GPS height time series: Short‐period origins of spurious long‐period signals
GPS height time series: Short‐period origins of spurious long‐period signals
复制标题
DOI：
10.1029/2005jb004047
复制
发表时间：
2007-02
影响因子：
--
通讯作者：
N. Penna;Matt A. King;M. Stewart
中科院分区：
文献类型：
--
作者：
N. Penna;Matt A. King;M. Stewart
地球物理研究中使用的GPS高程时间序列通常是由离散的、连续的、不重叠的24小时处理会话形成的。采用这种策略，通常假设具有近似半日和昼夜周期的未建模周期性地面位移平均接近于零。通过分析几年的连续GPS数据从全球分布的网站，在控制误差没有建模，本文表明这样的假设是错误的。结果表明，每个未建模的（子）每日周期位移可以传播到几个虚假的长波长的GPS高度时间序列中的功能，范围从约2周到1年。导纳（GPS高度时间序列中的伪长波长输出信号的振幅与未建模的周期性地面位移的振幅之比）取决于所考虑的坐标分量和潮汐分量。例如，它示出，一个未建模的S2北分量周期性地面位移可以传播到一个半年度的高度信号与导纳大于100%，而高度导纳约为5- 10%。由于海潮载荷、大气压力载荷和固体固体潮位移振幅的模型误差可能为几毫米，因此可能会在GPS高度时间序列中出现高达这些振幅的长波长寄生信号。本文提供了一个指示，这种错误将如何传播，这种错误是最大的，因此如何虚假的每两周，半年，并在某些情况下，每年的影响可能会出现在一些网站。版权所有2007年由美国地球物理联盟。
GPS height time series used in geophysical studies are often formed from discrete, continuous, nonoverlapping 24 hour processing sessions. With such a strategy, unmodeled periodic ground displacements with approximately semidiurnal and diurnal periods have often been assumed to average close to zero. By analyzing several years of continuous GPS data from globally distributed sites at which controlled errors were not modeled, this paper shows such an assumption to be erroneous. It is shown that each unmodeled (sub-) daily periodic displacement can propagate to several spurious long-wavelength features in a GPS height time series, ranging in period from about 2 weeks to 1 year. Admittances (ratio of amplitude of spurious long-wavelength output signal in the GPS height time series to amplitude of unmodeled periodic ground displacement) depend on the coordinate component and the tidal constituent considered. For example, it is shown that an unmodeled S2 north component periodic ground displacement can propagate to a semiannual height signal with admittance of greater than 100%, whereas the height admittance is around 5-10%. Since model errors in ocean tide loading, atmospheric pressure loading, and solid earth tide displacement amplitudes can be several millimeters, long-wavelength spurious signals of up to these amplitudes may be expected to appear in GPS height time series. This paper provides an indication of how such errors will propagate, where such errors are greatest and hence how spurious fortnightly, semiannual, and, in some cases, annual effects may be present at some sites. Copyright 2007 by the American Geophysical Union.