Key Laboratory for Semi-Arid Climate Change of the Ministry of Education,College of Atmospheric Sciences,Lanzhou University
Cloud base height (CBH) plays an important role in weather forecasting and flight service. However, there is lacking in CBH data with high spatio-temporal resolution. This study evaluates the CBH product of ERA5 reanalysis data using ground-based observations in eastern China, revealing the CBH feature in China by validated CBH data from ERA reanalysis. Overall, the CBH from ERA5 reanalysis data are lower than those from ground-based measurements, in which the low-clouds and middle-clouds are overestimated and underestimated, respectively. In addition, under precipitation condition, the CBHs from ERA5 data indicate a higher accuracy for low clouds than those under non-precipitation synoptic background, while the accuracy of ERA5 CBH is lower for middle- and high-cloud. The result shows that the CBHs are lower in the daytime than those at night, peaking at 9:00 and 22:00 over eastern China in the daytime and at night, respectively. On the whole, the monthly mean CBHs from ERA5 reanalysis are consistent with the ground-based measurements in autumn and winter. The revised CBHs of ERA5 data present a gradually decrease from northwest to southeast of China during 2010-2019. Besides, the CBHs over the southern China, northeastern China and Tibetan Plateau are relatively lower than other areas. The CBHs show lower over the Tibetan Plateau in summer and autumn but higher in spring and winter. Additionally, the desert region has higher CBH in all four seasons.