Editorial Type:
Article
Article Type:
Research Article

Interdecadal Sea Surface Temperature Variability in the Equatorial Pacific Ocean. Part II: The Role of Equatorial/Off-Equatorial Wind Stresses in a Hybrid Coupled Model

Shayne McGregor Department of Physical Geography, Macquarie University, Sydney, New South Wales, Australia

Search for other papers by Shayne McGregor in
Current site
Google Scholar
PubMed Close
,
Neil J. Holbrook Department of Physical Geography, Macquarie University, Sydney, New South Wales, Australia

Search for other papers by Neil J. Holbrook in
Current site
Google Scholar
PubMed Close
, and
Scott B. Power Centre for Australian Weather and Climate Research, Melbourne, Victoria, Australia

Search for other papers by Scott B. Power in
Current site
Google Scholar
PubMed Close
Print Publication:
01 Sep 2008
DOI:
https://doi.org/10.1175/2008JCLI2057.1
Page(s):
4242–4256
Restricted access

Abstract

Many modeling studies have been carried out to investigate the role of oceanic Rossby waves linking the off-equatorial and equatorial Pacific Ocean. Although the equatorial ocean response to off-equatorial wind stress forcing alone tends to be relatively small, it is clear that off-equatorial oceanic Rossby waves affect equatorial Pacific Ocean variability on interannual through to interdecadal time scales. In the present study, a hybrid coupled model (HCM) of the equatorial Pacific (between 12.5°S and 12.5°N) was developed and is used to estimate the magnitude of equatorial region variability arising from off-equatorial (poleward of 12.5° latitude) wind stress forcing. The HCM utilizes a reduced-gravity ocean shallow-water model and a statistical atmosphere derived from monthly output from a 100-yr Australian Bureau of Meteorology Research Centre (now the Centre for Australian Weather and Climate Research) coupled general circulation model integration. The equatorial region wind stress forcing is found to dominate both the interannual and interdecadal SST variability. The equatorial response to off-equatorial wind stress forcing alone is insufficient to initiate an atmospheric feedback that significantly amplifies the original equatorial region variability. Consequently, the predictability of equatorial region SST anomalies (SSTAs) could be limited to ∼1 yr (the maximum time it takes an oceanic Rossby wave to cross the Pacific Ocean basin in the equatorial region). However, the results also suggest that the addition of off-equatorial wind stress forcing to the HCM leads to variations in equatorial Pacific background SSTA of up to almost one standard deviation. This off-equatorially forced portion of the equatorial SSTA could prove critical for thresholds of El Niño–Southern Oscillation (ENSO) because they can constructively interfere with equatorially forced SSTA of the same sign to produce significant equatorial region ENSO anomalies.

Corresponding author address: Shayne McGregor, Department of Physical Geography, Macquarie University, Sydney, 2109, Australia. Email: mcgregor@els.mq.edu.au

Abstract

Many modeling studies have been carried out to investigate the role of oceanic Rossby waves linking the off-equatorial and equatorial Pacific Ocean. Although the equatorial ocean response to off-equatorial wind stress forcing alone tends to be relatively small, it is clear that off-equatorial oceanic Rossby waves affect equatorial Pacific Ocean variability on interannual through to interdecadal time scales. In the present study, a hybrid coupled model (HCM) of the equatorial Pacific (between 12.5°S and 12.5°N) was developed and is used to estimate the magnitude of equatorial region variability arising from off-equatorial (poleward of 12.5° latitude) wind stress forcing. The HCM utilizes a reduced-gravity ocean shallow-water model and a statistical atmosphere derived from monthly output from a 100-yr Australian Bureau of Meteorology Research Centre (now the Centre for Australian Weather and Climate Research) coupled general circulation model integration. The equatorial region wind stress forcing is found to dominate both the interannual and interdecadal SST variability. The equatorial response to off-equatorial wind stress forcing alone is insufficient to initiate an atmospheric feedback that significantly amplifies the original equatorial region variability. Consequently, the predictability of equatorial region SST anomalies (SSTAs) could be limited to ∼1 yr (the maximum time it takes an oceanic Rossby wave to cross the Pacific Ocean basin in the equatorial region). However, the results also suggest that the addition of off-equatorial wind stress forcing to the HCM leads to variations in equatorial Pacific background SSTA of up to almost one standard deviation. This off-equatorially forced portion of the equatorial SSTA could prove critical for thresholds of El Niño–Southern Oscillation (ENSO) because they can constructively interfere with equatorially forced SSTA of the same sign to produce significant equatorial region ENSO anomalies.

Corresponding author address: Shayne McGregor, Department of Physical Geography, Macquarie University, Sydney, 2109, Australia. Email: mcgregor@els.mq.edu.au

Save
Cover Journal of Climate
Journal of Climate

  • Allan, R. J., J. Lindesay, and D. Parker, 1996: El Niño, Southern Oscillation and Climatic Variability. CSIRO Publishing, 402 pp.

  • Arblaster, J. M., G. A. Meehl, and A. M. Moore, 2002: Interdecadal modulation of Australian rainfall. Climate Dyn., 18 , 519–531.

  • Barnett, T. P., D. W. Pierce, R. Saravanan, N. Schneider, D. Dommenget, and M. Latif, 1999: Origins of midlatitude Pacific decadal variability. Geophys. Res. Lett., 26 , 1453–1456.

    • Search Google Scholar
    • Export Citation

  • Battisti, D. S., and A. C. Hirst, 1989: Interannual variability in a tropical atmosphere–ocean model: Influence of the basic state, ocean geometry, and nonlinearity. J. Atmos. Sci., 46 , 1687–1712.

    • Search Google Scholar
    • Export Citation

  • Bettio, L., 2007: On the character, dynamics and predictability of ENSO in the observations and a coupled GCM. Ph.D. thesis, University of Melbourne, 314 pp.

  • Bretherton, C. S., C. Smith, and J. Wallace, 1992: An intercomparison of methods for finding coupled patterns in climate data. J. Climate, 5 , 541–560.

    • Search Google Scholar
    • Export Citation

  • Capotondi, A., and M. A. Alexander, 2001: Rossby waves in the tropical Pacific and their role in decadal thermocline variability. J. Phys. Oceanogr., 31 , 3496–3515.

    • Search Google Scholar
    • Export Citation

  • Capotondi, A., M. A. Alexander, and C. Deser, 2003: Why are there Rossby wave maxima in the Pacific at 10°S and 13°N? J. Phys. Oceanogr., 33 , 1549–1563.

    • Search Google Scholar
    • Export Citation

  • Cattell, R. B., 1966: The scree test for a number of factors. Multivariate Behav. Res., 1 , 245–276.

  • Davis, R. E., 1976: Predictability of sea surface temperature and sea level pressure anomalies over the North Pacific Ocean. J. Phys. Oceanogr., 6 , 249–266.

    • Search Google Scholar
    • Export Citation

  • Dijkstra, H. A., and G. Burgers, 2002: Fluid dynamics of El Niño variability. Annu. Rev. Fluid Mech., 34 , 531–558.

  • Folland, C. K., D. E. Parker, A. W. Coleman, and R. Washington, 1999: Large scale modes of ocean surface temperature since the late nineteenth century. Beyond El Niño: Decadal and Interdecadal Climate Variability, A. Navarra, Ed., Springer-Verlag, 73–102.

    • Search Google Scholar
    • Export Citation

  • Folland, C. K., J. A. Renwick, M. J. Salinger, and A. B. Mullan, 2002: Relative influences of the Interdecadal Pacific Oscillation and ENSO on the South Pacific Convergence Zone. Geophys. Res. Lett., 29 .1643, doi:10.1029/2001GL014201.

    • Search Google Scholar
    • Export Citation

  • Frankignoul, C., and K. Hasselmann, 1977: Stochastic climate models. Part II: Application to sea surface temperature variability and thermocline variability. Tellus, 29 , 284–305.

    • Search Google Scholar
    • Export Citation

  • Frankignoul, C., P. Muller, and E. Zorita, 1997: A simple model of the decadal response of the ocean to stochastic wind forcing. J. Phys. Oceanogr., 27 , 1533–1546.

    • Search Google Scholar
    • Export Citation

  • Galanti, E., and E. Tziperman, 2003: A midlatitude–ENSO teleconnection mechanism via baroclinically unstable long Rossby waves. J. Phys. Oceanogr., 33 , 1877–1888.

    • Search Google Scholar
    • Export Citation

  • Gu, D., and S. G. H. Philander, 1997: Interdecadal climate fluctuations that depend on exchanges between the Tropics and extratropics. Science, 275 , 805–807.

    • Search Google Scholar
    • Export Citation

  • Hazeleger, W., M. Visbeck, M. Cane, A. Karspeck, and N. Naik, 2001: Decadal upper ocean temperature variability in the tropical Pacific. J. Geophys. Res., 106 , 8971–8988.

    • Search Google Scholar
    • Export Citation

  • James, I. N., and P. M. James, 1992: Ultra low frequency variability of flow in a simple atmospheric circulation model. Quart. J. Roy. Meteor. Soc., 118 , 1211–1233.

    • Search Google Scholar
    • Export Citation

  • Jin, F. F., 1997: An equatorial ocean recharge paradigm for ENSO. Part I: A conceptual model. J. Atmos. Sci., 54 , 811–829.

  • Jin, F. F., J. D. Neelin, and M. Ghil, 1994: El Niño on the Devil’s Staircase: Annual subharmonic steps to chaos. Science, 264 , 70–72.

    • Search Google Scholar
    • Export Citation

  • Kiem, A. S., and S. W. Franks, 2004: Multidecadal variability of drought risk-eastern Australia. Hydrol. Processes, 18 , 1–12.

  • Kirtman, B. P., 1997: Oceanic Rossby wave dynamics and the ENSO period in a coupled model. J. Climate, 10 , 1690–1704.

  • Kleeman, R., J. J. P. McCreary, and B. A. Klinger, 1999: A mechanism for generating ENSO decadal variability. Geophys. Res. Lett., 26 , 1743–1746.

    • Search Google Scholar
    • Export Citation

  • Latif, M., 1998: Dynamics of interdecadal variability in coupled ocean–atmosphere models. J. Climate, 11 , 602–624.

  • Liu, Z., L. Wu, and E. Bayler, 1999: Rossby wave–coastal Kelvin wave interaction in the extratropics. Part I: Low-frequency adjustment in a closed basin. J. Phys. Oceanogr., 29 , 2382–2404.

    • Search Google Scholar
    • Export Citation

  • Luo, J-J., S. Masson, S. Behera, P. Delecluse, S. Gualdi, A. Navarra, and T. Yamagata, 2003: South Pacific origin of the decadal ENSO-like variation as simulated by a coupled GCM. Geophys. Res. Lett., 30 .2250, doi:10.1029/2003GL018649.

    • Search Google Scholar
    • Export Citation

  • Lysne, J., P. Chang, and B. Giese, 1997: Impact of extratropical Pacific on equatorial variability. Geophys. Res. Lett., 24 , 2589–2592.

    • Search Google Scholar
    • Export Citation

  • Mann, M. E., R. S. Bradley, and M. K. Hughes, 2000: Long-term variability in the El-Niño/Southern Oscillation and associated teleconnections. El Niño and the Southern Oscillation: Multiscale Variability and Global and Regional Impacts, H. F. Diaz and V. Markgraf, Eds., Cambridge University Press, 357–412.

    • Search Google Scholar
    • Export Citation

  • Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. C. Francis, 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Amer. Meteor. Soc., 78 , 1069–1079.

    • Search Google Scholar
    • Export Citation

  • McGregor, S., N. J. Holbrook, and S. B. Power, 2004: On the dynamics of interdecadal thermocline depth and sea surface temperature variability in the low to mid-latitude Pacific Ocean. Geophys. Res. Lett., 31 .L24201, doi:10.1029/2004GL021241.

    • Search Google Scholar
    • Export Citation

  • McGregor, S., N. J. Holbrook, and S. B. Power, 2007: Interdecadal sea surface temperature variability in the equatorial Pacific Ocean. Part I: The role of off-equatorial wind stresses and oceanic Rossby waves. J. Climate, 20 , 2643–2658.

    • Search Google Scholar
    • Export Citation

  • McPhaden, M. J., and D. Zhang, 2002: Slowdown of the meridional overturning circulation in the upper Pacific Ocean. Nature, 415 , 603–608.

    • Search Google Scholar
    • Export Citation

  • Miller, A. J., and N. Schneider, 2000: Interdecadal climate regime dynamics in the North Pacific Ocean: Theories, observations and ecosystem impacts. Prog. Oceanogr., 47 , 355–379.

    • Search Google Scholar
    • Export Citation

  • Moore, A. M., and R. Kleeman, 2001: The differences between the optimal perturbations of coupled models of ENSO. J. Climate, 14 , 138–163.

    • Search Google Scholar
    • Export Citation

  • Newman, M., G. P. Compo, and M. A. Alexander, 2003: ENSO-forced variability of the Pacific decadal oscillation. J. Climate, 16 , 3853–3857.

    • Search Google Scholar
    • Export Citation

  • Nonaka, M., S-P. Xie, and J. P. McCreary, 2002: Decadal variations in the subtropical cells and equatorial Pacific SST. Geophys. Res. Lett., 29 .1116, doi:10.1029/2001GL013717.

    • Search Google Scholar
    • Export Citation

  • North, G. R., T. L. Bell, R. F. Cahalan, and F. J. Moeng, 1982: Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev., 110 , 699–706.

    • Search Google Scholar
    • Export Citation

  • Pacanowski, R. C., K. Dixon, and A. Rosati, 1991: The GFDL Modular Ocean Model user’s guide, version 1.0. GFDL Ocean Group Tech. Rep. 2, 376 pp.

    • Search Google Scholar
    • Export Citation

  • Philander, S. G., 1990: El Niño, La Niña, and the Southern Oscillation. International Geophysical Series, Vol. 46, Academic Press, 293 pp.

    • Search Google Scholar
    • Export Citation

  • Pierce, D. W., T. P. Barnett, and M. Latif, 2000: Connections between the Pacific Ocean tropics and midlatitudes on decadal time scales. J. Climate, 13 , 1173–1194.

    • Search Google Scholar
    • Export Citation

  • Power, S. B., and R. Colman, 2006: Multi-year predictability in a coupled general circulation model. Climate Dyn., 26 , 247–272.

  • Power, S. B., F. Tseitkin, M. Dix, R. Kleeman, R. Colman, and D. Holland, 1995: Stochastic variability at the air sea interface on decadal timescales. Geophys. Res. Lett., 22 , 2593–2596.

    • Search Google Scholar
    • Export Citation

  • Power, S. B., F. Tseikin, A. W. Coleman, and A. Sulaiman, 1998: A coupled general circulation model for seasonal prediction and climate change research. BMRC Research Rep. 66, 52 pp.

  • Power, S. B., T. Casey, C. Folland, A. Colman, and V. Mehta, 1999: Inter-decadal modulation of the impact of ENSO in Australia. Climate Dyn., 15 , 319–324.

    • Search Google Scholar
    • Export Citation

  • Power, S. B., M. Haylock, R. Coleman, and X. Wang, 2006: The predictability of interdecadal changes in ENSO activity and ENSO teleconnections. J. Climate, 19 , 4755–4771.

    • Search Google Scholar
    • Export Citation

  • Rodgers, K. B., P. Friederichs, and M. Latif, 2004: Tropical Pacific decadal variability and its relation to decadal modulations of ENSO. J. Climate, 17 , 3761–3774.

    • Search Google Scholar
    • Export Citation

  • Ropelewski, C. F., and M. S. Halpert, 1987: Global and regional scale precipitation patterns associated with El Niño/Southern Oscillation. Mon. Wea. Rev., 115 , 1606–1626.

    • Search Google Scholar
    • Export Citation

  • Schopf, P. S., and M. J. Suarez, 1988: A delayed action ocsillator for ENSO. J. Atmos. Sci., 45 , 549–566.

  • Schopf, P. S., and R. J. Burgman, 2006: A simple mechanism for ENSO residuals and asymmetry. J. Climate, 19 , 3167–3179.

  • Syu, H-H., D. J. Neelin, and D. Gutzler, 1995: Seasonal and interannual variability in a hybrid coupled GCM. J. Climate, 8 , 2121–2143.

    • Search Google Scholar
    • Export Citation

  • Timmermann, A., F. F. Jin, and J. Abshagen, 2003: A nonlinear theory for El Niño bursting. J. Atmos. Sci., 60 , 152–165.

  • Tourre, Y. M., C. Cibot, L. Terray, W. B. White, and B. Dewitte, 2005: Quasi-decadal and inter-decadal climate fluctuations in the Pacific Ocean from a CGCM. Geophys. Res. Lett., 32 .L07710, doi:10.1029/2004GL022087.

    • Search Google Scholar
    • Export Citation

  • Tziperman, E., L. Stone, M. A. Cane, and H. Jarosh, 1994: El Niño chaos: Overlapping of resonances between the seasonal cycle and the Pacific ocean-atmosphere oscillator. Science, 264 , 72–74.

    • Search Google Scholar
    • Export Citation

  • Vimont, D. J., D. S. Battisti, and A. C. Hirst, 2002: Pacific interannual and interdecadal equatorial variability in a 1000-yr simulation of the CSIRO coupled GCM. J. Climate, 15 , 160–178.

    • Search Google Scholar
    • Export Citation

  • Walland, D. J., S. B. Power, and A. C. Hirst, 2000: Decadal climate variability simulated in a coupled GCM. Climate Dyn., 16 , 201–211.

    • Search Google Scholar
    • Export Citation

  • Wang, X., F. F. Jin, and Y. Wang, 2003a: A tropical recharge mechanism for climate variability. Part I: Equatorial heat content changes induced by the off-equatorial wind. J. Climate, 16 , 3585–3598.

    • Search Google Scholar
    • Export Citation

  • Wang, X., F. F. Jin, and Y. Wang, 2003b: A tropical recharge mechanism for climate variability. Part II: A unified theory for decadal and ENSO modes. J. Climate, 16 , 3599–3616.

    • Search Google Scholar
    • Export Citation

  • Wang, X. L., and C. F. Ropelewski, 1995: An assessment of ENSO-scale secular variability. J. Climate, 8 , 1584–1599.

  • White, W. B., Y. M. Tourre, M. Barlow, and M. Dettinger, 2003: A delayed action oscillator shared by bienial, interannual, and decadal signals in the Pacific Basin. J. Geophys. Res., 108 .3070, doi:10.1029/2002JC001490.

    • Search Google Scholar
    • Export Citation

  • Wu, L., Z. Liu, R. Gallimore, R. Jacob, D. Lee, and Y. Zhong, 2003: Pacific decadal variability: The tropical Pacific mode and the North Pacific mode. J. Climate, 16 , 3111–3131.

    • Search Google Scholar
    • Export Citation

  • Zavala-Garay, J., A. M. Moore, and C. L. Perez, 2003: The response of a coupled model of ENSO to observed estimates of stochastic forcing. J. Climate, 16 , 2827–2842.

    • Search Google Scholar
    • Export Citation

  • Zebiak, S. E., and M. A. Cane, 1987: A model El Niño–Southern Oscillation. Mon. Wea. Rev., 115 , 2262–2278.

  • Zhang, R. H., L. M. Rothstein, and A. J. Busalacchi, 1998: Origin of upper-ocean warming and El Niño change on decadal scales in the tropical Pacific Ocean. Nature, 391 , 879–883.

    • Search Google Scholar
    • Export Citation

  • Zhang, Y., J. M. Wallace, and D. S. Battisti, 1997: ENSO-like interdecadal variability: 1900–93. J. Climate, 10 , 1004–1020.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 243 78 5
PDF Downloads 186 68 4