西北地区气溶胶光学特性的时空变化特征

Spatio⁃temporal distribution and variation characteristics of aerosol optical properties over the Northwest of China

利用2003—2018年的Aqua⁃MODIS C6.1气溶胶产品对西北地区气溶胶光学厚度(AOD)和Angstrom波长指数(AE)的时空分布特征进行研究,并结合当地站点气象要素资料,分析了气象要素对AOD的影响.结果表明,西北地区AOD的高值区位于塔克拉玛干沙漠和陕西关中地区;青海南部及新疆北部等是AOD的低值区.AE指数从西到东逐渐增大,其低值区位于塔里木盆地及青海北部.从季节变化上看,西北地区春季AOD最高,而AE值最低,主要受沙尘气溶胶的影响较大;最低平均AOD和最高平均AE均出现在秋季.西北地区的AOD年均值为0.219,2006年后AOD呈明显下降趋势;AE指数在2009—2017年期间呈现微弱的上升趋势.西北地区AOD和AE的月均变化特征较为明显,这主要与沙尘天气出现的时间有关.2003—2018年期间西北地区各省AOD年均值呈现缓慢下降趋势,且2012年之后,内蒙古、陕西和宁夏等地月平均AOD的峰谷差值均有所减少.不同地区的气象要素对其AOD的影响不同.

Based on the aerosol product of Aqua⁃MODIS C6.1 from 2003 to 2018 over the northwest of China,the temporal variation and spatial distribution characteristics of aerosol optical depth(AOD)and Angstrom exponent(AE)were analyzed.The impact of meteorological factor on AOD was analyzed based on the meteorological data of local stations.The results showed that the Taklimakan desert and Guanzhong region of Shaanxi province had relatively high values of AOD.The spatial distribution of AE increased gradually from west to east,and Tarim basin and the north of Qinghai with low AE.In spring,AOD was the highest,while AE was the lowest,which was mainly attributed to dust aerosol.In autumn,the AE value was the highest,while the AOD value was the lowest.The annual mean of AOD in northwest China was 0.219,and AOD showed a significant downward trend after 2006.The Angstrom exponent showed a slight upward trend from 2009 to 2017.The monthly variation of AOD and AE in northwest China were obvious,which was mainly related to the occurrence of dust.The annual average of AOD in every provinces of the northwest China showed a slow downward trend from 2003 to 2018.The decrease of monthly peak⁃valley difference of AOD in Inner Mongolia,Shaanxi and Ningxia occurred after 2012.The influence of meteorological factors on AOD in different regions was different.