Methodology for the combination of sub-daily Earth rotation from GPS and VLBI observations
Methodology for the combination of sub-daily Earth rotation from GPS and VLBI observations
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DOI：
10.1007/s00190-011-0512-9
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发表时间：
2012-03-01
影响因子：
4.4
通讯作者：
Tesmer, S.
中科院分区：
文献类型：
--
作者：
Artz, T.;Bernhard, L.;Tesmer, S.
基于齐次法方程组，发展了全球定位系统(GPS)和甚长基线干涉测量(VLBI)观测的地球定向参数组合方法。该组合的重点和目的是确定长达13年的亚日极移(PM)和世界时(UT1)。估算了PM和UT1-TAI的逐时分辨率时间序列和潮汐变化模式(DUT1)。在这两种情况下，14天章动校正是与ERPs同时估计的。由于联合手术，保证了两种技术的优点得以保留。同时，只需要最小限度的解除关联或稳定约束。据此确定了PM时间序列，其精度主要由GPS观测值决定。然而，这种设置得益于VLBI同时提供章动和dUT1估计这一事实。对于dUT1估计，可以看到更大的改进，其中高频变化由GPS提供，而长期趋势由VLBI定义。估计的潮汐PM和dUT1组合模型主要是由GPS观测确定的。总体而言，组合潮汐模型首次完全包含了VLBI和GPS观测的几何益处。在均方根(RMS)差方面，潮汐振幅与其他经验的单技术潮汐模型在4亩以下一致，如PM和DUT1的S潮汐模型分别为0.25亩和0.25亩。用3种方法研究了潮汐ERP模型的噪声底限，结果表明，日PM约为1亩，日DUT1约为0.07亩，而半日分量的精度略有提高。
A combination procedure of Earth orientation parameters from Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) observations was developed on the basis of homogeneous normal equation systems. The emphasis and purpose of the combination was the determination of sub-daily polar motion (PM) and universal time (UT1) for a long time-span of 13 years. Time series with an hourly resolution and a model for tidal variations of PM and UT1-TAI (dUT1) were estimated. In both cases, 14-day nutation corrections were estimated simultaneously with the ERPs. Due to the combination procedure, it was warranted that the strengths of both techniques were preserved. At the same time, only a minimum of de-correlating or stabilizing constraints were necessary. Hereby, a PM time series was determined, whose precision is mainly dominated by GPS observations. However, this setup benefits from the fact that VLBI delivered nutation and dUT1 estimates at the same time. An even bigger enhancement can be seen for the dUT1 estimation, where the high-frequency variations are provided by GPS, while the long term trend is defined by VLBI. The estimated combined tidal PM and dUT1 model was predominantly determined from the GPS observations. Overall, the combined tidal model for the first time completely comprises the geometrical benefits of VLBI and GPS observations. In terms of root mean squared (RMS) differences, the tidal amplitudes agree with other empirical single-technique tidal models below 4 mu as in PM and 0.25 mu s in dUT1. The noise floor of the tidal ERP model was investigated in three ways resulting in about 1 mu as for diurnal PM and 0.07 mu s for diurnal dUT1 while the semi-diurnal components have a slightly better accuracy.