Levelling co-located GNSS and tide gauge stations using GNSS reflectometry
Levelling co-located GNSS and tide gauge stations using GNSS reflectometry
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DOI：
10.1007/s00190-014-0784-y
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发表时间：
2015-03
影响因子：
4.4
通讯作者：
A. Santamaría‐Gómez;C. Watson;M. Gravelle;Matt A. King;G. Wöppelmann
中科院分区：
文献类型：
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作者：
A. Santamaría‐Gómez;C. Watson;M. Gravelle;Matt A. King;G. Wöppelmann
GNSS 反射测量技术提供 GNSS 天线周围环境的几何信息，包括到反射表面的垂直距离。我们使用 GPS 信号的海面反射（记录为信噪比 (SNR) 振荡）来估计 GNSS 与验潮仪 (TG) 的水准关系，从而估计 TG 的椭球高度。我们开发了一些方法来隔离由海面反射主导的 SNR 数据，并消除动态海面引起的 SNR 频率变化。与八个站点的原位水准测量的比较显示，海拔高于 12 的卫星在厘米级的平均差异，其中四个站点的差异为 3 厘米或更小。这些差异包括原位水准测量、天线校准模型和 TG 测量中的误差，因此代表了我们技术误差的上限。数据采样（1 或 30 秒）不会对结果产生显着影响。我们检测到与低于 12 的卫星高度和海面高度相关的分米级系统误差，以及两个站点大于 15 厘米的 L1 和 L2 GPS 信号结果之间的差异。这些系统性错误仍然无法解释； GPS 信号之间的差异归因于 SNR 测量中与接收机相关的差异，而与海拔相关的误差则归因于未建模的相位效应，例如对流层折射和海面粗糙度引起的相位效应。使用我们的方法，我们确定了与 TG 传感器变化相关的 1.5 厘米的水平偏移，说明了我们的技术对于 TG 参考监测的价值。
The GNSS reflectometry technique provides geometric information on the environment surrounding the GNSS antenna including the vertical distance to a reflecting surface. We use sea-surface reflections of GPS signals, recorded as oscillations in signal-to-noise ratio (SNR), to estimate the GNSS to tide gauge (TG) levelling tie, and thus the ellipsoidal heights of the TG. We develop approaches to isolate SNR data dominated by sea-surface reflections and to remove SNR frequency changes caused by the dynamic sea surface. Comparison with in situ levelling at eight sites reveals mean differences at the centimetre level for satellites above 12elevation, with four sites showing differences of 3 cm or smaller. These differences include errors in the in situ levelling, in the antenna calibration model and in the TG measurements, and so represent an upper bound on our technique’s error. Data sampling (1 or 30 s) does not significantly affect the results. We detect systematic errors at the decimetre level related to satellite elevations below 12and to sea-surface height and also differences between results from the L1 and L2 GPS signals larger than 15 cm at two sites. These systematic errors remain unexplained; differences between GPS signals are attributed to receiver-dependent differences in the SNR measurements, while the elevation-dependent error is attributed to unmodelled phase effects such as those caused by tropospheric refraction and sea-surface roughness. Using our approach, we identify a levelling offset of 1.5 cm related to a TG sensor change, illustrating our technique’s value for TG reference monitoring.