This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis d...This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role.展开更多
The water vapor transport around the Tibetan Plateau（TP） and its effect on the rainfall in the Yangtze River valley（YRV） in summer are investigated by decomposing the moisture transport into rotational and diverge...The water vapor transport around the Tibetan Plateau（TP） and its effect on the rainfall in the Yangtze River valley（YRV） in summer are investigated by decomposing the moisture transport into rotational and divergent components.Based on the ERA-Interim and PREC/L（Precipitation Reconstruction over Land） data from 1985 to 2014,the vertically integrated features of the two components are examined.The results show that the divergent part dominates the western TP while the rotational part dominates the rest of the TP,implying that moisture may be mostly locally gathered in the western TP but could be advected to/from elsewhere over the rest of the TP.The divergent and rotational moisture fluxes exhibit great temporal variability along the southern periphery of the TP,showing sensitivity of water vapor to the steep topography there.Correlation analysis reveals that it is over the southeastern corner of the TP and to its south that a significant correlation between rotational zonal moisture transport and summer rainfall in the YRV appears,suggesting that the southeastern corner of the TP may serve as a moisture transport bridge between the South Asian（Indian） monsoon and the East Asian monsoon.Further composite analysis indicates that anomalous eastward（westward） zonal water vapor transport from the South Asian monsoon via the southeastern corner of the TP favors more（less） precipitation in the YRV in summer.展开更多
基金National Natural Science Foundation for Yong Scholars(41105059,41305079)General Program of the National Natural Science Foundation of China(41575070,41230422,41575102)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2012CB417201)China Meteorological Administration Special Public Welfare Research Fund(GYHY201406001)National Natural Science Foundation of China(41130960 and 91437215)
文摘The water vapor transport around the Tibetan Plateau（TP） and its effect on the rainfall in the Yangtze River valley（YRV） in summer are investigated by decomposing the moisture transport into rotational and divergent components.Based on the ERA-Interim and PREC/L（Precipitation Reconstruction over Land） data from 1985 to 2014,the vertically integrated features of the two components are examined.The results show that the divergent part dominates the western TP while the rotational part dominates the rest of the TP,implying that moisture may be mostly locally gathered in the western TP but could be advected to/from elsewhere over the rest of the TP.The divergent and rotational moisture fluxes exhibit great temporal variability along the southern periphery of the TP,showing sensitivity of water vapor to the steep topography there.Correlation analysis reveals that it is over the southeastern corner of the TP and to its south that a significant correlation between rotational zonal moisture transport and summer rainfall in the YRV appears,suggesting that the southeastern corner of the TP may serve as a moisture transport bridge between the South Asian（Indian） monsoon and the East Asian monsoon.Further composite analysis indicates that anomalous eastward（westward） zonal water vapor transport from the South Asian monsoon via the southeastern corner of the TP favors more（less） precipitation in the YRV in summer.
