利用美国大气研究中心(the National Center for Atmospheric Research,NCAR)的中层大气模式模拟了平流层准两年振荡(Quasi-Biennial Oscillation,QBO)过程对对流层顶和对流层上层的影响,并结合NCEP(the National Centers for Environme...利用美国大气研究中心(the National Center for Atmospheric Research,NCAR)的中层大气模式模拟了平流层准两年振荡(Quasi-Biennial Oscillation,QBO)过程对对流层顶和对流层上层的影响,并结合NCEP(the National Centers for Environmental Prediction)/NCAR、欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)月平均的风场资料和实际的探空观测资料,分析了平流层QBO对南海夏季风的影响作用.结果表明:平流层QBO会引起平流层的异常经向环流并向下传播,在QBO位相的中后期和位相转换期影响到对流层顶和对流层上层,使热带和低纬度的对流层上层形成异常的经向气压梯度,最终在夏季的对流层热带地区激发出不同类型的异常环流—西风位相时,激发出与南海夏季风环流相反的异常环流,在南海地区有显著的异常下沉运动,对南海夏季风有削弱作用;东风位相时,激发出反Hadley环流型的异常环流,在南海地区有明显的异常上升气流,对南海夏季风有加强的效果.虽然QBO对南海夏季风经向环流有影响,但它并不是决定南海夏季风准两年变化的唯一因子.展开更多
The intensity of interannual variability(IIV)of the monsoon and monsoon–ENSO biennial relationship(MEBR)were examined and compared for both the Indian summer monsoon(ISM)and western North Pacific summer monsoon(WNPSM...The intensity of interannual variability(IIV)of the monsoon and monsoon–ENSO biennial relationship(MEBR)were examined and compared for both the Indian summer monsoon(ISM)and western North Pacific summer monsoon(WNPSM)during 1958–2018.Covariability of the IIV and MEBR were identified for the two monsoons.When the MEBR was strong(weak),the IIV of the monsoon was observed to be large(small).This rule applied to both the ISM and WNPSM.Out-ofphase relationships were found between the ISM and the WNPSM.When the IIV and MEBR of the ISM were strong(weak),those of the WNPSM tended to be weak(strong).During the period with a stronger(weaker)ENSO–Atlantic coupling after(before)the mid-1980 s,the IIV and MEBR of the WNPSM(ISM)were observed to be stronger.The increasing influences from the tropical Atlantic sea surface temperature(SST)may trigger the observed seesaw pattern of the ISM and WNPSM in terms of the IIV and MEBR multidecadal variability.The results imply that tropical Atlantic SST may need to be given more attention and consideration when predicting future monsoon variability of the ISM and WNPSM.展开更多
This study focuses on the interdecadal changes in ENSO properties emerging around the year 2000. Compared to 1980-1999, after 2000, the ENSO amplitude weakened, the occurrence of the central Pacific （CP） Et Nino inc...This study focuses on the interdecadal changes in ENSO properties emerging around the year 2000. Compared to 1980-1999, after 2000, the ENSO amplitude weakened, the occurrence of the central Pacific （CP） Et Nino increased, and the eastern Pacific （EP） El Nino became suppressed. Meanwhile, the dominant period of ENSO shortened from quasi-quadrennial （QQ） to quasi-biennial （QB）. The authors show that these changes in ENSO properties are evidently consistent with the change in the stability of the ENSO mode through connecting the two ENSO types with the two coupled ENSO modes, i.e. the QQ and QB modes. It is suggested that the relative activity or stability of the two ENSO modes changed after the year 2000. The intensity of both the QQ and QB mode weakened. The QQ mode, which is linked to EP ENSO and was significantly strong during 1980-1999, became much weaker after 2000 in terms of the EP type almost disappearing. Compared with the weakness of the QQ mode, the QB mode, as manifested by the CP type, remained active and became dominant in the tropical Pacific after 2000. Analysis shows that the changes in mean states in the tropical Pacific were likely responsible for the interdecadal ENSO changes around the year 2000.展开更多
文摘利用美国大气研究中心(the National Center for Atmospheric Research,NCAR)的中层大气模式模拟了平流层准两年振荡(Quasi-Biennial Oscillation,QBO)过程对对流层顶和对流层上层的影响,并结合NCEP(the National Centers for Environmental Prediction)/NCAR、欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)月平均的风场资料和实际的探空观测资料,分析了平流层QBO对南海夏季风的影响作用.结果表明:平流层QBO会引起平流层的异常经向环流并向下传播,在QBO位相的中后期和位相转换期影响到对流层顶和对流层上层,使热带和低纬度的对流层上层形成异常的经向气压梯度,最终在夏季的对流层热带地区激发出不同类型的异常环流—西风位相时,激发出与南海夏季风环流相反的异常环流,在南海地区有显著的异常下沉运动,对南海夏季风有削弱作用;东风位相时,激发出反Hadley环流型的异常环流,在南海地区有明显的异常上升气流,对南海夏季风有加强的效果.虽然QBO对南海夏季风经向环流有影响,但它并不是决定南海夏季风准两年变化的唯一因子.
基金supported by the National Natural Science Foundation of China grant number 41776031the National Key Research and Development Program of China grant number 2018YFC1506903+2 种基金the Guangdong Natural Science Foundation grant number 2015A030313796the program for scientific research start-up funds of Guangdong Ocean Universitythe Foundation for Returned Scholars of the Ministry of Education of China。
文摘The intensity of interannual variability(IIV)of the monsoon and monsoon–ENSO biennial relationship(MEBR)were examined and compared for both the Indian summer monsoon(ISM)and western North Pacific summer monsoon(WNPSM)during 1958–2018.Covariability of the IIV and MEBR were identified for the two monsoons.When the MEBR was strong(weak),the IIV of the monsoon was observed to be large(small).This rule applied to both the ISM and WNPSM.Out-ofphase relationships were found between the ISM and the WNPSM.When the IIV and MEBR of the ISM were strong(weak),those of the WNPSM tended to be weak(strong).During the period with a stronger(weaker)ENSO–Atlantic coupling after(before)the mid-1980 s,the IIV and MEBR of the WNPSM(ISM)were observed to be stronger.The increasing influences from the tropical Atlantic sea surface temperature(SST)may trigger the observed seesaw pattern of the ISM and WNPSM in terms of the IIV and MEBR multidecadal variability.The results imply that tropical Atlantic SST may need to be given more attention and consideration when predicting future monsoon variability of the ISM and WNPSM.
基金jointly supported by the China Meteorological Special Projects[grant number GYHY201506013]the National Basic Reaseach Program of China(973)[grant number2015CB453203]+1 种基金the National Natural Science Foundation of China[grant numbers 41405080 and 41375062]partly supported by the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership China as part of the Newton Fund
文摘This study focuses on the interdecadal changes in ENSO properties emerging around the year 2000. Compared to 1980-1999, after 2000, the ENSO amplitude weakened, the occurrence of the central Pacific （CP） Et Nino increased, and the eastern Pacific （EP） El Nino became suppressed. Meanwhile, the dominant period of ENSO shortened from quasi-quadrennial （QQ） to quasi-biennial （QB）. The authors show that these changes in ENSO properties are evidently consistent with the change in the stability of the ENSO mode through connecting the two ENSO types with the two coupled ENSO modes, i.e. the QQ and QB modes. It is suggested that the relative activity or stability of the two ENSO modes changed after the year 2000. The intensity of both the QQ and QB mode weakened. The QQ mode, which is linked to EP ENSO and was significantly strong during 1980-1999, became much weaker after 2000 in terms of the EP type almost disappearing. Compared with the weakness of the QQ mode, the QB mode, as manifested by the CP type, remained active and became dominant in the tropical Pacific after 2000. Analysis shows that the changes in mean states in the tropical Pacific were likely responsible for the interdecadal ENSO changes around the year 2000.
