RING - Research Unit: P6 Environmental effects on long-period rotational measurements

• Applicants: Dr. Thomas Forbriger; Professor Dr. Andreas Güntner
• Subject Area: Geophysics ; Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553176123

Ring lasers and other rotational sensors rigidly attached to the Earth provide data on the motion of the Earth’s body and information to constrain models of the Earth’s interior. They are inevitably contaminated by local crustal deformation due to atmospheric pressure fluctuations and hydrological water storage variations. Gravitational attraction effects of mass fluctuations in the atmosphere and hydrosphere also disturb the ring laser signal through affecting tiltmeter observations that are used for the orientation correction. Such (noise-) signals of local to regional origin present a serious barrier to the analysis of small amplitude rotation signals of interest. We will set out to break this barrier by separating these noise components from the total signal, based on independent measurements and modeling of the noise sources. By this we contribute to the RING goals of substantially pushing down the limits of rotational ground motion measurements to expand applications in fundamental physics, geodesy and geophysics. In order to gain access to the causes of the signal contamination, we will collect unique data sets. A large-N barometer array will provide unprecedented data of the atmospheric loading behind crustal deformation and the so-called pressure gradient rotation. Detailed hydrological and geophysical monitoring will provide data on water storage changes in the unsaturated zone and in groundwater. With hydrological modeling based on these data and additional regional-scale models in the surroundings of the G-ring at the Geodetic Observatory Wettzell we will compute deflections of the plumb line due to Newtonian attraction and local crustal deformation. Based on these data and models we aim to separate the rotation signals of interest from the local disturbances. As a result, rotation data of improved signal-to-noise ratio will be available for the RING projects to analyze Earth orientation parameters, length of day and long-period seismic waves.

• DFG Programme: Research Units
• Subproject of: FOR 5939: RING: Rotational Motions in Physics, Geophysics, and Geodesy
• Co-Investigators: Dr. Thomas Klügel; Dr.-Ing. Hartmut Wziontek