利用MODIS C6产品分析2006～2015年西北地区气溶胶光学厚度(aerosol optical depth, AOD)与Angstrm波长指数的时空分布特征及相互关系。结果表明: 塔克拉玛干沙漠和陕西关中地区为气溶胶光学厚度高值区,青海和甘肃南部为AOD低值区,西北地 区东部为Angstrm波长指数高值区,北疆地区Angstrm波长指数空间分布差异较大;西北地区年均AOD为0.208±0.011, 年均Angstrm波长指数为1.185±0.025, 2010～2015年AOD呈下降趋势, 2008～2015年Angstrm波长指数呈上升趋势。 AOD与Angstrm波长指数存在相反的季节变化关系, AOD春季最大,秋季最小, Angstrm波长指数与之相反。AOD月均最大值出现在4月, 为0.35±0.038, 10月最小,为0.13±0.009, Angstrm波长指数12月最大,为1.34±0.035, 4月最小,为0.97±0.054; AOD与Angstrm波长指数呈负相关,春季的相关性最大,为-0.77,冬季的相关性最小,为-0.28。对不同季节气溶胶光学厚度与Angstrm波长指数的相关性进行分析, 结果说明西北地区全年粗、细粒径气溶胶粒子都占有一定比例,主要以小粒径的烟雾粒子为主,沙尘气溶胶粒子也占有一定比例,人为气溶胶排放从春季到冬季不断上升。

Analysis of spatio-temporal characteristics and correlations between aerosol optical depth(AOD) and Angstrm exponent over northwest was analyzed based on MODIS C6 product from 2006 to 2015. The results showed that the high AOD occurred in the area of Southern Xinjiang and Guanzhong region of Shaanxi Province, the south of Qinghai and Gansu Province existed low value. High Angstrm exponent occurred in the east of the northwest, and spatial distribution was quite different in the north of Xinjiang. The annual mean AOD was 0.208±0.011, Angstrm exponent was 1.185±0.025. AOD showed a downward trend during 2010 to 2015, and Angstrm exponent was on the rise during 2008 to 2015. AOD and Angstrm exponent were opposite to the seasonal changes, the largest AOD was in spring, the smallest in autumn, just the reverse to Angstrm exponent. The monthly mean AOD appeared in April, which was 0.35 ± 0. 038, the smallest in October was 0.13 ± 0.009, Angstrm exponent was the largest in December, which was 1.34 ± 0.35, the lowest in April was 0.97 ± 0.054; AOD and Angstrm exponent had negative correlation, the highest correlation in spring, which was -0.77, the lowest correlation in winter, which was -0.28. The correlation between AOD and the Angstrm wavelength index in different seasons was analyzed, the results indicated that coarse and fine particle size aerosol particles occupied a certain proportion, mainly in small particle size of the smoke particles, dust aerosol particles also occupy a certain proportion. Aerosol emission was increased from spring to winter.