| 摘要: |
| 采用球函数表征了南极冰川覆盖的高度，并运用位理论与地壳均衡观念，研究了南极冰盖形成、消融对大地水准面与相对海面的影响。结果表明，冰盖形成后的大地水准面发生了明显变化，在南极为＋115m，在南纬25°带上为－37m，在北极为＋8m；若地壳为弹性固体而地幔为流体，设地慢密度为3270 kg/m3，则在冰川消融、地壳均衡调整后的沿海大陆相对海面的变化仅为2.8m。 |
| 关键词: 南极冰盖 大地水准面 相对海面 |
| DOI： |
| 分类号: |
| 基金项目:南极考察委员会课题资助项目，85-03-01号 |
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| IMPACTS OF THE FORMATION AND ABLATION OF ANTARCTIC ICE SHEETS ON THE GLOBAL GEOID AND SEA-LEVEL CHANGES |
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ZHANG Chi-jun,LU Yang
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Institute of Geodesy and Geophysics, The Chinese Academy of Sciences, Wuhan, 430077
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| Abstract: |
| It is convenient to investigate into the gravimetry using a harmonic spheric function which describe the distribution and thickness of the Antarctic ice sheet. The gravitational theory and the stokes' harmonic spheric function of formula were used to determine the impact of the Antarctic ice cap on the global geoid. The Antarctic ice cap is formed from the condensation of seawater vapour whose mass is equal to a layer of seawater 59m thick of covering the earth's surface, i.e. 2.7×1019 kg. This will cause the global averaged geoid to decrease for around 23m. the authors' computations show that the Antarctic ice cap has a great impact on the global geoid, which increases (+) in some regions, but decreases (-) in other regions. The geoid is +115 m, -37 m and +8 m at the South Pole, the 25° S parallel and the North Pole, respectively. If the Antarctic ice cap melts completely, on the rigid Earth’s surface the seawater and geoid will return to its original position (and height) due to the balancing force of the fluid.
Since the crust is almost in a state of isostasy, assuming that the crust is an elastic solid and the mantle is an incompressive fluid, the load of seawater will deflect the crust and drive the mantle material to flow. The material above the isostatic surface compensates mutually. If the densities of the mantle and seawater are 3270 kg/m3 and 1230 kg/m3, respectively, then the variation in the elevation of the continent is only 2.8 m with respect to the sea level after the Antarctic ice cap melts. It is worth noting that the above results were derived from an ideal Earth model. In the real Earth, the mantle and crust are visco-elastic. |
| Key words: Antarctic ice sheet, Geoid undulation, Relative change of sea level |
