In only 10 years, the Argo Program has grown from an idea into a functioning global observing system for the subsurface ocean. More than 3000 Argo floats now cover the world ocean. With these instruments operating on 10-day cycles, the array provides 9000 temperature/salinity/depth profiles every month that are quickly available via the Global Telecommunications System and the Internet. Argo is recognized as a major advance for oceanography, and a success for Argo’s parent programs, the Global Ocean Data Assimilation Experiment and Climate Variability and Predictability, and for the Global Earth Observation System of Systems. The value of Argo data in ocean data assimilation (ODA) and other applications is being demonstrated, and will grow as the data set is extended in time and as experience in using the data set leads to new applications. The spatial coverage and quality of the Argo data set are improving, with consideration being given to sampling under seasonal ice at higher latitudes, in additional marginal seas, and to greater depths. Argo data products of value in ODA modeling are under development, and Argo data are being tested to confirm their consistency with related satellite and in situ data. Maintenance of the Argo Program for the next decade and longer is needed for a broad range of climate and oceanographic research and for many operational applications in ocean state estimation and prediction.

Roemmich, D., and the Argo Steering Team. 2009. Argo: The challenge of continuing 10 years of progress. Oceanography 22(3):46–55, https://doi.org/10.5670/oceanog.2009.65.

Boyer, T.P., J.I. Antonov, S. Levitus, and R. Locarnini. 2005. Linear trends of salinity for the world ocean, 1955–1998. Geophysical Research Letters 32, L01604, doi:1029/2004GL021791.

Cazenave, A., K. Dominh, and S. Guinehut. 2009. Sea level budget over 2003–2008: A reevaluation from GRACE space gravimetry, satellite altimetry and Argo. Global and Planetary Change 65(1–2):83–88.

Conkright, M.E., R.A. Locarnini, H.E. Garcia, T.D. O’Brien, T.P. Boyer, C. Stephens, and J.I. Antonov. 2002. World Ocean Atlas 2001: Objective Analyses, Data Statistics, and Figures, CD-ROM Documentation. National Oceanographic Data Center, Silver Spring, MD, 17 pp.

Curry, R., B. Dickson, and I. Yashayaev. 2003. A change in the freshwater balance of the Atlantic Ocean over the past four decades. Nature 426:826–829. 

Davis, R.E., C.E. Eriksen, and C.P. Jones. 2002. Autonomous buoyancy-driven underwater gliders. Pp. 37–58 in The Technology and Applications of Autonomous Underwater Vehicles. G. Griffiths, ed., Taylor and Francis, London.

Domingues, C.M., J.A. Church, N.J. White, P. Gleckler, S.E. Wijffels, P.M. Barker, and J.R. Dunn. 2008. Improved ocean-warming estimates: Implications for climate models and sea-level rise. Nature 453:1,090–1,093.

Ducet, N., P.-Y. Le Traon, and G. Reverdin. 2000. Global high resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. Journal of Geophysical Research 105:19,477–19,498.

Gaillard, F., E. Autret, V. Thierry, and P. Galaup. 2009. Quality control of large Argo data sets. Journal of Atmospheric and Oceanic Technology 26(2):337–351, doi:10.1175/2008JTECHO552.1.

Gill, A., and P. Niiler. 1973. The theory of the seasonal variability in the ocean. Deep-Sea Research 20:141–177.

Guinehut, S., P.Y. Le Traon, and G. Larnicol. 2006. What can we learn from global altimetry/hydrography comparisons? Geophysical Research Letters 33, L10604, doi:10.1029/2005GL025551.

Guinehut, S., C. Coatanoan, A.-L. Dhomps, P.-Y. Le Traon, and G. Larnicol. 2009. On the use of satellite altimeter data in Argo quality control. Journal of Atmospheric and Oceanic Technology 26(2):395–402, doi:10.1175/2008JTECHO648.1.

Josey, S.A., E.C. Kent, and P.K. Taylor. 1998. The Southampton Oceanography Centre (SOC) Ocean-Atmosphere Heat, Momentum and Freshwater Flux Atlas. Southampton Oceanography Centre Report No. 6, 30 pp.

Le Traon, P.-Y., G. Larnicol, S. Guinehut, S. Pouliquen, A. Bentamy, D. Roemmich, C. Donlon, H. Roquet, G. Jacobs, D. Griffin, and others. 2009. Data assembly and processing for operational oceanography: 10 years of achievements. Oceanography 22(3):56–69.

Leuliette, E.W., and L. Miller. 2009. Closing the sea level rise budget with altimetry, Argo, and GRACE. Geophysical Research Letters 36, L04608, doi:10.1029/2008GL036010.

Levitus, S., J.I. Antonov, T.P. Boyer. 2005. Warming of the world ocean, 1955–2003. Geophysical Research Letters 32, L02604, doi:10.1029/2004GL021592.

Levitus, S., J.I. Antonov, T.P. Boyer, R.A. Locarnini, H.E. Garcia, and A.V. Mishonov. 2009. Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems. Geophysical Research Letters 36, L07608, doi:10.1029/2008GL037155.

Oke, P.R., M.A. Balmaseda, M. Benkiran, J.A. Cummings, E. Dombrowsky, Y. Fujii, S. Guinehut, G. Larnicol, P.-Y. Le Traon, and M.J. Martin. 2009. Observing system evaluations using GODAE systems. Oceanography 22(3):144–153.

Reynolds, R.W., N.A. Rayner, T.M. Smith, D.C. Stokes, and W. Wang. 2002. An improved in situ and satellite SST analysis for climate. Journal of Climate 15:1,609–1,625.

Riser, S.C., and K.S. Johnson. 2008. Net production of oxygen in the subtropical ocean. Nature 451:323–326, doi:10.1038/nature06441.

Roemmich, D., and P. Sutton. 1998. The mean and variability of ocean circulation past northern New Zealand: Determining the representativeness of hydrographic climatologies. Journal of Geophysical Research 103:13,041–13,054.

Roemmich, D., and the Argo Science Team. 1999. On the Design and Implementation of Argo: An Initial Plan for a Global Array of Profiling Floats. International CLIVAR Project Office Report 21, GODAE Report 5. GODAE International Project Office, Melbourne, Australia, 32 pp.

Roemmich, D., and J. Gilson. 2009. The 2004–2008 mean and annual cycle of temperature, salinity and steric height in the global ocean from the Argo Program. Progress in Oceanography doi:10.1016/ j.pocean.2009.03.004.

Roemmich, D., G.C. Johnson, S. Riser, R. Davis, J. Gilson, W.B. Owens, S. Garzoli, C. Schmid, and M. Ignaszewski. 2009. The Argo Program: Observing the global ocean with profiling floats. Oceanography 22(2):34–43.

Stammer, D. 1997. Global characteristics of ocean variability estimated from regional TOPEX/Poseidon altimeter measurements. Journal of Physical Oceanography 27:1,743–1,769.

Uchida, H., and S. Imawaki. 2008. Estimation of the sea level trend south of Japan by combining satellite altimeter data with in situ hydrographic data. Journal of Geophysical Research 113, C09035, doi:10.1029/2008JC004796.

Wijffels, S., J. Willis, C. Domingues, P. Barker, N. White, A. Gronell, K. Ridgway, and J. Church. 2008. Changing expendable bathythermograph fall-rates and their impact on estimates of thermosteric sea level rise. Journal of Climate 21:5,657–5,672, doi:10.1175/2008JCLI2290.1.

Willis, J.K., J.M. Lyman, G.C. Johnson, and J. Gilson. 2007. Correction to “Recent cooling of the upper ocean.” Geophysical Research Letters 34, L16601, doi:10.1029/2007GL030323.

Willis, J.K., D.P. Chambers, and R.S. Nerem. 2008. Assessing the globally averaged sea level budget on seasonal to interannual timescales. Journal of Geophysical Research 113, C06015, doi:10.1029/2007JC004517.

Wong, A., N. Bindoff, and J. Church. 1999. Large-scale freshening of intermediate waters in the Pacific and Indian oceans. Nature 400:440–443.

Wong, A.P.S., G.C. Johnson, and W.B. Owens. 2003. Delayed-mode calibration of autonomous CTD profiling float salinity data by theta-S climatology. Journal of Atmospheric and Oceanic Technology 20:308–318.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.