京津冀中部夏季大气颗粒物空间分布特征

Spatial Distribution Properties of Atmospheric Particles over Central Beijing Tianjin-Hebei Region in Summer

为研究京津冀地区雾霾成因,以Y-12(运-12)飞机为大气颗粒物观测平台,对2016年夏季京津冀中部大气颗粒物污染特征进行了观测研究.结果表明,天津市颗粒物数浓度垂直分布特征为1 500 m(以下均为标准气压高度)以下呈单峰分布,1 500 m以上呈单调下降,峰值均出现在0.35~0.40μm之间,峰值的最大值出现在900 m左右;颗粒物体积浓度谱呈三峰分布,分别在0.30~0.40、0.50~0.60和1.00~2.00μm之间,峰值的最大值出现在450 m左右.天津市、保定市和衡水市600与2 400 m数浓度谱分布特征为单调下降和单峰分布并存;600 m表面积浓度谱呈三峰分布,分别在0.30~0.40、0.50~0.60和0.90~1.00μm之间;2 400 m表面积浓度谱呈双峰分布,分别在0.30~0.40和0.50~0.60μm之间;600与2 400 m体积浓度谱均呈三峰分布,分别在0.30~0.40、0.50~0.60和1.00~3.00μm之间.天津市大气颗粒物数浓度谱峰值的最大值出现在900 m左右,说明逆温层对气溶胶累积的形成有重要影响.城市间数浓度谱峰值高低受地面颗粒物质量浓度大小影响.京津冀中部大气颗粒物表面积浓度谱在600 m呈三峰分布,在2 400 m呈双峰分布,可能是因为2 400 m空中以细粒子为主.京津冀中部大气颗粒物体积浓度谱在600与2 400 m空中均为三峰分布,而国外为双峰分布,发现粗粒子峰值粒径范围差别较大,这是由于国内PM_(2.5)在PM_(10)中占比较大.研究显示,京津冀中部600和1 200 m大气颗粒物多来源于山东、河南,经近地面输送;2 400 m大气颗粒物多来源于内蒙古地区,经高空和近地面两种途径输送.

Taking the Yun12（ Y-12） plane as the observation platform of atmospheric particulate matter,aircraft measurements of aerosol properties in central Beijing-Tianjin-Hebei Region were carried out in the summer of 2016. It was found that the concentration spectrum under 1500 m（ the heights in the following were all standard pressure height.） was unimodal distribution which ranged from 0. 35 to 0. 40μm,while the concentration spectrum of above 1500 m was monotonically decreasing. The maximum value of the peak was about 900 m.The volume concentration spectrum under 2200 m was presented in trimodal distribution,which ranged from 0. 30 to 0. 40 μm,0. 50 to0. 60 and 1. 00 to 2. 00 μm,respectively. The maximum value of the peak occered at around 450 m.The concentration spectrum of 600 m and 2400 m atmospheric particles in Tianjin,Baoding and Hengshui were single-peak distribution and monotonically decreasing. The concentration spectrum of 600 m surface area was presented in trimodal distribution in Tianjin,Baoding and Hengshui,which ranged from0. 30 to 0. 40,0. 50 to 0. 60 and 1. 00 to 2. 00 μm respectively. The surface area concentration spectrum of 2400 m in Tianjin,Baoding and Hengshui was bimodal distribution,one of which ranged from 0. 30 to 0. 40 μm,and the other ranges from 0. 50 to 0. 60 μm. The volume concentration spectrum of 600 m and 2400 m in Tianjin,Baoding and Hengshui were presented in trimodal distribution,which ranged from 0. 30 to 0. 40,0. 50 to 0. 60,1. 00 to 3. 00 μm respectively. The vertical distribution characteristics of Tianjin were in the single peak distribution of the concentration spectrum under 1500 m,which appeared in the accumulation mode,and the concentration spectrum above 1500 m was monotonically decreasing. The maximum value of the peak was about 900 m. It was found that the inversion layer had an important influence on the formation of aerosol accumulation. The volume concentration spectrum under 2200 m was presented in trimodal distribution. The maximum value of the peak was around 450 m. The distribution characteristics of concentration spectrum distribution over Beijing-Tianjin-Hebei Region were the same as those of the atmospheric airborne particles of 600 and 2400 m,showing a monotonously decreasing and unimodal distribution. The differences in the peak of concentration spectrum between different cities were affected by the ground mass concentration of particles. The surface area concentration spectrum of 600 and 2400 m in central BeijingTianjin-Hebei Region were trimodal distributions and bimodal distribution respectively,owning to it was dominated by fine particles in the air of 2400 m. The volume concentration spectrum of 600 and 2400 m in central Beijing-Tianjin-Hebei Region were trimodal distributions,nevertheless,studies from foreign countries observed in bimodal distribution. It was found that there were much differences between crest value of size range of coarse particles,due to higher value of PM_（2. 5）PM10 ratio in our country. The atmospheric particles of 600 and 1200 m in central Beijing-Tianjin-Hebei Region were mostly transported from Shandong and Henan provinces near the ground. The atmospheric particles of 2400 m in central Beijing-Tianjin-Hebei Region were mostly transported from Inner Mongolia area by two ways of high aititude and near the ground.