CMIP6模式对青藏高原东坡暖季降水的模拟评估

青藏高原东坡陡峭地形区是气候模式陆地降水模拟偏差的大值区,且这一偏差长期未得到有效改善.基于17个参加国际耦合模式比较计划第六阶段(CMIP6)的全球气候模式的日降水结果,评估了当前最新一代的气候模式对青藏高原东坡地区2000—2014年暖季(5—9月)降水气候态及其季节内演变的模拟能力.结果表明:高原东坡降水正偏差存...

Assessment of warm season precipitation in the eastern slope of the Tibetan Plateau by CMIP6 models

The steep terrain area in the eastern slope of the Tibetan Plateau is a large deviation area for climate models in the processes of simulating land precipitation, and this deviation has not been effectively improved for a long time. Based on the daily precipitation of 17 global climate models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6), the ability of the latest climate models to simulate precipitation climatological characteristics and their intraseasonal evolution over the eastern slope of the Tibetan Plateau during the warm season (May to September) from 2000 to 2014 was assessed. The results show that the positive precipitation deviation in the eastern slope of the Tibetan Plateau exists in most CMIP6 models, and the false precipitation center mainly comes from the over-simulation of the heavy rainfall (precipitation≥6 mm/d), and the simulation of the weak rainfall (precipitation<6 mm/d) is smaller than that of TRMM observation. Although there is a consistent over-simulation of the warm season precipitation in the eastern slope of the Tibetan Plateau, there are large differences in the simulation of precipitation for different months between models. The analysis based on the circulation field shows that the intraseasonal evolution of the heavy rainfall in the eastern slope of the Tibetan Plateau is closely related to the evolution of southerly wind anomalies in the mid-troposphere in the eastern slope of the Tibetan Plateau and east to it. The above results indicate that although the simulation of the mid-tropospheric circulation is not the main factor causing the positive deviation of the simulation of heavy rainfall in the eastern slope of the Tibetan Plateau, the reasonable simulation of the intraseasonal variation of the circulation is a key factor for a model to reproduce the month-to-month variation of heavy rainfall on the eastern slope of the Tibetan Plateau.