天津市春季颗粒物污染特征及典型沙尘过程分析

Pollution Characteristics of Particulate Matters and a Dust Storm Episode in the Spring of Tianjin

利用2013-2016年空气自动观测数据结合同期气象资料分析天津市春季颗粒物污染特征,并采用后向轨迹分析沙尘传输过程。结果表明:天津市春季以西南风为主,全年最高风速出现在4-5月,平均在3.8 m/s以上。低风(<2 m/s)高湿(>50%)和高风(6 m/s左右)低湿(40%~50%之间)容易造成春季PM_(10)浓度较高。春季PM_(2.5)/PM_(10)比值从2013年的0.60降至2016年的0.54,呈下降趋势,粗颗粒的影响在增加。沙尘影响指数在1.17~1.95之间,呈明显上升趋势,中心城区、东部滨海新区指数相对较高。对2016年3月5-7日典型沙尘过程分析发现,沙尘传输过程中,部分点位二次扬尘对PM_(10)浓度也有相当贡献。

The characteristics of particulate matter in spring in Tianjin were analyzed based on the air quality data and meteorological observation data during 2013-2016, combined with the back trajectory model analysis. It was shown that the dominant winds were from the southwest in spring and the highest wind speeds occurred during March to April with the average value of 3.8 m/s. High PM（10） concentration always occurred when the wind speed was lower than 2 m/s and relative humidity was higher than 50%, and also occurred when the wind speed was higher than 6 m/s and the relative humidity was between40% and 50%. The average PM（2.5）/PM（10） ratio in spring decreased from 0.60 in 2013 to 0.54 in 2016, indicating of the more important influence of coarse particulate. The dust influence index increased from 1.17 to 1.95, with high value in the central and the east Binhai New Area. The typical dust pollution episode during March 5 th to 7 th, 2016 was analyzed and the result showed that secondary dust also contributed to PM（10） during the dust transport process.