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研究报告

Analysis of a typical autumn air pollution process in Shijiazhuang during typhoon

摘要：利用PM_2.5污染监测数据、气象资料和WRF模式,研究了2013年10月2日至10日石家庄地区秋季一次典型的空气污染过程,结果表明,PM_2.5质量浓度的上升和下降阶段与相继出现的台风"菲特"和"丹娜丝"输送气流及其背景场有关,本次污染过程同时受台风系统背景场、副热带高压系统和大陆高压系统协同控制.石家庄PM_2.5质量浓度演变分为上升、下降、再上升和下降4个阶段,浓度曲线呈现双峰特征,分别对应台风"菲特"加强、减弱、台风"丹娜丝"加强和减弱阶段.污染过程中,PM_2.5日均质量浓度最高值是425 μg·m^-3,导致这一现象的原因是由于台风"菲特"和"丹娜丝"系统外围东南暖湿气流进入石家庄地区,高空1000、1800和2600 m处出现逆温层,下沉气流最大风速是0.2 m·s^-1,覆盖并影响石家庄地区,形成稳定的大气条件,利于PM_2.5污染物持续积累,造成石家庄地区PM_2.5浓度达到峰值并出现重污染事件.

Abstract：A typical autumn air pollution process in Shijiazhuang from October 2^nd to 10^th, 2013 was investigated based on the WRF simulation, PM_2.5 monitoring data and the meteorological data. The results indicated that the rising and falling of PM_2.5 mass concentrations were related to the airflow and the background field during the typhoon "Fitow" and "Danas". The pollution process was affected by the background field of typhoon, subtropical anticyclone and the continental high pressure system at the same time. The PM_2.5 concentration curve showed the characteristics of twin peaks. The evolution of PM_2.5 mass concentration in Shijiazhuang could be divided into four stages: rising, falling, re-rising and re-falling, corresponding to the strengthening and weakening of the typhoon "Fitow" and "Danas", respectively. The peak daily average PM_2.5 mass concentration during the air pollution process was 425 μg·m^-3. The reason was that the peripheral southeast warm and the wet airflow of the typhoon "Fitow" and "Danas" transported into Shijiazhuang, causing the occurrence of the temperature inversion in the altitude of 1000,1800 and 2600 meters, with a maximum downdraft wind speed of 0.2 m·s^-1. The temperature inversion covered Shijiazhuang and led to a stable atmospheric condition, which favored PM_2.5 accumulation. This resulted in the high PM_2.5 concentration and the heavy air pollution event.