| 地表负载及GPS测站分布对参考框架转换的影响分析 |
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| 引用本文： | 魏娜,施闯,刘经南.地表负载及GPS测站分布对参考框架转换的影响分析[J].地球物理学报,2016,59(2):484-493. |
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| 作者姓名： | 魏娜 施闯 刘经南 |
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| 作者单位： | 武汉大学卫星导航定位技术研究中心, 武汉 430079 |
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| 基金项目： | 国家自然科学基金项目(41231174,41204009,41274049),国家高技术研究发展计划项目(2013AA122501)联合资助. |
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| 摘 要： | GPS数据处理通常采用Helmert七参数转换将瞬时站坐标转换到指定的框架下,但瞬时站坐标中尚未模型化的季节性地表负载会影响平移参数(地心运动)和尺度参数的估值,进而影响测站坐标;不均匀的测站分布会加剧这一影响.本文利用GRACE重力场系数仿真GPS地表负载的实验表明,基于网平移法采用实际的IGS站至少能够恢复90%的地心运动信号.地表负载及GPS实际测站的不均匀分布可以解释大约30%的GPS尺度的周年变化.相对于IGb08的所有框架站,目前采用91个全球均匀分布的核心站作为框架转换的基准是合理的.采用IGb08的所有框架站进行转换会导致U方向误差增加,特别是对框架站密集的欧洲区域(误差均值约为1mm).因此框架转换时,应尽量选取均匀分布的测站,同时不估计尺度参数.
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| 关 键 词： | 地心运动 尺度因子 负载效应 网效应 |
| 收稿时间： | 2014-11-16 |
Effects of surface loading and heterogeneous GPS network on Helmert transformation |
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| WEI Na,SHI Chuang,LIU Jing-Nan.Effects of surface loading and heterogeneous GPS network on Helmert transformation[J].Chinese Journal of Geophysics,2016,59(2):484-493. |
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| Authors: | WEI Na SHI Chuang LIU Jing-Nan |
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| Institution: | GNSS Research Center, Wuhan University, Wuhan 430079, China |
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| Abstract: | Seven-parameter transformation is usually used to transform fiducial-free GPS coordinates into the CF (center of surface figure) frame. However, in this case the un-modeled surface loading signals included in GPS coordinates would alias into the transformation parameters, including translation and scale parameters. The heterogeneous GPS station distribution makes it worse. We study the effects of loading aliasing errors and network aliasing errors on the transformation parameters and station coordinates. Seasonal GPS loading deformation is simulated using GRACE gravity coefficients. Results show that at least 90% of geocenter motion signals can be recovered using the real IGS station network. About 30% of the annual variations of the GPS scale can be explained by loading aliasing errors and the related network aliasing errors. For IGS data processing, it is reasonable to adopt 91 core stations as the datum to align weekly solutions to the IGS reference frame. If all IGS reference stations (232) are used, large errors are introduced in the Up component, especially within Europe where more dense ground networks are located. Therefore homogenous station network should be chosen as the datum for reference frame alignment and scale parameters should not be involved. |
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| Keywords: | Apparent geocenter motion Scale parameter Loading aliasing errors Network aliasing errors |
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