Ferrándiz José M, Modiri Sadegh, Belda Santiago, Barkin Mikhail, Bloßfeld Mathis, Heinkelmann Robert, Schuh Harald
UAVAC, University of Alicante, Campus de San Vicente, 03080 Alicante, Spain.
GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany.
Remote Sens (Basel). 2020 Jan 18;12(2):314. doi: 10.3390/rs12020314.
The location of the Earth's principal axes of inertia is a foundation for all the theories and solutions of its rotation, and thus has a broad effect on many fields, including astronomy, geodesy, and satellite-based positioning and navigation systems. That location is determined by the second-degree Stokes coefficients of the geopotential. Accurate solutions for those coefficients were limited to the stationary case for many years, but the situation improved with the accomplishment of Gravity Recovery and Climate Experiment (GRACE), and nowadays several solutions for the time-varying geopotential have been derived based on gravity and satellite laser ranging data, with time resolutions reaching one month or one week. Although those solutions are already accurate enough to compute the evolution of the Earth's axes of inertia along more than a decade, such an analysis has never been performed. In this paper, we present the first analysis of this problem, taking advantage of previous analytical derivations to simplify the computations and the estimation of the uncertainty of solutions. The results are rather striking, since the axes of inertia do not move around some mean position fixed to a given terrestrial reference frame in this period, but drift away from their initial location in a slow but clear and not negligible manner.
地球主要惯性轴的位置是其自转所有理论和解决方案的基础，因此对包括天文学、大地测量学以及基于卫星的定位和导航系统在内的许多领域都有广泛影响。该位置由地球引力位的二阶斯托克斯系数决定。多年来，这些系数的精确解仅限于静态情况，但随着重力恢复与气候实验（GRACE）的完成，情况有所改善，如今已基于重力和卫星激光测距数据得出了几种时变地球引力位的解，时间分辨率达到一个月或一周。尽管这些解已经足够精确，可以计算出地球惯性轴十多年来的演变情况，但从未进行过这样的分析。在本文中，我们利用先前的解析推导来简化计算和估计解的不确定性，首次对这个问题进行了分析。结果相当惊人，因为在此期间，惯性轴并非围绕固定在给定地球参考系上的某个平均位置移动，而是以缓慢但清晰且不可忽略的方式从其初始位置漂移开去。
