| 西太平洋边缘海对我国冰期干旱化影响的初步探讨 |
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| 引用本文： | 汪品先. 西太平洋边缘海对我国冰期干旱化影响的初步探讨[J]. 第四纪研究, 1995, 15(1): 32-42. |
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| 作者姓名： | 汪品先 |
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| 作者单位： | 同济大学海洋地质开放实验室 |
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| 摘 要： | 亚洲东部在冰期最为壮观的地理变化是边缘海大片浅海陆架的出露成陆。仅从我国到澳大利亚以北的三大浅海区,盛冰期成陆的面积便可达3.9×106km2.边缘海中的半封闭海,在冰期时发生海流改组,可以导致表层水温下降的异常。海区面积的减小和海水温度的下降,均导致蒸发量的降低。仅南海的估计,盛冰期水汽供应量便可减少800-1400×109m3/a,约相当现代我国年降水总量的1/8-1/4,是我国陆地冰期气候干旱化的重大因素。
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| 关 键 词： | 海陆相互作用 边缘海 冰期 干旱化 古海洋学 |
THE ROLE OF WEST PACIFIC MARGINAL SEAS IN GLACIAL ARIDIFICATION OF CHINA:A PRELIMINARY STUDY |
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| Wang Pinxian. THE ROLE OF WEST PACIFIC MARGINAL SEAS IN GLACIAL ARIDIFICATION OF CHINA:A PRELIMINARY STUDY[J]. Quaternary Sciences, 1995, 15(1): 32-42. |
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| Authors: | Wang Pinxian |
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| Affiliation: | Laboratory of Marine Geology, Tongji University |
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| Abstract: | The most conspicuous geographic change in East Asia at the glaciation was the.emergence of vast shelf areas of the West Pacific marginal seas, giving rise to remarkable alteration in sea configurations and to reduction in sea area. Only the three major shelves between north China and north Australia (East China Sea Shelf, Sum da Shelf, and Sahul Shelf) amount to 3 900 000km2, comparable in size to the indian Subcontinent. As the evaporation from sea is much higher than from land (the world average difference being 33.8cm/a or 50cm/a according to various estimations). the increase of the land area at the expense of the sea must have caused a reduction. of total annual evaporation from the 3 shelves by 1 318 or 1 950 milliard m3 of water. Meanwhile, the reorganization of surface circulation in marginal seas of enclosed basin type at the glacial time was partly responsible for the abnormally low sea surface temperature(SST) there, demonstrating the "amplifying effect" of marginal seas to glacial cycles. The lowered SST could again decrease the evaporation from the sea. Thus, a 2℃ decrease in temperature in the glacial tropical Pacific corresponded to 10gb reduction in evaporation, a 5℃ decrease in temperature in the glacial tropical Atlantic-to 25% reduction in evaporation (Lamb, 1978). For the South China Sea where the glacial SST was at least 2--sic lower than the present. the evaporation rate must have been 10-25% lower at the glaciation. Taking into account the evaporation reduction resulted both from the exposure of shelf and the SST cooling in the deeper-water part, the decrease of annual total amount of water evaporated from the South China Sea during the last glacial maximum should be some 800 to 1 400 milliard m3, or 1/8-1/4 of annual total precipitation in the whole of China now. All the above rough estimations convincingly show the critical role marginal seas in the intensified arid climate in China during glaciation. Much more data and. numerical modeling, however, are required for even a semi-quantitative analysis of climate role of marginal seas. |
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