Monument-antenna effects on GPS coordinate time series with application to vertical rates in Antarctica
Monument-antenna effects on GPS coordinate time series with application to vertical rates in Antarctica
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DOI：
10.1007/s00190-011-0491-x
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发表时间：
2011
影响因子：
4.4
通讯作者：
Matt A. King;M. Bevis;T. Wilson;B. Johns;F. Blume
中科院分区：
文献类型：
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作者：
Matt A. King;M. Bevis;T. Wilson;B. Johns;F. Blume
我们研究了GPS天线-纪念碑对的电磁耦合对长GPS坐标时间序列的模拟影响。我们的重点是地球和极地观测系统(POLENET)纪念碑设计，广泛部署在南极和格陵兰岛的项目中，特别是对垂直速度感兴趣的项目。我们的测试基于包括纪念碑顶部~0.15m的绝对机器人校准，并使用模拟来评估其对2000.0-2011.0期间南极八个代表性POLENET站点的站点坐标时间序列的影响。结果表明，忽略这一定标将引入平均坐标偏差，最重要的是对于速度估计，坐标噪声对观测几何高度敏感，因此对场地位置和观测周期非常敏感。仅考虑长于2.5年的子周期，我们发现垂直站点速度的偏差可能高达±0.4毫米/年，而高达0.2毫米/年的偏差可能持续8年的观测跨度。在均匀和随高程变化的观测权重之间改变会改变时间序列，但不能消除速度偏差，也不能确定模糊度。对水平坐标的影响可以忽略不计。模糊度固定序列频谱显示闪烁和随机游走之间的噪声，在最高频率具有近白噪声，平均谱指数(频率和lt；每年20个周期)约为−1.3(均匀加权)和−1.4(海拔相关加权)。虽然结果可能是高度特定于纪念碑的，但它们强调了在分析垂直坐标时间序列和速度时考虑纪念碑效应的重要性，以实现最高精度和准确度的地球物理研究。
We examine the electromagnetic coupling of a GPS antenna–monument pair in terms of its simulated affect on long GPS coordinate time series. We focus on the Earth and Polar Observing System (POLENET) monument design widely deployed in Antarctica and Greenland in projects interested particularly in vertical velocities. We base our tests on an absolute robot calibration that included the top ~0.15 m of the monument and use simulations to assess its effect on site coordinate time series at eight representative POLENET sites in Antarctica over the period 2000.0–2011.0. We show that the neglect of this calibration would introduce mean coordinate bias, and most importantly for velocity estimation, coordinate noise which is highly sensitive to observation geometry and hence site location and observation period. Considering only sub-periods longer than 2.5 years, we show vertical site velocities may be biased by up to ±0.4 mm/year, and biases up to 0.2 mm/year may persist for observation spans of 8 years. Changing between uniform and elevation-dependent observation weighting alters the time series but does not remove the velocity biases, nor does ambiguity fixing. The effect on the horizontal coordinates is negligible. The ambiguities fixed series spectra show noise between flicker and random walk with near-white noise at the highest frequencies, with mean spectral indices (frequencies <20 cycles per year) of approximately −1.3 (uniform weighting) and −1.4 (elevation-dependent weighting). While the results are likely highly monument specific, they highlight the importance of accounting for monument effects when analysing vertical coordinate time series and velocities for the highest precision and accuracy geophysical studies.