Based on the TOGA-TAO buoy chain observed data in the equatorial Pacific and the assimilation analysis results from SODA(simple ocean data assimilation analysis), the role of the meridional cells in the subsurface of ...Based on the TOGA-TAO buoy chain observed data in the equatorial Pacific and the assimilation analysis results from SODA(simple ocean data assimilation analysis), the role of the meridional cells in the subsurface of the tropical Pacific was discussed. It was found that, the seasonal varying direction of EUC(the quatorial Undercurrent)in the Peacific is westwards beginning from the eastern equatorial Pacific in the boreal spring. The meridional cell south of the equator plays important role on this seasonal change of EUC.On the other hand, although the varying direction is westwards, the seasonal variation of temperature in the same region gets its minimum values in the boreal autumn beginning from the eastern equatorial Pacific.The meridional cell north of the equator is most responsible for the seasonal temperature variation in the eastern equatorial Pacific while the meridional cell south of the equator mainly controls the seasonal temperature change in the central Pacific. It is probably true that the asymmetry by the equator is an important factor influencing the seasonal cycle of EUC and temperature in the tropical Pacific.展开更多
An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric R...An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric Research (NCEP/NCAR). It is found that the difference between the geopotential thickness over Guangzhou and Manila can be used as an alternative index for the onset of summer monsoon over the SCS. Since the convective heating alters the geopotential height and the distance between Guangzhou and Manila is of synoptic scale in the geostraphic framework, the index can represent the strength of heating and the first baroclinic cell over the SCS. By comparison between different indices, it is found that the summer monsoon onset over the SCS can be ascertained by the vertical zonal wind shear between 200 hPa and 850 hPa, the zonal wind at 850 hPa, the OLR anomaly, and the alternative index defined in the present paper. The meridional wind shear between 200 hPa and 850 hPa always appears over the SCS much earlier than the zonal wind shear and cannot be used as an index under consideration.展开更多
A synoptic snapshot in this study is made for the East Cape Eddy (ECE) basedon the World Ocean Circulation Experiment (WOCE) P14C Hydrographic Section and Shipboard ADCPvelocity vector data collected in September 1992...A synoptic snapshot in this study is made for the East Cape Eddy (ECE) basedon the World Ocean Circulation Experiment (WOCE) P14C Hydrographic Section and Shipboard ADCPvelocity vector data collected in September 1992. The ECE is an anticyclonic eddy, barotropicallystructured and centered at 33.64°S and 176.21°E, with warm and salinous-cored subsurface water.The radius of the eddy is of the order O (110 km) and the maximum circumferential velocity is O (40cm s^(-1)); as a result, the relative vorticity is estimated to be O (7 x 10^(-6)s^(-1)). Due to theexistence of the ECE, the mixed layer north of New Zealand becomes deeper, reaching a depth of 300m in the austral winter. The ECE plays an important role in the formation and distribution of theSubtropical Mode Water (STMW) over a considerable area in the South Pacific.展开更多
文摘Based on the TOGA-TAO buoy chain observed data in the equatorial Pacific and the assimilation analysis results from SODA(simple ocean data assimilation analysis), the role of the meridional cells in the subsurface of the tropical Pacific was discussed. It was found that, the seasonal varying direction of EUC(the quatorial Undercurrent)in the Peacific is westwards beginning from the eastern equatorial Pacific in the boreal spring. The meridional cell south of the equator plays important role on this seasonal change of EUC.On the other hand, although the varying direction is westwards, the seasonal variation of temperature in the same region gets its minimum values in the boreal autumn beginning from the eastern equatorial Pacific.The meridional cell north of the equator is most responsible for the seasonal temperature variation in the eastern equatorial Pacific while the meridional cell south of the equator mainly controls the seasonal temperature change in the central Pacific. It is probably true that the asymmetry by the equator is an important factor influencing the seasonal cycle of EUC and temperature in the tropical Pacific.
基金the support for this work from China Ministry of Education
文摘An alternative index for the onset of summer monsoon over the South China Sea (SCS) has been designed based on the reanalysis data of the National Centers for Environmental Prediction National Center for Atmospheric Research (NCEP/NCAR). It is found that the difference between the geopotential thickness over Guangzhou and Manila can be used as an alternative index for the onset of summer monsoon over the SCS. Since the convective heating alters the geopotential height and the distance between Guangzhou and Manila is of synoptic scale in the geostraphic framework, the index can represent the strength of heating and the first baroclinic cell over the SCS. By comparison between different indices, it is found that the summer monsoon onset over the SCS can be ascertained by the vertical zonal wind shear between 200 hPa and 850 hPa, the zonal wind at 850 hPa, the OLR anomaly, and the alternative index defined in the present paper. The meridional wind shear between 200 hPa and 850 hPa always appears over the SCS much earlier than the zonal wind shear and cannot be used as an index under consideration.
文摘A synoptic snapshot in this study is made for the East Cape Eddy (ECE) basedon the World Ocean Circulation Experiment (WOCE) P14C Hydrographic Section and Shipboard ADCPvelocity vector data collected in September 1992. The ECE is an anticyclonic eddy, barotropicallystructured and centered at 33.64°S and 176.21°E, with warm and salinous-cored subsurface water.The radius of the eddy is of the order O (110 km) and the maximum circumferential velocity is O (40cm s^(-1)); as a result, the relative vorticity is estimated to be O (7 x 10^(-6)s^(-1)). Due to theexistence of the ECE, the mixed layer north of New Zealand becomes deeper, reaching a depth of 300m in the austral winter. The ECE plays an important role in the formation and distribution of theSubtropical Mode Water (STMW) over a considerable area in the South Pacific.