GGOS-SIM-2: Simulation of the Global Geodetic Observing System

GGOS-SIM-2的总体目标是评估四种主要空间大地测量技术(由卫星、全球导航卫星系统、卫星激光测距、甚长基线干涉测量)在空间同时定位的潜力，即在一颗或多颗卫星上实现精度和稳定性满足国际大地测量协会(大地测量协会)全球大地观测系统(GGOS)规定的科学要求的全球地面参考系统。目前，这些质量要求没有达到，但为了可靠地解释全球过程，如全球海平面上升，这些要求是非常必要的。在GGOS-SIM项目的第一阶段内，所取得的结果表明，模拟四种主要的空间大地测量技术对于调查全球地球参考框架(TRF)的精度和稳定性是合适的。在第二阶段(GGOS-SIM-2)，我们计划通过考虑四种技术在空间中的共存来扩展这些模拟，并量化对TRF确定的影响。在GGOS-SIM-2中，将解决以下问题：·可以获得TRF和相关产品(如地球定位参数)的精度级别，通过一颗类似于GRAPH的卫星在空间中实行一地两检？·TRS在一颗(或多颗)卫星(S)上实现空间纽带与地面本地纽带相辅相成有什么附加值？·根据最佳轨道选择、地面站数量、观测时间和卫星数量，必须满足哪些标准才能使TRF满足GGOS要求？·公共POD内特定技术的系统学对TRF有什么影响？·地面地方纽带可以得出什么结论？·静态和时变重力场的前景是什么？

The overall objective of GGOS-SIM-2 is to assess the potential of co-location in space of the four main space geodetic techniques (Doppler Orbitography and Radiopositioning Integrated by Satellite, Global Navigation Satellite Systems, Satellite Laser Ranging, Very Long Baseline Interferometry), i.e. on board of one or more satellites, to realize a global terrestrial reference system (TRS) with an accuracy and stability meeting the science-driven requirements specified by the Global Geodetic Observing System (GGOS) of the IAG (International Association of Geodesy). Currently, these quality requirements are not achieved but are strongly required to reliably interpret global processes, such as the global sea level rise. Within the first phase of project GGOS-SIM, the achieved results have demonstrated the suitability of simulations of the four main space geodetic techniques for investigating the accuracy and stability of global terrestrial reference frames (TRF). In the second phase (GGOS-SIM-2) we plan extending these simulations by considering co-locations of the four techniques in space and quantifying the effects on the TRF determination. Using space ties instead of or additionally to ground local ties that are customarily interconnecting the individual techniques will allow validating these local ties, which are currently applied without any external control in the TRS realization approaches.Within GGOS-SIM-2 the following questions will be addressed:• Which level of accuracy of the TRF and the related products like Earth orientation parameters can be obtained, applying co-location in space through a GRASP-like satellite?• What is the added value for TRS realization of a space tie on one (or more) satellite(s) complementing the local ties on ground?• Which criteria have to be fulfilled in order to get a TRF meeting the GGOS requirements depending on optimal orbit selection, number of ground stations, observation time, and number of satellites? • What is the impact of technique-specific systematics within the common POD on the TRF?• What can be concluded for the local ties at the ground?• What are the prospects for the static and time-variable gravity field?