Retrieval of aerosol optical depth over bright targets in the urban areas of North China during winter
Retrieval of aerosol optical depth over bright targets in the urban areas of North China during winter
复制标题
华北城区冬季亮目标气溶胶光学深度反演
DOI：
10.1007/s11430-012-4432-1
复制
发表时间：
2012-09-01
影响因子：
5.7
通讯作者：
Yu Chao
中科院分区：
文献类型：
--
作者：
Li ShenShen;Chen LiangFu;Yu Chao
影响卫星反演气溶胶光学厚度（AOD）的两个因素是气溶胶模型假设和地面反射率的分离。NASA/MODIS密集暗植被（DDV）算法已被证明是有价值的气溶胶分布和属性在陆地上，但它不能适用于明亮的目标。作为对DDV算法的补充，本文利用MODIS数据建立了一种华北地区冬季气溶胶光学厚度的反演算法，包括：（1）利用2007 - 2008年的MOD 09产品生成并分析了邻近晴天的地面反射率;（2）利用AERONET数据建立了北京和香河地区的季节气溶胶模型。利用太阳光度计的地面观测数据对反演的气溶胶光学厚度进行了验证，相关系数达到0.931。特别是当气溶胶光学厚度（AOD）> 0.4时，更多的反演结果满足反演精度要求.结果表明，除异常天气外，蓝波段地表反射率的短期变化小于0.02，反演偏差小于0.08，相对误差随气溶胶光学厚度的增大而减小。
Two factors that affect satellite retrieval of Aerosol Optical Depth (AOD) are aerosol model assumptions and the separation of surface reflectance. NASA/MODIS Dense Dark Vegetation (DDV) algorithm has been proven valuable in deriving aerosol distribution and properties over land; however, it cannot be applied to bright targets. As a supplement to the DDV algorithm, an algorithm to retrieve AOD over urban areas in North China in winter is developed using MODIS data, including (1) the generation and analysis of adjacent clear-days surface reflectance using MOD09 product from 2007 to 2008, and (2) seasonal aerosol models derived from AERONET data in Beijing and Xianghe sites. Ground-based measurements using sun photometers were used to validate the retrieved AOD, and the correlation coefficient (r) is up to 0.931. Especially for high AOD values (AOD > 0.4), more retrievals meet the inversion accuracy. The temporal variations of retrieval errors over urban, rural and mountain regions were examined, and the results indicated that the variation of blue-band surface reflectance is less than 0.02 in a short period except for unusual weather conditions, the retrieval bias is under 0.08, and the relative error decreases as the AOD increases.