CMIP6全球气候模式对长江流域气候变化的模拟评估与未来预估

Evaluation of the Performance of CMIP6 Models and Future Changes Over the Yangtze River Basin

以全球变暖为主要特征的全球气候变化对自然环境和社会经济发展产生了巨大影响。长江流域作为中国最大的流域,对气候变化的影响非常敏感,对未来气候变化的预测可以为应对未来的不确定性提供重要的科学依据。为了更准确地预测长江流域未来的温度和降水,针对第六次国际耦合模式比较计划(CMIP6)对长江流域26个气候模式进行评估,选择并校正性能更好的模式,讨论了长江流域未来的气温和降水。主要结论如下:(1)气候模式在温度上的模拟效果优于降水,在时间尺度上表现为月尺度>日尺度>年尺度。温度模拟存在一定程度的低估,降水模拟存在一定程度的高估。(2)区域尺度利用气候模式进行研究工作前的评估和校正是必要的,经过评估优化和季节校正后,数据的精度得到了显著提高,分位数映射法可以应用于气候模型数据的校正,但对于极端降水和温度的校正仍存在一些不足。(3)在SSP1-2.6情景中,未来温度和降水变化将在一段时间内持续不稳定增加,然后随着时间趋于稳定。在其他3种情景下,变化的速度随着时间的推移而加快。未来长江流域的降水和气温在所有情景下都将高于历史时期,表现为SSP5-8.5>SSP3-7.0>SSP2-4.5>SSP1-2.6。从季节上看,春季和冬季温度变化较大,降水在春季、夏季和冬季变化较大。在空间上,降水量增加较大的区域主要位于长江上游和东北部,而气温增加较大的区域主要位于长江上游和上游。

Global climate change mainly characterized by global warming has a great impact on the natural environment and socioeconomic development.As the largest basin in China,the Yangtze River Basin very sensitive to the impact of climate change.Prediction of future climate change can provide important scientific basis to deal with the future uncertainty.In order to make more accurate prediction of temperature and precipitation in the Yangtze River basin in the future,this paper assesses the performance of historical rainfall data and temperature data from the Coupled Model Intercomparison Project phase 6(CMIP6)over the Yangtze River Basin.The better performed models are selected and corrected.In addition,the future temperature and precipitation in the Yangtze River Basin are discussed.The main conclusions were as follows:(1)The performance of climate models on temperature is better than that of precipitation,and on the time scale is monthly scale>daily scale>annual scale.There is a certain degree of underestimation for temperature simulation and a certain degree of overestimation for precipitation simulation.(2)Regional scale research using climate models is necessary to conduct evaluation and calibration.After evaluating optimization and corrected by seasonal scale,correction of the data accuracy has been significantly improved,witch proves quantile mapping method can be applied to climate model correction of the data,but for extreme precipitation and temperature calibration still exist some shortcomings.In the SSP1-2.6 scenario,future temperature and precipitation changes will continue to increase instably for a period of time,and then tend to stabilize over time.In the other three scenarios,the rate of change accelerated over time.In the future,the precipitation and temperature in the Yangtze River Basin will be higher than that in the historical period under all scenarios,and the performance is SSP5-8.5>SSP3-7.0>SSP2-4.5>SSP1-2.6.Seasonally,the temperature changes greatly in spring and winter,while the precipitation changes little in autumn.Spatially,the regions with higher precipitation increase are mainly located in the headwaters and northeast of the Yangtze River,while the regions with higher temperature increase are mainly located in the upper reaches and headwaters of the Yangtze River.