中国北方地区地面气候对全球1.5/2℃增温阈值和路径的响应

Response of Surface Climate in Northern China to 1.5/2℃ Global Warming Threshold and Scenario

通过分析中国北方干旱/半干旱区气候和水热循环及其分量对不同增温阈值和路径的响应,加深对区域尺度气候变化的理解,为应对和缓解未来气候变暖提供参考思路。本文利用NESM(Nanjing University Information Science and Technology Earth System Model)大尺度模式驱动WRF(Weather Research and Forecasting model)区域模式,模拟预估中国对未来增暖1.5/2℃时不同排放路径下区域气候的响应。对中国北方干旱/半干旱区气候场和水热循环未来变化进行定量评估表明,稳定增暖1.5℃情景下,干旱/半干旱区内温度和降水的增加幅度由西向东递减,水分收支分量受到降水影响;净辐射将在整个区域内增加1%~3%,并更多以潜热通量的形式向大气输送热量。增暖达到2℃时干旱区内温升超过2.6℃,降水和水分收支分量增多,净辐射和感热通量将在大部分地区相比增暖1.5℃时减少。对比稳定增暖2℃情景,瞬变增暖2℃下温度的升温幅度在大部分区域减小0.1~0.3℃,瞬变增暖路径下净辐射的减弱可能是导致温度升温幅度降低的原因之一。夏季可用水(降水减去蒸发)对增暖路径的敏感响应导致不同区域内干旱的可能变化存在差异。相比瞬变增暖路径,稳定增暖2℃下干旱及半湿润区干旱缓解有所减缓,而半干旱区内干旱状态进一步缓解。

Analyzing the response of climate,water,and energy budgets,along with their components,to various warming thresholds and scenarios in the arid and semi-arid regions of northern China can further elucidate regional climate changes and form strategies for addressing future global warming.Using simulations from the global climate model,NESM(Nanjing University Information Science and Technology Earth System Model),and the regional model,WRF(Weather Research and Forecasting model),we project the regional climate response to different warming scenarios under future temperature increases of 1.5℃ and 2℃.Quantitative assessments of future changes in climate,water,and energy budgets in these arid and semi-arid areas indicate that under a stabilized 1.5℃ warming scenario,the amplification of temperature and precipitation decreases from west to east.Additionally,the components of the water budget are influenced by changes in precipitation.Net radiation is expected to increase across the entire region,resulting in a greater transfer of heat to the atmosphere in the form of latent heat flux.When the stabilized warming reaches 2℃,temperatures in arid areas may exceed 2.6℃,accompanied by increases in precipitation and water budget components.However,changes in net radiation and sensible heat flux are projected to decrease in most regions compared with those under 1.5℃ warming.In contrast to the case of stabilized 2℃ warming,under the transient 2℃ warming scenario,the increase in temperature is less pronounced across most areas,and weakening of net radiation may contribute to this reduction.The response of summer available water(precipitation−evaporation)to warming scenarios results in varying degrees of potential aridity changes among subregions.Compared with transient warming scenarios,the mitigation of aridification in arid and semi-humid areas is retarded under a stabilized 2℃ warming scenario,and further alleviated aridification occurs in semi-arid areas.