云南省气溶胶光学厚度时空变化特征的遥感研究

Temporal-Spatial Variations Characteristics of Aerosol Optical Thickness using Satellite Remote Sensing over Yunnan Province,China

利用中分辨率成像光谱仪（MODIS）的气溶胶产品研究云南省气溶胶光学厚度（AOT）的时空变化特征。研究结果表明：在长时间尺度上,区域月平均AOT没有明显的增长趋势,年平均值大约为0.19,反映了人为活动排放进入大气的气溶胶没有明显的增加;月平均AOT的变化呈双峰分布特征,2个峰值分别出现在3、8月,AOT大约为0.35±0.08和0.31±0.05,5月出现明显的谷值（0.20±0.03）,AOT减少的原因可能是该地区降水增多,大量的降水可以清除大气中的气溶胶粒子,最小值常出现在1月或12月,AOT大约为0.09±0.02。在空间上,云南省AOT普遍较低,年平均值的空间分布为0-0.4,低值区出现在西北部的迪庆州、怒江州和丽江市;AOT高值区分布在云南省的南部和东北部地区,3月AOT值最大可达0.80以上,南部和北部差值达到0.60以上,8月AOT的高值区主要出现在中部的玉溪市红河州北部、玉溪市和昆明市。云南省AOT北高南低分布格局的原因主要是北部地区人为气溶胶排放较少,另外,由于地形的影响,北部地区风速较大,气溶胶停留在大气中的时间较短,AOT较小。

The characteristics of temporal-spatial variation of aerosol optical thickness（ AOT） were analyzed using the Moderate Resolution Imaging Spectroradiometer（ MODIS） aerosol products over Yunnan province,China. The results indicated that,in a long term scale,the AOT presents not obvious increasing trend. The yearly mean AOT value is about 0. 19,this reflects there is no obvious increasing aerosols from anthropogenic activities emission into atmosphere. The multi-year monthly variation shows the characteristics of bimodal distribution,the two peaks appear in March and August,respectively. There is a valley value at0. 20 ± 0. 03 in May. The reason for the lower AOT is likely due to the increasing precipitation over this region,which washing away partial aerosol particles from atmosphere. The smallest value always appears in January or December and the AOT is about0. 09 ± 0. 02. In space scale,the AOT is generally lower,the yearly mean values are from 0 to 0. 4. The lower values appear in Diqing Tibetan Autonomous Prefecture,Nujiang of the Lisu Autonomous Prefecture and Lijiang city. Larger values are distribute in south and northeastern Yunnan,AOT is up to 0. 8 in March and the difference between northern and southern region is up to0. 60. The second peak at August and compared to AOT in March,higher values appear in the northern Hani-Yi Autonomous Prefecture of Honghe,Yuxi and Kunming cities. The reasons for the pattern of higher in north lower in south is due to the less anthropogenic aerosol emission over the northern region,and in the other hand,there is the higher wind speed in northern region due to the effect of terrain,which makes the aerosols in the atmosphere shorter time,and have a lower AOT.