摘要
本文采用地球上四个最大的冰帽参数，计算了冰帽的融化对地球转动惯量的影响．根据冰期后地壳反弹理论，由现代天体测量空间技术观测资料分析得到的地球自转变化非潮汐项，估计给出了基于１０６６Ｂ地球模型的下地幔粘性系数为１．３５×１０（２２）≥Ｖ（ＬＭ）≤１．９１×１０（２２）Ｐａｓ．结果表明，用冰期后的地壳反弹理论和上述的地球下地幔粘性系数基本可以解释现代空间技术观测得到的地球自转变化中的非潮汐项．
Over the last 18000 yeras,the Earth's crust has been rebounding from the effects of the ice sheets associated with the last ice age. Post-glacial rebound and long term changes in ice sheet mass balance created secular changes in Earth's momentum of inertia, which led to the non-tidal component of the acceleration of rotation.In this paper, the perturbation of maximum major momentum of inertia of Earth is calculated by using the data of four ice sheets including the Laurentia, Fennoscandia, Antarctica and Greenland from the recent medel of Post-glacial rebound ICE-3G, and then the lower mantle viscosity is well estimated with the parameters of lithospheric thickness 120km, upper mantle viscosity (0.5-1.5)×10(21)Pas and 1066B elastic structure. This estimation is based upon the theory of Post-glacial rebound and the strong restraint of the observed result of non-tidal acceleration of Earth's rotation observed with modern space geodetic techniques.The result which fits the observed acceleration data has the lower mantle viscosity V(LM) ranging from 1.35×10(22) to 1.91×10(22) Pas. This result agrees very well with that of the order of maghtude 10(22) Pas obtained from the data of the free air gravity by many authors.The result and discussion in this paper show that the Post-glacial rebound can be used to interpret the observed non-tidal acceleration of Earth's rotation. However, more accurate value of lower maotle viscosity depends on further analysis of the Post-glacial rebound of crust with modern. space geodetic data.
出处
《天文学报》
CSCD
北大核心
1996年第3期313-319,共7页
Acta Astronomica Sinica
基金
国家自然科学基金
关键词
地球自转
非潮汐项
更新世
地壳反弹
Non-tidal term, Post-glacial rebound, Lower mantle viscosity
