Optimally combined regional geoid models for the realization of height systems in de-veloping countries

物理高度系统的定义是重力场研究的主要应用之一。虽然全球有100多个国家和区域高度系统，但许多发展中国家和新兴工业化国家根本没有任何垂直参照系。然而，在这些国家，对准确和易于获取的身高信息的社会和经济需求往往迅速增加。一个重要的经济潜力在于，相当便宜的全球导航卫星系统测量与精确的大地水准面信息（称为全球导航卫星系统调平）相结合，可以取代人力和成本昂贵、费力的精神调平任务。该项目的主要目标是制定一个通过gnss调平实现和建立高程系统的一般科学概念，重点是大地测量基础设施不发达、地面数据质量低和/或稀疏的国家。如今，GRACE和GOCE卫星重力任务的结果能够确定高度，甚至在这些国家，精度达到几分米。这主要是由于卫星重力模型的频谱限制，导致省略了高频重力信号。因此，这些基于卫星的模型必须与互补的地面或航空数据相结合，从而产生区域增强的重力场模型，作为高度系统实现的基础。考虑到地面数据质量差或不明确、数据分布稀疏和不均匀以及地形粗糙等具体边界条件，应开发和加强创新方法，将高程系统实现所需的所有数据进行最佳组合。识别主要误差源，分析其对最终解决方案的影响。根据两个数字案例研究（南美洲、沙特阿拉伯），将得出一个普遍的科学概念，包括关于适当数据处理、最佳处理技术和验证程序的建议。该项目的研究结果将在国际层面公布，作为全球大地测量观测系统（GGOS）的重要投入，并将作为科学和行政方面进一步应用的指导方针。因此，该项目将基础研究和方法开发与高社会效益的实际应用相结合。

The definition of physical height systems is one of the main applications of gravity field research. Although globally more than 100 national and regional height systems exist, many developing and newly industrializing countries are lacking any vertical reference frame at all. However, in these countries there is often a rapidly increasing societal and economic need for accurate and easily accessible height information. A significant economic potential lies in the fact that a combination of rather inexpensive GNSS measurements with accurate geoid information (which is called GNSS-levelling) can replace the man-power and cost expensive, laborious task of spirit levelling. The main objective of the project is the formulation of a general scientific concept for the realization and establishment of height systems by GNSS-levelling with emphasis on countries with underdeveloped geodetic infrastructure and low-quality and/or sparse terrestrial data basis. Nowadays, results from the satellite gravity missions GRACE and GOCE enable to determine heights, even in these countries, with a level of accuracy of a few decimeters. This value is mainly due to the spectral limitation of satellite gravity models, resulting in omitted high-frequency gravity signals. Therefore, these satellite-based models have to be combined with complementary terrestrial or airborne data, resulting in regionally enhanced gravity field models as a basis for a height system realization. Innovative methods for an optimal combination of all data required for height system realization, taking the specific boundary conditions of poor or undefined terrestrial data quality, sparse and inhomogeneous data distribution and rough topography into account, shall be developed and enhanced. Furthermore, the main error sources shall be identified and their impact on the final solution shall be analyzed. Based on two numerical case studies (South America, Saudi Arabia), a generalized scientific concept will be derived, including recommendations concerning appropriate data handling, optimized processing techniques and validation procedures. The outcome of the project shall be placed on international level as a significant input to the Global Geodetic Observing System (GGOS), and shall serve as a guideline for further use in science and administration. Therefore, the project will combine fundamental research and methodological development with a practical application of high societal benefit.