• Ambaum, M. H., 2008: Unimodality of wave amplitude in the Northern Hemisphere. J. Atmos. Sci., 65 , 10771086.

  • Anstey, J. A., and T. G. Shepherd, 2008: Response of the northern stratospheric polar vortex to the seasonal alignment of QBO phase transitions. Geophys. Res. Lett., 35 , L22810. doi:10.1029/2008GL035721.

    • Search Google Scholar
    • Export Citation
  • Baldwin, M. P., and T. J. Dunkerton, 1998: Biennial, quasi-biennial, and decadal oscillations of potential vorticity in the northern stratosphere. J. Geophys. Res., 103 , 39193928.

    • Search Google Scholar
    • Export Citation
  • Baldwin, M. P., and Coauthors, 2001: The quasi-biennial oscillation. Rev. Geophys., 39 , 179229.

  • Christiansen, B., 2000: Chaos, quasi-periodicity and interannual variability: Studies of a stratospheric vacillation model. J. Atmos. Sci., 57 , 31613173.

    • Search Google Scholar
    • Export Citation
  • Christiansen, B., 2002: On the physical nature of the Arctic Oscillation. Geophys. Res. Lett., 29 , 1805. doi:10.1029/2002GL015208.

  • Christiansen, B., 2003: Evidence for nonlinear climate change: Two stratospheric regimes and a regime shift. J. Climate, 16 , 36813689.

    • Search Google Scholar
    • Export Citation
  • Christiansen, B., 2005: Bimodality of the planetary-scale atmospheric wave amplitude index. J. Atmos. Sci., 62 , 25282541.

  • Christiansen, B., 2007: Atmospheric circulation regimes: Can cluster analysis provide the number? J. Climate, 20 , 22292250.

  • Christiansen, B., 2009: Is the atmosphere interesting? A projection pursuit study of the circulation in the Northern Hemisphere winter. J. Climate, 22 , 12391254.

    • Search Google Scholar
    • Export Citation
  • Corti, S., S. F. Molteni, and T. N. Palmer, 1999: Signature of recent climate change in frequencies of natural atmospheric circulation regimes. Nature, 398 , 799802.

    • Search Google Scholar
    • Export Citation
  • Coughlin, K., and L. J. Gray, 2009: A continuum of sudden stratospheric warmings. J. Atmos. Sci., 66 , 531540.

  • Dunkerton, T. J., 1990: Annual variation of deseasonalized mean flow acceleration in the equatorial lower stratosphere. J. Meteor. Soc. Japan, 68 , 499508.

    • Search Google Scholar
    • Export Citation
  • Fioletov, V. E., G. E. Bodeker, A. J. Mileer, R. D. McPeters, and R. Stolarski, 2002: Global and zonal total ozone variations estimated from ground-based and satellite measurements: 1964–2000. J. Geophys. Res., 107 , 4647. doi:10.1029/2001JD001350.

    • Search Google Scholar
    • Export Citation
  • Garfinkel, C. I., and D. L. Hartmann, 2007: Effects of the El Niño–Southern Oscillation and the quasi-biennial oscillation on polar temperatures in the stratosphere. J. Geophys. Res., 112 , D19112. doi:10.1029/2007JD008481.

    • Search Google Scholar
    • Export Citation
  • Gray, L. J., 2010: Equatorial dynamics. The Stratosphere: Dynamics, Transport and Chemistry: A Festschrift to Celebrate Alan Plumb’s 60th Birthday, L. Polvani and A. Sobel, Eds., Amer. Geophys. Union.

    • Search Google Scholar
    • Export Citation
  • Gray, L. J., and T. J. Dunkerton, 1990: The role of the seasonal cycle in the quasi-biennial oscillation of ozone. J. Atmos. Sci., 47 , 24292451.

    • Search Google Scholar
    • Export Citation
  • Gray, L. J., S. A. Crooks, C. L. Pascoe, S. Sparrow, and M. Palmer, 2004: Solar and QBO influences on the timing of stratospheric sudden warmings. J. Atmos. Sci., 61 , 27772796.

    • Search Google Scholar
    • Export Citation
  • Hampson, J., and P. Haynes, 2006: Influence of the equatorial QBO on the extratropical stratosphere. J. Atmos. Sci., 63 , 936951.

  • Hannachi, A., 2007: Tropospheric planetary wave dynamics and mixture modeling: Two preferred regimes and a regime shift. J. Atmos. Sci., 64 , 35213541.

    • Search Google Scholar
    • Export Citation
  • Holton, J. R., and H-C. Tan, 1980: The influence of the equatorial quasi-biennial oscillation on the global circulation at 50 mb. J. Atmos. Sci., 37 , 22002208.

    • Search Google Scholar
    • Export Citation
  • Hsu, C. J., and F. Zwiers, 2001: Climate change in recurrent regimes and modes of Northern Hemisphere atmospheric variability. J. Geophys. Res., 106 , 2014520159.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Labitzke, K., 1987: Sunspots, the QBO, and the stratospheric temperature in the north polar region. Geophys. Res. Lett., 14 , 535537.

  • Lenton, T. M., H. Held, E. Kriegler, J. W. Hall, W. Lucht, S. Rahmstorf, and H. J. Schellnhuber, 2008: Tipping elements in the earth’s climate system. Proc. Natl. Acad. Sci. USA, 105 , 17861793.

    • Search Google Scholar
    • Export Citation
  • Lu, H., M. P. Baldwin, L. J. Gray, and M. J. Jarvis, 2008: Decadal-scale changes in the effect of the QBO on the northern stratospheric polar vortex. J. Geophys. Res., 113 , D10114. doi:10.1029/2007JD009647.

    • Search Google Scholar
    • Export Citation
  • Lu, J., and R. J. Greatbatch, 2002: The changing relationship between the NAO and Northern Hemisphere climate variability. Geophys. Res. Lett., 29 , 1148. doi:10.1029/2001GL014052.

    • Search Google Scholar
    • Export Citation
  • Michelangeli, P-A., R. Vautard, and B. Legras, 1995: Weather regimes: Recurrence and quasi stationarity. J. Atmos. Sci., 52 , 12371256.

    • Search Google Scholar
    • Export Citation
  • Mo, K., and M. Ghil, 1988: Cluster analysis of multiple planetary flow regimes. J. Geophys. Res., 93 , 1092710952.

  • Nason, G. P., and R. Sibson, 1992: Measuring multimodality. Stat. Comput., 2 , 153160.

  • Naujokat, B., 1986: An update of the observed quasi-biennial oscillation of the stratospheric winds over the tropics. J. Atmos. Sci., 43 , 18731877.

    • Search Google Scholar
    • Export Citation
  • Palmer, T. N., 1993: A nonlinear dynamical perspective on climate change. Weather, 48 , 314326.

  • Pascoe, C. L., L. J. Gray, S. A. Crooks, M. N. Juckes, and M. P. Baldwin, 2005: The quasi-biennial oscillation: Analysis using ERA-40 data. J. Geophys. Res., 110 , D08105. doi:10.1029/2004JD004941.

    • Search Google Scholar
    • Export Citation
  • Pawson, S., K. Labitzke, R. Lenschow, B. Naujokat, B. Rajewski, M. Wiesner, and R-C. Wohlfart, 1993: Climatology of the Northern Hemisphere stratosphere derived from Berlin analyses. Part 1: Monthly means. Tech. Rep. Series A, Band 7, Heft 3, Institut für Meteorologie der F. U. Berlin, 299 pp.

    • Search Google Scholar
    • Export Citation
  • Schreiber, T., and A. Schmitz, 1997: Discrimination power of measures for nonlinearity in a time series. Phys. Rev. E, 55 , 54435447.

  • Silverman, B. W., 1986: Density Estimation for Statistics and Data Analysis. Chapman and Hall, 175 pp.

  • Smyth, P., K. Ide, and M. Ghil, 1999: Multiple regimes in Northern Hemisphere height fields via mixture model clustering. J. Atmos. Sci., 56 , 37043723.

    • Search Google Scholar
    • Export Citation
  • Stephenson, D. B., A. Hannachi, and A. O’Neill, 2004: On the existence of multiple climate regimes. Quart. J. Roy. Meteor. Soc., 130 , 583605.

    • Search Google Scholar
    • Export Citation
  • Sura, P., M. Newman, C. Penland, and P. D. Sardeshmukh, 2005: Multiplicative noise and non-Gaussianity: A paradigm for atmospheric regimes? J. Atmos. Sci., 62 , 13911409.

    • Search Google Scholar
    • Export Citation
  • Sutera, A., 1986: Probability density distribution of large-scale atmospheric flow. Advances in Geophysics, Vol. 29, Academic Press, 227–249.

    • Search Google Scholar
    • Export Citation
  • Swanson, K. L., and A. A. Tsonis, 2009: Has the climate recently shifted? Geophys. Res. Lett., 36 , L06711. doi:10.1029/2008GL037022.

  • Thejll, P., B. Christiansen, and H. Gleisner, 2003: On correlations between the North Atlantic Oscillation, geopotential heights, and geomagnetic activity. Geophys. Res. Lett., 30 , 1347. doi:10.1029/2002GL016598.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1990: Recent observed interdecadal climate changes in the Northern Hemisphere. Bull. Amer. Meteor. Soc., 71 , 988993.

    • Search Google Scholar
    • Export Citation
  • Uppala, S. M., and Coauthors, 2005: The ERA-40 re-analysis. Quart. J. Roy. Meteor. Soc., 131 , 29613012.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 2 2 2
PDF Downloads 0 0 0

Stratospheric Bimodality: Can the Equatorial QBO Explain the Regime Behavior of the NH Winter Vortex?

View More View Less
  • 1 Danish Meteorological Institute, Copenhagen, Denmark
Restricted access

Abstract

The Northern Hemisphere extended winter mean stratospheric vortex alternates between a strong and a weak state, which is manifested in a statistically significant bimodal distribution. In the end of the 1970s a regime change took place, increasing the frequency of the strong phase relative to the weak phase. This paper investigates the connection between the regime behavior of the vortex and the equatorial quasi-biennial oscillation (QBO) in three different datasets. Although there are some differences between the datasets, they agree regarding the general picture. It is found that stratospheric equatorial wind between 70 and 8 hPa shows a bimodal structure in the Northern Hemisphere winter. Such bimodality is nontrivial as it requires only weak variability in the amplitude. Unimodality is found above 8 hPa, where the semiannual oscillation dominates. A strong coincidence is found between strong (weak) vortex winters and winter in the westerly (easterly) QBO regime. Furthermore, the change of the vortex in the late 1970s can be related to a change in the QBO from a period with strong bimodality to a period with weak bimodality. Careful consideration of the statistical significance shows that this change in the QBO can be a random process simply related to the annual sampling of the QBO. Finally, previous findings of phase locking between the QBO and the annual cycle are considered; it is shown that the phase locking is related to the seasonal variations in the bimodality of the QBO.

Corresponding author address: Bo Christiansen, Danish Meteorological Institute, Danish Climate Centre, Lyngbyvej 100, DK-2100 Copenhagen Ø, Denmark. Email: boc@dmi.dk

Abstract

The Northern Hemisphere extended winter mean stratospheric vortex alternates between a strong and a weak state, which is manifested in a statistically significant bimodal distribution. In the end of the 1970s a regime change took place, increasing the frequency of the strong phase relative to the weak phase. This paper investigates the connection between the regime behavior of the vortex and the equatorial quasi-biennial oscillation (QBO) in three different datasets. Although there are some differences between the datasets, they agree regarding the general picture. It is found that stratospheric equatorial wind between 70 and 8 hPa shows a bimodal structure in the Northern Hemisphere winter. Such bimodality is nontrivial as it requires only weak variability in the amplitude. Unimodality is found above 8 hPa, where the semiannual oscillation dominates. A strong coincidence is found between strong (weak) vortex winters and winter in the westerly (easterly) QBO regime. Furthermore, the change of the vortex in the late 1970s can be related to a change in the QBO from a period with strong bimodality to a period with weak bimodality. Careful consideration of the statistical significance shows that this change in the QBO can be a random process simply related to the annual sampling of the QBO. Finally, previous findings of phase locking between the QBO and the annual cycle are considered; it is shown that the phase locking is related to the seasonal variations in the bimodality of the QBO.

Corresponding author address: Bo Christiansen, Danish Meteorological Institute, Danish Climate Centre, Lyngbyvej 100, DK-2100 Copenhagen Ø, Denmark. Email: boc@dmi.dk

Save