Project Details
Projekt
Mutual benefits of integrating ring laser into space geodetic data analysis for determining Earth rotation
Subject Area
Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Geophysics
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Geophysics
Term
since 2026
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 553176123
Very accurate knowledge of the Earth's orientation is required for a wide range of applications such as positioning and navigation on Earth and in space. The Earth Orientation Parameters (EOPs), i.e., terrestrial pole coordinates, UT1-UTC, length of day (LOD), and celestial pole coordinates, can be determined by space geodetic techniques such as GNSS, SLR, VLBI. These techniques have individual strengths and weaknesses, and, therefore, need to be combined for a high-quality solution. For instance, VLBI is the unique source for determining UT1-UTC and celestial pole, but does not provide continuous observations. The strengths of GNSS and SLR compared to VLBI are the continuous observations as well as the accuracy reached for pole coordinates and LOD. Furthermore, typical EOP series operationally available nowadays have a daily resolution only. In contrast, ring laser (RL) provides continuous information about Earth’s rotation with high temporal resolution, although it measures a slightly different quantity than space geodesy. The recent developments in the RL technology open a unique opportunity to determine EOP series with higher accuracy and temporal resolution. This project aims to elevate EOPs to a new level of accuracy and temporal resolution by a rigorous combination of RL and space geodetic data. Such high-quality products are urgently needed as the accuracy requirements, in particular for an accurate and reliable Earth system observation (e.g., global sea level rise) set by the Global Geodetic Observing System (GGOS), are not yet met. We will extensively analyze RL and space geodetic data (VLBI, GNSS, SLR) individually with common state-of-the-art procedures and consistent software. The optimal and maximal possible temporal resolution is investigated for all data types. Once the strengths and weaknesses of all data sets are understood, the VLBI, GNSS, SLR and RL data are combined. The combination is done step-wise in order to study the benefit of a combination of each subset of data, and to be able to develop the optimal combination strategy. Dedicated validation procedures need to be designed. Special attention is paid to the impact of the improved combined EOPs on other geodetic key products such as satellite orbits and global reference frames. Furthermore, as all space geodetic techniques have weaknesses in separating the rotational parts of sub-daily polar motion and nutation, the benefit by a combination with RL data will be investigated. Additionally, simulation studies will assess the impact of more RL distributed worldwide with different specifications on high-resolution EOPs. Based on these results, we will feed back the requirements for further developments of RL technology in a mutually beneficial way. The overall research question to be answered is: What improvements and mutual benefits can be achieved through the combination of space geodetic observations with RL data, and can the accuracy requirements of GGOS be achieved?
DFG Programme
Research Units
