北方蒸散对气候变暖响应随降水类型转换特征  

Transition features of surface evapotranspiration responding to climate warming with spatial precipitation-based climate type in northern China

作　　者：张强[1,2] 杨泽粟 郝小翠[4] 岳平[1] Qiang Zhang;Zesu Yang;Xiaocui Hao;Ping Yue(Key Laboratory of Arid Climatic Change and Reducing Disaster of Gansu Province, Key Open Laboratory of Arid Climatic Change and Disaster Reduction, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China;Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, College of Atmospheric Sciences, Chengdu University oflnformation Technology, Chengdu 610225, China;Gansu Meteorological Bureau, Lanzhou 730020, China;Northwest Regional Climate Centre, Lanzhou 730020, China)

机构地区：[1]中国气象局兰州干旱气象研究所甘肃省干旱气候变化与减灾重点实验室中国气象局干旱气候变化与减灾重点开放实验室,兰州730020 [2]甘肃省气象局,兰州730020 [3]成都信息工程大学大气科学学院高原大气与环境四川省重点实验室,成都610225 [4]西北区域气候中心,兰州730020

出　　处：《科学通报》2018年第11期1035-1049,共15页Chinese Science Bulletin

基　　金：国家自然科学基金重点项目(41630426); 国家重点基础研究发展计划(2013CB430206)资助

摘　　要：地表蒸散量是对全球气候变暖响应最显著的水分循环分量,但以往不同研究得出的气候变暖背景下各地地表蒸散量的变化趋势差异很大,有时甚至表现出相反的趋势.然而,对于地表蒸散对气候变暖响应的差异性具有怎样的规律以及是何原因造成了这种差异至今也并不完全清楚.为此,在对中国北方地区的蒸散量格点资料(FLUXNET)和全球陆面同化资料(GLDAS)进行观测试验验证的基础上,利用可靠性相对较高的蒸散量格点资料及以往研究常用的CRU和ERA-Interim气候格点资料,分析了我国北方不同降水气候空间类型时地表蒸散量对气温增加的响应特征.分析发现:地表蒸散量对气温升高的响应程度随降水气候类型不同变化比较明显,地表蒸散量的增温倾向率表现出随降水气候类型变化的显著转换特征.降水量在200~400 mm的气候区间时,正好是倾向率发生转折的气候敏感区间;在更湿润气候类型时,气候越湿润,地表蒸散量随气温升高增加的就越明显;而在更干燥气候类型时,气候越干燥,地表蒸散量反而随气温升高减少的越明显.地表蒸散量对气候变暖的这种响应特征在全球其他气候过渡比较明显的典型地区也有不同程度的表现.同时,就地表蒸散量对气候变暖的响应机制而言,主要有气温升高直接引起的潜在蒸散力增加与气温升高通过蒸散过程造成的土壤水分损失再反过来间接抑制蒸散这两个作用过程.前者在湿润地区起主导作用,导致蒸散增强;而后者在干燥地区主导作用,导致蒸散减弱.该研究结论对地表蒸散的气候变化响应特征有新认识,对改进全球水资源评估方法和干旱监测技术具有重要科学参考意义.Global surface evapotranspiration is one of the most significant components of the response of the water cycle to a warming climate. However, trends in surface evapotranspiration have varied widely from the trend in climate warming according to recent studies, and some studies have even shown an opposing trend. The reason for this difference in the response of surface evapotranspiration to climate warming is still not completely understood. We validated the gridded FLUXNET evapotranspiration dataset and the Global Land Data Assimilation System（GLDAS） against evapotranspiration data observed in Northern China by eddy covariance systems. The response of evapotranspiration to increases in temperature varies with climate type in Northern China and there is a correlation with the amount of precipitation. Climate types with a mean annual precipitation of 200–400 mm（P250 and P350） are a sensitive interval in which the climatological trend of evapotranspiration changes from negative to positive and the response of evapotranspiration to an increase in temperature is less obvious. In more humid climates, evapotranspiration increases with increasing temperature, whereas in drier climates evapotranspiration decreases with increasing temperature. Similar transition zones for surface evapotranspiration are also seen in other regions. This is a new understanding of global changes in surface evapotranspiration and can explain the different trends in the response of surface evapotranspiration to temperature reported previously. Although the methods and data used are different from these earlier studies, the differences between precipitation-based climate types are clearer. These transition zones can be explained by the different mechanisms for the effect of temperature on evapotranspiration. Temperature directly affects the potential evapotranspiration and an increase in temperature will increase the potential evapotranspiration. However, this increase in evapotranspiration can result in a decrease in the soil moisture

关 键 词：气候过渡区 地表蒸散量 降水气候类型 增温倾向率 转换特征 

分 类 号：P461[天文地球—大气科学及气象学]