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Optimal antenna locations of the VLBI Global Observing System for the estimation of Earth orientation parameters
Earth, Planets and Space ( IF 3.0 ) Pub Date : 2020-06-18 , DOI: 10.1186/s40623-020-01214-1
Matthias Schartner 1 , Johannes Böhm 1, 2 , Axel Nothnagel 1, 2
Affiliation  

To support monitoring subtle effects in the Earth system such as a mean sea level rise of 3 mm/year, a next-generation VLBI system, the VLBI Global Observing System (VGOS), has been developed and a new VGOS station network is being built. However, the geometry of the current VGOS network and its planned extension suffer from a lack of stations in the southern hemisphere. In this investigation, we identify optimal locations for additional VGOS radio telescopes with a new method based on bulk observing schedule generation and subsequent large-scale Monte-Carlo simulations. The location of the additional station is varied over 477 possible locations, homogeneously distributed over land areas on the globe. For each antenna location, several schedules have been generated and simulated to minimize the effects of scheduling and the randomness of simulations. Thereby, it is possible to judge, in which regions an additional VGOS station would have the biggest impact on the precision of the estimated geodetic parameters, in our case assessed by the repeatabilities of the estimated Earth orientation parameters (EOPs). To generate highly optimized schedules and to remove effects due to non-optimized scheduling, a total of 93 thousand schedules were iteratively generated, investigating over 300 billion scans and 2.4 trillion observations. Each schedule was further simulated 1000 times, leading to over 5 trillion simulated and analyzed observations. Although the optimum location of a future VLBI station depends on the EOP of interest and the geometry of the existing network, it is shown that the more the VGOS network grows, the more the lack of southern stations becomes prominent. The best location for an additional VGOS station for most EOP components and especially in the case of future VGOS networks would be the southern part of South America. It is further shown that the location of the additional antenna highly determines the expectable precision of the EOP estimates. For a 6-station network, the location of an additional seventh antenna can improve the precision of the EOP by a factor of 2.4 to 3.8. For an 18-station network, the location of an additional 19th station still improves the repeatability by a factor of 1.6. It is also found that adding a station at some locations will not improve the precision at all.

中文翻译:

用于估计地球定向参数的 VLBI 全球观测系统的最佳天线位置

为支持监测地球系统中的细微影响,例如平均海平面上升 3 毫米/年,开发了下一代 VLBI 系统,即 VLBI 全球观测系统 (VGOS),并正在建设新的 VGOS 台站网络. 然而,当前 VGOS 网络的几何形状及其计划扩展受到南半球缺乏台站的影响。在这项调查中,我们使用基于批量观测计划生成和随后的大规模蒙特卡洛模拟的新方法来确定额外 VGOS 射电望远镜的最佳位置。附加站的位置在 477 个可能的位置上有所不同,均匀分布在全球陆地区域。对于每个天线位置,已经生成并模拟了几个时间表,以尽量减少调度的影响和模拟的随机性。因此,在我们的案例中,通过估计的地球定向参数 (EOP) 的可重复性进行评估,可以判断在哪些区域增加 VGOS 站会对估计的大地测量参数的精度产生最大的影响。为了生成高度优化的调度并消除非优化调度的影响,总共迭代生成了 9.3 万个调度,调查了超过 3000 亿次扫描和 2.4 万亿次观测。每个时间表都进一步模拟了 1000 次,产生了超过 5 万亿次模拟和分析的观察结果。尽管未来 VLBI 站的最佳位置取决于感兴趣的 EOP 和现有网络的几何形状,结果表明,VGOS 网络发展得越多,南方站的缺乏就越突出。对于大多数 EOP 组件,尤其是在未来 VGOS 网络的情况下,附加 VGOS 站的最佳位置将是南美洲的南部。进一步表明,附加天线的位置在很大程度上决定了 EOP 估计的预期精度。对于 6 站网络,增加第七根天线的位置可以将 EOP 的精度提高 2.4 到 3.8 倍。对于 18 个站点的网络,额外的第 19 个站点的位置仍将可重复性提高了 1.6 倍。还发现在某些位置增加一个站点根本不会提高精度。对于大多数 EOP 组件,尤其是在未来 VGOS 网络的情况下,附加 VGOS 站的最佳位置将是南美洲的南部。进一步表明,附加天线的位置在很大程度上决定了 EOP 估计的预期精度。对于 6 站网络,增加第七根天线的位置可以将 EOP 的精度提高 2.4 到 3.8 倍。对于 18 个站点的网络,额外的第 19 个站点的位置仍可将重复性提高 1.6 倍。还发现在某些位置增加一个站点根本不会提高精度。对于大多数 EOP 组件,尤其是在未来 VGOS 网络的情况下,附加 VGOS 站的最佳位置将是南美洲的南部。进一步表明,附加天线的位置在很大程度上决定了 EOP 估计的预期精度。对于 6 站网络,增加第七根天线的位置可以将 EOP 的精度提高 2.4 到 3.8 倍。对于 18 个站点的网络,额外的第 19 个站点的位置仍将可重复性提高了 1.6 倍。还发现在某些位置增加一个站点根本不会提高精度。进一步表明,附加天线的位置在很大程度上决定了 EOP 估计的预期精度。对于 6 站网络,增加第七根天线的位置可以将 EOP 的精度提高 2.4 到 3.8 倍。对于 18 个站点的网络,额外的第 19 个站点的位置仍将可重复性提高了 1.6 倍。还发现在某些位置增加一个站点根本不会提高精度。进一步表明,附加天线的位置在很大程度上决定了 EOP 估计的预期精度。对于 6 站网络,增加第七根天线的位置可以将 EOP 的精度提高 2.4 到 3.8 倍。对于 18 个站点的网络,额外的第 19 个站点的位置仍将可重复性提高了 1.6 倍。还发现在某些位置增加一个站点根本不会提高精度。
更新日期:2020-06-18
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