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根据不同地幔粘滞度的冰川均衡调整(glacial isostatic adjustment,GIA)模型,研究了地球内部各个圈层对GIA粘性重力扰动速率的贡献,检验了粘性重力扰动速率与径向位移速率的近似关系及其是否独立于地幔粘滞度,同时利用绝对重力和GPS(global positioning system)径向位移数据从实测角度对Wahr的近似关系进行比较和验证.结果表明:岩石圈对GIA重力扰动速率和大地水准面异常速率的贡献都超过了86%,而岩石圈以下5个圈层的总贡献不大于14%;利用近似关系,由重力信号转换的径向位移速率与有限元模拟的结果相对差异大约为15%,且相对差异的大小不依赖于地幔粘滞度的变化;根据北美绝对重力和GPS径向位移数据得到实测的粘性重力-径向位移比值为0.141±0.014μGal/mm,与Wahr的理论值(0.154μGal/mm)非常接近,相对差异仅为9.2%.因此,定量给出了粘性重力-径向位移近似关系的不确定性为9.2%~15.0%,为利用此近似关系分离GIA和现今地表质量变化粘弹信号的不确定性估计提供了重要参考.
Based on the glacial isostatic adjustment (GIA) model with different mantle viscosities, the contribution of each circle in the Earth to the GIA viscous gravity disturbance is investigated. The approximate relationship between the viscous gravity disturbance rate and the radial displacement rate is obtained. Whether it is independent of the viscosity of the mantle or not and at the same time compares and verifies the Wahr’s approximate relationship by using the data of absolute gravitation and global positioning system (GPS) radial displacement data.The results show that the lithospheric GIA gravity disturbance rate and geodetic level The contribution rates of surface anomalous velocities exceed 86%, while the total contribution of the five layers below the lithosphere is less than 14%. By using the approximate relationship, the relative difference between the radial displacement rate converted by gravity signals and the finite element simulation is approximately 15%, and the relative difference does not depend on the change of the viscosity of the mantle; According to the North American absolute gravity and GPS radial displacement data obtained viscous gravity - radial displacement ratio was 0.141 ± 0.014μGal / mm, and Wahr’s theory Value (0.154μGal / mm) is very close, the relative difference is only 9.2% .Therefore, the uncertainty of viscous gravity-radial displacement approximation is given quantitatively as 9.2% ~ 15.0%, which provides an important reference for using this approximate relationship to separate GIA from the uncertainty estimation of viscoelastic signals of surface mass change.