地球工程对全球陆地极端降雨影响的空间分异研究

地球工程应对气候变暖已成为近年来学界广泛讨论的焦点问题之一。基于BNU-ESM模式数据,采用百分位数阈值方法界定强降雨和极端强降雨事件,从气候态特征、变化趋势和波动特征三个角度对比分析了地球工程情景(G4试验)和非地球工程情景(RCP4.5)下全球陆地强降雨量和极端强降雨量的空间分异特征。结果表明:(1)在气候态特征上,地球工程实施并未从根本上改变强降雨和极端强降雨量的空间高低分异格局,仅数值上有所差异。两种情景下气候态差异特征表明地球工程在2020—2069年实施期间对北(南)半球以抑制(促进)作用为主,而在2070—2099年实施结束后对北(南)半球以促进(抑制)作用为主。地球工程实施结束后相比实施期间促进了全球多数地区的强降雨和极端强降雨量。(2)在变化趋势上,两种情景下的强降雨量变化趋势在2020—2069年存在一定差异特征,而在2010—2099年和2070—2099年具有较高的一致性。两种情景下的极端强降雨量变化趋势则在2020—2069年和2070—2099年呈现出异质性。两种情景下变化趋势差异特征表明, 2070—2099年地球工程均促进了强降雨和极端强降雨量增加趋势。强降雨和极端强降雨量在地球工程实施前后均具有不同的区域性特征。(3)在波动特征上,地球工程实施不同阶段强降雨和极端强降雨量波动特征的空间高低分异格局相差不大,仅数值上有一定差异。两种情景下波动差异表明地球工程实施不同阶段均减小了强降雨量的波动特征。但极端强降雨量则在2020—2069年和2070—2099年呈现出相反的波动差异特征。地球工程情景下实施结束后的波动特征明显高于实施期间。

Study on spatial differentiation of impact from geoengineering project on extreme rainfall of global land

Dealing climate warming with geoengineering project becomes one of the focus issues within the relevant academic circle in recent years. Based on BNU-ESM model datasets，heavy rainfall and extreme rainfall events are defined with the percentile threshold method，while the spatial differentiation characteristics of global land heavy rainfall and extreme rainfall under geoengineering scenarios ( G4 test) and non-geoengineering scenarios ( RCP4. 5) are comparatively analyzed from three perspectives， i. e. climatological characteristics，variation trends and fluctuation characteristics. The results show that ( 1) From the aspect of climatological characteristics，the spatial differentiation patterns of both the heavy rainfall amounts and the extreme rainfall amounts are not to be fundamentally changed by the implementation of the relevant geoengineering project at all，but only some differences are to be numerically there. The difference of the climatological characteristics between both the scenarios indicates that the geoengineering project is mainly to play an inhibiting ( promoting) role on the northern ( southern) hemisphere during the implementation period ( 2020—2069) ，but is mainly to play a promoting ( inhibiting) role on the northern ( southern) hemisphere after the implementation period ( 2070—2099) . After the implementation of the geoengineering project，heavy rainfalls and extreme rainfalls are to be promoted in most parts of the world if compared with those during the implementation period. ( 2) From the aspect of the variation trend，some difference characteristics between the variation trends of the heavy rainfall amounts under both the scenarios are to be there during 2020—2069，but the variation trends are to have higher consistency during the periods of 2010—2099 and 2070—2099. Nevertheless，the variation trends of extreme rainfall amounts under both the scenarios are to exhibit heterogeneities. The difference characteristics of the variation trends under both the scenarios indicate that the increasing trends of both heavy rainfall amounts and extreme rainfall amounts are to be promoted by the geoengineering project during the period of 2070—2099，while both the heavy rainfall amounts and extreme rainfall amounts are to have different regional characteristics as well. ( 3) From the aspect of the fluctuation characteristics，the spatial differentiation patterns of the fluctuation characteristics of both the heavy rainfall amounts and the extreme rainfall amounts are not to be very different during the different stages of the implementation of the geoengineering project，but only some differences are to be numerically there. The fluctuation differences under both the scenarios show that the fluctuation characteristics of heavy rainfall amounts are to be decreased in different stages of the implementation of the geoengineering project. However，extreme rainfall amounts are to exhibit opposite fluctuation differences during the periods of 2020—2069 and 2070—2099. The fluctuation characteristics after the implementation of geoengineering project are to be significantly higher than those during the implementation period under the geoengineering scenarios.