Evaluation of Historical Snow Cover over the Tibetan Plateau in CMIP6

Snow cover over the Tibetan Plateau (TP) (TPSC) has garnered significant attention as a crucial indicator of climate change, along with its variations and related climate processes. However, due to the complex terrain of the TP, most numerical models exhibit notable uncertainty in simulating snow conditions in this area. This study evaluates historical snow simulations and related climate anomalies over the TP in numerical models from phase 6 of the Coupled Model Intercomparison Project (CMIP6). The CMIP6 model simulations are compared with two observation-based products across different seasons and temporal scales, and the results indicate that the CMIP6 multimodel ensemble (MME) mean reasonably captures the spatial distribution of the annual and seasonal climatological mean TP snow, albeit with weaker magnitudes compared to observations. The CMIP6 MME performs better over the western TP than the eastern regions, showing a higher reproducibility of the long-term warming trends and declining snow cover trends, partly due to the atmospheric circulation anomalies related to global warming. Additionally, some CMIP6 models successfully capture the interannual variability of TPSC and its relationship with associated climate factors. Our work emphasizes the importance of CMIP6 model selection and pays attention to data reliability in interpreting CMIP6 model results across different TP regions when studying snow cover variations and climate effects using numerical models.