基于细模态AOT的中国PM_(0.5)时空分布特征

Temporal and Spatial Distributions of PM_(0.5) in China Based on Fine Mode Aerosol Optical Thickness

利用2006—2011年PARASOL卫星细模态AOT(aerosol optical thickness,气溶胶光学厚度)的观测值,探讨中国PM0.5浓度的时空分布特征,并对中国与全球PM0.5的空间分布进行对比分析.结果表明:细模态AOT高值出现在中国、非洲中部和南美洲,分别为0.5～1.0、0.4～0.9和0.4～0.6,反映出这些地区PM0.5污染严重.在中国范围内,细模态AOT高值区主要分布在6个区域,包括重庆市、四川省成都市及其周边地区,华北平原地区,湖北省和湖南省的两湖平原地区,广西壮族自治区,珠三角地区,陕西渭河平原以及山西汾河河谷地区,各区域细模态AOT最大值分别为1.1、0.9、1.0、1.0、1.1和0.8,这些PM0.5污染严重地区的分布与SO2、OC、VOC、NOx等的污染源及其排放强度分布特征相一致,并且PM0.5浓度呈逐年升高趋势.2006—2011年,冬、春季细模态AOT平均值升高了18.09%,而夏、秋季平均值升高了9.00%,表明冬、春季PM0.5浓度显著高于夏、秋季.细模态AOT的多年月均值变化表明,其较高值出现在1月、3月,分别为0.37、0.36,最低值(0.18)出现在8月.但在局部地区,如华北地区(115°E～125°E、33°N～42°N),细模态AOT表现为夏季高于冬季.主要原因是华北地区受夏季副热带高压以及太阳辐射的影响,加强了南方污染物的长距离输送以及大气光化学反应,致使该地区夏季PM0.5浓度增高.

In order to explore the temporal and spatial distributions of PM0. 5in China and around the world,the aerosol optical thickness（ fine mode） observed by the PARASOL satellite from 2006-2011 was analyzed. The results showed that the AOT（ fine mode） in China,mid-Africa and South America reached 0. 5-1. 0,0. 4-0. 9 and 0. 4-0. 6,respectively,which indicated high PM0. 5concentrations in countries and areas in these parts of the world. Six high PM0. 5concentration areas in China were selected according to pollution distribution and aggregation characteristics of SO2,OC,VOC and NOxin the surface wind field. The selected areas included Chongqing,Chengdu and the surrounding areas in Sichuan Province,the North China Plain,Lianghu Plain in Hunan and Hubei Provinces,Guangxi Province,the Pearl River Delta,Weihe Plain in Shaanxi and Fenhe River Valley in Shanxi Province. The highest AOT（ fine mode） values in the six areas were approximately 1. 1,0. 9,1. 0,1. 0,1. 1 and 0. 8,respectively. Time evolution analysis illustrated that the concentrations of PM0. 5increased over the past seven years,especially in winter and spring. Statistical analysis showed that the AOT（ fine mode） in winter and spring increased by 18. 09% from 2006-2011 in the research region（ 71°E-135°E,16°N-55°N）,but it increased by only 9. 00% over the same period in summer and autumn. It could be concluded that the PM0. 5concentrations in winter and spring were significantly higher than those in summer and autumn. The highest AOT（ fine mode） values appeared in January（ 0. 37） and March（ 0.36）,while the lowest one was in August（ 0.18）. However,the results in some local areas such as northern China（ 115° E-125° E,33°N-42°N） showed the opposite result： AOT（ fine mode） in summer was higher than in winter. The main reason for this phenomenon was the influence of the subtropical anticyclone and solar radiation in summer,which enhanced the long range transport of pollutants from southern China and atmosphericphotochemical reactions,resulting in higher winter and spring PM0. 5concentrations in northern China.