夏季局地环流对京津冀区域大气污染影响

为研究局地环流对京津冀大气污染分布特征的影响,利用京津冀区域大气污染监测网7个站点的大气污染物浓度观测资料,结合WRF数值模式对气象场的模拟结果,对区域夏季局地环流对大气污染浓度水平和空间分布特征进行了研究。结果表明,2010年6月局地环流发生时,京津冀大气中PM10的平均浓度可高达156.4 μg/m3,而在强天气系统过境时仅为89.1 μg/m3。京津冀受区域局地环流控制时,大气中可吸入颗粒物比强天气系统过境时高75%;海-陆风回流携带的高浓度污染物,导致海滨区域夜间大气中PM10平均浓度从46.2 μg/m3上升到64.7 μg/m3;山地-平原风导致京津冀大气本底区域河北兴隆臭氧浓度峰值较北京城区滞后3 h。京津冀近年来强天气过程比例逐渐下降,目前仅占月20%,而以山地-平原风和海-陆风叠加的局地环流气象条件占比增加,造成京津冀区域大气污染易聚难散。

Effects of local circulation on atmospheric pollutants in Beijing-Tianjin-Hebei region during summer

To study the effects of local circulation on the distribution of atmospheric pollution, observational data (NOx, SO2, PM10 and O3) of air pollution monitoring network at 7 sites, combining with the meteorological field simulated by the WRF model, were analyzed in Beijing-Tianjin-Hebei region in June 2010. The results showed that the average concentration of PM10 was only 89.1 μg/m3 during the passage of strong weather system. However, the average PM10 concentration was approximately 156.4 μg/m3 when the local circulation mainly dominated in Beijing-Tianjin-Hebei region in June 2010, which was 75% higher than that of the strong weather system. while sea-land breeze, which carried PM10 from inland to the coastal area in nighttime, led to the average PM10 concentration increase from 46.2 μg/m3 to 64.7 μg/m3. Due to the existence of the mountain-plain wind, the peak of the ozone concentration at Xinglong postponed 3 hours compared with Beijing site. In recent years, the frequency of strong weather system gradually declined, which was only 20% of the total number of days. The increase of the frequency for the local circulation which was caused by the combination of mountain-plain wind and sea-land breeze, led to the unfavorable for the dispersion and accumulation of the atmospheric pollutants.