塔克拉玛干沙漠地区气溶胶光学厚度卫星遥感产品验证

Verification for the Satellite Remote Sensing Products of Aerosol Optical Depth in Taklimakan Desert Area

基于塔克拉玛干沙漠地区地基太阳光度计数据,系统验证2007～2008年星载多角度成像光谱仪(MISR)、中分辨率成像光谱仪(MODIS)和臭氧监测仪(OMI)气溶胶反演产品,旨在定量评估这些产品在我国沙漠地区的气溶胶光学厚度(AOD)反演精度。结果表明:MODIS/AOD的相关系数在4种产品中最高(0.91),OMI/AOD次之(0.87),其次为MISR/AOD(0.84),OMI/UVAI相关系数偏低(0.51)。MISR/AOD均方根误差(0.14)和平均偏差(-0.06)在4种反演产品中最低。与地基观测相比,MISR/AOD、MODIS/AOD系统偏低,OMI/AOD、OMI/UVAI系统偏高。在相同比较条件下(地基观测气溶胶光学厚度值限定在2.0以内),MISR的均方根误差和平均偏差在4种反演产品中最低,且相关系数也较高(0.84)。尽管存在诸多不同,但3种探测器气溶胶反演产品均能较好地展示该地区的气溶胶季节变化。塔克拉玛干沙漠春、夏季AOD较大,秋、冬季AOD相对较小。ngstrm波长指数的结果表明,春季(3～5月)最小(均值为0.11),夏季(6～8月)次之,秋季(9～11月)和冬季(12月至次年2月)较大(均值达到0.61),这表明在春、夏季气溶胶粒子偏大,秋、冬季气溶胶粒子偏小。此外,通过研究2000～2010年AOD年际变化表明,由于塔克拉玛干沙漠地区属于沙尘源区,气溶胶类型较为单一,所以总体来说,变化趋势不是较为明显。从反演结果来看,2003年的气溶胶含量为此10年中最高,年均值达到0.32;2005年的气溶胶含量在这10年中最低,年均值为0.28。

Using ground-based Aerosol Optical Depth （AOD） data at Tazhong, Taklimakan desert area, four sets of satellite aerosol data, from the Multi-angle Imaging Spectrometer （MISR）, the Moderate Resolution Imaging Spectrometer （MODIS）, and the Ozone Monitoring Instrument （OMI） from 2007 to 2008 were validated. The results show that satellite aerosol retrievals are significantly correlated with the ground-based ones. The correlation coefficient for MODIS/AOD is the largest （0.91）, followed by OMI/AOD （0.87）, MISR/AOD （0. 84）, and OMI/ UVAI （0.51）. MISR/AOD root-mean-square error （0. 14） and the average deviation （-0.06） are the lowest in the four products. MISR/AOD and MODIS/AOD is relatively less than the ground-based AOD, however, OMI/AOD and OMI/UVAI exceeds the ground-based ones. Under the same conditions （ground-based AOD is limited to less than 2.0）, the root-mean-square error and the standard deviation of MISR is the lowest. Seasonal variation of aerosol is captured by satellite data. AOD is relatively larger in spring and summer and is relatively lower in autumn and winter. The result of Angstr6m wavelength exponent shows that the spring has the minimum （0. 11）, followed by summer and autumn, and winter has the maximum （0. 61）, which shows that the aerosol particle is larger in spring and summer while it is smaller in autumn and winter. Besides, Taklimakan desert area belongs to the sand source where aerosol type is single. In summary, the annual variability tendency of AOD from 2000 to 2010 is not obvious. The result of the retrieval shows that there is the maximal aerosol content in 2003 during the decade and the annual average is up to 0. 32, while there is the minimal aerosol content in 2005 and the annual average is 0.28.