedback led to the following effect:(1) solar radiation reduced by 39.80W/m²; (2) temperature reduced by 0.34℃; (3) the boundary layer height reduced by 36.64m; (4) relative humidity increased by 0.90%. The feedback effect in the southern region was more obvious than that in the north region. The feedback effect in the pollution days was stronger than the average periods and clean days. The feedback effect makes the meteorological elements appear to be unfavorable to the diffusion of pollutants, and results in the further increase of PM_2.5 concentration.