Geodetic observations of ocean surface topography, ocean currents, ocean mass, and ocean volume changes

Abstract The tools of geodesy have the potential to transform the ocean observing system. Geodetic observations are unique in the way that they produce accurate, quantitative, and integrated observations of gravity, ocean circulation, sea surface height, ocean bottom pressure, and mass exchanges among the ocean, cryosphere, and land. Geodetic observations have made fundamental contributions to monitoring and understanding physical ocean processes. In particular, geodesy is the basic technique to enable determination of an accurate geoid model, allowing for the determination of absolute surface geostrophic currents, which are necessary to quantify heat transport of the ocean. The present geodetic satellites can measure total sea level and its mass component, both of which are vital for understanding global climate change. Continuation of current satellite missions and the development of new geodetic technologies can be expected to further support monitoring of the ocean. IAG’s GGOS provides the means for integrating the geodetic techniques that monitor Earth's time-variable surface geometry (including ocean and ice surfaces), gravity field, and rotation into a consistent system for measuring ocean surface topography, ocean currents, ocean mass, and ocean volume changes. This system depends on both globally coordinated ground-based networks of tracking stations as well as an uninterrupted series of satellite missions. GGOS works with GEO, CEOS and space agencies to ensure the availability of the necessary expertise and infrastructure. In this white paper, we summarize a community consensus of critical oceanographic parameters currently observed by geodetic observational systems, and requirements to continue such measurements. Achieving this potential will depend on merging the remote sensing techniques with