• Ambaum, M. H. P., and B. J. Hoskins, 2002: The NAO troposphere–stratosphere connection. J. Climate, 15 , 19691978.

  • Anderson, J. R., and R. D. Rosen, 1983: The latitude–height structure of 40–50 day variations in the atmospheric angular momentum. J. Atmos. Sci., 40 , 15841591.

    • Search Google Scholar
    • Export Citation
  • Andrews, D. G., 1983: A finite-amplitude Eliassen–Palm theorem in isentropic coordinates. J. Atmos. Sci., 40 , 18771883.

  • Baldwin, M. P., and T. J. Dunkerton, 1999: Propagation of the Arctic Oscillation from the stratosphere to the troposphere. J. Geophys. Res., 104 , 3093730946.

    • Search Google Scholar
    • Export Citation
  • Baldwin, M. P., and T. J. Dunkerton, 2001: Stratospheric harbingers of anomalous weather regimes. Science, 294 , 581584.

  • Baldwin, M. P., D. B. Stephenson, D. W. J. Thompson, T. J. Dunkerton, A. J. Charlton, and A. O’Neill, 2003: Stratospheric memory and extended-range weather forecasts. Science, 301 , 636640.

    • Search Google Scholar
    • Export Citation
  • Black, R. X., 2002: Stratospheric forcing of surface climate in the Arctic Oscillation. J. Climate, 15 , 268277.

  • Cai, M., 2003: Potential vorticity intrusion index and climate variability of surface temperature. Geophys. Res. Lett., 30 .1119, doi:10.1029/2002GL015926.

    • Search Google Scholar
    • Export Citation
  • Cai, M., and R-C. Ren, 2006: 40–70 day meridional propagation of global circulation anomalies. Geophys. Res. Lett., 33 .L06818, doi:10.1029/2005GL025024.

    • Search Google Scholar
    • Export Citation
  • Coughlin, K., and K. K. Tung, 2005: Tropospheric wave response to decelerated stratosphere seen as downward propagation in northern annular mode. J. Geophys. Res., 110 .D01103, doi:10.1029/2004JD004661.

    • Search Google Scholar
    • Export Citation
  • Davies, H. C., and A. M. Rossa, 1998: PV frontogenesis and upper-tropospheric fronts. Mon. Wea. Rev., 126 , 15281539.

  • Dunkerton, T. J., 2000: Midwinter deceleration of the subtropical mesospheric jet and interannual variability of the high-latitude flow in UKMO analyses. J. Atmos. Sci., 57 , 38383855.

    • Search Google Scholar
    • Export Citation
  • Feldstein, S., and S. Lee, 1998: Is the atmospheric zonal index driven by an eddy feedback? J. Atmos. Sci., 55 , 30773086.

  • Hartley, D. E., J. T. Villarin, R. X. Black, and C. A. Davis, 1998: A new perspective on the dynamical link between the stratosphere and troposphere. Nature, 391 , 471474.

    • Search Google Scholar
    • Export Citation
  • Haynes, P., 2005: Stratospheric dynamics. Annu. Rev. Fluid Mech., 37 , 263293.

  • Holton, J. R., P. H. Haynes, M. E. McIntyre, A. R. Douglass, R. B. Rood, and L. Pfister, 1995: Stratosphere-troposphere exchange. Rev. Geophys., 33 , 403439.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., 1997: A potential vorticity view of synoptic development. Meteor. Appl., 4 , 325334.

  • Hoskins, B. J., M. E. McIntyre, and A. W. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc., 111 , 877946.

    • Search Google Scholar
    • Export Citation
  • Johnson, D. R., 1989: The forcing and maintenance of global monsoonal circulations: An isentropic analysis. Advances in Geophysics, Vol. 31, Academic Press, 43–316.

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

  • Kistler, R., and Coauthors, 2001: The NCEP/NCAR 50-Year Reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82 , 247267.

    • Search Google Scholar
    • Export Citation
  • Kodera, K., and Y. Kuroda, 1990: Downward propagation of upper stratospheric mean zonal wind perturbation to the troposphere. Geophys. Res. Lett., 17 , 12631266.

    • Search Google Scholar
    • Export Citation
  • Kodera, K., Y. Kuroda, and S. Pawson, 2000: Stratospheric sudden warmings and slowly propagating zonal-mean wind anomalies. J. Geophys. Res., 105 , 1235112359.

    • Search Google Scholar
    • Export Citation
  • Kuroda, Y., 2002: Relationship between the Polar-Night Jet Oscillation and the Annular Mode. Geophys. Res. Lett., 29 .1240, doi:10.1029/2001GL013933.

    • Search Google Scholar
    • Export Citation
  • Limpasuvan, V., and D. L. Hartmann, 2000: Wave-maintained annular modes of climate variability. J. Climate, 13 , 44144429.

  • Limpasuvan, V., D. W. J. Thompson, and D. Hartmann, 2004: The life cycle of the Northern Hemisphere sudden stratospheric warmings. J. Climate, 17 , 25842596.

    • Search Google Scholar
    • Export Citation
  • Morgan, M. C., and J. W. Nielsen-Gammon, 1998: Using tropopause maps to diagnose midlatitude weather systems. Mon. Wea. Rev., 126 , 25552579.

    • Search Google Scholar
    • Export Citation
  • Namias, J., 1950: The index cycle and its role in the general circulation. J. Meteor., 7 , 130139.

  • Newton, C. W., and E. O. Holopainen, 1990: Extratropical Cyclones: The Erik Palmén Memorial Volume. Amer. Meteor. Soc., 262 pp.

  • Norton, W. A., 1994: Breaking Rossby waves in a model stratosphere diagnosed by a vortex-following coordinate system and a technique for advecting material contours. J. Atmos. Sci., 51 , 654673.

    • Search Google Scholar
    • Export Citation
  • Palmén, E., and C. W. Newton, 1969: Atmospheric Circulation Systems: Their Structure and Physical Interpretation. Academic Press, 603 pp.

    • Search Google Scholar
    • Export Citation
  • Perlwitz, J., and N. Harnik, 2003: Observational evidence of a stratosphere influence on the troposphere by planetary wave reflection. J. Climate, 16 , 30113026.

    • Search Google Scholar
    • Export Citation
  • Reed, R. J., 1955: A study of a characteristic type of upper-level frontogenesis. J. Meteor., 12 , 226236.

  • Reed, R. J., and F. Sanders, 1953: An investigation of the development of a mid-tropospheric frontal zone and its associated vorticity field. J. Meteor., 10 , 338349.

    • Search Google Scholar
    • Export Citation
  • Ren, R-C., and M. Cai, 2006: Polar vortex oscillation viewed in an isentropic potential vorticity coordinate. Adv. Atmos. Sci., 23 , 884900.

    • Search Google Scholar
    • Export Citation
  • Sanders, F., 1955: An investigation of the structure and dynamics of an intense surface frontal zone. J. Meteor., 12 , 542552.

  • Schneider, T., 2006: The general circulation of the atmosphere. Annu. Rev. Earth Planet. Sci., 34 , 655688.

  • Shapiro, M. A., and D. A. Keyser, 1990: Fronts, jet streams and the tropopause. Extratropical Cyclones: The Erik Palmén Memorial Volume, C. W. Newton and E. O. Holopainen, Eds., Amer. Meteor. Soc., 167–191.

    • Search Google Scholar
    • Export Citation
  • Shapiro, M. A., and S. Crønås, 1999: The Life Cycles of Extratropical Cyclones. Amer. Meteor. Soc., 359 pp.

  • Shepherd, T. G., 2002: Issues in stratosphere-troposphere coupling. J. Meteor. Soc. Japan, 80 , 769792.

  • Song, Y., and W. A. Robinson, 2004: Dynamical mechanisms of stratosphere influences on the troposphere. J. Atmos. Sci., 61 , 17111725.

    • Search Google Scholar
    • Export Citation
  • Stan, C., and D. A. Randall, 2007: Potential vorticity as meridional coordinate. J. Atmos. Sci., 64 , 621633.

  • Thompson, D. W. J., and J. M. Wallace, 1998: The Arctic Oscillation signature in the wintertime geopotential height and temperature fields. Geophys. Res. Lett., 25 , 12971300.

    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and J. M. Wallace, 2001: Regional climate impacts of the Northern Hemisphere annular mode and associated climate trends. Science, 293 , 8589.

    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and D. J. Lorenz, 2004: The signature of the annular modes in the tropical troposphere. J. Climate, 17 , 43304342.

    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., M. P. Baldwin, and J. M. Wallace, 2002: Stratospheric connection to Northern Hemisphere wintertime weather: Implications for prediction. J. Climate, 15 , 14211428.

    • Search Google Scholar
    • Export Citation
  • Tung, K. K., and H. Yang, 1994: Global QBO in circulation and ozone. Part I: Reexamination of observational evidence. J. Atmos. Sci., 51 , 26992707.

    • Search Google Scholar
    • Export Citation
  • Zhou, S. T., A. J. Miller, and J. K. Angell, 2002: Downward-propagating temperature anomalies in the preconditioned polar stratosphere. J. Climate, 15 , 781792.

    • Search Google Scholar
    • Export Citation
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Meridional and Downward Propagation of Atmospheric Circulation Anomalies. Part I: Northern Hemisphere Cold Season Variability

Ming CaiDepartment of Meteorology, The Florida State University, Tallahassee, Florida

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R-C. RenDepartment of Meteorology, The Florida State University, Tallahassee, Florida, and LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

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Abstract

The Northern Hemisphere cold season circulation anomalies are diagnosed in a semi-Lagrangian θPVLAT (potential vorticity surfaces as latitudes) coordinate by following contours of the daily potential vorticity (PV) field on isentropic (θ) surfaces using the NCEP–NCAR reanalysis II dataset from 1979 to 2003. It is found that circulation anomalies propagate poleward and downward simultaneously in the stratosphere and equatorward in the extratropical troposphere. On average, it takes about 40 days for warm anomalies and 70 days for cold anomalies to travel from the equator to the Pole. The beginning of the equatorward propagation of the tropospheric temperature anomalies coincides with the arrival of the poleward and downward propagating temperature anomalies of the opposite sign over the polar stratosphere. Accompanied with warm (cold) anomalies is a successive leveling (steepening) of isentropic surfaces propagating poleward and downward. The zonal wind anomalies follow the poleward and downward propagating temperature anomalies of the opposite sign.

A global mass circulation paradigm is proposed to qualitatively explain the simultaneous meridional and downward propagation of circulation anomalies that appears responsible for the annular mode variability. The meridional propagation of circulation anomalies can be viewed as an intensity variation of the zonally averaged isentropic mass circulation. When the mass circulation is weaker, the isentropic surfaces in the extratropical stratosphere (troposphere) are steeply (gently) sloped, corresponding to the positive phase of the annular mode. The cold air mass is effectively imprisoned within the polar cap when the mass circulation is weaker, responsible for warm surface temperature anomalies prevailing in the extratropics. Meanwhile, the weaker mass circulation also implies a temporary reduction of airmass supply over the polar cap, leading to a negative surface pressure anomaly. The warm anomalies brought by the stronger mass circulation cause a lowering of isentropic surfaces in the polar stratosphere, resulting in more gently sloped isentropic surfaces in the extratropical stratosphere. This corresponds to the negative phase of the annular mode in which the meridional temperature gradient in the extratropical stratosphere is weaker, accompanied with a weakened polar jet and a falling of the tropopause. The stronger warm air branch of the mass circulation aloft requires a strengthening of the compensating equatorward advancement of the surface air mass, causing massive cold air outbreaks in the extratropics. The more air mass aloft brought by the stronger mass circulation contributes to a rising of the surface pressure over the polar cap till the surface cold air moves out. This explains why the surface pressure anomalies in high latitudes are positive during the negative phase of the annular mode.

The well-known apparent downward propagation of geopotential height and zonal wind anomalies into the troposphere from the stratosphere in the polar region can be explained as the local dynamic PV response to the arrival of the simultaneous poleward/downward propagating heating anomalies in the polar stratosphere and the compensating equatorward propagating tropospheric heating anomalies of the opposite sign, rather than suggesting the stratospheric origin of the anomalies. The apparent equivalent barotropic structure of the annular mode mainly results from the dynamic response to the heating anomaly that has an opposite polarity between the stratosphere and lower troposphere.

Corresponding author address: Ming Cai, Department of Meteorology, The Florida State University, Tallahassee, FL 32306. Email: cai@met.fsu.edu

Abstract

The Northern Hemisphere cold season circulation anomalies are diagnosed in a semi-Lagrangian θPVLAT (potential vorticity surfaces as latitudes) coordinate by following contours of the daily potential vorticity (PV) field on isentropic (θ) surfaces using the NCEP–NCAR reanalysis II dataset from 1979 to 2003. It is found that circulation anomalies propagate poleward and downward simultaneously in the stratosphere and equatorward in the extratropical troposphere. On average, it takes about 40 days for warm anomalies and 70 days for cold anomalies to travel from the equator to the Pole. The beginning of the equatorward propagation of the tropospheric temperature anomalies coincides with the arrival of the poleward and downward propagating temperature anomalies of the opposite sign over the polar stratosphere. Accompanied with warm (cold) anomalies is a successive leveling (steepening) of isentropic surfaces propagating poleward and downward. The zonal wind anomalies follow the poleward and downward propagating temperature anomalies of the opposite sign.

A global mass circulation paradigm is proposed to qualitatively explain the simultaneous meridional and downward propagation of circulation anomalies that appears responsible for the annular mode variability. The meridional propagation of circulation anomalies can be viewed as an intensity variation of the zonally averaged isentropic mass circulation. When the mass circulation is weaker, the isentropic surfaces in the extratropical stratosphere (troposphere) are steeply (gently) sloped, corresponding to the positive phase of the annular mode. The cold air mass is effectively imprisoned within the polar cap when the mass circulation is weaker, responsible for warm surface temperature anomalies prevailing in the extratropics. Meanwhile, the weaker mass circulation also implies a temporary reduction of airmass supply over the polar cap, leading to a negative surface pressure anomaly. The warm anomalies brought by the stronger mass circulation cause a lowering of isentropic surfaces in the polar stratosphere, resulting in more gently sloped isentropic surfaces in the extratropical stratosphere. This corresponds to the negative phase of the annular mode in which the meridional temperature gradient in the extratropical stratosphere is weaker, accompanied with a weakened polar jet and a falling of the tropopause. The stronger warm air branch of the mass circulation aloft requires a strengthening of the compensating equatorward advancement of the surface air mass, causing massive cold air outbreaks in the extratropics. The more air mass aloft brought by the stronger mass circulation contributes to a rising of the surface pressure over the polar cap till the surface cold air moves out. This explains why the surface pressure anomalies in high latitudes are positive during the negative phase of the annular mode.

The well-known apparent downward propagation of geopotential height and zonal wind anomalies into the troposphere from the stratosphere in the polar region can be explained as the local dynamic PV response to the arrival of the simultaneous poleward/downward propagating heating anomalies in the polar stratosphere and the compensating equatorward propagating tropospheric heating anomalies of the opposite sign, rather than suggesting the stratospheric origin of the anomalies. The apparent equivalent barotropic structure of the annular mode mainly results from the dynamic response to the heating anomaly that has an opposite polarity between the stratosphere and lower troposphere.

Corresponding author address: Ming Cai, Department of Meteorology, The Florida State University, Tallahassee, FL 32306. Email: cai@met.fsu.edu

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