东亚地区晴空湍流未来变化趋势预估:基于CORDEX-WRF模式降尺度  

Future change of clear-air turbulence over East Asia:base on CORDEX-WRF downscaling technology

作　　者：胡伯彦[1,2] 汤剑平 王淑瑜[1] HU BoYan;TANG JianPing;WANG ShuYu(School of Atmospheric Sciences,Nanjing University,Nanjing 210023,China;East China Regional Air Traffic Management Bureau,Shanghai 200335,China)

机构地区：[1]南京大学大气科学学院,南京210023 [2]中国民用航空华东地区空中交通管理局,上海200335

出　　处：《地球物理学报》2022年第7期2432-2447,共16页Chinese Journal of Geophysics

基　　金：国家重点研发计划项目(2018YFA0606003)资助。

摘　　要：利用耦合模式比较计划(CMIP5)的全球环流模式CNRM-CM5、GFDL-ESM2M、EC-EARTH和MPI-ESM-LR分别驱动区域气候模式(RCM)WRF,在国际间区域气候降尺度试验(CORDEX)框架下对东亚地区当代和RCP 8.5情景下未来气候进行高分辨率模拟.通过计算21个晴空湍流指数研究了东亚地区2041—2060年三个高度层上(200 hPa、250 hPa和300 hPa)五种强度湍流(轻度、轻-中度、中度、中-重度和重度)的季节变化特征.首先检验RCM对1981—2000年气候的模拟能力,结果显示,模式能够较好再现东亚地区高空变量气候平均态空间分布特征,同时对晴空湍流指数分布特征亦具有较好模拟能力.晴空湍流未来变化趋势预估结果显示,东亚地区所有季节中均存在湍流强度越强、湍流频率增幅越大的特征.各强度湍流增幅冬季最大,其次为春季和秋季,夏季最小.从不同高度对比来看,200 hPa和250 hPa各强度湍流增幅普遍大于300 hPa,且在夏季和秋季增幅随高度降低而减小,春季和冬季则250 hPa上增幅最大,300 hPa上增幅最小.就中国不同子区域而言,纬度越高的区域湍流频率增幅越大,且北方地区各高度上还存在增幅“东高西低”的分布特征,南方地区则在250 hPa和300 hPa上为“西高东低”分布特征.未来东亚中纬度地区垂直风切变作用增强可能是引起晴空湍流增多的重要原因之一.Driven by four global circulation models(GCMs)from the Coupled Model Intercomparison Project Phase 5(CMIP5)ensemble(CNRM-CM5,GFDL-ESM2 M,EC-EARTH,and MPI-ESM-LR),the future seasonal changes(2041—2060)of clear-air turbulence in five strength categories(light,light-to-moderate,moderate,moderate-to-severe,and severe)at three altitude levels(200 hPa,250 hPa,and 300 hPa)over East Asia are projected with Regional Climate Model(RCM)Weather Research and Forecasting(WRF),as well as 21 clear-air turbulence diagnostics.The RCM simulations are carried out under the Representative Concentration Pathway 8.5(RCP 8.5)scenario and the second phase of the Coordinated Regional Downscaling Experiment East Asia(CORDEX-EA-II)framework.Evaluation results show that RCM can well reproduce the spatial distribution of high-level climatological characteristics and clear-air turbulence diagnostics over East Asia at present climate background(1981—2000).Prediction results show that the stronger the turbulence strength categories,the more significant percentage changes in the occurrence frequency of the turbulence in each season;meanwhile,the most significant increment appears in winter,whereas the smallest increment appears in summer.The magnitude of turbulence increment is generally larger at 200 hPa and 250 hPa than at 300 hPa,decreasing magnitude with reducing altitude in summer and autumn,and largest/smallest magnitude at 250 hPa/300 hPa in spring and winter.The frequency increment in northern regions is more significant than in southern regions.Additionally,a more considerable increment appears in Northeast China than in Northwest China at all levels;however,it is a more significant increment in Southwest China than in Southeast China at 250 hPa and 300 hPa.It should be noted that the enhanced vertical wind shear in the mid-latitudes of East Asia in the future might be one of the important reasons for the increment of clear-air turbulence.

关 键 词：晴空湍流 未来变化 WRF模式 降尺度技术 CORDEX 

分 类 号：P467[天文地球—大气科学及气象学]