西北地区MODIS气溶胶产品的对比应用分析

利用气溶胶自动监测网（AERONET）的太阳光度计（CE-318）资料，对2003-2010年西北干旱半干旱区MODIS暗像元算法和深蓝算法2种气溶胶光学厚度（AOD）产品进行对比验证，在此基础上进一步研究了该区域AOD的空间分布特征及变化趋势。结果表明，MODIS暗像元算法AOD产品在半干旱区原生植被覆盖地表精度优于深蓝算法，而西北干旱区荒漠地表深蓝算法产品精度较高。Aqua—MODIS深蓝算法AOD产品能够较好地给出我国西北荒漠亮地表地区AOD的分布及季节变化情况，AOD高值区多分布在沙尘源区，且春季AOD最大。2003～2010年，塔里木盆地、准噶尔盆地和柴达木盆地年均AOD分别在0．5、0．4和0．3附近波动；沙尘区各区域年均AOD大多呈现增加趋势。其中，塔里木盆地AOD增加趋势较大，而内蒙古西部和准噶尔盆地呈现微弱减少趋势。

Contrast and Application of MODIS Aerosol Products over the Arid and Semiarid Region in Northwest China

In this study, Aerosol Optical Depth （AOD） at 550 nm from the MODIS sensor on board the Aqua satellite were compared with sun photometer （CE -318） data from 5 AERONET stations over the arid and semiarid region in northwest China. On this basis, the spatial distribution characteristics and change trends of the AOD were studied. Results show that AOD with Dark Target algorithm from MODIS were better than that with Deep Blue algorithm in semiarid areas covered with native vegetations, but AOD with Deep Blue algorithm from MODIS had higher precision than that with Dark Target algorithm in Hexi Corridor covered mostly with desert. In com- parison, AOD products with Deep Blue algorithm from Aqua - MODIS were better for retrieving AOD over bright surface of the deserts in northwest China than that with Dark Target algorithm, so it was used to analyze the distribution and seasonal change of AOD. The ~ spatial distribution of AOD over the arid and semiarid region in northwest China Was far from uniformity, AOD in the dust source re- gions was large, and the value of AOD was 0.4 to 0.8. AOD had obvious seasonal variations, which was the largest in spring. Being greatly influenced by dust weather, the ration of AOD in the three dust source regions and Hexi Corridor had changed significantly. The annual averaged AOD had fluctuation around 0.5, O. 4 and 0.3 in the Tarim Basin, Junggar Basin and Qaidam Basin from 2003 to 2010, respectively. The annual variations of AOD in dust areas showed mostly increasing trends, and the trend in Tarim Basin was ob- vious, but it bad weak decreasing trends in Junggar Basin and the west of Inner Mongolia.