基于CMIP6气候模式的西南地区极端气候指数评估与预估

Evaluation and projection of extreme climate indices in Southwest China by CMIP6 models

采用8个常用极端气候指数评估第六次国际耦合模式的相互比较计划模式(CMIP6)对中国西南地区1990—2014年极端气温与极端降水特征的模拟能力,并采用4个共享社会经济路径及代表性浓度路径(SSP-RCP)组合情景,预估2023—2100年该地区极端气候事件变化趋势.结果表明:①CMIP6大部分模式能模拟西南地区极端气温自西到东逐渐升高、在南部边缘极端降水较多的空间分布特征;极端气温比极端降水的模拟效果更好;②相比观测值,预估的2015—2022年西南地区极端高温偏低,极端低温偏高,极端降水指数偏低;③未来2023—2100年的4个情景下,极端高温、暖昼日数和极端低温均呈上升趋势,冷夜日数呈下降趋势,未来西南地区具有较大的概率出现高温事件,出现低温事件的可能性降低;降水强度、最大连续5 d降水量和强降水总量呈上升趋势,未来中国西南地区降水强度和降水量将增加.

Based on 8 commonly used extreme climate indices,the research evaluates and analyzes thesimulation capabilities of the coupled model intercomparison program in phase 6(CMIP6)for extreme temperatureand precipitation characteristics in Southwest China from 1990 to 2014.It also estimates the trend of extremeclimate events from 2023 to 2100,using a combination of four shared socioeconomic pathways and representativeconcentration pathways(SSP−RCP).The results show that:①most models of CMIP6 can reasonably simulate thegradual increase of extreme temperatures from west to east in southwest China,and larger spatial distribution ofextreme precipitation in its southern margin.The simulation effect of extreme temperature is better than that ofextreme precipitation;②The estimated extreme high temperatures in the southwestern region from 2015 to 2022are lower than the observed values,with higher extreme low temperatures and lower extreme precipitation indices;③In the next four scenarios from 2023 to 2100,extreme high temperatures,warm day numbers,and extreme lowtemperatures all show an upward trend,while cold day numbers show a downward trend,indicating that theprobability of high-temperature-and-heat-wave weather in Southwest China would increase significantly in thefuture,and the probability of low-temperature-and-cold damage would decrease.The precipitation intensity,theannual maximum 5−day precipitation amount(Rx5day)and the annual total heavy precipitation show an upwardtrend,indicating that the intensity and total of precipitation in southwest China would increase in the future.