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南极海冰、冰穴和冰川冰及其对水团形成和变性的作用

【标题】南极海冰、冰穴和冰川冰及其对水团形成和变性的作用

【Title】THE ROLE OF ANTARCTIC SEA ICE,POLYNYAS AND GLACIER ICE IN FORMATION AND MODIFICATION OF THE ANTARCTIC WATER MASSES

【作者】 董兆乾;梁湘三

【Author】

【期刊】极地研究

【Journal】

【期刊年份】1993

【卷】5

【期】

【关键词】 南极;海冰;冰穴;冰川冰;水团

【Keywords】

【摘要】本文利用前人的成果及笔者1992/1993年的南极海冰观测和收集的资料以及水文观测资料数据阐述了南极海冰的特性,特别是南极海冰过程、冰穴以及冰川冰对南极水团(南极表层水、南极底层水、南极陆架水、南极中层水以及南极冰架水)的形成和变性所起的特殊作用。 南极海冰覆盖面积的年际变化,夏季最大年份是最小年份的2倍多,冬季年间变化较小,最大仅为20%;但其季节变化非常大,冬季平均覆盖面积通常是夏季的5倍。南极海冰对大气-海洋间相互作用有重大影响,特别是深海洋区中冬季的结冰和发育造成的垂向对流、夏季的融化是形成南极表层水(含南极冬季水和南极夏季表层水),进而形成南极中层水的主要原因;南极陆架区的的海冰兴衰过程是形成南极陆架水的直接原因,它与变性南极绕极深层水混合并受到冰川冰的进一步冷却作用,成为形成南极底层水的主要水团;南极冰架底部的冷却、融化和冰架以下水体的结冰作用形成的高盐对流过程产生的南极冰架水,亦是形成南极底层水的贡献者。 冰穴是70年代以来卫星观测的重大发现。对其形成和对大气、海洋的影响作用尚不完全清楚,初步的研究成果表明,冰穴中产生的热盐对流对南极水团的形成、变性、大洋深层的翻转以及海洋-大气间的热量传输和气体交换起有非常重要的作用。

【Abstract】By the achievements of the previous scientific research and the observations on conditions of the Antarctic sea ice as well .as CTD survey in 1992/1993 austral summer by the authors, the present paper discusses the characteristics of the Antarctic sea ice and the polynyas in the Southern Ocean. Based on those,the essencial effect on the formation and modification of Antarctic water masses, such as the Antarctic Surface Water (AASW),the Antarctic Bottom Water(AABW) ,the Antarctic Shelf Water(SW) ,the Antarctic Intermediate Water (AATW)and the Antarctic Ice Shelf Water(ISW) by the processes of the antarctic sea ice, polynyas and glacier ice is discussed in detail. The result shows that the anual change of the antarctic sea ice cover is not much-the northern limit of the cover in winter varies only a few degrees in latitude from year to year and the maximum coverage in summer is no more than twice its minimum. The seasonal change, however, is significant-the average area of sea ice cover in winter is usually more than five times the area of the summer's. The dynamics and thermodynamics oi the antarctic sea ice cover are intricately linked with me ocean atmosphere exchange of heat,water and gas. And in the deep ocean area of the Southern Ocean,the vetical convection,mainly caused by the rejected salt from freezing of sea ice is one of the major factors for the WW and AAIW formation,and melting of sea ice in summer,together with heating,leads to form the Antarctic Summer Surface Water (AASSW). And more importantly in the antarctic continental shelf,the process of sea ice, together with supercooling beneath ice shelves, drives deep mixing and convection on the continental shelf and form the continental Shelf Water (SW) , which in turn to contribute greatly to the formation of the Ice Shelf Water and the Antarctic Bottom Water, which spreads northward to the world's oceans along the sea floor. Polynyas in the Southern Ocean,which could be derived into sensible heat polynyas and latent heat polynyas,is a discovery by the satellite observation in the mid-1970's. Polynyas and their effect are only incompletely understood, but according to the recent research, polynyas at least accelerate the processes of the exchanges of energy, water and gases between the ocean and the atmosphere around Antarctica,which have a major role in determining the large scale motion, temperature and chemical composition of the ocean and atmosphere throughout the globe. The latent heat polynyas,which take ph.ce near the Antarctic coast, are sea-ice-making "factories". They have thus great effect on the formation and modification of the Antarctic water masses.

【基金/项目】

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