江苏省大气气溶胶光学厚度时空分布研究

SPATIO-TEMPORAL DISTRIBUTION OF ATMOSPHERIC AEROSOL OPTICAL DEPTH IN JIANGSU PROVINCE

气溶胶光学厚度（AOD）是气溶胶总含量的基本参数,可以用来反映大气污染程度.利用卫星遥感获取气溶胶光学厚度,可以弥补地面观测难以反映AOD空间分布和整体变化趋势的不足.以江苏省为例,利用2010年4～9月EOS-TERRA MODIS数据,分别基于暗像元法（DDV法）和改进的暗像元法（V5.2法）,反演研究区2010年夏半年/春夏两季气溶胶光学厚度,并结合地面观测数据验证两种反演算法结果精度,最后分析研究区AOD时空变化特征.研究结果表明：在研究区,两种算法反演结果在整体趋势上保持一致,研究区AOD均表现出与植被指数NDVI较为明显的负相关关系,但V5.2法反演精度要明显优于DDV法;研究区气溶胶光学厚度存在较明显的区域差异和季节变化,具体表现为苏南AOD明显高于苏中、苏北地区,而在春、夏两个不同季节上,不同区域变化趋势不同,苏南地区春季AOD高于夏季,而在苏北地区则刚好相反,夏季AOD要高于春季.

Aerosol Optical Depth （AOD） is a basic parameter in total aerosol content,which can be used to represent the degree of atmospheric pollution.The AOD data from ground observation is difficult to reflect the spatial and temporal distribution.Some studies have demonstrated that the AOD retrieved using satellite remote sensing data can make up for this shortage.As the one of the most developed economic province of China,Jiangsu province has a high proportion of total GDP and total industrial output in China.Meanwhile,due to large amounts of toxic substances by industrial production and exhausts emissions,air pollution has become increasingly hazardous in Jiangsu province.The haze weather frequently occurred in recent years.These environmental issues have threatened seriously people′s health and environment quality.Aerosol is a key factor which contributes to haze weather.It will be useful to obtain the overall information of aerosol spatial and temporal distribution for atmospheric monitoring and air pollution controlling.Therefore,taking Jiangsu province as the study area,this paper obtained AOD distribution of spring and summer in 2010 using Dark Dense Vegetation （DDV） and V5.2 method based on EOS-TERRA MODIS data.Then the two results of AOD distribution were validated using AOD measured data from CE-318 instrument on the ground and the MODIS NDVI product as well.Finally,the spatial and temporal distribution of AOD and the possible affecting factors in the study area have been discussed based on AOD map from V5.2 method.The results showed that there was a significant negative correlation between AOD and NDVI.The AOD from V5.2 was more accurate than that from DDV in the study area.The absolute error and relative error of AOD from V5.2 was 0.16 and 33% respectively.In the study area,there was difference of AOD distribution in both spatial and seasonal.In detail,AOD gradually decreased from southern area of Jiangsu province to the northern area.The mean AOD of southern Jiangsu,center Jiangsu and northern Jiangsu was 0.77,0.65and 0.58 respectively.It can be found that the distribution of AOD was affected by the geographical environment,population density and industrial distribution.For seasonal changes,AOD mean value changed in a small range in spring and summer in 2010.But variation tendency was distinct in different regions.In the south of Jiangsu,AOD in spring was significantly lower than that in summer.The mean value was reduced from 0.81 to 0.70.In the north of Jiangsu,AOD was increased with the mean value rising from 0.56 to 0.62.In the center Jiangsu,seasonal change was not obvious with AOD mean value being 0.66 and 0.63.The changes of AOD value was mainly affected by natural and human activities.In the natural factors,rainfall erosion can greatly reduce aerosol life cycle to reduce its value.According to the 2010 climate impact assessment of Jiangsu province issued by the Jiangsu meteorological bureau,the precipitation of southern Jiangsu was greater than northern in spring of 2010,but little different,both around 200 mm.However,the precipitation was mainly concentrated in the areas along the Yangtze River in summer of 2010,southern region rainfall reached 500 mm,while the northern and center hovered at 300 mm and thus made AOD value in south of Jiangsu was significantly lower than that in the northern.Besides,the effect of human activities was also an important factor in affecting AOD value.A large number of construction projects in the areas along the Yangtze River in spring of 2010 were contributed to produce local dust weather which can result in high value of AOD.This was an objective factors lead to higher AOD value in the areas along the Yangtze River in spring of 2010 than that in summer during the study period.