GNSS and Global Geodesy

该研究计划由三个相互交错的项目组成，受益于我们早先的发展，涵盖大地测量学的物理和几何方面。*第一个研究项目涉及全球高度系统的非常基本的主题。正在努力在地球位势水平上建立全球高度系统，即大地水准面，并在全球高度系统和国家高度系统之间建立关系。各国使用的是标准身高或正常身高。前者指的是物理表面(大地水准面)，而后者指的是近似的准大地水准面。正高是根据赫尔默特公式计算的。我们开发了一个更严格的公式，严格的垂直高度。该项目需要调查地形密度变化对全球尺度上重力和高度的影响，在全球尺度上确定严格和赫尔默特垂直高度与正常高度之间的关系，考虑到空间变化和精度，设计和实施一个计算程序包，以简化严格垂直高度的计算，并将这三种常见类型的高度相互转换以用于实际目的。*第二个研究项目涉及气候大地测量学的使用。其最终目标是向气候界提供一种稳健可靠的算法，可用于中性大气参数时间序列在用于气候分析之前的同质化。这些参数可以从全球导航卫星系统的观测或从数值天气预报模型(NWM)中产生。该项目需要设计、实施和评估全球导航卫星系统处理过程中的射线跟踪，通过误差传播对射线跟踪操作期间的不确定性进行全面评估，设计和测试中性大气时间序列质量控制的组合算法，并设计、测试和验证可供气候界使用的全球导航卫星系统和北半球气象卫星系统得出的中性大气参数的同质化算法。*第三个项目评估实时全球导航卫星系统精密单点定位(PPP)的用途和能力及其在车辆导航中的应用。提出了自主导航的协同定位和车道保持的概念。它加强了地图匹配的概念，并探索了使用Wi-Fi来弥补定位中断的情况。它需要优化集成卡尔曼滤波器，它集成了实时PPP定位、Wi-Fi、惯性和来自地图数据库的信息，评估Wi-Fi以弥补定位中断，并评估与接收真实场景中PPP所需的实时数据流相关的问题。

The research program is composed by three interlaced projects, benefiting from earlier developments we have made, covering physical and geometrical aspects of Geodesy. ******The first research project deals with the very fundamental subject of global heights system. There is an effort for establishing a global height system at the geopotential level, the geoid, and to establish relationships between the global height system and national ones. Countries use either orthometric or normal heights. The former relates to a physical surface (geoid) whereas the latter to a close approximation, the quasi-geoid. Orthometric heights are computed based on Helmert's formulation. We have developed a more rigorous formulation, the rigorous orthometric heights. The project entails the investigation of the effect of topo-density variation on gravity and heights on global scale, the determination of relationships between rigorous and Helmert's orthometric heights with normal heights, on a global scale, taking into consideration spatial variations and accuracy, the design and implementation a computational package to simplify the computation of rigorous orthometric height and to convert these three common types of heights to each other to be used for practical purposes. ******The second research project deals with the use of Geodesy for climate. Its final objective is to provide the climate community with a robust and reliable algorithm that can be used in the homogenization of neutral-atmospheric parameters time series before their use in climate analysis. The parameters can be generated from GNSS observations or from numerical weather prediction models (NWM). The project entails the designing, implementation and assessment of ray-tracing inside the GNSS processing, a full evaluation of uncertainties during the ray tracing operation via error propagation, the design and test of combination algorithms for quality control of neutral-atmospheric time series, and the design, test and validation of algorithm for homogenization of GNSS- and NWM- derived neutral-atmospheric parameters to be made available to the climate community. ******The third project assesses the use and capabilities of real-time GNSS precise point positioning (PPP) and its application in vehicle navigation. It advances the concept of cooperative positioning and lane-keeping for autonomous navigation. It enhances the concept of map-matching and explores the use of Wi-Fi to complement positioning outages. It entails the optimization of the integration Kalman Filter that integrates real-time PPP positioning, Wi-Fi, inertial and information from the map database, assessment of Wi-Fi to complement positioning outages and assess problems associated with reception of the real-time data stream necessary for PPP in a real scenario.