Argo: The Global Array of Profiling Floats

ABSTRACT – The Argo network of autonomous profiling floats will provide the first global views of the time-varying temperature (T) and salinity (S) fields of the upper ocean. Argo will serve a broad community of scientific and operational users, with objectives falling into several categories. It will provide a quantitative description of the evolving physical state of the upper ocean and the patterns of ocean climate variability, including heat and freshwater storage and transport. The data will enhance the value of the Jason altimeter through measurement of the subsurface vertical structure of T and S, plus reference velocity, with sufficient coverage and resolution for interpreting altimetric sea surface height variability. Argo data will be used for initializing ocean and coupled forecast models, for data assimila-tion and for dynamical model testing. A primary focus of Argo is seasonal-to-decadal climate variability and predictability, but many applications for high-quality global ocean analyses are anticipated. The initial design of the Argo network is based on experience from the present observing system, on newly gained knowledge of variability from the TOPEX/Poseidon altimeter, and on estimated requirements for climate and high-resolution ocean models. Argo will provide 100 000 T–S profiles and reference velocity measurements per year from about 3000 floats distributed over the global oceans at 3-degree spacing. Floats will cycle to 2000 m depth every 10 days, with a 4–5 year lifetime for individual instruments. All Argo data will be publicly available in near real-time via the Global Telecommunications System (GTS), and in scientif-ically quality-controlled form with a few months delay. Global coverage will be achieved during the Global Ocean Data Assimilation Experiment (GODAE, 2003–2005), which together with the Climate Variability and Predictability Programme (CLIVAR) and th