Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both g...Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.展开更多
为探究汤旺河上游流域未来气温、降水及径流的变化情况,采用第六次国际耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中CanESM5模式下的3种情景(SSP1-2.6、SSP2-4.5、SSP5-8.5)数据,基于Delta降尺度方法对未...为探究汤旺河上游流域未来气温、降水及径流的变化情况,采用第六次国际耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中CanESM5模式下的3种情景(SSP1-2.6、SSP2-4.5、SSP5-8.5)数据,基于Delta降尺度方法对未来气温和降水进行处理,并结合SWAT(Soil and Water Assessment Tool)水文模型预估未来径流变化。未来整个时期(2015—2100年)最高、最低气温和降水均有所增加,但在不同情境下的增速不同,分别为0.65℃/10a、0.65℃/10a、12.23 mm/10a(SSP1-2.6),0.25℃/10a、0.39℃/10a、11.14 mm/10a(SSP2-4.5),0.81℃/10a、0.86℃/10a、23.57 mm/10a(SSP5-8.5);汤旺河上游流域未来径流在3种情境下有增加现象,增幅位于-2.12%~52.04%,且近期(2017—2050年)SSP1-2.6、SSP5-8.5和中期(2050—2100年)SSP1-2.6、SSP2-4.5、SSP5-8.5情境下流域内8、9月份峰值径流量高于基准期,最大增量为36.69 m^(3)/s。未来整个汤旺河上游流域可能出现暖湿现象,发生极端水文事件的风险可能变大。通过对未来气候进行模拟,分析汤旺河上游流域径流变化特征,可为区域水资源配置、水资源利用和预防旱涝灾害提供科学依据与理论支撑。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U2342210 and 42275043)the National Institute of Natural Hazards,Ministry of Emergency Management of China(Grant Nos.J2223806,ZDJ2024-25 and ZDJ2025-34)。
文摘Climate models are essential for understanding past,present,and future changes in atmospheric circulation,with circulation modes providing key sources of seasonal predictability and prediction uncertainties for both global and regional climates.This study assesses the performance of models participating in phase 6 of the Coupled Model Intercomparison Project in simulating interannual variability modes of Northern Hemisphere 500-hPa geopotential height during winter and summer,distinguishing predictable(potentially predictable on seasonal or longer timescales)and unpredictable(intraseasonal and essentially unpredictable at long range)components,using reanalysis data and a variance decomposition method.Although most models effectively capture unpredictable modes in reanalysis,their ability to reproduce dominant predictable modes-specifically the Pacific-North American pattern,Arctic Oscillation,and Western Pacific Oscillation in winter,and the East Atlantic and North Atlantic Oscillations in summer-varies notably.An optimal ensemble is identified to distinguish(a)predictable-external modes,dominated by external forcing,and(b)predictable-internal modes,associated with slow internal variability,during the historical period(1950-2014)and the SSP5-8.5 scenario(2036-2100).Under increased radiative forcing,the leading winter/summer predictable-external mode exhibits a more uniform spatial distribution,remarkably larger trend and annual variance,and enhanced height-sea surface temperature(SST)covariance under SSP5-8.5 compared to historical conditions.The dominant winter/summer predictable-internal modes also exhibit increased variance and height-SST covariance under SSP5-8.5,along with localized changes in spatial configuration.Minimal changes are observed in spatial distribution or variance for dominant winter/summer unpredictable modes under SSP5-8.5.This study,from a predictive perspective,deepens our understanding of model uncertainties and projected changes in circulations.
文摘为探究汤旺河上游流域未来气温、降水及径流的变化情况,采用第六次国际耦合模式比较计划(Coupled Model Intercomparison Project Phase 6,CMIP6)中CanESM5模式下的3种情景(SSP1-2.6、SSP2-4.5、SSP5-8.5)数据,基于Delta降尺度方法对未来气温和降水进行处理,并结合SWAT(Soil and Water Assessment Tool)水文模型预估未来径流变化。未来整个时期(2015—2100年)最高、最低气温和降水均有所增加,但在不同情境下的增速不同,分别为0.65℃/10a、0.65℃/10a、12.23 mm/10a(SSP1-2.6),0.25℃/10a、0.39℃/10a、11.14 mm/10a(SSP2-4.5),0.81℃/10a、0.86℃/10a、23.57 mm/10a(SSP5-8.5);汤旺河上游流域未来径流在3种情境下有增加现象,增幅位于-2.12%~52.04%,且近期(2017—2050年)SSP1-2.6、SSP5-8.5和中期(2050—2100年)SSP1-2.6、SSP2-4.5、SSP5-8.5情境下流域内8、9月份峰值径流量高于基准期,最大增量为36.69 m^(3)/s。未来整个汤旺河上游流域可能出现暖湿现象,发生极端水文事件的风险可能变大。通过对未来气候进行模拟,分析汤旺河上游流域径流变化特征,可为区域水资源配置、水资源利用和预防旱涝灾害提供科学依据与理论支撑。
