Characteristics of Stratiform Cloud over the East of Tibetan Plateau Simulated by Two Versions of the FGOALS2 Climate System Model

Eastern China, on the east of Tibetan Plateau (22°N–32°N，102°E–118°E), is covered by stratiform clouds in winter time. This cloud type is unique to like latitudes of the global subtropical continent. A reasonable simulation of these clouds over the leeside of the Tibet Plateau remains a challenge for the current state-of-the art climate models. In this study, we compared the Cloud radiation forcing and other cloud properties and their radiative forcing at the top of the atmosphere from two LASG/IAP climate system models, Atmospheric Model Intercomparison Project (AMIP) of Flexible Global Ocean–Atmosphere–Land System-s2 and g2 (FGOALS-s2 and FGOALS-g2), and observations from the International Satellite Cloud Climatology Project (ISCCP). It was found that both models underestimated the strength of shortwave cloud forcing, cloud water path, and cloud fraction over Eastern China. FGOALS-s2 can reproduce the domination of low stratiform clouds over Eastern China, while FGOALS-g2 overestimated the proportion of high clouds. Such bias in the simulation of stratiform clouds is related to weak lower tropospheric stability and insufficient low-level moisture. In addition, the overestimated average cloud top height in FGOALS-g2 was explained as an unrealistic updraft, which produced stronger vertical moisture transports over the east of Tibetan Plateau.