海洋中有多少水?
文章来源:未知 文章作者:meng 发布时间:2009-11-13 03:22 字体: [ ]  进入论坛
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The calculation of variations(变更) in the sea level is relatively1 simple. It is by far more complicated to then determine the change in the water mass. A team of geodesists(测地学) and oceanographers(海洋学家) from the University of Bonn, as well as from the GFZ German Research Centre for Geosciences and the Alfred-Wegener Institute for Polar and Marine2 Sciences, two centres of the Helmholtz Association, have now, for the first time succeeded in doing this. The researchers were able to observe short-term fluctuations3(起伏现象) in the spatial4 distribution(空间分布) of the ocean water masses. Their results are, amongst others, important for improved climate models. In order to determine the ocean volume in a certain region, one only needs to know, in addition to the topography(地形,地势) of the seabed, the height of the sea level. For this purpose, researchers have long been resorting to gauging5 stations(水位站) and satellite altimetric(高度计) procedures. The ocean mass depends, however, not only on the volume, but also on the temperature and on the salt content. Water expands when heated. Warm water, thus, weighs less than the same quantity of cold water.

For the calculation of the ocean mass it is, therefore, necessary to know the temperature and salt content profiles. However, this is not easy to quantify(定量,量化). "For our study we, therefore, combined different procedures so as to be able to judge changes in mass", explains Professor Dr. Juergen Kusche. The geodesist from Bonn is co-author of a scientific paper, which has just been published in the Journal of Geophysical Research.

On the one hand the researchers used data from the German-American satellite mission GRACE where the distance between two satellites (popularly known as Tom and Jerry as one chases the other in the same orbit ) are measured exactly to thousandths of millimetres. The larger the ocean mass at a certain point of the Earth, the stronger the gravitational strength. This influences the flight altitude of the satellites and thus the distance from each other. The gravitation(引力) and, hence(今后,从此), the mass distribution can be calculated from the change in distance between the two satellites.



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1 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
2 marine 77Izo     
adj.海的;海生的;航海的;海事的;n.水兵
参考例句:
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
3 fluctuations 5ffd9bfff797526ec241b97cfb872d61     
波动,涨落,起伏( fluctuation的名词复数 )
参考例句:
  • He showed the price fluctuations in a statistical table. 他用统计表显示价格的波动。
  • There were so many unpredictable fluctuations on the Stock Exchange. 股票市场瞬息万变。
4 spatial gvcww     
adj.空间的,占据空间的
参考例句:
  • This part of brain judges the spatial relationship between objects.大脑的这部分判断物体间的空间关系。
  • They said that time is the feeling of spatial displacement.他们说时间是空间位移的感觉。
5 gauging 43b7cd74ff2d7de0267e44c307ca3757     
n.测量[试],测定,计量v.(用仪器)测量( gauge的现在分词 );估计;计量;划分
参考例句:
  • The method is especially attractive for gauging natural streams. 该方法对于测量天然的流注具有特殊的吸引力。 来自辞典例句
  • Incommunicative as he was, some time elapsed before I had an opportunity of gauging his mind. 由于他不爱说话,我过了一些时候才有机会探测他的心灵。 来自辞典例句
TAG标签: sea water ocean
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