Editorial Type:
Article
Article Type:
Research Article

An Observational Estimate of Inferred Ocean Energy Divergence

Kevin E. Trenberth National Center for Atmospheric Research,* Boulder, Colorado

Search for other papers by Kevin E. Trenberth in
Current site
Google Scholar
PubMed Close
and
John T. Fasullo National Center for Atmospheric Research,* Boulder, Colorado

Search for other papers by John T. Fasullo in
Current site
Google Scholar
PubMed Close
Print Publication:
01 May 2008
DOI:
https://doi.org/10.1175/2007JPO3833.1
Page(s):
984–999
Restricted access

Abstract

Monthly net surface energy fluxes (FS) over the oceans are computed as residuals of the atmospheric energy budget using top-of-atmosphere (TOA) net radiation (RT) and the complete atmospheric energy (AE) budget tendency (δAE/δt) and divergence (∇ · FA). The focus is on TOA radiation from the Earth Radiation Budget Experiment (ERBE) (February 1985–April 1989) and the Clouds and Earth’s Radiant Energy System (CERES) (March 2000–May 2004) satellite observations combined with results from two atmospheric reanalyses and three ocean datasets that enable a comprehensive estimate of uncertainties. Surface energy flux departures from the annual mean and the implied annual cycle in “equivalent ocean energy content” are compared with the directly observed ocean energy content (OE) and tendency (δOE/δt) to reveal the inferred annual cycle of divergence (∇ · FO). In the extratropics, the surface flux dominates the ocean energy tendency, although it is supplemented by ocean Ekman transports that enhance the annual cycle in ocean heat content. In contrast, in the tropics, ocean dynamics dominate OE variations throughout the year in association with the annual cycle in surface wind stress and the North Equatorial Current. An analysis of the regional characteristics of the first joint empirical orthogonal function (EOF) of FS, δOE/δt, and ∇ · FO is presented, and the largest sources of uncertainty are attributed to variations in OE. The mean and annual cycle of zonal mean global ocean meridional heat transports are estimated. The annual cycle reveals the strongest poleward heat transports in each hemisphere in the cold season, from November to April in the north and from May to October in the south, with a substantial across-equatorial transport, exceeding 4 PW in some months. Annual mean results do not differ greatly from some earlier estimates, but the sources of uncertainty are exposed. Comparison of annual means with direct ocean observations gives reasonable agreement, except in the North Atlantic, where transports from the ocean transects are slightly greater than the estimates presented here.

Corresponding author address: Kevin E. Trenberth, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000. Email: trenbert@ucar.edu

Abstract

Monthly net surface energy fluxes (FS) over the oceans are computed as residuals of the atmospheric energy budget using top-of-atmosphere (TOA) net radiation (RT) and the complete atmospheric energy (AE) budget tendency (δAE/δt) and divergence (∇ · FA). The focus is on TOA radiation from the Earth Radiation Budget Experiment (ERBE) (February 1985–April 1989) and the Clouds and Earth’s Radiant Energy System (CERES) (March 2000–May 2004) satellite observations combined with results from two atmospheric reanalyses and three ocean datasets that enable a comprehensive estimate of uncertainties. Surface energy flux departures from the annual mean and the implied annual cycle in “equivalent ocean energy content” are compared with the directly observed ocean energy content (OE) and tendency (δOE/δt) to reveal the inferred annual cycle of divergence (∇ · FO). In the extratropics, the surface flux dominates the ocean energy tendency, although it is supplemented by ocean Ekman transports that enhance the annual cycle in ocean heat content. In contrast, in the tropics, ocean dynamics dominate OE variations throughout the year in association with the annual cycle in surface wind stress and the North Equatorial Current. An analysis of the regional characteristics of the first joint empirical orthogonal function (EOF) of FS, δOE/δt, and ∇ · FO is presented, and the largest sources of uncertainty are attributed to variations in OE. The mean and annual cycle of zonal mean global ocean meridional heat transports are estimated. The annual cycle reveals the strongest poleward heat transports in each hemisphere in the cold season, from November to April in the north and from May to October in the south, with a substantial across-equatorial transport, exceeding 4 PW in some months. Annual mean results do not differ greatly from some earlier estimates, but the sources of uncertainty are exposed. Comparison of annual means with direct ocean observations gives reasonable agreement, except in the North Atlantic, where transports from the ocean transects are slightly greater than the estimates presented here.

Corresponding author address: Kevin E. Trenberth, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000. Email: trenbert@ucar.edu

Save
Cover Journal of Physical Oceanography
Journal of Physical Oceanography

  • Antonov, J. I., S. Levitus, and T. P. Boyer, 2004: Climatological annual cycle of ocean heat content. Geophys. Res. Lett., 31 .L04304, doi:10.1029/2003GL018851.

    • Search Google Scholar
    • Export Citation

  • Arnault, S., 1987: Tropical Atlantic geostrophic currents and ship drifts. J. Geophys. Res., 92 , 5076–5088.

  • Bacon, S., 1997: Circulation and fluxes in the North Atlantic between Greenland and Ireland. J. Phys. Oceanogr., 27 , 1420–1435.

  • Baringer, M. O., and J. C. Larsen, 2001: Sixteen years of Florida Current transport at 27°N. Geophys. Res. Lett., 28 , 3179–3182.

  • Barkstrom, B. R., and J. B. Hall, 1982: Earth Radiation Budget Experiment (ERBE)—An overview. J. Energy, 6 , 141–146.

  • Behringer, D. W., 2007: The Global Ocean Data Assimilation System (GODAS) at NCEP. Proc. 11th Symp. on Integrated Observing and Assimilation Systems for the Atmosphere, Oceans, and Land Surface (IOAS-AOLS), San Antonio, TX, Amer. Meteor. Soc., 3.3. [Available online at http://ams.confex.com/ams/pdfpapers/119541.pdf.].

    • Search Google Scholar
    • Export Citation

  • Behringer, D., and Y. Xue, 2004: Evaluation of the global ocean data assimilation system at NCEP: The Pacific Ocean. Proc. Eighth Symp. on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface, Seattle, WA, Amer. Meteor. Soc., 2.3. [Available online at http://ams.confex.com/ams/84Annual/techprogram/paper_70720.htm.].

  • Böning, C. W., and P. Herrmann, 1994: Annual cycle of poleward heat transport in the ocean: Results from high-resolution modeling of the North and equatorial Atlantic. J. Phys. Oceanogr., 24 , 91–107.

    • Search Google Scholar
    • Export Citation

  • Bryden, H. L., D. H. Roemmich, and J. A. Church, 1991: Ocean heat-transport across 24°N in the Pacific. Deep-Sea Res., 38 , 297–324.

  • Bryden, H. L., H. R. Longworth, and S. A. Cunningham, 2005: Slowing of the Atlantic meridional overturning at 25°N. Nature, 438 , 655–657.

    • Search Google Scholar
    • Export Citation

  • Bunker, A. F., 1976: Computations of surface energy flux and annual air–sea interaction cycles of the North Atlantic Ocean. Mon. Wea. Rev., 104 , 1122–1140.

    • Search Google Scholar
    • Export Citation

  • Cunningham, S. A., and Coauthors, 2007: Temporal variability of the Atlantic Meridional Overturning circulation at 26.5°N. Science, 317 , 935–938.

    • Search Google Scholar
    • Export Citation

  • Deser, C., M. A. Alexander, and M. S. Timlin, 1999: Evidence for a wind-driven intensification of the Kuroshio Current extension from the 1970s to the 1980s. J. Climate, 12 , 1697–1706.

    • Search Google Scholar
    • Export Citation

  • Fasullo, J. T., and K. E. Trenberth, 2008a: The annual cycle of the energy budget. Part I: Global mean and land–ocean exchanges. J. Climate, 21 , 2297–2313.

    • Search Google Scholar
    • Export Citation

  • Fasullo, J. T., and K. E. Trenberth, 2008b: The annual cycle of the energy budget. Part II: Meridional Structures and Poleward Transports. J. Climate, 21 , 2314–2326.

    • Search Google Scholar
    • Export Citation

  • Ganachaud, A., and C. Wunsch, 2000: Improved estimates of global ocean circulation, heat transport and mixing from hydrographic data. Nature, 408 , 453–457.

    • Search Google Scholar
    • Export Citation

  • Grist, J. P., and S. A. Josey, 2003: Inverse analysis adjustment of the SOC air–sea flux climatology using ocean heat transport constraints. J. Climate, 16 , 3274–3295.

    • Search Google Scholar
    • Export Citation

  • Hansen, J., and Coauthors, 2005: Earth’s energy imbalance: Confirmation and implications. Science, 308 , 1431–1435.

  • Holfort, J., and G. Siedler, 2001: The meridional oceanic transports of heat and nutrients in the South Atlantic. J. Phys. Oceanogr., 31 , 5–29.

    • Search Google Scholar
    • Export Citation

  • Huang, S., 2006: Land warming as part of global warming. Eos, Trans. Amer. Geophys. Union, 87 , 477.

  • Ishii, M., M. Kimoto, K. Sakamoto, and S. I. Iwasaki, 2006: Steric sea level changes estimated from historical ocean subsurface temperature and salinity analyses. J. Oceanogr., 62 , 155–170.

    • Search Google Scholar
    • Export Citation

  • Ivchenko, V. O., N. C. Wells, and D. L. Aleynik, 2006: Anomaly of heat content in the northern Atlantic in the last 7 years: Is the ocean warming or cooling? Geophys. Res. Lett., 33 .L22606, doi:10.1029/2006GL027691.

    • Search Google Scholar
    • Export Citation

  • Jayne, S. R., and J. Marotzke, 2001: The dynamics of ocean heat transport variability. Rev. Geophys., 39 , 385–411.

  • Kistler, R., and Coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82 , 247–267.

    • Search Google Scholar
    • Export Citation

  • Klein, B., R. L. Molinari, T. J. Muller, and G. Siedler, 1995: A transatlantic section at 14.5n—Meridional volume and heat fluxes. J. Mar. Res., 53 , 929–957.

    • Search Google Scholar
    • Export Citation

  • Kobayashi, T., and N. Imasato, 1998: Seasonal variability of heat transport derived from hydrographic and wind stress data. J. Geophys. Res., 103 , 24663–24674.

    • Search Google Scholar
    • Export Citation

  • Köberle, C., and R. Gerdes, 2003: Mechanisms determining the variability of Arctic sea ice conditions and export. J. Climate, 16 , 2843–2858.

    • Search Google Scholar
    • Export Citation

  • Koltermann, K. P., A. V. Sokov, V. P. Tereschenkov, S. A. Dobroliubov, K. Lorbacher, and A. Sy, 1999: Decadal changes in the thermohaline circulation of the North Atlantic. Deep-Sea Res. II, 46 , 109–138.

    • Search Google Scholar
    • Export Citation

  • Lavin, A., H. L. Bryden, and G. Parrilla, 1998: Meridional transport and heat flux variations in the subtropical North Atlantic. Global Atmos. Ocean. Syst., 6 , 269–293.

    • Search Google Scholar
    • Export Citation

  • Levitus, S., 1984: Annual cycle of temperature and heat storage in the World Ocean. J. Phys. Oceanogr., 14 , 727–746.

  • Levitus, S., 1987: Rate of change of heat storage in the World Ocean. J. Phys. Oceanogr., 17 , 518–528.

  • Levitus, S., and J. Antonov, 1997: Climatological and Interannual Variability of Temperature, Heat Storage, and Rate of Heat Storage in the World Ocean. NOAA Atlas NESDIS 16, 6 pp.+186 figs.

    • Search Google Scholar
    • Export Citation

  • Levitus, S., J. Antonov, and T. Boyer, 2005: Warming of the world ocean, 1955–2003. Geophys. Res. Lett., 32 .L02604, doi:10.1029/2004GL021592.

    • Search Google Scholar
    • Export Citation

  • Locarnini, R. A., A. V. Mishonov, J. I. Antonov, T. P. Boyer, and H. E. Garcia, 2006: Temperature. Vol. 1, World Ocean Atlas 2005, NOAA Atlas NESDIS 61, 182 pp.

    • Search Google Scholar
    • Export Citation

  • Loeb, N. G., and Coauthors, 2007: Multi-instrument comparison of top-of-atmosphere reflected solar radiation. J. Climate, 20 , 575–591.

    • Search Google Scholar
    • Export Citation

  • Loschnigg, J., and P. J. Webster, 2000: A coupled ocean–atmosphere system of SST modulation for the Indian Ocean. J. Climate, 13 , 3342–3360.

    • Search Google Scholar
    • Export Citation

  • Macdonald, A. M., 1998: The global ocean circulation: A hydrographic estimate and regional analysis. Prog. Oceanogr., 41 , 281–382.

  • Macdonald, A. M., and C. Wunsch, 1996: An estimate of global ocean circulation and heat fluxes. Nature, 382 , 436–439.

  • Minster, J. F., A. Cazenave, Y. V. Serafini, F. Mercier, M. C. Gennero, and P. Rogel, 1999: Annual cycle in mean sea level from Topex-Poseidon and ERS-1: Inference on the global hydrological cycle. Global Planet. Change, 20 , 57–66.

    • Search Google Scholar
    • Export Citation

  • Moisan, J. R., and P. P. Niiler, 1998: The seasonal heat budget of the North Pacific: Net heat flux and heat storage rates (1950–1990). J. Phys. Oceanogr., 28 , 401–421.

    • Search Google Scholar
    • Export Citation

  • Qiu, B., and R. Lukas, 1996: Seasonal and interannual variability of the North Equatorial Current, the Mindanao Current, and the Kuroshio along the Pacific western boundary. J. Geophys. Res., 101 , 12315–12330.

    • Search Google Scholar
    • Export Citation

  • Robbins, P. E., and J. M. Toole, 1997: The dissolved silica budget as a constraint on the meridional overturning circulation of the Indian Ocean. Deep-Sea Res., 44 , 879–906.

    • Search Google Scholar
    • Export Citation

  • Roemmich, D., J. Gilson, B. Cornuelle, and R. Weller, 2001: Mean and time-varying meridional transport of heat at the tropical subtropical boundary of the North Pacific Ocean. J. Geophys. Res., 106 , 8957–8970.

    • Search Google Scholar
    • Export Citation

  • Sato, O. T., and T. Rossby, 2000: Seasonal and low-frequency variability of the meridional heat flux at 36° N in the North Atlantic. J. Phys. Oceanogr., 30 , 606–621.

    • Search Google Scholar
    • Export Citation

  • Saunders, P. M., and B. A. King, 1995: Oceanic fluxes on the WOCE A11 section. J. Phys. Oceanogr., 25 , 1942–1958.

  • Serreze, M. C., and Coauthors, 2006: The large-scale freshwater cycle of the Arctic. J. Geophys. Res., 111 .C11010, doi:10.1029/2005JC003424.

    • Search Google Scholar
    • Export Citation

  • Serreze, M. C., A. P. Barrett, A. G. Slater, M. Steele, J. Zhang, and K. E. Trenberth, 2007: The large-scale energy budget of the Arctic. J. Geophys. Res., 112 .D11122, doi:10.1029/2006JD008230.

    • Search Google Scholar
    • Export Citation

  • Speer, K. G., J. Holfort, T. Reynard, and G. Siedler, 1996: South Atlantic heat transport at 11°S. The South Atlantic: Present and Past Circulation, G. Wefer, G. Siedler, and D. J. Webb, Eds., Springer, 105–120.

    • Search Google Scholar
    • Export Citation

  • Talley, L. D., 2003: Shallow, intermediate, and deep overturning components of the global heat budget. J. Phys. Oceanogr., 33 , 530–560.

    • Search Google Scholar
    • Export Citation

  • Trenberth, K. E., 1997: Using atmospheric budgets as a constraint on surface fluxes. J. Climate, 10 , 2796–2809.

  • Trenberth, K. E., and J. M. Caron, 2001: Estimates of meridional atmosphere and ocean heat transports. J. Climate, 14 , 3433–3443.

  • Trenberth, K. E., and D. P. Stepaniak, 2003a: Covariability of components of poleward atmospheric energy transports on seasonal and interannual timescales. J. Climate, 16 , 3690–3704.

    • Search Google Scholar
    • Export Citation

  • Trenberth, K. E., and D. P. Stepaniak, 2003b: Seamless poleward atmospheric energy transports and implications for the Hadley circulation. J. Climate, 16 , 3705–3721.

    • Search Google Scholar
    • Export Citation

  • Trenberth, K. E., and D. P. Stepaniak, 2004: The flow of energy through the Earth’s climate system. Quart. J. Roy. Meteor. Soc., 130 , 2677–2701.

    • Search Google Scholar
    • Export Citation

  • Trenberth, K. E., J. M. Caron, and D. P. Stepaniak, 2001: The atmospheric energy budget and implications for surface fluxes and ocean heat transports. Climate Dyn., 17 , 259–276.

    • Search Google Scholar
    • Export Citation

  • Trenberth, K. E., D. P. Stepaniak, and J. M. Caron, 2002: Interannual variations in the atmospheric heat budget. J. Geophys. Res., 107 .4066, doi:10.1029/2000JD000297.

    • Search Google Scholar
    • Export Citation

  • Uppala, S. M., and Coauthors, 2005: The ERA-40 reanalysis. Quart. J. Roy. Meteor. Soc., 131 , 2961–3012.

  • Wielicki, B. A., B. R. Barkstrom, E. F. Harrison, R. B. Lee, G. L. Smith, and J. E. Cooper, 1996: Clouds and the Earth’s Radiant Energy System (CERES): An earth observing system experiment. Bull. Amer. Meteor. Soc., 77 , 853–868.

    • Search Google Scholar
    • Export Citation

  • Wielicki, B. A., K. Priestley, P. Minnis, N. Loeb, D. Kratz, T. Charlock, D. Doelling, and D. Young, 2006: CERES radiation budget accuracy overview. Preprints, 12th Conf. on Atmospheric Radiation, Madison, WI, Amer. Meteor. Soc., 9.1. [Available online at http://ams.confex.com/ams/Madison2006/techprogram/paper_112371.htm.].

  • Wijffels, S. E., J. M. Toole, H. L. Bryden, R. A. Fine, W. J. Jenkins, and J. L. Bullister, 1996: The water masses and circulation at 10°N in the Pacific. Deep-Sea Res. I, 43 , 501–544.

    • Search Google Scholar
    • Export Citation

  • Willis, J. K., D. Roemmich, and B. Cornuelle, 2004: Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales. J. Geophys. Res., 109 .C12036, doi:10.1029/2003JC002260.

    • Search Google Scholar
    • Export Citation

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

    • Search Google Scholar
    • Export Citation

  • Yan, X-H., P. P. Niiler, S. K. Nadiga, R. Stewart, and D. Cayan, 1995: The seasonal heat storage in the North Pacific. J. Geophys. Res., 100 , 6899–6926.

    • Search Google Scholar
    • Export Citation

  • Zhang, D., W. E. Johns, and T. N. Lee, 2002: The seasonal cycle of meridional heat transport at 24°N in the North Pacific and in the global ocean. J. Geophys. Res., 107 .3083, doi:10.1029/2001JC001011.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 725 195 11
PDF Downloads 409 148 8