Using GPS and absolute gravity observations to separate the effects of present-day and Pleistocene ice-mass changes in South East Greenland
Using GPS and absolute gravity observations to separate the effects of present-day and Pleistocene ice-mass changes in South East Greenland
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使用 GPS 和绝对重力观测来区分格陵兰岛东南部当今和更新世冰块变化的影响
DOI：
10.1016/j.epsl.2016.11.014
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发表时间：
2015
影响因子：
5.3
通讯作者：
M. Broeke
中科院分区：
文献类型：
--
作者：
T. Dam;O. Francis;J. Wahr;S. Khan;M. Bevis;M. Broeke
在格陵兰冰盖边缘附近的基岩点测量地壳垂直抬升，可以用来限制现今的质量损失。解释任何观察到的地壳位移在今天的冰的变化是复杂的，但是，由冰川均衡调整（GIA）信号。仅凭GPS观测，不可能将现今质量变化驱动的隆升与过去冰质量变化驱动的隆升分开。Wahr等人（1995）证明粘弹性表面位移通过比例常数与粘弹性重力变化相关，该比例常数几乎与地球粘度或冰历史模型的选择无关。因此，通过在基岩地点测量重力和表面运动，可以从观测中消除粘弹性效应，我们将能够限制目前冰量的变化。或者，我们可以使用相同的表面位移和重力观测值来确定GIA信号。在本文中，我们扩展了Wahr等人的理论。（1995）通过引入一个常数Z，该常数代表重力的弹性变化和由于现今质量变化而在特定地点产生的弹性隆起之间的比率。此外，我们结合联合收割机20年的GPS观测隆起与8个绝对重力观测在同一时期，以确定GIA信号附近的Kulusuk，一个网站的东南侧的GrIS，实验证明的理论。我们估计该区域的GIA信号为4.49±1.44 mm/yr，这与大多数先前报道的模型预测不一致，这些模型预测表明此处的GIA信号为负。然而，由于在格陵兰的这一部分很少有现场数据来限制GIA速率，因此地球模型或冰史重建可能不准确（Khan等人，2016年）。改进格陵兰岛这一地区的GIA估计值将使我们能够更好地确定该地区冰量的现今变化，例如来自GRACE。
Measurements of vertical crustal uplift from bedrock sites around the edge of the Greenland ice sheet (GrIS) can be used to constrain present day mass loss. Interpreting any observed crustal displacement around the GrIS in terms of present day changes in ice is complicated, however, by the glacial isostatic adjustment (GIA) signal. With GPS observations alone, it is impossible to separate the uplift driven by present day mass changes from that due to ice mass changes in the past. Wahr et al.(1995) demonstrated that viscoelastic surface displacements were related to the viscoelastic gravity changes through a proportionality constant that is nearly independent of the choice of Earth viscosity or ice history model. Thus, by making measurements of both gravity and surface motion at a bedrock site, the viscoelastic effects could be removed from the observations and we would be able to constrain present day ice mass changes. Alternatively, we could use the same observations of surface displacements and gravity to determine the GIA signal. In this paper, we extend the theory of Wahr et al.(1995) by introducing a constant, Z, that represents the ratio between the elastic changes in gravity and elastic uplift at a particular site due to present day mass changes. Further, we combine 20 yrs of GPS observations of uplift with eight absolute gravity observations over the same period to determine the GIA signal near Kulusuk, a site on the southeastern side of the GrIS, to experimentally demonstrate the theory. We estimate that the GIA signal in the region is 4.49±1.44 mm/yr and is inconsistent with most previously reported model predictions that demonstrate that the GIA signal here is negative. However, as there is very little in situ data to constrain the GIA rate in this part of Greenland, the Earth model or the ice history reconstructions could be inaccurate (Khan et al., 2016). Improving the estimate of GIA in this region of Greenland will allow us to better determine the present day changes in ice mass in the region, eg from GRACE.
Helheim、Kangerdlugssuaq 和其他 14 个主要格陵兰出口冰川过去 25 年的冰川动态
DOI：
10.5194/tcd-6-1637-2012
发表时间：
2012
期刊：
--
影响因子：
--
作者：
Bevan S
通讯作者：
Bevan S
影响因子：
13.6
作者：
Khan SA;Sasgen I;Bevis M;van Dam T;Bamber JL;Wahr J;Willis M;Kjær KH;Wouters B;Helm V;Csatho B;Fleming K;Bjørk AA;Aschwanden A;Knudsen P;Munneke PK
通讯作者：
Munneke PK