Using Models of the Ocean's Mean Dynamic Topography to Identify Errors in Coastal Geodetic Levelling
Using Models of the Ocean's Mean Dynamic Topography to Identify Errors in Coastal Geodetic Levelling
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使用海洋平均动态地形模型来识别海岸大地水准测量中的误差
DOI：
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发表时间：
2014
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通讯作者：
M. Filmer
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作者：
M. Filmer
在沿海大地测量水准网中识别误差（粗差和系统误差）常常是有问题的，主要有两个原因。首先，验潮仪处的平均海平面（MSL）不能直接与水准测量得到的高差进行比较，因为大地水准面/似大地水准面与平均海平面不平行，它们被海洋平均动力地形（MDT）分隔开。其次，水准网边缘缺乏冗余。本文阐述了一种方法，利用MDT模型考虑验潮仪处大地水准面/似大地水准面与平均海平面之间的间隔，独立识别大地测量水准测量中（长距离的）粗差和/或系统误差。然后在一个案例研究中使用海洋MDT模型、平均海平面观测值、全球导航卫星系统（GNSS）数据和一个似大地水准面模型对该方法进行了测试。结果是显著的，因为仅靠标准水准测量闭合差检查无法检测到所发现的误差，而借助MDT模型的补充数据以及来自GNSS - 似大地水准面的交叉验证则能够检测到这些误差。此外，似乎仅基于海洋的MDT在检测水准测量误差方面与GNSS和似大地水准面模型一样有效，这对于那些在其水准网中存在沿海水准测量误差且无法通过常规水准测量闭合差检查识别的国家可能特别有用。
Identifying errors (blunders and systematic errors) in coastal geodetic levelling networks has often been problematic, primarily for two reasons. First, mean sea level (MSL) at tide gauges cannot be directly compared to height differences from levelling because the geoid/quasigeoid and MSL are not parallel, being separated by the ocean's mean dynamic topography (MDT). Second, there is a the lack of redundancy at the edge of the levelling network. This article sets out a methodology to independently identify blunders and/or systematic errors (over long distances) in geodetic levelling using MDT models to account for the separation between the geoid/quasigeoid and MSL at tide gauges. This method is then tested in a case study using an oceanographic MDT model, MSL observations, GNSS data, and a quasigeoid model. The results are significant because the errors found could not be detected by standard levelling misclosure checks alone, with supplementary data from an MDT model, with cross-validation from GNSS-quasigeoid allowing their detection. In addition, it appears that an oceanographic-only MDT is as effective as GNSS and a quasigeoid model for detecting levelling errors, which could be particularly useful for countries with coastal levelling errors in their levelling networks that cannot be identified by conventional levelling closure checks.