• Betts, A. K., and M. J. Miller, 1986: A new convective adjustment scheme. Part II: Single-column testing using GATE wave, BOMEX, ATEX, and arctic air-mass data sets. Quart. J. Roy. Meteor. Soc., 112 , 693709.

    • Search Google Scholar
    • Export Citation
  • Carr, M. T., and C. S. Bretherton, 2001: Convective momentum transport over the tropical Pacific: Budget estimates. J. Atmos. Sci., 58 , 16731693.

    • Search Google Scholar
    • Export Citation
  • Carvalho, L. M. V., C. Jones, and T. Ambrizzi, 2005: Opposite phases of the Antarctic Oscillation and relationships with intraseasonal and interannual activity in the tropics during the austral summer. J. Climate, 18 , 702718.

    • Search Google Scholar
    • Export Citation
  • Dudhia, J., 1989: Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model. J. Atmos. Sci., 46 , 30773107.

    • Search Google Scholar
    • Export Citation
  • Dudhia, J., 1993: A nonhydrostatic version of the Penn State–NCAR Mesoscale Model: Validation tests and simulation of an Atlantic cyclone and cold front. Mon. Wea. Rev., 121 , 14931513.

    • Search Google Scholar
    • Export Citation
  • Ferranti, L., T. N. Palmer, F. Molteni, and K. Klinker, 1990: Tropical–extratropical interaction associated with the 30–60-day oscillation and its impact on medium and extended range prediction. J. Atmos. Sci., 47 , 21772199.

    • Search Google Scholar
    • Export Citation
  • Frederiksen, J. S., and C. S. Frederiksen, 1997: Mechanisms of the formation of intraseasonal oscillations and Australian monsoon disturbances: The roles of latent heat, barotropic and baroclinic instability. Contrib. Atmos. Phys., 70 , 3956.

    • Search Google Scholar
    • Export Citation
  • Ghil, M., and K. Mo, 1991: Intraseasonal oscillations in the global atmosphere. Part I: Northern Hemisphere and tropics. J. Atmos. Sci., 48 , 752779.

    • Search Google Scholar
    • Export Citation
  • Grell, G. A., J. Dudhia, and D. R. Stauffer, 1995: A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5). NCAR Tech. Note NCAR/TN-398, 117 pp.

    • Search Google Scholar
    • Export Citation
  • Gustafson, W. I., and B. C. Weare, 2004a: MM5 modeling of the Madden–Julian oscillation in the Indian and west Pacific Oceans: Model description and control run results. J. Climate, 17 , 13201337.

    • Search Google Scholar
    • Export Citation
  • Gustafson, W. I., and B. C. Weare, 2004b: MM5 modeling of the Madden–Julian oscillation in the Indian and west Pacific Oceans: Implications of 30–70-day boundary effects on MJO development. J. Climate, 17 , 13381351.

    • Search Google Scholar
    • Export Citation
  • Hoskins, B. J., and G-Y. Yang, 2000: The equatorial response to higher-latitude forcing. J. Atmos. Sci., 57 , 11971213.

  • Hsu, H. H., B. J. Hoskins, and F-F. Jin, 1990: The 1985/86 intraseasonal oscillation and the role of the extratropics. J. Atmos. Sci., 47 , 823839.

    • Search Google Scholar
    • Export Citation
  • Inness, P. M., J. M. Slingo, E. Guilyardi, and J. Cole, 2003: Simulation of the Madden–Julian oscillation in a coupled general circulation model. Part II: The role of the basic state. J. Climate, 16 , 365382.

    • Search Google Scholar
    • Export Citation
  • Janjic, Z. I., 1994: The step-mountain eta coordinate model: Further developments of the convection, viscous sublayer, and turbulence closure schemes. Mon. Wea. Rev., 122 , 927945.

    • Search Google Scholar
    • Export Citation
  • Jones, C., and J-K. E. Schemm, 2000: The influence of intraseasonal variations on medium- to extended-range weather forecasts over South America. Mon. Wea. Rev., 128 , 486494.

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

  • Lau, K-M., and T. J. Philips, 1986: Coherent fluctuations of extratropical geopotential height and tropical convection in intraseasonal time scales. J. Atmos. Sci., 43 , 11641181.

    • Search Google Scholar
    • Export Citation
  • Lau, K-M., and D. E. Waliser, 2005: Intraseasonal Variability in the Atmosphere–Ocean Climate System. Praxis, 436 pp.

  • Liebmann, B., and D. L. Hartmann, 1984: An observational study of tropical–midlatitude interaction on intraseasonal timescales during winter. J. Atmos. Sci., 41 , 33333350.

    • Search Google Scholar
    • Export Citation
  • Lin, H., G. Brunet, and J. Derome, 2007: Intraseasonal variability in a dry atmospheric model. J. Atmos. Sci., 64 , 24222441.

  • Lin, J-L., M. Zhang, and B. Mapes, 2005: Zonal momentum budget of the Madden–Julian oscillation: The source and strength of equivalent linear damping. J. Atmos. Sci., 62 , 21722188.

    • Search Google Scholar
    • Export Citation
  • Madden, R. A., and P. R. Julian, 1971: Detection of a 40–50-day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28 , 702708.

    • Search Google Scholar
    • Export Citation
  • Madden, R. A., and P. R. Julian, 1972: Description of global-scale circulation cells in the tropics with a 40–50-day period. J. Atmos. Sci., 29 , 11091123.

    • Search Google Scholar
    • Export Citation
  • Magnusdottir, G., and P. Haynes, 1996: Wave activity diagnostics applied to baroclinic wave life cycles. J. Atmos. Sci., 53 , 23172353.

    • Search Google Scholar
    • Export Citation
  • Matthews, A. J., 2008: Primary and successive events in the Madden–Julian oscillation. Quart. J. Roy. Meteor. Soc., 134 , 439453.

  • Matthews, A. J., and G. N. Kiladis, 1999: The tropical–extratropical interaction between high-frequency transients and the Madden–Julian oscillation. Mon. Wea. Rev., 127 , 661677.

    • Search Google Scholar
    • Export Citation
  • Matthews, A. J., B. J. Hoskins, and M. Masutani, 2004: The global response to tropical heating in the Madden–Julian oscillation during the northern winter. Quart. J. Roy. Meteor. Soc., 130 , 19912011.

    • Search Google Scholar
    • Export Citation
  • Mlawer, E. J., S. J. Taubman, P. D. Brown, M. J. Jacono, and S. A. Clough, 1997: Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102 , 1666316682.

    • Search Google Scholar
    • Export Citation
  • Mo, K., and R. W. Higgins, 1998: Tropical convection and precipitation regimes in the western United States. J. Climate, 10 , 24042423.

    • Search Google Scholar
    • Export Citation
  • Moncrieff, M. W., and E. Klinker, 1997: Organized convective system in the tropical western Pacific as a process in general circulation models: A TOGA COARE case study. Quart. J. Roy. Meteor. Soc., 123 , 805827.

    • Search Google Scholar
    • Export Citation
  • Ray, P., 2008: The initiation of the Madden–Julian oscillation. Ph.D. thesis, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 186 pp.

  • Ray, P., C. Zhang, J. Dudhia, and S. S. Chen, 2009: A numerical case study on the initiation of the Madden–Julian oscillation. J. Atmos. Sci., 66 , 310331.

    • Search Google Scholar
    • Export Citation
  • Rui, H., and B. Wang, 1990: Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. J. Atmos. Sci., 47 , 357379.

    • Search Google Scholar
    • Export Citation
  • Salby, M. L., and H. H. Hendon, 1994: Planetary-scale circulations in the presence of climatological and wave-induced heating. J. Atmos. Sci., 51 , 23442367.

    • Search Google Scholar
    • Export Citation
  • Schubert, S. D., and C-K. Park, 1991: Low-frequency intraseasonal tropical–extratropical interactions. J. Atmos. Sci., 48 , 629650.

  • Simmons, A. J., J. M. Wallace, and G. W. Branstator, 1983: Barotropic wave propagation and instability, and atmospheric teleconnection patterns. J. Atmos. Sci., 40 , 13631392.

    • Search Google Scholar
    • Export Citation
  • Straus, D. M., and R. S. Lindzen, 2000: Planetary-scale baroclinic instability and the MJO. J. Atmos. Sci., 57 , 36093626.

  • Takaya, K., and H. Nakamura, 1997: A formulation of a wave-activity flux for stationary Rossby waves on a zonally varying basic flow. Geophys. Res. Lett., 24 , 29852988.

    • Search Google Scholar
    • Export Citation
  • Takaya, K., and H. Nakamura, 2001: A formulation of a phase-independent wave-activity flux for stationary and migratory quasigeostrophic eddies on a zonally varying basic flow. J. Atmos. Sci., 58 , 608627.

    • Search Google Scholar
    • Export Citation
  • Webster, P. J., and J. R. Holton, 1982: Cross-equatorial response to middle-latitude forcing in a zonally varying basic state. J. Atmos. Sci., 39 , 722733.

    • Search Google Scholar
    • Export Citation
  • Weickmann, K., and E. Berry, 2009: The tropical Madden–Julian oscillation and the global wind oscillation. Mon. Wea. Rev., 137 , 16011614.

    • Search Google Scholar
    • Export Citation
  • Weickmann, K., G. Kiladis, and P. Sardeshmukh, 1997: The dynamics of intraseasonal atmospheric angular momentum oscillations. J. Atmos. Sci., 54 , 14451461.

    • Search Google Scholar
    • Export Citation
  • Wheeler, M., and H. Hendon, 2004: An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction. Mon. Wea. Rev., 132 , 19171932.

    • Search Google Scholar
    • Export Citation
  • Yano, J-I., R. Blender, C. Zhang, and K. Fraedrich, 2004: 1/f noise and pulse-like events in the tropical atmospheric surface variabilities. Quart. J. Roy. Meteor. Soc., 130 , 16971721.

    • Search Google Scholar
    • Export Citation
  • Zhang, C., 2005: Madden–Julian oscillation. Rev. Geophys., 43 , RG2003. doi:10.1029/2004RG000158.

  • Zhang, C., and M. Dong, 2004: Seasonality in the Madden–Julian oscillation. J. Climate, 17 , 31693180.

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A Case Study of the Mechanics of Extratropical Influence on the Initiation of the Madden–Julian Oscillation

Pallav RayRSMAS, University of Miami, Miami, Florida

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Chidong ZhangRSMAS, University of Miami, Miami, Florida

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Abstract

Mechanisms for extratropical influences on the initiation of the Madden–Julian oscillation (MJO) are investigated using numerical simulations and a global reanalysis product. Previous simulations by a tropical channel model captured the timing and gross features of the initiations of two MJO events and suggested that the initiations were due to influences from the extratropics. In this study, latitudinal transport of momentum from the extratropics is found to be crucial in generating the lower tropospheric westerlies in the tropics associated with the MJO initiation. The diagnoses of the zonal momentum budget for the MJO initiation region revealed that the advection by meridional winds could be important prior to the initiation of the MJO. The time evolution of the wave activity identifies its source over the southern Indian Ocean where it grows by extracting kinetic energy from the mean flow. The time scale of the lateral boundary conditions that is responsible for the MJO initiation is also investigated. The implications of the results and limitations of the approach are discussed.

Corresponding author address: Dr. Pallav Ray, RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149. Email: pray@rsmas.miami.edu

Abstract

Mechanisms for extratropical influences on the initiation of the Madden–Julian oscillation (MJO) are investigated using numerical simulations and a global reanalysis product. Previous simulations by a tropical channel model captured the timing and gross features of the initiations of two MJO events and suggested that the initiations were due to influences from the extratropics. In this study, latitudinal transport of momentum from the extratropics is found to be crucial in generating the lower tropospheric westerlies in the tropics associated with the MJO initiation. The diagnoses of the zonal momentum budget for the MJO initiation region revealed that the advection by meridional winds could be important prior to the initiation of the MJO. The time evolution of the wave activity identifies its source over the southern Indian Ocean where it grows by extracting kinetic energy from the mean flow. The time scale of the lateral boundary conditions that is responsible for the MJO initiation is also investigated. The implications of the results and limitations of the approach are discussed.

Corresponding author address: Dr. Pallav Ray, RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149. Email: pray@rsmas.miami.edu

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