A GNSS velocity field for crustal deformation studies: The influence of glacial isostatic adjustment on plate motion models
A GNSS velocity field for crustal deformation studies: The influence of glacial isostatic adjustment on plate motion models
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用于地壳变形研究的 GNSS 速度场：冰川均衡调整对板块运动模型的影响
DOI：
10.1093/gji/ggac047
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发表时间：
2022
影响因子：
2.8
通讯作者：
Vardic K
中科院分区：
文献类型：
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作者：
Vardic K
构造板块运动和冰川均衡调整（GIA）是全球尺度地球长期变形的两个主要原因。我们创建了一个定制的全球3D GNSS表面速度场“NCL 20”，以研究构造板块运动和GIA对板块运动模型（PMM）的影响，并绘制了一组1D和3D GIA模型预测。创建NCL 20的主要动机是在受GIA影响最大的调查区域，即北美、欧洲和南极洲，纳入更多的GNSS站点。我们使用IGS repro 2数据和其他类似处理的GNSS数据集来实现这一点。我们最终的GNSS速度场的水平不确定度大部分在±0.5 mm yr-1以内，垂直不确定度大部分在±1 mm yr-1以内（置信度为95%），这使得它适合于测试GIA模型。我们通过将三种不同的冰史模型（ICE-5G，ICE-6 G和W12）与一系列一维和三维地球模型相结合，生成了一套117个全球GIA模型预测。通过从GNSS速度场中减去该集合，我们确定并比较了一系列预计不受GIA影响的PMM。我们的方法使我们能够包括GNSS网站，通常被排除在PMM估计，由于其位置在GIA影响的地区。我们表明，显着的GIA相关的水平运动以外的迅速上升的地区可能会偏置PMM，如果不加以纠正。根据它们解释观测到的表面速度场的能力，为三个感兴趣的区域：北美，欧洲和南极洲选择了一组性能最好的GIA模型。在每个表现最好的组的GIA预测的范围被假定为代表在区域GIA建模的不确定性，因为它可以由现今的大地测量速度的约束。在水平分量中，我们注意到3D GIA模型在预测速度的方向上比1D GIA模型显示出更多的变化，这证实了水平速度对地球结构的横向变化非常敏感。此外，对于南极洲，预测的GIA垂直速度的变化表明，GIA对年重力质量变化的总贡献范围为-3至22 Gt yr-1，具体取决于使用的是哪种性能最好的GIA模型。
The two main causes of global-scale secular deformation of the Earth are tectonic plate motion and glacial isostatic adjustment (GIA). We create a bespoke global 3D GNSS surface velocity field ‘NCL20’ to investigate tectonic plate motion and the effect of GIA on plate motion models (PMMs), drawing on a set of 1D and 3D GIA model predictions. The main motivation for creating NCL20 is to include a larger number of GNSS sites in the most GIA-affected areas of investigation, namely North America, Europe, and Antarctica. We do this using the IGS repro2 data and other similarly processed GNSS data sets. Our final GNSS velocity field has horizontal uncertainties mostly within ±0.5 mm yr–1and vertical uncertainties mostly within ±1 mm yr–1(at 95 per cent confidence), which make it suitable for testing GIA models. We generate a suite of 117 global GIA model predictions by combining three different ice history models (ICE-5G, ICE-6G and W12) with a range of 1D and 3D Earth models. By subtracting this ensemble from the GNSS velocity field, we identify and compare a range of PMMs which are expected to be unaffected by GIA. Our method allows us to include GNSS sites that are typically excluded from PMM estimations due to their location in GIA-affected regions. We demonstrate that significant GIA-related horizontal motion outside of the rapidly uplifting regions may bias PMMs if left uncorrected. Based on their ability to explain the observed surface velocity field, a group of best-performing GIA models is selected for three regions of interest: North America, Europe and Antarctica. The range of GIA predictions in each best-performing group is assumed to represent the uncertainty in regional GIA modelling insofar as it can be constrained by present-day geodetic velocities. In the horizontal component, we note that 3D GIA models show more variation in the direction of predicted velocities than 1D GIA models, confirming that horizontal velocities are strongly sensitive to lateral variations in Earth structure. Furthermore, for Antarctica the variation in predicted GIA vertical velocities suggests that the total GIA contribution to annual gravimetric mass change ranges from –3 to 22 Gt yr–1depending on which of the best-performing GIA models is used.