CMIP6 Evaluation and Projection of Temperature and Precipitation over China

Abstract

This article evaluates the performance of 20 Coupled Model Intercomparison Project phase 6 (CMIP6) models in simulating temperature and precipitation over China through comparisons with gridded observation data for the period of 1995–2014, with a focus on spatial patterns and interannual variability. The evaluations show that the CMIP6 models perform well in reproducing the climatological spatial distribution of temperature and precipitation, with better performance for temperature than for precipitation. Their interannual variability can also be reasonably captured by most models, however, poor performance is noted regarding the interannual variability of winter precipitation. Based on the comprehensive performance for the above two factors, the “highest-ranked” models are selected as an ensemble (BMME). The BMME outperforms the ensemble of all models (AMME) in simulating annual and winter temperature and precipitation, particularly for those subregions with complex terrain but it shows little improvement for summer temperature and precipitation. The AMME and BMME projections indicate annual increases for both temperature and precipitation across China by the end of the 21st century, with larger increases under the scenario of the Shared Socioeconomic Pathway 5/Representative Concentration Pathway 8.5 (SSP585) than under scenario of the Shared Socioeconomic Pathway 2/Representative Concentration Pathway 4.5 (SSP245). The greatest increases of annual temperature are projected for higher latitudes and higher elevations and the largest percentage-based increases in annual precipitation are projected to occur in northern and western China, especially under SSP585. However, the BMME, which generally performs better in these regions, projects lower changes in annual temperature and larger variations in annual precipitation when compared to the AMME projections.

摘 要

通过与1995–2014年中国温度和降水格点观测数据的对比, 评估了第六次耦合模式比较计划 (CMIP6) 中的20个全球气候模式对中国温度和降水空间型态与年际变率的模拟能力. 评估结果表明:CMIP6模式能够较好地再现观测中温度和降水的气候态分布, 其中对温度的模拟优于降水. 其年际变率也能被大多数模式合理模拟出, 不过对冬季降水年际变率的模拟较差. 基于模式对温度和降水空间型态和年际变率模拟能力的综合表现, 选择了“排名最高”的模式集合 (BMME), 发现BMME对年平均和冬季的温度与降水的模拟优于所有模式集合 (AMME), 尤其在具有复杂地形的区域; 而对于夏季温度和降水的模拟与AMME相比没有明显改善. AMME和BMME的预估结果均表明, 到21世纪末, 中国区域温度和降水都将增加, 其中SSP585情景下的增幅大于SSP245. 年平均温度最大增幅出现在高纬度和高海拔地区, 年降水量最大百分比增幅出现在中国西北部地区. 不过, 对于上述BMME模拟明显改善的地区, BMME预估的年平均温度变化幅度要比AMME预估的小, 而预估的年降水量变化幅度则比AMME预估的要大.