• Alexander, M. J., and T. J. Dunkerton, 1999: A spectral parameterization of mean-flow forcing due to breaking gravity waves. J. Atmos. Sci., 56, 41674182.

    • Search Google Scholar
    • Export Citation
  • Alexander, M. J., J. R. Holton, and D. R. Durran, 1995: The gravity wave response above deep convection in a squall line simulation. J. Atmos. Sci., 52, 22122226.

    • 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
  • Clark, G., W. D. Hall, and J. L. Coen, 1996: Source code documentation for the Clark-Hall cloud-scale model: Code version G3CH01. NCAR Tech. Note NCAR/TN-426+STR, 137 pp.

  • Edmon, H. J., B. J. Hoskins, and M. E. McIntyre, 1980: Eliassen-Palm cross sections for the troposphere. J. Atmos. Sci., 37, 26002616.

    • Search Google Scholar
    • Export Citation
  • Eliassen, A., and E. Palm, 1961: On the transfer of energy by mountain waves. Geofys. Publ., 22, 94101.

  • Fovell, R., D. Durran, and J. R. Holton, 1992: Numerical simulations of convectively generated stratospheric gravity waves. J. Atmos. Sci., 49, 14271442.

    • Search Google Scholar
    • Export Citation
  • Fritts, D. C., and M. J. Alexander, 2003: Gravity wave dynamics and effects in the middle atmosphere. Rev. Geophys., 41, 1003, doi:10.1029/2001RG000106.

    • Search Google Scholar
    • Export Citation
  • Haynes, P. H., 1988: Forced, dissipative generalizations of finite-amplitude wave-activity conservation relations for zonal and nonzonal basic flows. J. Atmos. Sci., 45, 23522362.

    • Search Google Scholar
    • Export Citation
  • Held, I. M., and B. J. Hoskins, 1985: Large-scale eddies and the general circulation of the troposphere. Advances in Geophysics, Vol. 28, Academic Press, 3–31.

    • Search Google Scholar
    • Export Citation
  • Houze, R. A., 2004: Mesoscale convective systems. Rev. Geophys., 42, RG4003, doi:10.1029/2004RG000150.

  • Lane, T. P., 2008: The vortical response to penetrative convection and the associated gravity-wave generation. Atmos. Sci. Lett., 9, 103110.

    • Search Google Scholar
    • Export Citation
  • Lane, T. P., and M. W. Moncrieff, 2008: Stratospheric gravity waves generated by multiscale tropical convections. J. Atmos. Sci., 65, 25982614.

    • Search Google Scholar
    • Export Citation
  • Lane, T. P., and M. W. Moncrieff, 2010: Characterization of momentum transport associated with organized moist convection and gravity waves. J. Atmos. Sci., 67, 32083225.

    • Search Google Scholar
    • Export Citation
  • Lane, T. P., and F. Zhang, 2011: Coupling between gravity waves and tropical convection at mesoscales. J. Atmos. Sci., 68, 25822598.

  • Lane, T. P., M. J. Reeder, and T. L. Clark, 2001: Numerical modeling of gravity wave generation by deep tropical convection. J. Atmos. Sci., 58, 12491274.

    • Search Google Scholar
    • Export Citation
  • LeMone, M. A., 1983: Momentum transport by a line of cumulonimbus. J. Atmos. Sci., 40, 18151834.

  • LeMone, M. A., G. M. Barnes, and E. J. Zipser, 1984: Momentum flux by lines of cumulonimbus over the tropical ocean. J. Atmos. Sci., 41, 19141932.

    • Search Google Scholar
    • Export Citation
  • Lin, J.-L., M. Zhang, and B. Mapes, 2005: Momentum budget of the Madden–Julian oscillation: The sources and sinks of equivalent linear damping. J. Atmos. Sci., 62, 21722188.

    • Search Google Scholar
    • Export Citation
  • Lindzen, R. S., 1981: Turbulence and stress owing to gravity wave and tidal breakdown. J. Geophys. Res., 86 (C10), 97079714.

  • Lindzen, R. S., 1990: Dynamics in Atmospheric Physics: Lecture Notes for an Introductory Graduate-Level Course. Cambridge University Press, 310 pp.

  • Lipps, F. B., and R. S. Hemler, 1982: On the anelastic approximation of deep convection. J. Atmos. Sci., 39, 21922210.

  • Moncrieff, M. W., 1992: Organized convective systems: Archetypal dynamical models, mass and momentum flux theory, and parametrization. Quart. J. Roy. Meteor. Soc., 118, 819850.

    • Search Google Scholar
    • Export Citation
  • Richter, J. H., and P. J. Rasch, 2008: Effects of convective momentum transport on the atmospheric circulation in the Community Atmosphere Model, version 3. J. Climate, 21, 14871499.

    • Search Google Scholar
    • Export Citation
  • Scinocca, J. F., and T. G. Shepherd, 1992: Nonlinear wave-activity conservation laws and Hamiltonian structure for the two-dimensional anelastic equations. J. Atmos. Sci., 49, 527.

    • Search Google Scholar
    • Export Citation
  • Scinocca, J. F., and W. R. Peltier, 1994: Finite-amplitude wave-activity diagnostics for Longs stationary solution. J. Atmos. Sci., 51, 613622.

    • Search Google Scholar
    • Export Citation
  • Song, I.-S., H.-Y. Chun, and T. P. Lane, 2003: Generation mechanisms of convectively forced internal gravity waves and their propagation to the stratosphere. J. Atmos. Sci., 60, 19601980.

    • Search Google Scholar
    • Export Citation
  • Wu, X., X.-Z. Liang, and G. J. Zhang, 2003: Seasonal migration of ITCZ precipitation across the equator: Why can't GCMs simulate it? Geophys. Res. Lett., 30, 1824, doi:10.1029/2003GL017198.

    • Search Google Scholar
    • Export Citation
  • Wu, X., L. Deng, X. Song, G. Vettoretti, W. R. Peltier, and G. J. Zhang, 2007: Impact of a modified convective scheme on the Madden–Julian Oscillation and El Niño–Southern Oscillation in a coupled climate model. Geophys. Res. Lett., 34, L16823, doi:10.1029/2007GL030637.

    • Search Google Scholar
    • Export Citation
  • Zhang, G. J., and N. A. McFarlane, 1995: Role of convective-scale momentum transport in climate simulation. J. Geophys. Res., 100 (D1), 14171426.

    • Search Google Scholar
    • Export Citation
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Toward an Understanding of Vertical Momentum Transports in Cloud-System-Resolving Model Simulations of Multiscale Tropical Convection

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  • 1 Department of Earth and Environmental Sciences, and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York
  • | 2 School of Earth Sciences, and ARC Centre of Excellence for Climate System Science, The University of Melbourne, Parkville, Victoria, Australia
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Abstract

This study examines the characteristics of convective momentum transport (CMT) and gravity wave momentum transport (GWMT) in two-dimensional cloud-system-resolving model simulations, including the relationships between the two transports. A linear group velocity criterion is shown to objectively separate CMT and GWMT. The GWMT contribution is mostly consistent with upward-propagating gravity waves and is present in the troposphere and the stratosphere. The CMT contribution forms a large part of the residual (nonupward-propagating contribution) and dominates the fluxes in the troposphere. Additional analysis of the vertical sensible heat flux supports the physical interpretation of the two contributions, further isolating the effects of unstable convection from vertically propagating gravity waves.

The role of transient and nonconservative (friction and diabatic heating) processes in generating momentum flux and their dependence on changes in convective organization was assessed using a pseudomomentum budget analysis. Nonconservative effects were found to dominate the transports; the GWMT contribution involved a diabatic source region in the troposphere and a dissipative sink region in the stratosphere. The CMT contribution was consistent with transport between the boundary layer and free troposphere via tilted convection. Transient buoyancy–vorticity correlations highlighted wave sources in the region of convective outflow and the boundary layer. These sources were akin to the previously described “mechanical oscillator” mechanism. Fluxes associated with this upper-level source were most sensitive to convective organization, highlighting the mechanism by which changes in organization are communicated to GWMT. The results elucidate important interactions between CMT and GWMT, adding further weight to suggestions that the two transports should be linked in parameterizations.

Corresponding author address: Dr. Tiffany A. Shaw, Department of Earth and Environmental Sciences and Department of Applied Physics and Applied Mathematics, Columbia University, P.O. Box 1000, 61 Route 9W, Palisades, NY 10964. E-mail: tas2163@columbia.edu

Abstract

This study examines the characteristics of convective momentum transport (CMT) and gravity wave momentum transport (GWMT) in two-dimensional cloud-system-resolving model simulations, including the relationships between the two transports. A linear group velocity criterion is shown to objectively separate CMT and GWMT. The GWMT contribution is mostly consistent with upward-propagating gravity waves and is present in the troposphere and the stratosphere. The CMT contribution forms a large part of the residual (nonupward-propagating contribution) and dominates the fluxes in the troposphere. Additional analysis of the vertical sensible heat flux supports the physical interpretation of the two contributions, further isolating the effects of unstable convection from vertically propagating gravity waves.

The role of transient and nonconservative (friction and diabatic heating) processes in generating momentum flux and their dependence on changes in convective organization was assessed using a pseudomomentum budget analysis. Nonconservative effects were found to dominate the transports; the GWMT contribution involved a diabatic source region in the troposphere and a dissipative sink region in the stratosphere. The CMT contribution was consistent with transport between the boundary layer and free troposphere via tilted convection. Transient buoyancy–vorticity correlations highlighted wave sources in the region of convective outflow and the boundary layer. These sources were akin to the previously described “mechanical oscillator” mechanism. Fluxes associated with this upper-level source were most sensitive to convective organization, highlighting the mechanism by which changes in organization are communicated to GWMT. The results elucidate important interactions between CMT and GWMT, adding further weight to suggestions that the two transports should be linked in parameterizations.

Corresponding author address: Dr. Tiffany A. Shaw, Department of Earth and Environmental Sciences and Department of Applied Physics and Applied Mathematics, Columbia University, P.O. Box 1000, 61 Route 9W, Palisades, NY 10964. E-mail: tas2163@columbia.edu
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