• Alexander, M. A., I. Bladé, M. Newman, J. R. Lanzante, N-C. Lau, and J. D. Scott, 2002: The atmospheric bridge: The influence of ENSO teleconnections on air–sea interaction over the global oceans. J. Climate, 15 , 22052231.

    • Search Google Scholar
    • Export Citation
  • Alexander, M. A. Coauthors 2006: Extratropical atmosphere–ocean variability in CCSM3. J. Climate, 19 , 24962525.

  • Collins, W. D. Coauthors 2006: The Community Climate System Model Version 3 (CCSM3). J. Climate, 19 , 21222143.

  • Conkright, M. E., R. A. Locarnini, H. E. Garcia, T. D. O’Brien, T. P. Boyer, C. Stephens, and J. I. Antonov, 2002: World Ocean Atlas 2001: Objective Analyses, Data Statistics, and Figures, CD-ROM Documentation. National Oceanographic Data Center, 17 pp.

    • Search Google Scholar
    • Export Citation
  • Danabasoglu, G., 2008: On multidecadal variability of the atlantic meridional overturning circulation in the Community Climate System Model version 3. J. Climate, 21 , 55245544.

    • Search Google Scholar
    • Export Citation
  • Dawe, J. T., and L. Thompson, 2005: Viscosity-dependent internal variability in a model of the North Pacific. J. Phys. Oceanogr., 35 , 747756.

    • Search Google Scholar
    • Export Citation
  • Deser, C., and M. L. Blackmon, 1995: On the relationship between tropical and North Pacific sea surface temperature variations. J. Climate, 8 , 16771680.

    • 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 , 16971706.

    • Search Google Scholar
    • Export Citation
  • Ducet, N., P-Y. L. Traon, and G. Reverdin, 2000: Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2. J. Geophys. Res., 105 , 1947719498.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., and J. C. McWilliams, 1990: Isopycnal mixing in ocean circulation models. J. Phys. Oceanogr., 20 , 150155.

  • Gent, P. R., and G. Danabasoglu, 2004: Heat uptake and the thermohaline circulation in the Community Climate System Model, version 2. J. Climate, 17 , 40584069.

    • Search Google Scholar
    • Export Citation
  • Gent, P. R., S. G. Yeager, R. B. Neale, S. Levis, and D. A. Bailey, 2009: Improvements in a half-degree atmosphere–land version of the CCSM. Climate Dyn., 34 , 819833.

    • Search Google Scholar
    • Export Citation
  • Hanawa, K., and L. D. Talley, 2001: Mode waters. Ocean Circulation and Climate, G. Siedler and J. Church, Eds., International Geophysics Series, Vol. 77, Academic Press, 373–386.

    • Search Google Scholar
    • Export Citation
  • Hazeleger, W., and S. S. Drijfhout, 2000: A model study on internally generated variability in subtropical mode water formation. J. Geophys. Res., 105 , 1396513979.

    • Search Google Scholar
    • Export Citation
  • Kelly, K. A., 1991: The meandering Gulf Stream as seen by the geosat altimeter: Surface transport, position, and velocity variance from 73° to 46°W. J. Geophys. Res., 96 , 1672116738.

    • Search Google Scholar
    • Export Citation
  • Kelly, K. A., M. J. Caruso, S. Singh, and B. Qiu, 1996: Observations of atmosphere–ocean coupling in midlatitude western boundary currents. J. Geophys. Res., 101 , 62956312.

    • Search Google Scholar
    • Export Citation
  • Kelly, K. A., L. Thompson, W. Cheng, and E. J. Metzger, 2007: Evaluation of HYCOM in the Kuroshio Extension region using new metrics. J. Geophys. Res., 112 , C01004. doi:10.1029/2006JC003614.

    • Search Google Scholar
    • Export Citation
  • Knutson, T. R. Coauthors 2006: Assessment of twentieth-century regional surface temperature trends using the GFDL CM2 coupled models. J. Climate, 19 , 16241651.

    • Search Google Scholar
    • Export Citation
  • Kobayashi, T., 1999: Study of the formation of North Pacific Intermediate Water by a general circulation model and the particle-tracking method 1. A pitfall of general circulation model studies. J. Geophys. Res., 104 , 54235440.

    • Search Google Scholar
    • Export Citation
  • Kobayashi, T., 2000: Study of the formation of North Pacific Intermediate Water by a general circulation model and the particle-tracking method: 2. Formation mechanism of salinity minimum from the view of the “critical gradient” of the Oyashio mixing ratio. J. Geophys. Res., 105 , 10551070.

    • Search Google Scholar
    • Export Citation
  • Kwon, Y-O., and C. Deser, 2007: North Pacific decadal variability in the Community Climate System model version 2. J. Climate, 20 , 24162433.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., and S. G. Yeager, 2004: Diurnal to decadal global forcing for ocean and sea ice models: The data sets and flux climatologies. NCAR Tech. Rep. TN-460+STR, 105 pp.

    • Search Google Scholar
    • Export Citation
  • Large, W. G., and G. Danabasoglu, 2006: Attribution and impacts of upper-ocean biases in CCSM3. J. Climate, 19 , 23252346.

  • Latif, M., and T. P. Barnett, 1996: Decadal climate variability over the North Pacific and North America: Dynamics and predictability. J. Climate, 9 , 24072423.

    • Search Google Scholar
    • Export Citation
  • Maltrud, M., F. Bryan, and S. Peacock, 2010: Boundary impulse response functions in a century-long eddying global ocean simulation. Environ. Fluid Mech., 10 , 275295.

    • Search Google Scholar
    • Export Citation
  • Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. Francis, 1997: A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. Amer. Meteor. Soc., 78 , 10691079.

    • Search Google Scholar
    • Export Citation
  • Maximenko, N. A., and P. P. Niiler, 2004: Hybrid decade-mean global sea level with mesoscale resolution. Recent Advances in Marine Science and Technology, N. Saxena, Ed., PACON International, 55–59.

    • Search Google Scholar
    • Export Citation
  • Nakamura, H., and A. S. Kazmin, 2003: Decadal changes in the North Pacific oceanic frontal zones as revealed in ship and satellite observations. J. Geophys. Res., 108 , 3078. doi:10.1029/1999JC000085.

    • Search Google Scholar
    • Export Citation
  • Nonaka, M., H. Nakamura, Y. Tanimoto, T. Kagimoto, and H. Sasaki, 2006: Decadal variability in the Kuroshio–Oyashio Extension simulated in an eddy-resolving OGCM. J. Climate, 19 , 19701989.

    • Search Google Scholar
    • Export Citation
  • Pierce, D. W., T. P. Barnett, N. Schneider, R. Saravanan, D. Dommenget, and M. Latif, 2001: The role of ocean dynamics in producing decadal climate variability in the North Pacific. Climate Dyn., 18 , 5170.

    • Search Google Scholar
    • Export Citation
  • Primeau, F., 2002: Multiple equilibria and low-frequency variability of wind-driven ocean currents. J. Phys. Oceanogr., 32 , 22322256.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., 2000: Interannual variability of the Kuroshio Extension system and its impact on the wintertime SST field. J. Phys. Oceanogr., 30 , 14861502.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., 2003: Kuroshio Extension variability and forcing of the Pacific decadal oscillations: Responses and potential feedback. J. Phys. Oceanogr., 33 , 24652482.

    • Search Google Scholar
    • Export Citation
  • Qiu, B., N. Schneider, and S. Chen, 2007: Coupled decadal variability in the North Pacific: An observationally constrained idealized model. J. Climate, 20 , 36023620.

    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., T. M. Smith, C. Liu, D. B. Chelton, K. S. Casey, and M. G. Schlax, 2007: Daily high-resolution-blended analyses for sea surface temperature. J. Climate, 20 , 54735496.

    • Search Google Scholar
    • Export Citation
  • Schneider, N., and A. J. Miller, 2001: Predicting western North Pacific Ocean climate. J. Climate, 14 , 39974002.

  • Schneider, N., A. J. Miller, and D. W. Pierce, 2002: Anatomy of North Pacific decadal variability. J. Climate, 15 , 586605.

  • Seager, R., Y. Kushnir, N. H. Naik, M. A. Cane, and J. Miller, 2001: Wind-driven shifts in the latitude of the Kuroshio–Oyashio Extension and generation of SST anomalies on decadal timescales. J. Climate, 14 , 41494165.

    • Search Google Scholar
    • Export Citation
  • Smith, T. M., R. W. Reynolds, T. C. Peterson, and J. Lawrimore, 2008: Improvements to NOAA’s historical merged land–ocean surface temperature analysis (1880–2006). J. Climate, 21 , 22832296.

    • Search Google Scholar
    • Export Citation
  • Talley, L. D., 1993: Distribution and formation of North Pacific intermediate water. J. Phys. Oceanogr., 23 , 517537.

  • Talley, L. D., 1997: North Pacific Intermediate Water transports in the mixed water region. J. Phys. Oceanogr., 27 , 17951803.

  • Thompson, L., and W. Cheng, 2008: Water masses in the Pacific in CCSM3. J. Climate, 21 , 45144528.

  • Wu, L., D. E. Lee, and Z. Liu, 2005: The 1976/77 North Pacific climate regime shift: The role of subtropical ocean adjustment and coupled ocean–atmosphere feedbacks. J. Climate, 18 , 51255140.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 34 34 34
PDF Downloads 1 1 1

An Enhancement of Low-Frequency Variability in the Kuroshio–Oyashio Extension in CCSM3 owing to Ocean Model Biases

View More View Less
  • 1 University of Washington, Seattle, Washington
  • | 2 Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
Restricted access

Abstract

Enhanced decadal variability in sea surface temperature (SST) centered on the Kuroshio Extension (KE) has been found in the Community Climate System Model version 3 (CCSM3) as well as in other coupled climate models. This decadal peak has higher energy than is found in nature, almost twice as large in some cases. While previous analyses have concentrated on the mechanisms for such decadal variability in coupled models, an analysis of the causes of excessive SST response to changes in wind stress has been missing. Here, a detailed comparison of the relationships between interannual changes in SST and sea surface height (SSH) as a proxy for geostrophic surface currents in the region in both CCSM3 and observations, and how these relationships depend on the mean ocean circulation, temperature, and salinity, is made. We use observationally based climatological temperature and salinity fields as well as satellite-based SSH and SST fields for comparison. The primary cause for the excessive SST variability is the coincidence of the mean KE with the region of largest SST gradients in the model. In observations, these two regions are separated by almost 500 km. In addition, the too shallow surface oceanic mixed layer in March north of the KE in the subarctic Pacific contributes to the biases. These biases are not unique to CCSM3 and suggest that mean biases in current, temperature, and salinity structures in separated western boundary current regions can exert a large influence on the size of modeled decadal SST variability.

Corresponding author address: LuAnne Thompson, Box 355351, School of Oceanography, University of Washington, Seattle, WA 98195. Email: luanne@u.washington.edu

This article included in the CLIVAR - Western Boundary Currents special collection.

Abstract

Enhanced decadal variability in sea surface temperature (SST) centered on the Kuroshio Extension (KE) has been found in the Community Climate System Model version 3 (CCSM3) as well as in other coupled climate models. This decadal peak has higher energy than is found in nature, almost twice as large in some cases. While previous analyses have concentrated on the mechanisms for such decadal variability in coupled models, an analysis of the causes of excessive SST response to changes in wind stress has been missing. Here, a detailed comparison of the relationships between interannual changes in SST and sea surface height (SSH) as a proxy for geostrophic surface currents in the region in both CCSM3 and observations, and how these relationships depend on the mean ocean circulation, temperature, and salinity, is made. We use observationally based climatological temperature and salinity fields as well as satellite-based SSH and SST fields for comparison. The primary cause for the excessive SST variability is the coincidence of the mean KE with the region of largest SST gradients in the model. In observations, these two regions are separated by almost 500 km. In addition, the too shallow surface oceanic mixed layer in March north of the KE in the subarctic Pacific contributes to the biases. These biases are not unique to CCSM3 and suggest that mean biases in current, temperature, and salinity structures in separated western boundary current regions can exert a large influence on the size of modeled decadal SST variability.

Corresponding author address: LuAnne Thompson, Box 355351, School of Oceanography, University of Washington, Seattle, WA 98195. Email: luanne@u.washington.edu

This article included in the CLIVAR - Western Boundary Currents special collection.

Save