The Global Geodetic Observing System (GGOS) is an international collaboration of geodetic services and experts working together to provide geodetic data and products that serve science and society beyond the traditional task of measuring and mapping the Earth's surface. GGOS integrates ground- and space-based geodetic observations in order to monitor the Earth's time-variable shape, rotation and gravity. Changes to these characteristics are inherently related to interactions within and between the various components of the Earth system, ranging from the solid lithosphere to the upper atmosphere, demonstrating the importance of geodesy in monitoring the changing Earth. To advance our understanding of the underlying processes, the accuracy of geodetic measurements must be one to two levels higher than the magnitude of the changes to be detected. Examples of particularly demanding applications of geodetic measurements include mass transport across the Earth's spheres, the effects of climate change, and geohazards. This session is a forum for discussing ongoing and planned improvements to observing systems for the Earth's geometry, gravity, and rotation, as well as the impacts of Space Weather on geodetic measurements. We are particularly interested in the application of new methods and technologies, such as relativistic geodesy, quantum sensors, next-generation lasers, ionospheric modelling, Low Earth Orbit (LEO) satellites, machine learning, and high-resolution accelerometers, as well as advancements in traditional geodetic instruments (e.g., GNSS, VLBI, DORIS, and InSAR). Furthermore, we encourage studies assessing the ionosphere and thermosphere to better understand the impacts of neutral density and the space weather on LEO satellite orbits and geodetic measurements. We also welcome general contributions on GGOS, including progress reports and plans for the next generation of geodetic observatories integrating measurements of the Earth's geometry, gravimetry, rotation, and atmospheric environment.
Sébastien Merlet