水平GPS站速度的构造和局部分量的分离：东南极洲冰川均衡调整的实例研究
Separation of tectonic and local components of horizontal GPS station velocities: a case study for glacial isostatic adjustment in East Antarctica
摘要：
在全球定位系统台站精确测量大地运动的局部分量是一项挑战，因为需要将这种信号与构造板块旋转分开。一个紧迫的例子是对冰川均衡调整（GIA）的观察，它限制了地球对冰卸载的反应，因此，南极洲等冰盖地区对冰量损失后全球海平面上升的贡献。我们专注于水平GPS速度，通常包含一个大的板块旋转和一个较小的本地组件主要涉及GIA的组成部分。这些分量的不完全分离将显著偏差引入GIA运动向量的估计中。我们提出了一系列的测试结果的基础上的运动的GPS站从东南极洲：1）信号分离的合成数据集，复制的几何特征的不可分离的，可分离的，GIA的水平速度;和2）信号分离的真实GPS站数据的不确定性的评估。对于合成和真实的运动，我们比较的结果，其中站是不加权的，每个站是面积加权使用的度量表示相邻站的空间密度的倒数。从合成测试中，我们表明，GIA样的信号是可恢复的板块旋转信号，提供它的几何变化整个东南极洲。我们还表明，面积加权有一个非常显着的效果，恢复GIA样的信号与几何变化的能力，因此分离板块旋转和本地组件。对于真实数据，假设南极洲板块为刚性，拟合的板块旋转参数与文献中的其他研究结果相当。我们发现，在东南极洲的36个GPS站中，有25个在2 $σ$水平上，信号分离后的非零本地水平速度。
英文摘要：
Accurate measurement of the local component of geodetic motion at GPS stations presents a challenge due to the need to separate this signal from the tectonic plate rotation. A pressing example is the observation of glacial isostatic adjustment (GIA) which constrains the Earth's response to ice unloading, and hence, contributions of ice-covered regions such as Antarctica to global sea level rise following ice mass loss. We focus on horizontal GPS velocities which typically contain a large component of plate rotation and a smaller local component primarily relating to GIA. Incomplete separation of these components introduces significant bias into estimates of GIA motion vectors. We present the results of a series of tests based on the motions of GPS stations from East Antarctica: 1) signal separation for sets of synthetic data that replicate the geometric character of non-separable, and separable, GIA-like horizontal velocities; and 2) signal separation for real GPS station data with an appraisal of uncertainties. For both synthetic and real motions, we compare results where the stations are unweighted, and where each station is areal-weighted using a metric representing the inverse of the spatial density of neighbouring stations. From the synthetic tests, we show that a GIA-like signal is recoverable from the plate rotation signal providing it has geometric variability across East Antarctica. We also show that areal-weighting has a very significant effect on the ability to recover a GIA-like signal with geometric variability, and hence on separating the plate rotation and local components. For the real data, assuming a rigid Antarctic plate, fitted plate rotation parameters compare well with other studies in the literature. We find that 25 out of 36 GPS stations examined in East Antarctica have non-zero local horizontal velocities, at the 2$σ$ level, after signal separation.
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