Satellite altimetry and operational oceanography: from Jason-1 to SWOT

Abstract. The development and evolution of satellite altimetry and operational oceanography are very closely linked. By providing all weather, global, and real-time observations of sea level, a key variable to constrain ocean analysis and forecasting systems, satellite altimetry has had a profound influence on the advancement of operational oceanography. Over the past 20 years, satellite altimetry has been providing a continuous observation of the ocean in near-real time. From the launch of Jason-1 in 2001 to the launch of SWOT in 2022, satellite altimetry capabilities have been regularly improved through refinements of geophysical corrections and processing algorithms, including real-time processing, as well as through the evolution of altimeter radar technology (synthetic aperture radar (SAR) mode, swath altimetry). Resolution has also improved through the use of multiple altimeters and, now, swath altimetry. In parallel, major improvements in ocean prediction systems have occurred, from the Global Data Assimilation Experiment (GODAE) demonstration in the 2000s to the fully operational systems now serving a large range of applications in the 2020s. This paper provides an overview of the development and evolution of satellite altimetry and operational oceanography over the past 20 years in the context of the Mercator Ocean prediction centre, DUACS (data unification and altimeter combination system), and the EU Copernicus Marine Service. The impact of altimetry on the performances of ocean prediction systems (based on observing-system evaluations (OSEs) and observing-system simulation experiments (OSSEs)) is reviewed. The future contribution of swath altimetry to ocean prediction is also discussed. Prospects for the next decade are addressed as part of our conclusions.