Decadal Variability in the North Pacific as Simulated by a Hybrid Coupled Model

W. Xu Scripps Institute of Oceanography, La Jolla, California

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T. P. Barnett Scripps Institute of Oceanography, La Jolla, California

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M. Latif Max-Planck Institute for Meteorology, Hamburg, Germany

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Abstract

In this study, a hybrid coupled model (HCM) is used to investigate the physics of decadal variability in the North Pacific. This aids in an understanding of the inherent properties of the coupled ocean–atmosphere system in the absence of stochastic forcing by noncoupled variability. It is shown that the HCM simulates a self-sustained decadal oscillation with a period of about 20 yr, similar to that found in both the observations and coupled GCMs.

Sensitivity experiments are carried out to determine the relative importance of wind stresses, net surface heat flux, and freshwater flux on the initiation and maintenance of the decadal oscillation in the North Pacific. It is found that decadal variability is a mode of the coupled system and involves interaction of sea surface temperature, upper-ocean heat content, and wind stress. This interaction is mainly controlled by the wind stress but can be strongly modified by the surface heat flux. The effect of the salinity is relatively small and is not necessary to generate the model decadal oscillation in the North Pacific.

There are some limitations with this study. First, the effect of a stochastic forcing is not included. Second, a weak negative feedback is needed to run the control experiment for a longer time period. These two areas will be addressed in a future investigation.

Corresponding author address: Dr. Weimin Xu, Department of Atmospheric and Oceanic Science, University of Wisconsin—Madison, 1225 W. Dayton Street, Madison, WI 53706.

Email: xu@climate.scar.utoronto.ca

Abstract

In this study, a hybrid coupled model (HCM) is used to investigate the physics of decadal variability in the North Pacific. This aids in an understanding of the inherent properties of the coupled ocean–atmosphere system in the absence of stochastic forcing by noncoupled variability. It is shown that the HCM simulates a self-sustained decadal oscillation with a period of about 20 yr, similar to that found in both the observations and coupled GCMs.

Sensitivity experiments are carried out to determine the relative importance of wind stresses, net surface heat flux, and freshwater flux on the initiation and maintenance of the decadal oscillation in the North Pacific. It is found that decadal variability is a mode of the coupled system and involves interaction of sea surface temperature, upper-ocean heat content, and wind stress. This interaction is mainly controlled by the wind stress but can be strongly modified by the surface heat flux. The effect of the salinity is relatively small and is not necessary to generate the model decadal oscillation in the North Pacific.

There are some limitations with this study. First, the effect of a stochastic forcing is not included. Second, a weak negative feedback is needed to run the control experiment for a longer time period. These two areas will be addressed in a future investigation.

Corresponding author address: Dr. Weimin Xu, Department of Atmospheric and Oceanic Science, University of Wisconsin—Madison, 1225 W. Dayton Street, Madison, WI 53706.

Email: xu@climate.scar.utoronto.ca

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  • Anderson, D. L. T., and A. E. Gill, 1975: Spin-up of a stratified ocean, with applications to upwelling. Deep-Sea Res.,22, 583–596.

  • Barnett, T. P., M. Latif, E. Kirk, and E. Roeckner, 1991: On ENSO Physics. J. Climate,4, 487–515.

  • ——, M. Latif, N. Graham, M. Flügel, S. Pazan, and W. White, 1993:ENSO and ENSO-related predictability. Part I: Prediction of equatorial Pacific sea surface temperature with a hybrid coupled ocean–atmosphere model. J. Climate,6, 1545–1566.

  • Bjerknes, J., 1964: Atlantic air–sea interaction. Advances in Geophysics, Vol. 10, Academic Press, 1–82.

  • Davis, R. E., 1978: Predictability of sea level pressure anomalies over the North Pacific Ocean. J. Phys. Oceanogr.,8, 233–246.

  • Delworth, T., S. Manabe, and R. J. Stouffer, 1993: Interdecadal variations of the thermohaline circulation in a coupled ocean–atmosphere model. J. Climate,6, 1993–2011.

  • Deser, C., and M. L. Blackmon, 1993: Surface climate variations over the North Atlantic Ocean during winter: 1900–1989. J. Climate,6, 1743–1753.

  • ——, and ——, 1995: On the relationship between tropical and North Pacific sea surface temperature variations. J. Climate,8, 1677–1680.

  • ——, M. A. Alexander, and M. S. Timlin, 1997: Upper ocean thermal variations in the North Pacific during 1970–1991. J. Climate,9, 1840–1855.

  • Favorite, F., and D. R. McClain, 1973: Coherence in trans-Pacific movements of positive and negative anomalies of sea-surface temperature 1953–1960. Nature,244, 139–143.

  • Frankignoul, C., 1985: Sea surface temperature anomalies, planetary waves, and air–sea feedback in the middle latitudes. Rev. Geophys.,23, 357–390.

  • Graham, N. E., T. P. Barnett, R. Wilde, M. Ponater, and S. Schubert, 1994: On the roles of tropical and midlatitude SSTs in forcing interannual to interdecadal variability in the winter Northern Hemisphere circulation. J. Climate,7, 1416–1441.

  • Haney, R. L., 1985: Midlatitude sea surface temperature anomalies: A numerical hindcast. J. Phys. Oceanogr.,15, 787–799.

  • Jacobs, G. A., H. E. Hurlburt, J. C. Kindle, E. J. Metzger, J. L. Mitchell,W. J. Teague, and A. J. Wallcraft, 1994: Decadal-scale trans-Pacific propagation and warming effects of an El Niño anomaly. Nature,370, 360–363.

  • Kushnir, Y., 1994: Interdecadal variations in North Atlantic sea surface temperature and associated atmospheric conditions. J. Climate,7, 141–157.

  • Latif, M., 1987: Tropical ocean circulation experiments. J. Phys. Oceanogr.,17, 246–263.

  • ——, and T. P. Barnett, 1994: Causes of decadal climate variability over the North Pacific/North American sector. Sciences,266, 634–637.

  • ——, and ——, 1996: Decadal climate variability over the North Pacific and North America: Dynamics and predictability. J. Climate,9, 2407–2423.

  • ——, A. Sterl, E. Maier-Reimer, and M. M. Junge, 1993a: Climate variability in a coupled GCM. Part I: The tropical Pacific. J. Climate,6, 5–21.

  • ——, ——, ——, and ——, 1993b: Structure and predictability of the El Niño/Southern Oscillation phenomenon in a coupled ocean–atmosphere general circulation model. J. Climate,6, 700–708.

  • ——, T. Stockdale, J. Wolff, G. Burgers, E. Maier-Reimer, M. M. Junge, K. Arpe, and L. Bengtsson, 1994: Climatology and variability in the ECHO coupled GCM. Tellus,46A, 351–366.

  • Lau, N. C., and M. J. Nath, 1994: A modeling study of the relative roles of tropical and extratropical SST anomalies in the variability of the global atmosphere–ocean system. J. Climate,7, 1184–1207.

  • Levitus, S., 1982: Climatological Atlas of the World Ocean. NOAA Prof. Pap. 13, U.S. Department of Commerce, 173 pp. [Available from NOAA/NWS/NCEP, 5200 Auth Road, Washington, DC 20233.].

  • Luksch, U., and H. von Storch, 1992: Modeling the low-frequency sea surface temperature variability in the North Pacific. J. Climate,5, 893–906.

  • ——, ——, and E. Maier-Reimer, 1990: Modeling North Pacific SST anomalies as a response to anomalous atmospheric forcing. J. Mar. Syst.,1, 155–168.

  • Michaelsen, J., 1982: A statistical study of large-scale, long-period variability in North Pacific sea surface temperature anomalies. J. Phys. Oceanogr.,12, 694–703.

  • Miller, A. J., A. R. Cayan, T. P. Barnett, N. E. Graham, and J. M. Oberhuber, 1994: Interdecadal variability of the Pacific Ocean: Model response to observed heat flux and wind stress anomalies. Climate Dyn.,9, 287–302.

  • Miyakoda, K., and A. Rosati, 1984: The variation of sea surface temperature in 1976 and 1977. 2: The simulation with mixed layer models. J. Geophys. Res.,89, 6533–6542.

  • Namias, J., 1959: Recent seasonal interactions between North Pacific waters and the overlying atmospheric circulation. J. Geophys. Res.,64, 631–646.

  • ——, 1969: Seasonal interactions between North Pacific and the atmosphere during the 1960s. Mon. Wea. Rev.,97, 173–192.

  • Neelin, J. D., 1990: A hybrid coupled general circulation model for El Niño studies. J. Atmos. Sci.,47, 674–693.

  • Nitta, T., and S. Yamada, 1989: Recent warming of tropical sea temperature and its relationship to the Northern Hemisphere circulation. J. Meteor. Soc. Japan.,67, 375–383.

  • Oberhuber, J. M., 1993: Simulation of the Atlantic circulation with a coupled sea ice-mixed layer-isopycnal general circulation model. Part I: Model description. J. Phys. Oceanogr.,23, 808–829.

  • Palmer, T. N., and Z. Sun, 1985: A modelling and observational study of the relationship between sea surface temperatures in the northwest Atlantic and the atmospheric general circulation. Quart. J. Roy. Meteor. Soc.,111, 947–975.

  • Paulson, C. A., and J. J. Simpson, 1977: Irradiance measurements in the upper ocean. J. Phys. Oceanogr.,7, 952–956.

  • Peng, S. L., L. A. Mysak, H. Ritchie, J. Derome, and B. Dugas, 1995:The differences between early and midwinter atmospheric responses to sea surface temperature anomalies in the northwest Atlantic. J. Climate,8, 137–157.

  • Roeckner, E., and Coauthors, 1992. Simulation of the present-day climate with the ECHAM model: Impact of model physics and resolution. Max-Planck-Institut für Meteorologie Rep. 93. [Available from Max-Planck-Institut für Meteorologie, Bundesstrasse, 55 D-20146 Hamburg, Germany.].

  • Rosati, A., and K., Miyakoda, 1988: A general circulation model for upper ocean simulation. J. Phys. Oceanogr.,18, 1601–1626.

  • Sausen, R., K. Barthel, and K. Hasselmann, 1988: Coupled ocean–atmosphere models with flux correction. Climate Dyn.,2, 145–163.

  • Schneider, N., T. Barnett, M. Latif, and T. Stockdale, 1996: Warm pool physics in a coupled GCM. J. Climate,9, 219–239.

  • Seckel, G. R., 1993: Zonal gradient of the winter sea level atmospheric pressure at 50°N: An indicator pf atmospheric forcing of North Pacific surface conditions. J. Geophys. Res.,98, 22615–22628.

  • Sterl, A., and A. Kattenberg, 1994: Embedding a mixed layer model into an ocean general circulation model of the Atlantic: The importance of surface mixing for heat flux and temperature. J. Geophys. Res.,99, 14139–14157.

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

  • Tanimoto, Y., N. Iwasaka, K. Hanawa, and Y. Toba, 1993: Characteristic variations of sea surface temperature with multiple time scales in the North Pacific. J. Climate,6, 1153–1160.

  • Trenberth, K. E., and J. W. Hurrel, 1994: Decadal atmosphere–ocean variations in the Pacific. Climate Dyn.,9, 303–319.

  • Venrick, E. L., J. A. McGowan, D. R. Cayan, and T. L. Hayward, 1987:Climate and chlorophyll: Long-term trends in the central North Pacific Ocean. Science,238, 70–72.

  • Wolff, J.-O., and E. Maier-Reimer, 1997. HOPE: The Hamburg Ocean Primitive Equation Model. Tech. Rep. 13, Deutsches Klimarechenzentrum, 103 pp. [Available from Max-Planck-Institut für Meteorologie, Bundesstrasse, 55 D-20146 Hamburg, Germany.].

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