Comparison of cloud type and frequency over China from surface, FY-2E, and CloudSat observations

Abstract
Cloud Occurrence Frequency (COF) of different cloud types from three cloud classification products are evaluated in this study over six sub-regions of China in 2012, including surface products, Feng-Yun-2E (FY-2E) and CloudSat satellite products. The spatial distribution and seasonal variation of cloud types are compared on the macro-characteristics. The main cloud types are cirrus (Ci), cirrostratus (Cs), stratocumulus (Sc), altocumulus (Ac), altostratus (As), cumulus (Cu) and nimbostratus (Ns). The results of this study show that the surface observation in general overestimates a lot more than FY-2E and CloudSat; FY-2E provides more accurate high cloud estimates; CloudSat provides better middle cloud type detection; surface and CloudSat observation capture more consistent distribution of Sc, Ac, Cu and high cloud; all three datasets provide similar evidence on seasonal cycle, especially on Cu, Cb, Ac, with the pattern of peak in summer, their COF seasonal variation decrease. Seasonal variations of Sc, As, Ns COF especially from CloudSat are more reasonable. Cloud type and frequency is also compared among the three datasets by using limited temporal and spatial thresholds. In general, all three datasets yield more consistent detection of high cloud types than the other cloud types. Although this paper emphasizes on the comparison of spatial distribution, seasonal variation and coincident samples, it also discusses the strengths and weakness of different passive/active techniques.
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