• Abernathey, R., and C. Wortham, 2015: Phase speed cross spectra of eddy heat fluxes in the eastern Pacific. J. Phys. Oceanogr., 45, 12851301, doi:10.1175/JPO-D-14-0160.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ait-Chaalal, F., and T. Schneider, 2015: Why eddy momentum fluxes are concentrated in the upper troposphere. J. Atmos. Sci., 72, 15851604, doi:10.1175/JAS-D-14-0243.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ambaum, M. H. P., and L. Novak, 2014: A nonlinear oscillator describing storm track variability. Quart. J. Roy. Meteor. Soc., 140, 26802684, doi:10.1002/qj.2352.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Andrews, D. G., and M. E. McIntyre, 1976: Planetary waves in horizontal and vertical shear: The generalized Eliassen-Palm relation and the mean zonal acceleration. J. Atmos. Sci., 33, 20312048, doi:10.1175/1520-0469(1976)033<2031:PWIHAV>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Andrews, D. G., J. R. Holton, and C. B. Leovy, 1987: Middle Atmosphere Dynamics. International Geophysics Series, Vol. 40, Academic Press, 489 pp.

  • Chang, E. K. M., 2005: The role of wave packets in wave–mean flow interactions during Southern Hemisphere summer. J. Atmos. Sci., 62, 24672483, doi:10.1175/JAS3491.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chang, E. K. M., 2006: An idealized nonlinear model of the Northern Hemisphere winter storm tracks. J. Atmos. Sci., 63, 18181839, doi:10.1175/JAS3726.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chang, E. K. M., and I. Orlanski, 1993: On the dynamics of a storm track. J. Atmos. Sci., 50, 9991015, doi:10.1175/1520-0469(1993)050<0999:OTDOAS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Charney, J. G., 1947: The dynamics of long waves in a baroclinic westerly current. J. Meteor., 4, 136162, doi:10.1175/1520-0469(1947)004<0136:TDOLWI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Charney, J. G., and P. G. Drazin, 1961: Propagation of planetary-scale disturbances from the lower into the upper atmosphere. J. Geophys. Res., 66, 83109, doi:10.1029/JZ066i001p00083.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Charney, J. G., and M. E. Stern, 1962: On the stability of internal baroclinic jets in a rotating atmosphere. J. Atmos. Sci., 19, 159172, doi:10.1175/1520-0469(1962)019<0159:OTSOIB>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, T.-C., M.-C. Yen, and D. P. Nune, 1987: Dynamic aspects of the Southern-Hemisphere medium-scale waves during the southern summer season. J. Meteor. Soc. Japan, 65, 401421.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dee, D. P., and et al. , 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553597, doi:10.1002/qj.828.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Eady, E. T., 1949: Long waves and cyclone waves. Tellus, 1, 3352, doi:10.1111/j.2153-3490.1949.tb01265.x.

  • Held, I. M., 1985: Pseudomomentum and the orthogonality of modes in shear flows. J. Atmos. Sci., 42, 22802288, doi:10.1175/1520-0469(1985)042<2280:PATOOM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Held, I. M., and M. J. Suarez, 1994: A proposal for the intercomparison of the dynamical cores of atmospheric general circulation models. Bull. Amer. Meteor. Soc., 75, 18251830, doi:10.1175/1520-0477(1994)075<1825:APFTIO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Held, I. M., and T. Schneider, 1999: The surface branch of the zonally averaged mass transport circulation in the troposphere. J. Atmos. Sci., 56, 16881697, doi:10.1175/1520-0469(1999)056<1688:TSBOTZ>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Herman, A., 2015: Trends and variability of the atmosphere–ocean turbulent heat flux in the extratropical Southern Hemisphere. Sci. Rep., 5, 14900, doi:10.1038/srep14900.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., and K. I. Hodges, 2005: A new perspective on Southern Hemisphere storm tracks. J. Climate, 18, 41084129, doi:10.1175/JCLI3570.1.

  • Huang, C. S. Y., and N. Nakamura, 2016: Local finite-amplitude wave activity as a diagnostic of anomalous weather events. J. Atmos. Sci., 73, 211229, doi:10.1175/JAS-D-15-0194.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lachmy, O., and N. Harnik, 2014: The transition to a subtropical jet regime and its maintenance. J. Atmos. Sci., 71, 13891409, doi:10.1175/JAS-D-13-0125.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lee, R. W., 2014: Storm track biases and changes in a warming climate from an extratropical cyclone perspective using CMIP5. Ph.D. thesis, University of Reading. [Available online at https://rdg.ent.sirsidynix.net.uk/client/en_GB/library/search/detailnonmodal/ent:$002f$002fSD_ILS$002f1565$002fSD_ILS:1565689/ada?qu=robert+lee&lm=EXCL_LR2.]

  • Lee, S., and I. M. Held, 1993: Baroclinic wave packets in models and observations. J. Atmos. Sci., 50, 14131428, doi:10.1175/1520-0469(1993)050<1413:BWPIMA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lee, S., and H. Kim, 2003: The dynamical relationship between subtropical and eddy-driven jets. J. Atmos. Sci., 60, 14901503, doi:10.1175/1520-0469(2003)060<1490:TDRBSA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lindzen, R. S., B. Farrell, and D. Jacqmin, 1982: Vacillations due to wave interference: Applications to the atmosphere and to annulus experiments. J. Atmos. Sci., 39, 1423, doi:10.1175/1520-0469(1982)039<0014:VDTWIA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lorenz, D. J., 2014: Understanding midlatitude jet variability and change using Rossby wave chromatography: Poleward-shifted jets in response to external forcing. J. Atmos. Sci., 71, 23702389, doi:10.1175/JAS-D-13-0200.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lorenz, D. J., and D. L. Hartmann, 2001: Eddy–zonal flow feedback in the Southern Hemisphere. J. Atmos. Sci., 58, 33123327, doi:10.1175/1520-0469(2001)058<3312:EZFFIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lorenz, E. N., 1955: Available potential energy and the maintenance of the general circulation. Tellus, 7, 157167, doi:10.1111/j.2153-3490.1955.tb01148.x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McGraw, M., and E. A. Barnes, 2016: Seasonal sensitivity of the eddy-driven jet to tropospheric heating in an idealized AGCM. J. Climate, 29, 52235240, doi:10.1175/JCLI-D-15-0723.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nakamura, H., and A. Shimpo, 2004: Seasonal variations in the Southern Hemisphere storm tracks and jet streams as revealed in a reanalysis dataset. J. Climate, 17, 18281844, doi:10.1175/1520-0442(2004)017<1828:SVITSH>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nakamura, N., and A. Solomon, 2010: Finite-amplitude wave activity and mean flow adjustments in the atmospheric general circulation. Part I: Quasigeostrophic theory and analysis. J. Atmos. Sci., 67, 39673983, doi:10.1175/2010JAS3503.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nakamura, N., and D. Zhu, 2010: Finite-amplitude wave activity and diffusive flux of potential vorticity in eddy–mean flow interaction. J. Atmos. Sci., 67, 27012716, doi:10.1175/2010JAS3432.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1964: The stability of currents in the atmosphere and the ocean: Part I. J. Atmos. Sci., 21, 201219, doi:10.1175/1520-0469(1964)021<0201:TSOCIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1970: Finite-amplitude baroclinic waves. J. Atmos. Sci., 27, 1530, doi:10.1175/1520-0469(1970)027<0015:FABW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pedlosky, J., 1971: Finite-amplitude baroclinic waves with small dissipation. J. Atmos. Sci., 28, 587597, doi:10.1175/1520-0469(1971)028<0587:FABWWS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Plumb, R. A., 1983: A new look at the energy cycle. J. Atmos. Sci., 40, 16691688, doi:10.1175/1520-0469(1983)040<1669:ANLATE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Randel, W. J., and J. L. Stanford, 1985: An observational study of medium-scale wave dynamics in the Southern Hemisphere summer. Part I: Wave structure and energetics. J. Atmos. Sci., 42, 11721188, doi:10.1175/1520-0469(1985)042<1172:AOSOMS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Randel, W. J., and I. M. Held, 1991: Phase speed spectra of transient eddy fluxes and critical layer absorption. J. Atmos. Sci., 48, 688697, doi:10.1175/1520-0469(1991)048<0688:PSSOTE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ring, M. J., and R. A. Plumb, 2007: Forced annular mode patterns in a simple atmospheric general circulation model. J. Atmos. Sci., 64, 36113626, doi:10.1175/JAS4031.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rotunno, R., and M. Fantini, 1989: Petterssen’s “type B” cyclogenesis in terms of discrete, neutral Eady modes. J. Atmos. Sci., 46, 35993604, doi:10.1175/1520-0469(1989)046<3599:PBITOD>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Salby, M. L., 1982: A ubiquitous wavenumber-5 anomaly in the Southern Hemisphere during FGGE. Mon. Wea. Rev., 110, 17121721, doi:10.1175/1520-0493(1982)110<1712:AUWAIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schneider, T., P. A. O’Gorman, and X. J. Levine, 2010: Water vapor and the dynamics of climate changes. Rev. Geophys., 48, RG3001, doi:10.1029/2009RG000302.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Swanson, K. L., and R. T. Pierrehumbert, 1997: Lower-tropospheric heat transport in the Pacific storm track. J. Atmos. Sci., 54, 15331543, doi:10.1175/1520-0469(1997)054<1533:LTHTIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and E. A. Barnes, 2014: Periodic variability in the large-scale Southern Hemisphere atmospheric circulation. Science, 343, 641645, doi:10.1126/science.1247660.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and Y. Li, 2014: Baroclinic and barotropic annular variability in the Northern Hemisphere. J. Atmos. Sci., 72, 11171136, doi:10.1175/JAS-D-14-0104.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and J. D. Woodworth, 2014: Barotropic and baroclinic annular variability in the Southern Hemisphere. J. Atmos. Sci., 71, 14801493, doi:10.1175/JAS-D-13-0185.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, L., and N. Nakamura, 2015: Covariation of finite-amplitude wave activity and the zonal mean flow in the midlatitude troposphere: 1. Theory and application to the Southern Hemisphere summer. Geophys. Res. Lett., 42, 81928200, doi:10.1002/2015GL065830.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Webster, P. J., and J. L. Keller, 1974: Strong long-period tropospheric and stratospheric rhythm in the Southern Hemisphere. Nature, 248, 212213, doi:10.1038/248212a0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Webster, P. J., and J. L. Keller, 1975: Atmospheric variations: Vacillations and index cycles. J. Atmos. Sci., 32, 12831301, doi:10.1175/1520-0469(1975)032<1283:AVVAIC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yamada, R., and O. Pauluis, 2016: Momentum balance and Eliassen–Palm flux on moist isentropic surfaces. J. Atmos. Sci., 73, 12931314, doi:10.1175/JAS-D-15-0229.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 51 51 10
PDF Downloads 40 40 9

Covariation of Finite-Amplitude Wave Activity and the Zonal-Mean Flow in the Midlatitude Troposphere. Part II: Eddy Forcing Spectra and the Periodic Behavior in the Southern Hemisphere Summer

View More View Less
  • 1 University of Chicago, Chicago, Illinois
© Get Permissions
Restricted access

Abstract

Previously, in Part I of this study, the authors used latitude-by-latitude budgets of the vertically integrated finite-amplitude wave activity (FAWA) to describe the covariation of the zonal-mean state and eddy amplitude. In the austral summer within 40°–55°S, FAWA exhibits a marked 20–30-day periodicity driven mainly by the low-level meridional eddy heat flux, consistent with the recently identified baroclinic annular mode (BAM).

The present article examines the spectra of eddy heat flux that produce the periodic behavior in the Southern Hemisphere storm track. Analysis of the ERA-Interim product reveals that the 20–30-day periodicity in raw FAWA and eddy heat flux is particularly robust during the warm season. A dry GCM is shown to reproduce qualitatively BAM-like eddy heat flux spectra if the zonal-mean state resembles that of the austral summer and if the surface thermal damping is sufficiently strong. The observed eddy heat flux cospectra in summer contain a few dominant frequencies for each of the energy-containing zonal wavenumbers (4–6). The corresponding Fourier modes are heat transporting but neutral, with slightly different meridional structures. As these modes travel at different phase speeds they interfere with each other and produce an amplitude modulation to the eddy heat flux with a periodicity consistent with the BAM. The meridionally confined baroclinic zone in the mean state of the austral summer provides a waveguide that directs the mode propagation and interference along the latitude circle. However, the processes that give rise to the quasi-discrete Fourier modes remain to be identified.

© 2016 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author address: Noboru Nakamura, Department of the Geophysical Sciences, University of Chicago, 5734 S. Ellis Avenue, Chicago, IL 60637. E-mail: nnn@uchicago.edu

Abstract

Previously, in Part I of this study, the authors used latitude-by-latitude budgets of the vertically integrated finite-amplitude wave activity (FAWA) to describe the covariation of the zonal-mean state and eddy amplitude. In the austral summer within 40°–55°S, FAWA exhibits a marked 20–30-day periodicity driven mainly by the low-level meridional eddy heat flux, consistent with the recently identified baroclinic annular mode (BAM).

The present article examines the spectra of eddy heat flux that produce the periodic behavior in the Southern Hemisphere storm track. Analysis of the ERA-Interim product reveals that the 20–30-day periodicity in raw FAWA and eddy heat flux is particularly robust during the warm season. A dry GCM is shown to reproduce qualitatively BAM-like eddy heat flux spectra if the zonal-mean state resembles that of the austral summer and if the surface thermal damping is sufficiently strong. The observed eddy heat flux cospectra in summer contain a few dominant frequencies for each of the energy-containing zonal wavenumbers (4–6). The corresponding Fourier modes are heat transporting but neutral, with slightly different meridional structures. As these modes travel at different phase speeds they interfere with each other and produce an amplitude modulation to the eddy heat flux with a periodicity consistent with the BAM. The meridionally confined baroclinic zone in the mean state of the austral summer provides a waveguide that directs the mode propagation and interference along the latitude circle. However, the processes that give rise to the quasi-discrete Fourier modes remain to be identified.

© 2016 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author address: Noboru Nakamura, Department of the Geophysical Sciences, University of Chicago, 5734 S. Ellis Avenue, Chicago, IL 60637. E-mail: nnn@uchicago.edu
Save