基于CMIP6多模式的长江流域蒸散发预估及影响因素

蒸散发是水文循环和能量传输的中间环节，同时也是联结土壤、植被、大气过程的纽带。基于第六次国际耦合模式比较计划（CMIP6）12个全球气候模式数据，研究了SSP1-2.6、SSP2-4.5和SSP5-8.5三种情景下，长江流域2020-2099年实际蒸散发E_T（Evapotranspiration，简称ET）的时空变化及其影响因素。研究结果表明，在3种气候变化情景下长江流域ET相较基准期（1995-2014年）均存在显著增加趋势，且长江中下游地区增加趋势最为显著；SSP1-2.6情景ET较基准期先快速增加，21世纪60年代之后减缓并趋于平稳，SSP2-4.5和SSP5-8.5情景下均呈持续增加趋势。研究了降水（Precipitation，简称Pr）、气温（Air Temperature，简称T）和叶面积指数L_AI（Leaf Area Index，简称LAI）对长江流域ET的影响；SSP1-2.6和SSP2-4.5情景下，长江流域ET受T影响最为显著，而SSP5-8.5情景下，LAI是影响ET的主导因素。在3种气候情景下，辐射强迫越大，植被增加趋势越显著，对ET的影响越强（SSP5-8.5、SSP2-4.5、SSP1-2.6情景下影响逐渐减弱），而ET对LAI的敏感性则逐渐降低（SSP1-2.6、SSP2-4.5、SSP5-8.5情景下敏感性逐渐降低）。

Projected evapotranspiration and the influencing factors in the Yangtze River Basin based on CMIP6 models

Evapotranspiration (ET) is the bridge among hydrologic and energy cycles,linking soil,vegetation and atmospheric processes.In this paper,based on the output of 12 CMIP6 (Coupled Model Intercomparison Project,phase 6) models,the actual ET change during 2020-2099 and the influencing factors in the Yangtze River basin are studied under SSP1-2.6,SSP2-4.5 and SSP5-8.5 climate change scenarios.The results show that the land ET has significantly increased under the three scenarios compared with the baseline period (1995-2015),particularly in the middle and lower reaches of the Yangtze River Basin.Under the SSP1-2.6 scenario,the ET increases rapidly until the 2060s,and then levels off,after which a continuous increase is indicated under both SSP2-4.5 and SSP5-8.5 scenarios.The influencing factors of precipitation (Pr),air temperature (T) and leaf area index (LAI) are studied,and T appears to be the most important factor influencing Yangtze ET under SSP1-2.6 and SSP2-4.5 scenarios;however,the LAI becomes dominant across the Yangtze River Basin under the SSP5-8.5 scenario.Under the three scenarios,the LAI increases significantly with increased radiative forcing,leading to significantly increased vegetation impact on land ET (SSP5-8.5 > SSP2-4.5 > SSP1-2.6);however,the sensitivity of ET to LAI change appears to decrease with increased radiative forcing (SSP1-2.6 > SSP2-4.5 > SSP5-8.5).