Comparison of Cloud Amounts from ISCCP and CloudSat over China and Its Neighborhood

Using the CloudSat 2B-GEOPROF-LIDAR product data and the monthly mean data of ISCCP (International Satellite Cloud Climatology Project) D2 from July 2006 to June 2007, the distributions of annual mean total cloud amounts over China and its neighborhood were analyzed and compared at noon and wee hours, respectively. The results show that both the distributive patterns of cloud amounts agree well with each other, and the locations of the maximum and minimum from two kinds of data are close. However, there are some quantitative differences between the two kinds of observations, especially at wee hours. For the whole areas, the difference of mean cloud amounts between ISCCP and CloudSat is respectively -8.9% and -15.1% at noon and wee hours. The annual mean cloud amounts of ISCCP are generally less than those of CloudSat, except in the northern zones of China and the sea area lying to the north of Japanese islands. In addition, the differences of cloud amounts between ISCCP and CloudSat over the Tibetan Plateau, the Pamir Plateau, the Hengduan Mountains, the Yungui Plateau, the southern part of India peninsula and some islands in the Tropics are more significant. Furthermore, it is indicated that the difference of cloud amounts between ISCCP and CloudSat changes linearly with CloudSat cloud amounts increasing. The ISCCP cloud amounts are slightly higher in the case of low CloudSat cloud amounts, and remarkably lower in the case of high CloudSat cloud amounts. Finally, by comparing the difference in annual mean cloud amounts from ISCCP between daytime and nighttime with that from CloudSat, it is found that the disagreements are significantly larger over the Tibetan Plateau than the other areas.