基于中国通量网的MODIS短波反照率验证与分析

Evaluation of MODIS Shortwave Albedo Products over ChinaFLUX Sites

遥感地表反照率产品的验证与分析是将其应用于环境研究的基础。采用中国通量网的地表实测短波反照率数据对MODIS反照率产品进行对比和分析,针对选取的8个地面站点,提取了2004年的MODIS反照率产品并进行验证。这些站点的植被覆盖情况涵盖了草地、森林和农业用地。结果显示MODIS在多数情况下能提供准确的地表反照率产品。针对各个站点的误差、均方根误差、相关系数分析都显示了这个结果,总体反演误差在0.002左右。较大的误差出现在有冰雪影响的时候,排除受积雪影响的数据,总体均方根误差可达0.028。分析了引起误差的原因并提出了改进意见。

The use of land surface albedo products from satellite observations is based on the evaluation of their inversion quality. In this paper,MODIS surface shortwave albedo products are compared with in-situ measurements from ChinaFLUX. Eight sites over forest, grassland and cropland are chosen in this study. Corresponding MODIS data in 2004 are extracted from surface albedo products（MCD43B3）. The results show MODIS shortwave albedo products match ground measurements well except some cases with snow cover. The error of all the eight sites is about 0. 002,and root-mean-square error （RMSE） can reach 0. 028 without gestlons snow cover situations. This paper analyses the factors that cause the errors and proposes some sug- for improvement of inversion quality.