We apply the AUSGeoid data processing and computation methodologies to data provided for the International Height Reference System (IHRS) Colorado experiment as part of the International Association of Geodesy Joint Working Groups 0.1.2 and 2.2.2. This experiment is undertaken to test a range of different geoid computation methods from international research groups with a view to standardising these methods to form a set of conventions that can be established as an IHRS. The IHRS can realise an International Height Reference Frame to be used to study physical changes on and within the Earth. The Colorado experiment study site is much more mountainous (maximum height 4401 m) than the mostly flat Australian continent (maximum height 2228 m), and the available data over Colorado are different from Australian data (e.g. much more extensive airborne gravity coverage). Hence, we have tested and applied several modifications to the AUSGeoid approach, which had been tailored to the Australian situation. This includes different methods for the computation of terrain corrections, the gridding of terrestrial gravity data, the treatment of long-wavelength errors in the gravity anomaly grid and the combination of terrestrial and airborne data. A new method that has not previously been tested is the application of a spherical harmonic high-pass filter to residual anomalies. The results indicate that the AUSGeoid methods can successfully be used to compute a high accuracy geoid in challenging mountainous conditions. Modifications to the AUSGeoid approach lead to root-mean-square differences between geoid models up to ~ 0.028 m and agreement with GNSS-levelling data to ~ 0.044 m, but the benefits of these modifications cannot be rigorously assessed due to the limitation of the GNSS-levelling accuracy over the computation area.

中文翻译：

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迈向国际高度参考系统：使用 AUSGeoid 计算方法的科罗拉多大地水准面实验的见解

我们将 AUSGeoid 数据处理和计算方法应用于为国际高程参考系统 (IHRS) 科罗拉多实验提供的数据，作为国际大地测量协会联合工作组 0.1.2 和 2.2.2 的一部分。本实验旨在测试来自国际研究小组的一系列不同的大地水准面计算方法，以期将这些方法标准化，形成一套可作为 IHRS 建立的惯例。IHRS 可以实现国际高度参考框架，用于研究地球内外的物理变化。科罗拉多实验研究地点的山地（最大高度 4401 m）比大部分平坦的澳大利亚大陆（最大高度 2228 m）要多得多，科罗拉多上空的可用数据与澳大利亚的数据（例如 更广泛的空中重力覆盖）。因此，我们测试并应用了针对澳大利亚情况量身定制的 AUSGeoid 方法的若干修改。这包括地形改正计算的不同方法、地面重力数据的网格化、重力异常网格中长波长误差的处理以及地面和机载数据的组合。一种以前未经过测试的新方法是将球谐高通滤波器应用于残差异常。结果表明，AUSGeoid 方法可以成功地用于计算具有挑战性的山区条件下的高精度大地水准面。对 AUSGeoid 方法的修改导致大地水准面模型之间的均方根差异高达 ~ 0.028 m，并且与 GNSS 水准数据的一致性达到 ~ 0。