Correction methods of MODIS cloud product basedon ground observation data
基于地面观测资料的MODIS云量产品订正

Comparative analysis of cloud fraction obtained from Moderate-resolution Imaging Spectroradiometer (MODIS)and ground observations shows the existence of considerable deviations. Five correction methods, based on cloud fraction observedfrom ground meteorological stations, have been proposed in this paper, including difference correction, ratio correction,difference-mixed correction, ratio-mixed correction and normalization-mixed correction of MODIS cloud product. The resultsshow that all of the five correction methods are workable. Comparatively, the ratio correction method has the highest precisionand is easy to be implemented. Hence it is the best recommended correction method for MODIS cloud product. After correction,the cloud fraction of MODIS is identical with that of ground observations, both in spatial distribution and quantitative analysis.Furthermore, intensive observations test show that monthly Mean Absolute Bias Error (MABE) of cloud fraction obtained from MODIS after ratio correction is less than 5%. This study gives a reference for relative researches using ground observation datato correct the related satellite products, which is of great significance to the related investigations of plateau, mountains anddesert with sparse stations.