Finite element modelling of atmosphere loading effects on strain, tilt and displacement at multi-sensor stations
Finite element modelling of atmosphere loading effects on strain, tilt and displacement at multi-sensor stations
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DOI：
10.1111/j.1365-246x.2010.04549.x
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发表时间：
2010-06
影响因子：
2.8
通讯作者：
A. Gebauer;H. Steffen;C. Kroner;T. Jahr
中科院分区：
文献类型：
--
作者：
A. Gebauer;H. Steffen;C. Kroner;T. Jahr
应变仪和倾斜仪观测结果由不同来源的信号组成。潮汐是一种众所周知的现象，可以通过潮汐分析从时间序列中提取。然而，根据台站的位置，残差包含来自海洋负荷、大气或水文负荷变化、人为引起的信号和构造的不同量级的贡献。残差变化的减少对于例如纯构造信号的提取是必不可少的。减少的挑战之一是了解载荷和局部条件（例如地形、洞穴和地质特征）之间的传递机制，这些机制会导致额外或修改的变形。在这项研究中，系统的数值模拟，使用有限元法与弹性流变进行估计这些影响。大气压力变化被用作载荷的示例，以确定附加变形。应变仪和倾斜仪被视为仪器，标称分辨率分别为0.2 nstrain和1 nrad。空腔和地形的影响进行了系统的研究与复杂的模型，结合典型的地形特征，如平原，丘陵侧翼和山谷。以中欧的四个具有代表性的观测站为模型：Wettzell大地测量观测站（德国）、索普隆观测站（匈牙利）、艾草地球动力观测站和黑森林观测站（均为德国）。模拟表明，空腔和地形效应发生在同一数量级，这两种效应相互作用，导致变形部分交织在一个复杂的方式。尽管如此，这些结果解释了观测站观测到的变形信号。系统建模有助于更好地了解基本过程，从中推断出未来观测地点的选择标准。
SUMMARY Strain- and tiltmeter observations are composed of signals of different origin. Tides are a wellknown phenomenon that can be extracted from the time series by tidal analysis. Depending on the location of the station, residuals, however, contain contributions of different magnitudes from ocean loading, changes in atmospheric or hydrological loading, anthropogenic induced signals and tectonics. Reductions of the residual variations are indispensable for extraction of, for example the pure tectonical signal. One of the challenges in view of the reductions is to understand transfer mechanisms between loading and local conditions, such as topography, cavity and geological features, which lead to additional or modified deformations. In this study, systematic numerical modelling using the Finite Element method with elastic rheology is carried out to estimate these effects. Barometric pressure changes are used as example for the load to determine the additional deformations. Strain- and tiltmeters are considered as instrumentation, having nominal resolutions of 0.2 nstrain and 1 nrad, respectively. The cavity and the topographic effect are systematically investigated with sophisticated models incorporating typical topographic features, such as a plain, a hill flank and a valley. Representative for stations worldwide, four observatories in Central Europe are modelled: the Geodetic Observatory Wettzell (Germany), the Sopron Observatory (Hungary), the Geodynamic Observatory Moxa and the Black Forest Observatory (BFO) (both Germany). The modelling shows that cavity and topographic effects occur in the same order of magnitude and that both effects interact leading to deformations partly intertwined in a complex way. This notwithstanding, the results explain observed deformation signals at the observatories. The systematic modelling helps to better understand the basic processes, from which criteria for the selection of future observation sites are inferred.