Subdaily signals in GPS observations and their effect at semiannual and annual periods
Subdaily signals in GPS observations and their effect at semiannual and annual periods
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DOI：
10.1029/2007gl032252
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发表时间：
2008-02-01
影响因子：
5.2
通讯作者：
Clarke, Peter J.
中科院分区：
文献类型：
--
作者：
King, Matt A.;Watson, Christopher S.;Clarke, Peter J.
GPS季节性地球物理负荷的估计可能会受到传播的未建模的每日信号的影响。虽然主要的地球物理信号在半日和周日的频率，现在例行建模的GPS分析，未建模或错误建模的亚日信号的特性并不为人所知。在这里，使用网站坐标估计每5分钟，我们研究了subdaily的坐标光谱特性相似的90个全球GPS站点。振幅在10 mm水平的未建模信号存在于类似于1/天和奈奎斯特频率之间的频率处。这些被证明是传播到24小时的解决方案（除其他频率）每年和半年的周期与振幅高达5毫米，在0.8毫米（每年）和0.6毫米（半年）的高度分量的中值振幅。他们被证明偏置地球物理负载的低阶球谐估计在5- 10%的水平，虽然确切的效果将是网络依赖。
Estimates of seasonal geophysical loading from GPS may be biased by propagated unmodeled subdaily signals. Although the major geophysical signals at semidiurnal and diurnal frequencies are now routinely modeled in GPS analyses, the characteristics of unmodeled or mismodeled subdaily signals are not well known. Here, using site coordinates estimated every 5 minutes, we examine the subdaily coordinate spectral characteristics for similar to 90 global GPS sites. Unmodeled signals with amplitudes at the 10 mm level are present at frequencies between similar to 1/day and the Nyquist frequency. These are shown to propagate into 24 h solutions with (among other frequencies) annual and semiannual periods with amplitudes up to 5 mm, with a median amplitude in the height component of 0.8 mm (annual) and 0.6 mm (semiannual). They are shown to bias low-degree spherical harmonics estimates of geophysical loading at the level of 5-10%, although the exact effect will be network dependent.