• Bindoff, N. L., , and T. J. McDougall, 1994: Diagnosing climate change and ocean ventilation using hydrographic data. J. Phys. Oceanogr., 24 , 11371152.

    • Search Google Scholar
    • Export Citation
  • Bograd, S. J., , and R. J. Lynn, 2003: Long-term variability in the Southern California Current System. Deep-Sea Res. II, 50 , 23552370.

    • Search Google Scholar
    • Export Citation
  • Chelton, D. B., , P. A. Bernal, , and J. A. McGowan, 1982: Large-scale interannual physical and biological interaction in the California Current. J. Mar. Res., 40 , 10951125.

    • Search Google Scholar
    • Export Citation
  • Chhak, K. C., , E. Di Lorenzo, , P. Cummins, , and N. Schneider, 2009: Forcing of low-frequency ocean variability in the northeast Pacific. J. Climate, 22 , 12551276.

    • Search Google Scholar
    • Export Citation
  • Combes, V., , and E. Di Lorenzo, 2007: Intrinsic and forced interannual variability of the Gulf of Alaska mesoscale circulation. Prog. Oceanogr., 75 , 266286.

    • Search Google Scholar
    • Export Citation
  • Cummins, P. F., , and G. S. E. Lagerloef, 2002: Low-frequency pycnocline depth variability at Ocean Weather Station P in the northeast Pacific. J. Phys. Oceanogr., 32 , 32073215.

    • Search Google Scholar
    • Export Citation
  • Cummins, P. F., , and G. S. E. Lagerloef, 2004: Wind-driven interannual variability over the northeast Pacific Ocean. Deep-Sea Res. I, 51 , 21052121.

    • Search Google Scholar
    • Export Citation
  • Davis, R. E., 1976: Predictability of sea surface temperature and sea level pressure anomalies over the North Pacific Ocean. J. Phys. Oceanogr., 6 , 249266.

    • Search Google Scholar
    • Export Citation
  • de Boyer Montégut, C., , G. Madec, , A. S. Fischer, , A. Lazar, , and D. Iudicone, 2004: Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. J. Geophys. Res., 109 , C12003. doi:10.1029/2004JC002378.

    • Search Google Scholar
    • Export Citation
  • Di Lorenzo, E., and Coauthors, 2008: North Pacific Gyre Oscillation links ocean climate and ecosystem change. Geophys. Res. Lett., 35 , L08607. doi:10.1029/2007GL032838.

    • Search Google Scholar
    • Export Citation
  • Di Lorenzo, E., and Coauthors, 2009: Nutrient and salinity decadal variations in the central and eastern North Pacific. Geophys. Res. Lett., 36 , L14601. doi:10.1029/2009GL038261.

    • Search Google Scholar
    • Export Citation
  • Dottori, M., , and A. J. Clarke, 2009: Rossby waves and the interannual and interdecadal variability of temperature and salinity off California. J. Phys. Oceanogr., 39 , 25432561.

    • Search Google Scholar
    • Export Citation
  • Frankignoul, C., 1981: Low-frequency temperature fluctuations off Bermuda. J. Geophys. Res., 86 , (C7). 65226528.

  • Frankignoul, C., , and K. Hasselmann, 1977: Stochastic climate models, Part II. Application to sea-surface temperature anomalies and thermocline variability. Tellus, 29 , 289305.

    • Search Google Scholar
    • Export Citation
  • Frankignoul, C., , and R. W. Reynolds, 1983: Testing a dynamical model for mid-latitude sea surface temperature anomalies. J. Phys. Oceanogr., 13 , 11311145.

    • Search Google Scholar
    • Export Citation
  • Frankignoul, C., , P. Müller, , and E. Zorita, 1997: A simple model of the decadal response of the ocean to stochastic wind forcing. J. Phys. Oceanogr., 27 , 15331546.

    • Search Google Scholar
    • Export Citation
  • Fukumori, I., , T. Lee, , B. Cheng, , and D. Menemenlis, 2004: The origin, pathway, and destination of Niño-3 water estimated by a simulated passive tracer and its adjoint. J. Phys. Oceanogr., 34 , 582604.

    • 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 , 805807.

    • Search Google Scholar
    • Export Citation
  • Hall, A., , and S. Manabe, 1997: Can local linear stochastic theory explain sea surface temperature and salinity variability? Climate Dyn., 13 , 167180.

    • Search Google Scholar
    • Export Citation
  • Hasselmann, K., 1976: Stochastic climate models. Part 1, Theory. Tellus, 28 , 473485.

  • Iselin, C. O. D., 1939: The influence of vertical and lateral turbulence on the characteristics of the waters at mid-depths. Trans. Amer. Geophys. Union, 20 , 414417.

    • Search Google Scholar
    • Export Citation
  • Ito, T., , and C. Deutsch, 2010: A conceptual model for the temporal spectrum of oceanic oxygen variability. Geophys. Res. Lett., L03601. doi:10.1029/2009GL041595.

    • Search Google Scholar
    • Export Citation
  • James, I. N., , and P. M. James, 1989: Ultra-low-frequency variability in a simple atmospheric circulation model. Nature, 342 , 5355.

  • Johnson, G. C., 2006: Generation and initial evolution of a mode water θS anomaly. J. Phys. Oceanogr., 36 , 739751.

  • Kalnay, E., and Coauthors, 1996: The NCEP–NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kessler, W. S., 1999: Interannual variability of the subsurface high salinity tongue south of the equator at 165°E. J. Phys. Oceanogr., 29 , 20382049.

    • Search Google Scholar
    • Export Citation
  • Lagerloef, G. S. E., 1995: Interdecadal variations in the Alaska gyre. J. Phys. Oceanogr., 25 , 22422258.

  • 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. Rev. Geophys., 32 , 363403.

    • Search Google Scholar
    • Export Citation
  • Laurian, A., , A. Lazar, , G. Reverdin, , K. Rodgers, , and P. Terray, 2006: Poleward propagation of spiciness anomalies in the North Atlantic Ocean. Geophys. Res. Lett., 33 , L13603. doi:10.1029/2006GL026155.

    • Search Google Scholar
    • Export Citation
  • Laurian, A., , A. Lazar, , and G. Reverdin, 2009: Generation mechanism of spiciness anomalies: An OGCM analysis in the North Atlantic subtropical gyre. J. Phys. Oceanogr., 39 , 10031018.

    • Search Google Scholar
    • Export Citation
  • Ledwell, J. R., , A. J. Watson, , and C. S. Law, 1993: Evidence for slow mixing across the pycnocline from an open-ocean tracer-release experiment. Nature, 364 , 701703.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., , R. Burgett, , and T. P. Boyer, 1994: Salinity. Vol. 3, World Ocean Atlas 1994, NOAA Atlas NESDIS 3, 99 pp.

  • Liu, Z., , and S-I. Shin, 1999: On thermocline ventilation of active and passive tracers. Geophys. Res. Lett., 26 , 357360.

  • Lukas, R., 2001: Freshening of the upper thermocline in the North Pacific subtropical gyre associated with decadal changes in rainfall. Geophys. Res. Lett., 28 , 34853488.

    • Search Google Scholar
    • Export Citation
  • Lukas, R., , and F. Santiago-Mandujano, 2008: Interannual to interdecadal salinity variations observed near Hawaii: Local and remote forcing by surface freshwater fluxes. Oceanography, 21 , 4655.

    • Search Google Scholar
    • Export Citation
  • Luo, Y., , L. M. Rothstein, , R-H. Zhang, , and A. J. Busalacchi, 2005: On the connection between South Pacific subtropical spiciness anomalies and decadal equatorial variability in an ocean general circulation model. J. Geophys. Res., 110 , C10002. doi:10.1029/2004JC002655.

    • 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 , 10691079.

    • Search Google Scholar
    • Export Citation
  • Marchesiello, P., , J. C. McWilliams, , and A. Shchepetkin, 2001: Open boundary conditions for long-term integration of regional oceanic models. Ocean Modell., 3 , 120.

    • Search Google Scholar
    • Export Citation
  • Marchesiello, P., , J. C. McWilliams, , and A. Shchepetkin, 2003: Equilibrium structure and dynamics of the California Current System. J. Phys. Oceanogr., 33 , 753783.

    • Search Google Scholar
    • Export Citation
  • Masumoto, Y., and Coauthors, 2004: A fifty-year eddy-resolving simulation of the World Ocean—Preliminary outcomes of OFES (OGCM for the Earth Simulator). J. Earth Simulator, 1 , 3556.

    • Search Google Scholar
    • Export Citation
  • Mignot, J., , and C. Frankignoul, 2003: On the interannual variability of surface salinity in the Atlantic. Climate Dyn., 20 , 555565.

  • Müller, P., , and J. Willebrand, 1986: Compressibility effects in the thermohaline circulation: A manifestation of the temperature–salinity mode. Deep-Sea Res., 33 , 559571.

    • Search Google Scholar
    • Export Citation
  • Munk, W., 1981: Internal waves and small-scale processes. Evolution of Physical Oceanography, B. A. Warren and C. Wunsch, Eds., The MIT Press, 264–291.

    • Search Google Scholar
    • Export Citation
  • Nonaka, M., , and H. Sasaki, 2007: Formation mechanism for isopycnal temperature–salinity anomalies propagating from the eastern South Pacific to the equatorial region. J. Climate, 20 , 13051315.

    • 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
  • Ren, L., , and S. C. Riser, 2010: Observations of decadal time scale salinity changes in the subtropical thermocline of the North Pacific Ocean. Deep-Sea Res. II, 57 , 11611170.

    • Search Google Scholar
    • Export Citation
  • Roemmich, D., , and J. McGowan, 1995: Climatic warming and the decline of zooplankton in the California Current. Science, 267 , 13241326.

    • Search Google Scholar
    • Export Citation
  • Sasaki, Y. N., , N. Schneider, , N. Maximenko, , and K. Lebedev, 2010: Observational evidence for propagation of decadal spiciness anomalies in the North Pacific. Geophys. Res. Lett., 37 , L07708. doi:10.1029/2010GL042716.

    • Search Google Scholar
    • Export Citation
  • Schneider, N., 1999: Pacific thermocline bridge revisited. Geophys. Res. Lett., 26 , 13291332.

  • Schneider, N., 2000: A decadal spiciness mode in the tropics. Geophys. Res. Lett., 27 , 257260.

  • Schneider, N., 2004: The response of tropical climate to the equatorial emergence of spiciness anomalies. J. Climate, 17 , 10831095.

  • Schneider, N., , and B. D. Cornuelle, 2005: The forcing of the Pacific decadal oscillation. J. Climate, 18 , 43554373.

  • Schneider, N., , E. Di Lorenzo, , and P. P. Niiler, 2005: Salinity variations in the southern California Current. J. Phys. Oceanogr., 35 , 14211436.

    • Search Google Scholar
    • Export Citation
  • Schwing, F. B., , and R. Mendelssohn, 1997: Increased coastal upwelling in the California Current System. J. Geophys. Res., 102 , (C2). 34213438.

    • Search Google Scholar
    • Export Citation
  • Shchepetkin, A., , and J. C. McWilliams, 2005: The Regional Oceanic Modeling System (ROMS): A split-explicit, free-surface, topography-following-coordinate ocean model. Ocean Modell., 9 , 347404.

    • Search Google Scholar
    • Export Citation
  • Smith, T. M., , and R. W. Reynolds, 2004: Improved extended reconstruction of SST (1854–1997). J. Climate, 17 , 24662477.

  • Spall, M. A., 1993: Variability of sea surface salinity in stochastically forced systems. Climate Dyn., 8 , 151160.

  • Stammer, D., , S. Park, , A. Kohl, , R. Lukas, , and F. Santiago-Mandujano, 2008: Causes for large-scale hydrographic changes at the Hawaii Ocean time series station. J. Phys. Oceanogr., 38 , 19311948.

    • Search Google Scholar
    • Export Citation
  • Suga, T., , A. Kato, , and K. Hanawa, 2000: North Pacific Tropical Water: Its climatology and temporal changes associated with the climate regime shift in the 1970s. Prog. Oceanogr., 47 , 223256.

    • Search Google Scholar
    • Export Citation
  • Tailleux, R., , A. Lazar, , and C. J. C. Reason, 2005: Physics and dynamics of density-compensated temperature and salinity anomalies. Part I: Theory. J. Phys. Oceanogr., 35 , 849864.

    • Search Google Scholar
    • Export Citation
  • Vallis, G. K., 2006: Atmospheric and Oceanic Fluid Dynamics. Cambridge University Press, 745 pp.

  • Veronis, G., 1972: On properties of seawater defined by temperature, salinity, and pressure. J. Mar. Res., 30 , 227255.

  • Williams, P. D., , E. Guilyardi, , R. Sutton, , J. Gregory, , and G. Madec, 2007: A new feedback on climate change from the hydrological cycle. Geophys. Res. Lett., 34 , L08706. doi:10.1029/2007GL029275.

    • Search Google Scholar
    • Export Citation
  • Yeager, S. G., , and W. G. Large, 2004: Late-winter generation of spiciness on subducted isopycnals. J. Phys. Oceanogr., 34 , 15281547.

  • Yeager, S. G., , and W. G. Large, 2007: Observational evidence of winter spice injection. J. Phys. Oceanogr., 37 , 28952919.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 75 75 7
PDF Downloads 49 49 11

Generation of Low-Frequency Spiciness Variability in the Thermocline

View More View Less
  • 1 Department of Oceanography, and International Pacific Research Center, University of Hawaii at Manoa, Honolulu, Hawaii
  • | 2 School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

The generation of variance by anomalous advection of a passive tracer in the thermocline is investigated using the example of density-compensated temperature and salinity anomalies, or spiciness. A coupled Markov model is developed in which wind stress curl forces the large-scale baroclinic ocean pressure that in turn controls the anomalous geostrophic advection of spiciness. The “double integration” of white noise atmospheric forcing by this Markov model results in a frequency (ω) spectrum of large-scale spiciness proportional to ω−4, so that spiciness variability is concentrated at low frequencies.

An eddy-permitting regional model hindcast of the northeast Pacific (1950–2007) confirms that time series of large-scale spiciness variability are exceptionally smooth, with frequency spectra ∝ ω−4 for frequencies greater than 0.2 cpy. At shorter spatial scales (wavelengths less than ∼500 km), the spiciness frequency spectrum is whitened by mesoscale eddies, but this eddy-forced variability can be filtered out by spatially averaging. Large-scale and long-term measurements are needed to observe the variance of spiciness or any other passive tracer subject to anomalous advection in the thermocline.

Corresponding author address: Thomas Kilpatrick, Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI 96822. Email: thomaski@hawaii.edu

Abstract

The generation of variance by anomalous advection of a passive tracer in the thermocline is investigated using the example of density-compensated temperature and salinity anomalies, or spiciness. A coupled Markov model is developed in which wind stress curl forces the large-scale baroclinic ocean pressure that in turn controls the anomalous geostrophic advection of spiciness. The “double integration” of white noise atmospheric forcing by this Markov model results in a frequency (ω) spectrum of large-scale spiciness proportional to ω−4, so that spiciness variability is concentrated at low frequencies.

An eddy-permitting regional model hindcast of the northeast Pacific (1950–2007) confirms that time series of large-scale spiciness variability are exceptionally smooth, with frequency spectra ∝ ω−4 for frequencies greater than 0.2 cpy. At shorter spatial scales (wavelengths less than ∼500 km), the spiciness frequency spectrum is whitened by mesoscale eddies, but this eddy-forced variability can be filtered out by spatially averaging. Large-scale and long-term measurements are needed to observe the variance of spiciness or any other passive tracer subject to anomalous advection in the thermocline.

Corresponding author address: Thomas Kilpatrick, Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI 96822. Email: thomaski@hawaii.edu

Save