Effects of atmospheric pressure loading and seven-parameter transformations on estimates of geocenter motion and station heights from space geodetic observations
Effects of atmospheric pressure loading and seven-parameter transformations on estimates of geocenter motion and station heights from space geodetic observations
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DOI：
10.1029/2004jb003334
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发表时间：
2005-03-23
影响因子：
3.9
通讯作者：
van Dam, T
中科院分区：
文献类型：
--
作者：
Tregoning, P;van Dam, T
[1]海洋和大气等流体负荷的变化使地球表面变形。可以估计的站点坐标的精度，特别是高度，取决于人们如何很好地将这些表面变形与固体地球的质心和总地球(CM)之间的相关平移运动分开。我们将模拟的大气压力载荷效应应用于CM框架中的站点坐标，以探索从大地测量分析中实际上可以恢复地心运动和准确的台站坐标的精度水平。我们发现，标准的七参数变换(三个旋转、三个平移、比例)通常可以恢复约80%的地心运动；然而，比例因子的加入允许表面加载变形的混叠，引入高达0.3 ppb的比例误差和高达4 mm的日高度误差。这限制了可以使用大地测量分析结果在信号幅度较小的地方准确执行的地球物理研究(例如，验潮仪的构造运动、用于解释冰川均衡调整的抬升速率)。大地测量结果的质量对用于估计转换的站点的数量和分布极为敏感，当使用区域(而不是全球)站点集时，质量变得更差。如果省略比例因子参数，则表面载荷效应的混叠量将显著减少，并实现更准确的场地速度和地心运动估计。
[1] Variations in fluid loads such as the oceans and the atmosphere deform the surface of the Earth. The accuracy of station coordinates, in particular, heights, that can be estimated depends on how well one can separate these surface deformations from the associated translational motion between the center of mass of the solid Earth and the total Earth ( CM). We applied simulated atmospheric pressure loading effects to the coordinates of sites in the CM frame to explore to what level of accuracy both geocenter motion and accurate station coordinates can actually be recovered from geodetic analyses. We found that standard seven-parameter transformations ( three rotations, three translations, scale) generally recover about 80% of the geocenter motion; however, the inclusion of a scale factor permits the aliasing of surface loading deformation, introducing scale errors of up to 0.3 ppb and daily height errors as large as 4 mm. This limits the geophysical studies that can be performed accurately using the results of geodetic analyses where the magnitudes of the signals are small ( e. g., tectonic movement of tide gauges, uplift rates for interpreting glacial isostatic adjustment). The quality of the geodetic results is extremely sensitive to the number and distribution of sites used to estimate the transformations and becomes worse when regional ( rather than global) sets of sites are used. If the scale factor parameter is omitted, then the amount of aliasing of surface loading effects is reduced considerably and more accurate site velocities and geocenter motion estimates are achieved.