Abstract:

The WOCE consecutive six-year temperature data in the upper layer of a section between Tasmania Island and Antarctica in the austral summers obtained by the French supply/research vessel "l'Astrolabeare" were used to determine the locations of fronts and to analyze their relation to the local variations of wind stress and wind stress curl derived from the ERS-1/2 satellite wind field data.The result shows that the zonal and meridional wind stress of this section has a seasonal cycle with a period of six months and the phase of zonal wind stress lags behind that of meridional wind stress for one month.Wind stress curl has a periodic variation of two months.The magnitude of seasonally meridional migration in the location of the primary Polar Front(PF1) is much less than that of the climatic monthly mean zero wind stress curl,but is near the mean position of zero wind stress curl.In the north of PF1 the Antarctic Surface Water(AASW) subducts as it continuously moves northward,and encounters the Subantarctic Mode Water(SAMW).The obvious difference in the characteristics of AASW and SAMW may result in the formation of the Subantarctic Front(SAF).Convergence is stronger than divergence in the Polar Front Zone(PFZ),indicating that a part of the converging water must come from the cold water transporting northward from south of PFZ and contribute to the formation and maintenance of the lateral temperature gradient of SAF.The negative maximum of the wind stress curl may determine the intensity of the Southern Antarctic Circumpolar Current Front(SACCF):The stronger the Ekman Pumping caused by the negative maximum of the wind stress curl is,the more intense the SACCF is.