Coupled Ocean-Atmosphere-Ice Response to variations in the Southern Annular Mode

We have examined the coupled ocean-atmosphere-ice response to variations in the Southern Annular Mode (SAM) in the the NCAR Community Coupled Climate Model (version 2). The model shows considerable skill in capturing the predominantly zonally symmetric SAM while regional deviations between model and observation SAM winds go a long way in explaining the generally small differences between simulated and observed SAM responses in the ocean and sea-ice systems.

Vacillations in the position and the strength of the circumpolar winds and the ensuing variations in advection of heat and moisture result in a dynamic and thermodynamic forcing of the ocean and sea-ice. Both meridional and zonal components of ocean circulation are modified through Ekman transport which in turn leads to anomalous surface convergences and divergences that strongly affect the meridional overturning circulation, and potentially the pathways of intermediate water ventilation. A heat budget analysis demonstrates a conspiring of oceanic meridional heat advection, surface heat fluxes and changes in mixed-layer-depth, which act in phase to imprint a strong circumpolar SAM signature onto sea surface temperatures (SST) while, other oceanic processes, including vertical advection, are shown to play only a minor role in contrast to previous suggestions. Lagged correlations show that although the SAM is mainly controlled by internal atmospheric mechanisms, the thermal inertia of the ocean re-imprints the SAM signature back to surface air temperatures (SAT) on timescales longer than the initial atmospheric signal.

Sea-ice variability is well explained by a combination of atmospheric and ocean dynamic and thermodynamic forcing, and by an albedo feedback mechanism that allows ice extent anomalies to persist for many months.

Non zonally-symmetric components to the SAM winds, particularly in the region surrounding the Antarctic Peninsula, have important effects for other climate variables.
Ancilliary online information
Correlation maps between atmosphere/ocean properties and SAM index. Only values that are significant at the 95% level (simulation) or 90% level (observations) are shown.
CCSM Variables:

SLP
Zonal Wind
Meridional Wind
SAT
Cloud Cover
Total Precopitation
SST
SSS
MLD
Zonal Current
Meridional Current
Reanalysis Variables:
SLP (ECMWF)
Zonal Wind (ECMWF)
Meridional Wind (ECMWF)
SAT (NCEP/NCAR)
Cloud Cover (ECMWF)
Total Precopitation (ECMWF)
SST (NOAA)
Zonal Current, Meridional Current (SODA)

References

  • Adler, R., G. Huffman, A. Chang, R. Ferraro, P. Xie, J. Janowiak, B. Rudolf, U. Schneider, S. Curtis, D. Bolvin, A. Gruber, J. Susskind, P. Arkin, and E. Nelkin, 2003: The version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979-present) . Journal of Hydrometeorology, 4, 1147–1167.
  • Arkin, P. A. and P. Xie, 1996: Analyses of global monthly precipitation using gauge observations, satellite estimates, and numerical model predictions . Journal of Climate, 9, 840–858.
  • Bitz, C. M., M. M. Holland, M. Eby, and A. J. Weaver, 2001: Simulating the ice-thickness distribution in a coupled climate model . Journal of Geophysical Research, 106, 2441–2463.
  • Bitz, C. M. and W. H. Lipscomb, 1999: An energy-conserving thermodynamic model of sea ice . Journal of Geophysical Research, 104, 15669–15677.
  • Boer, G. J., S. Fourest, and B. Yu, 2001: The signature of the Annular Modes in the moisture budget . Journal of Climate, 14, 3655–3665.
  • Branstetter, M. L. and D. J. I. Erickson, 2003: Continental runoff dynamics in the Community Climate System Model (CCSM-2) control simulations . Journal of Geophysical Research, 108, 4550.
  • Bromwich, D. and R. Fogt, 2004: Strong trends in the skill of the ERA-40 and NCEP/NCAR Reanalyses in the high and middle latitudes of the Southern Hemisphere .Journal of Climate, 17, 4603–4619.
  • Cai, W. and I. G. Watterson, 2002: Modes of interannual variability of the Southern Hemisphere circulation simulated by the CSIRO climate model . Journal of Climate, 15, 1159–1174.
  • Cai, W. J., P. H. Whetton, and D. J. Karoly, 2003: The response of the Antarctic Oscillation to increasing and stabilized atmospheric CO2 . Journal of Climate, 16, 1525–1538.
  • Carril, A. F. and A. Navarra, 2001: The interannual leading modes of the extratropical variability in the Southern Hemisphere simulated by the ECHAM-4 atmospheric model . Climate Dynamics, 18, 1–16.
  • Carton, J. and B. Giese, 2005: SODA: A Reanalysis of Ocean Climate . Journal of Geophysical Research, (submitted).
  • Carton, J. A., G. Chepurin, X. H. Cao, and B. S. Giese, 2000: A simple ocean sata assimilation analysis of the global upper ocean 1950-95. Part I: methodology . Journal of Physical Oceanography, 30, 294–309.
  • Codron, F., 2005: Relation between Annular Modes and the mean state: Southern Hemisphere summer . Journal of Climate, 18, 320–330.
  • Collins, W. D., 2001: Parameterization of generalized cloud overlap for radiative calculations in general circulation models . Journal of the Atmospheric Sciences, 58, 3224–3242.
  • Collins, W. D., J. K. Hackney, and D. P. Edwards, 2002: An updated parameterization for infrared emission and absorption by water vapor in the National Center for Atmospheric Research Community Atmosphere Model . Journal of Geophysical Research, 104, 4664.
  • Cook, A. J., A. J. Fox, D. G. Vaughan, and J. G. Ferrigno, 2005: Retreating glacier fronts on the Antarctic Peninsula over the past half-century . Science, 308, 541 – 544.
  • Fyfe, J. C., G. J. Boer, and G. M. Flato, 1999: The Arctic and Antarctic Oscillations and their projected changes under global warming . Geophysical Research Letters, 26, 1601–1604.
  • Gent, P. R. and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models . Journal of Physical Oceanography, 20, 150–155.
  • Gibson, R., P. Kallberg, and S. Uppala, 1996: The ECMWF re-analysis (ERA) project. ECMWF Newsletter No. 73. 7–17 .
  • Gillett, N. P. and D. W. J. Thompson, 2003: Simulation of recent Southern Hemisphere climate change . Science, 302, 273–275.
  • Hall, A. and M. Visbeck, 2002: Synchronous variability in the Southern Hemisphere atmosphere, sea ice, and ocean resulting from the Annular Mode . Journal of Climate, 15, 3043–3057.
  • Hartmann, D. L. and F. Lo, 1998: Wave-driven zonal flow vacillation in the Southern Hemisphere . Journal of the Atmospheric Sciences, 55, 1303–1315.
  • Holland, M., 2003: The North Atlantic Oscillation in the CCSM2 and its influence on Arctic climate variability . Journal of Climate, 16, 2767–2781.
  • Holland, M., C. M. Bitz, and E. Hunke, 2005: Mechanisms forcing an Antarctic dipole in simulated sea ice and surface ocean conditions . Journal of Climate, 18, 2052–2066.
  • Hughes, C. W., P. L. Woodworth, M. Meredith, V. Stepanov, T. Whitworth, and A. Pyne, 2003: Coherence of Antarctic sea levels, Southern hemisphere Annular Mode, and flow through Drake Passage . Geophysical Research Letters, 30, 1464, doi:10.1029/2003GL017240.
  • Hunke, E. C. and J. K. Dukowicz, 1997: An elastic-viscous-plastic model for sea ice dynamics . Journal of Physical Oceanography, 27, 1849–1867.
  • Kalnay, E. e. a., 1996: The NCEP/NCAR 40-year reanalysis project . Bull. Amer. Meteor.
    Soc., 77, 1057–1072.
  • Karoly, D. J., 1990: The role of transient eddies in low-frequency zonal variations of the Southern Hemisphere circulation . Tellus, 42A, 41–50.
  • Kiehl, J. T. and P. R. Gent, 2004: The Community Climate System Model, version 2 . Journal of Climate, 17, 3666–3682.
  • Kushner, P. J., I. M. Held, and T. L. Delworth, 2001: Southern Hemisphere atmospheric circulation response to global warming . Journal of Climate, 14, 2238–2249.
  • Lachlan-Cope, T., W. Connolley, and J. Turner, 2001: The Role of the Non-Axisymmetric Antarctic Orography in forcing the Observed Pattern of Variability of the Antarctic Climate . Geophysical Research Letters, 28, doi:10.1029/2001GL013465.
  • Large, W. G., J. C. McWilliams, and S. C. Doney, 1994: Oceanic vertical mixing: A review and a model with a nonlocal boundary layer parameterization . Reveiws of Geophysics, 32, 363–403.
  • Lefebvre, W., H. Goosse, R. Timmermann, and T. T. Fichefet, 2004: Influence of the Southern Annular Mode on the sea ice-ocean system . Journal of Geophysical Research, 109, doi:10.1029/2004JC002403.
  • Limpasuvan, V. and D. L. Hartmann, 2000: Wave-maintained Annular Modes of climate variability . Journal of Climate, 13, 4414–4429.
  • Liu, J., J. A. Curry, and D. G. Martinson, 2004: Interpretation of recent Antarctic sea ice variability . Geophysical Research Letters, 31, L02205, doi:10.1029/2003GL018732.
  • Lorenz, D. J. and D. L. Hartmann, 2001: Eddy-zonal flow feedback in the Southern Hemisphere . Journal of the Atmospheric Sciences, 58, 3312–3327.
  • Lovenduski, N. and N. Gruber, 2005: Impact of the Southern Annular Mode on Southern Ocean circulation and biology . Geophysical Research Letters, 32, L11603,doi:10.1029/2005GL022727.
  • Marshall, G. J., 2003: Trends in the Southern Annular Mode from observations and reanalyses . Journal of Climate, 16, 4134–4143.
  • Marshall, G. J., P. A. Stott, J. Turner, W. M. Connolley, J. C. King, and T. A. Lachlan-Cope, 2004: Causes of exceptional atmospheric circulation changes in the Southern Hemisphere . Geophysical Research Letters, 31, doi:10.1029/2004GL019952.
  • McDougall, T. J., D. R. Jackett, and D. G. F. R. Wright, 2003: Accurate and computationally efficient algorithms for potential temperature and density of seawater . Journal of Atmospheric and Oceanic Technology, 20, 730–741.
  • Meredith, M. P., P. L. Woodworth, C. W. Hughes, and V. N. Stepanov, 2004: Changes in the ocean transport through Drake Passage during the 1980s and 1990s, forced by changes in the Southern Annular Mode . Geophysical Research Letters, 31, L21305,doi:10.1029/2004GL021169.
  • Mo, K. C., 2000: Relationships between low-frequency variability in the Southern Hemisphere and sea surface temperature anomalies . Journal of Climate, 13, 3599–3610.
  • North, G. R., T. L. Bell, R. F. Cahalan, and F. G. Moeng, 1982: Sampling Errors in the Estimation of Empirical Orthogonal Functions . Monthly Weather Review, 110, 699–706.
  • Oke, P. R. and M. H. England, 2004: Oceanic response to changes in the latitude of the Southern Hemisphere subpolar westerly winds . Journal of Climate, 17, 1040–1054.
  • Orr, A., G. J. Cresswell, D.and Marshall, J. C. R. Hunt, J. Sommeria, C. G. Wang, and M. Light, 2004: A ’low-level’ explanation for the recent large warming trend over the western Antarctic Peninsula involving blocked winds and changes in zonal circulation .Geophysical Research Letters, 31, L06204, doi:10.1029/2003GLO19160.
  • Rasch, P. J. and J. E. Kristjansson, 1998: A comparison of the CCM3 model climate using diagnosed and predicted condensate parameterizations . Journal of Climate, 11, 1587–1614.
  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century . Journal of Geophysical Research, 108, doi:10.1029/2002JD002670.
  • Reynolds, R. W., N. A. Rayner, D. C. Smith, T. M.and Stokes, and W. Wang, 2002: An improved in situ and satellite SST analysis for climate . Journal of Climate, 15, 1609–1625.
  • Reynolds, R. W., T. M. Smith, D. C. Stokes, and W. Wang, 2001: An improved in-situ satellite SST analysis for climate . Journal of Climate, 15, 1609–1624.
  • Rintoul, S. and M. H. England, 2002: Ekman transport dominates air-sea fluxes in driving variability of Subantarctic Mode Water . Journal of Physical Oceanography, 32, 1308–1321.
  • Robinson, W. A., 1991: The dynamics of the zonal index in a simple model of the atmosphere . Tellus, 43A, 295–305.
  • Santoso, A. and M. H. England, 2004: Antarctic Intermediate Water variability in a coupled climate model . Journal of Physical Oceanography, 34, 2160–2179.
  • Sciremammano Jr, F., 1979: A suggestion for the presentation of correlations and their significance levels . Journal of Physical Oceanography, 9, 1273–1276.
  • Sexton, D. M. H., 2001: The effect of stratospheric ozone depletion on the phase of the Antarctic Oscillation . Geophysical Research Letters, 28, 3697–3700.
  • Silvestri, G. E. and C. S. Vera, 2003: Antarctic Oscillation signal on precipitation anomalies over southeastern South America . Geophysical Research Letters, 30, 215.
  • Smith, R. D. and J. C. McWilliams, 2003: Anisotropic horizontal viscosity for ocean models . Ocean Modelling, 5, 129–156.
  • Thompson, D. W. J. and S. Solomon, 2002: Interpretation of recent Southern Hemisphere climate change . Science, 296, 895–899.
  • Thompson, D. W. J. and J. M. Wallace, 2000: Annular modes in the extratropical circulation. Part I: month-to-month variability . Journal of Climate, 13, 1000–1016.
  • Turner, J., 2004: The El-Ni˜no Southern Oscillation and Antarctica . International Journal of Climatology, 24, 1–31.
    V. Brahmananda Rao, V., A. M. C. do Carmo, and S. Franchito, 2003: Interannual variations of storm tracks in the Southern Hemisphere and their connections with the Antarctic Oscillation . International Journal of Climatology, 23, 1537–1545.
  • Visbeck, M. and A. Hall, 2004: Relpy to: comments on synchronous variability in the Southern Hemisphere atmosphere, sea ice, and ocean resulting from the Annular Mode . Journal of Climate, 17, 2255–2258.
  • Watterson, I. G., 2000: Southern midlatitude zonal wind vacillation and its interaction with the ocean in GCM Simulations . Journal of Climate, 13, 562.
  • White, W. B., 2004: Comments on synchronous variability in the Southern Hemisphere atmosphere, sea ice, and ocean resulting from the Annular Mode . Journal of Climate, 17, 2249–2254.
  • Yuan, X. and D. G. Martinson, 2001: The Antarctic Dipole and its predictability . Geophysical Research Letters, 28, 3609–3612.
  • Zhou, T. and R. Yu, 2004: Sea-surface temperature induced variability of the Southern Annular Mode in an atmospheric general circulation model . Geophysical Research Letters, 31, L24206, doi:10.1029/2004GL021473.