| 摘要: |
| Mosby(1934)指出,如果南极区的陆架水由于海冰的形成而变得足够咸,那么该陆架水将因其密度较大而沿着大陆坡下沉,并因此而形成底层水。当然,在南极周围的海域中，由于较高密度的海水下沉而引起的混合过程是十分复杂的。由于南极底层水( Antarctic Bottom Water,AABW)的主要源区在威德尔海,故以往研究者对于这种混合过程的研究多数集中于威德尔海( Foster et al.,1987)。
至于位于印度洋扇形区的普里兹湾及其邻近海区,一般认为这种类型的海水混合过程实际上并不强烈。Smith et al.,(1984)曾经根据1980-1981年澳大利亚对普里兹湾区的考察资料,分析了这一区域的水团和环流。他们认为,在这一区域中,南极底层水的主要部分源于威德尔海和罗斯海。Middleton and Humphries (1989)利用澳大利亚1981-1985年夏天对普里兹湾海区的考察资料,分析了那里的混合过程,他们认为那里的绕极深层水(CDW)在周期性的上升流过程(它与潮汐和陆架波有关)的参与下与陆架上较冷的陆架水(SW,它与陆架上的海冰形成有关)相混合,形成了低温、高盐的混合水,这种混合水被称为普里兹湾底层水(PBBW),他们认为在多数年份中,这一混合过程可能对普里兹湾中活跃的底层水的形成起主导作用。
在上一篇文章(乐肯堂等,1996:以下简称“上文”)中,我们以中国第六次(CNARE-Ⅵ)和第七次(CNARE-Ⅶ)南极考察中所获得的温、盐资料为基础,并结合有关的化学要素资料,对普里兹湾区的水团分布特性进行了分析。分析结果表明,1991年1月,在普里兹湾外的陆架底部确实存在着上述的PBBW,且这一较重(密度较大)的水有可能沿着大陆坡下滑而达到800m以下的水层。
在本文中,我们仍以上述考察资料为基础,对普里兹湾区的环流和混合过程进行分析,进一步探讨普里兹湾区底层水形成的可能方式。本文所用的考察资料和站位均与“上文”相同,故相同部分不再赘述。 |
| 关键词: 南极普里兹湾区环流、混合 |
| DOI： |
| 分类号: |
| 基金项目:中国科学院海洋研究所调查研究报告第2843号
本课题为国家自然科学基金资助项目，49376260号 |
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| A STUDY OF CIRCULATION AND MIXING IN THE REGION OF PRYDZ BAY, ANTARCTICA |
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Le Kentang, Shi Jiuxin
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Institute of Oceanology,Chinese Academy of Sciences
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| Abstract: |
| The circulation and mixing in the region of Prydz Bay, Antarctica were studied on the basis of the hydrographical data acquired from the Seventh Chinese National Antarctic Research Expedition (1990/1991). The main results are: (1)In the observed region,the Antarctic Divergence is located within the range of 60°30′-66°S, and is the boundary between the Antarctic Circumpolar Current (ACC) and the Antarctic Coastal Current (AACC). (2) The eastward ACC consists of both barotropic and baroclinic components having the same order of magnitude. (3) The westward AACC driven mainly by east winds is barotropic with its speed of 5-10cm/s. (4)In the 63-64°S region of the 73°E section the geostrophic currents at the surface layer (0-32.5m) and subsurface layer (32.5m-112.5m) had opposite directions, which seems to indicate that there was a kind of internal wave propagating vertically in January, 1991.(5)In the study area the 68°-73°E and 98°-108°E region were the strong mixing area due to vertical convection between the Circumpolar Deep Water and Antarctic Shelf Water, which produced heavier water(σt=27.90)down to below 800m. |
| Key words: Prydz Bay,Antarctica,CIRCULATION,MIXING |
