Spurred by the development of satellite and in situ observing systems, global ocean state estimation has flourished in the past decade. Today, a suite of global ocean state estimates has been generated and is being applied to studies over a wide range of subjects in physical oceanography and climate research as well as other disciplines. This paper highlights some examples of using ocean state estimations for ocean and climate research. Many assimilation groups from different countries participated in a Climate Variability and Predictability program/Global Ocean Data Assimilation Experiment global ocean reanalysis evaluation effort in which intercomparisons were performed for a suite of diagnostic quantities and indices, including evaluations against observations. Examples of the intercomparisons are presented to highlight the consistencies and uncertainties of the estimation products and to examine the ability of these products to detect climate signals. Future challenges for state estimation for climate applications are also discussed.
Lee, T., T. Awaji, M.A. Balmaseda, E. Greiner, and D. Stammer. 2009. Ocean state estimation for climate research. Oceanography 22(3):160–167, https://doi.org/10.5670/oceanog.2009.74.
Balmaseda, M.A., and A. Weaver. 2006. Temperature, salinity, and sea-level changes: Climate variability from ocean reanalyses. Paper presented at the CLIVAR/GODAE Meeting on Ocean Synthesis Evaluation, August 31–September 1, 2006, ECMWF, Reading, UK. Meeting presentation available at: http://www.clivar.org/organization/gsop/synthesis/groups/Items3_4.ppt (accessed May 26, 2009).
Balmaseda, M.A., G.C. Smith, K. Haines, D. Anderson, T.N. Palmer, and A. Vidard. 2007. Historical reconstruction of the Atlantic meridional overturning circulation from the ECMWF operational ocean reanalysis. Geophysical Research Letters 34, L23615, doi:10.1029/2007GL031645.
Balmaseda, M.A., O.J. Alves, A. Arribas, T. Awaji, D. Behringer, N. Ferry, Y. Fujii, T. Lee, M. Rienecker, T. Rosati, and D. Stammer. 2009. Ocean initialization for seasonal forecasts. Oceanography 22(3):154–159.
Bryden, H.L., H.R. Longworth, and S.A. Cunningham. 2005. Slowing of the Atlantic meridional overturning circulation at 25 degrees N. Nature 438:655–657.
Cabanes, C., T. Lee, and L.-L. Fu. 2008. Mechanisms of interannual variations of the meridional overturning circulation of the North Atlantic Ocean. Journal of Physical Oceanography 38:467–480.
Carton, J.A., B.S. Giese, and S.A. Grodsky. 2005. Sea level rise and the warming of the oceans in the Simple Ocean Data Assimilation (SODA) ocean reanalysis. Journal of Geophysical Research 110, C09006, doi:10.1029/2004JC002817.
Carton, J.A., and A. Santorelli. 2009. Global decadal upper-ocean heat content as viewed in nine analyses. Journal of Climate 21:6,015–6,035.
Capotondi, A., A. Wittenberg, and S. Masina. 2006. Spatial and temporal structure of ENSO in 20th century coupled simulations. Ocean Modelling 15(3–4):274–298, doi:10.1016/ j.ocemod.2006.02.004.
Cooper, M., and K. Haines. 1996. Altimetric assimilation with water property conservation. Journal of Geophysical Research 101:1,059–1,077.
Cunningham, S.A., T. Kanzow, and D. Rayner, M.O. Baringer, W.E. Johns, J. Marotzke, H.R. Longworth, E.M. Grant, J.J.-M. Hirschi, L.M. Beal, and others. 2007. Temporal variability of the Atlantic meridional overturning circulation at 26.5 degrees N. Science 317:935–938.
Dickey, J.O., S.L. Marcus, O. de Viron, and I. Fukumori. 2002. Recent Earth oblateness variations: Unraveling climate and postglacial rebound effects. Science 298:1,975–1,977.
Du, Y., T.-D. Qu, and G. Meyers. 2008. Interannual variability of sea surface temperature off Java and Sumatra in a global GCM. Journal of Climate 21:2,451–2,465.
Dutkiewicz, S., M.J. Follows, P. Heimbach, and J. Marshall. 2006. Controls on ocean productivity and air-sea carbon flux: An adjoint model sensitivity study. Geophysical Research Letters 33, L02603, doi:10.1029/2005GL024987.
Fukumori, I., and P. Malanotte-Rizzoli. 1995. An approximate Kalman filter for ocean data assimilation: An example with an idealized Gulf-Stream model. Journal of Geophysical Research 100:6,777–6,793.
Fukumori, I., T. Lee, B. Cheng, and D. Menemenlis. 2004. The origin, pathway, and destination of NINO3 water estimated by a simulated passive tracer and its adjoint. Journal of Physical Oceanography 34:582–604.
Gemmell, A.L., G. Smith, K. Haines, and J.D. Blower. 2008. Evaluation of water masses in ocean synthesis products. Clivar-Exchanges 13(47):7–9.
Halkides, D., and T. Lee. 2009. Mechanisms controlling seasonal-to-interannual mixed-layer temperature variability in the southeastern tropical Indian Ocean. Journal of Geophysical Research 114, C02012, doi:10.1029/2008JC004949.
Hurlburt, H.E., G.B. Brassington, Y. Drillet, M. Kamachi, M. Benkiran, R. Bourdallé-Badie, E.P. Chassignet, G.A. Jacobs, O. Le Galloudec, J.-M. Lellouche, and others. 2009. High-resolution global and basin-scale ocean analyses and forecasts. Oceanography 22(3):110–127.
Kim, S.-B., T. Lee, and I. Fukumori. 2004. The 1997–99 abrupt change of the upper ocean temperature in the northcentral Pacific. Geophysical Research Letters 31, L22304, doi:10.1029/2004GL021142.
Kim, S.-B., T. Lee, and I. Fukumori. 2007. Mechanisms controlling the interannual variation of mixed layer temperature averaged over the NINO3 region. Journal of Climate 20:3,822–3,843.
Köhl, A., D. Stammer, and B. Cornulle. 2007. Interannual to decadal changes in the ECCO global synthesis. Journal of Physical Oceanography 37:313–337.
Köhl, A., and D. Stammer. 2008a. Decadal sea level changes in the 50-year GECCO ocean synthesis. Journal of Climate 21:1,866–1,890.
Köhl, A., and D. Stammer. 2008b. Variability of the meridional overturning in the North Atlantic from 50-year GECCO state estimation. Journal of Physical Oceanography 38:1,913–1,930.
Lee, T., and I. Fukumori. 2003. Interannual to decadal variation of tropical-subtropical exchange in the Pacific Ocean: Boundary versus interior pycnocline transports. Journal of Climate 16:4,022–4,042.
Masuda, S., T. Awaji, N. Sugiura, T. Toyoda, Y. Ishikawa, and K. Horiuchi. 2006. Interannual variability of temperature inversions in the subarctic North Pacific. Geophysical Research Letters 33, doi:10.1029/2006GL027865.
Masina S., P. Di Pietro, and A. Navarra. 2004. Interannual-to-decadal variability of the North Atlantic from an ocean data assimilation system. Climate Dynamics 23:531–546, doi:10.1007/s00382-004-0453-6.
McKinley, G., M.J. Follows, and J. Marshall. 2004. Mechanisms of air-sea CO2 flux variability in the Equatorial Pacific and North Atlantic. Global Biogeochemical Cycles 18(2), GB2011, doi:10.1029/2003GB002179.
Ponte, R.M., D. Stammer and C. Wunsch. 2001. Improving ocean angular momentum estimates using a model constrained by data. Geophysical Research Letters 28:1,775–1,778.
Rabe, B., F.A. Schott, and A. Köhl. 2008. Mean circulation and variability of the tropical Atlantic during 1952–2001 in the GECCO assimilation fields. Journal of Physical Oceanography 38:177–192.
Schoenefeldt, R., and F.A. Schott. 2006. Decadal variability of the Indian Ocean cross-equatorial exchange in SODA. Geophysical Research Letters 33, L08602, doi:10.1029/2006GL025891.
Schott, F.A., W.-Q. Wang, and D. Stammer. 2007. Variability of Pacific subtropical cells in the 50-year ECCO assimilation. Geophysical Research Letters 34, L05604, doi:10.1029/2006GL028478.
Schott, F.A., L. Stramma, W. Wang, B.S. Giese, and R. Zantopp. 2008. Pacific Subtropical Cell variability in the SODA 2.0.2/3 assimilation. Geophysical Research Letters 35, L10607, doi:10.1029/2008GL033757.
Stammer, D., C. Wunsch, R. Giering, C. Eckert, P. Heimbach, J. Marotzke, A. Adcroft, C.N. Hill, and J. Marshall. 2003. Volume, heat, and freshwater transports of the global ocean circulation 1993–2000, estimated from a general circulation model constrained by World Ocean Circulation Experiment (WOCE) data. Journal of Geophysical Research 108(C1), 3007, doi:10.1029/2001JC001115.
Stammer, D., K. Ueyoshi, A. Köhl, W.B. Large, S. Josey, and C. Wunsch. 2004. Estimating air-sea fluxes of heat, freshwater and momentum through global ocean data assimilation. Journal of Geophysical Research 109, C05023, doi:10.1029/2003JC002082.
Sugiura, N., T. Awaji, S. Masuda, T. Mochizuki, T. Toyoda, T. Miyama, H. Igarashi, and Y. Ishikawa. 2008. Development of a four-dimensional variational coupled data assimilation system for enhanced analysis and prediction of seasonal to interannual climate variations. Journal of Geophysical Research 113, C10017, doi:10.1029/2008JC004741.
Wang, O., I. Fukumori, T. Lee, and B. Cheng. 2004. On the cause of eastern equatorial Pacific Ocean T-S variations associated with El Niño. Geophysical Research Letters 31, L15310, doi:10.1029/2004GL02472.
Wunsch, C., R.M. Ponte, and P. Heimbach. 2007. Decadal trends in sea level patterns: 1993–2004. Journal of Climate 20:5,889–5,911.
Wunsch, C., and P. Heimbach. 2007. Estimated decadal changes in the North Atlantic meridional overturning circulation and heat flux 1993–2004. Journal of Physical Oceanography 36(11):2,012–2,024.
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.