Dynamics of Lower-Tropospheric Vorticity in Idealized Simulations of Tropical Cyclone Formation

Yaping Wang National Center for Atmospheric Research, Boulder, Colorado

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Christopher A. Davis National Center for Atmospheric Research, Boulder, Colorado

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Yongjie Huang National Center for Atmospheric Research, Boulder, Colorado

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Abstract

Idealized simulations are conducted using the Cloud Model version 1 (CM1) to explore the mechanism of tropical cyclone (TC) genesis from a preexisting midtropospheric vortex that forms in radiative–convective equilibrium. With lower-tropospheric air approaching near saturation during TC genesis, convective cells become stronger, along with the intensifying updrafts and downdrafts and the larger area coverage of updrafts relative to downdrafts. Consequently, the low-level vertical mass flux increases, inducing vorticity amplification above the boundary layer. Of interest is that while surface cold pools help organize lower-tropospheric updrafts, genesis still proceeds, only slightly delayed, if subcloud evaporation cooling and cold pool intensity are drastically reduced. More detrimental is the disruption of near saturation through the introduction of weak vertical wind shear. The lower-tropospheric dry air suppresses the strengthening of convection, leading to weaker upward mass flux and much slower near-surface vortex spinup. We also find that surface spinup is similarly inhibited by decreasing surface drag despite the existence of a nearly saturated column, whereas larger drag accelerates spinup. Increased vorticity above the boundary layer is followed by the emergence of a horizontal pressure gradient through the depth of the boundary layer. Then the corresponding convergence resulting from the gradient imbalance in the frictional boundary layer causes vorticity amplification near the surface. It is suggested that near saturation in the lower troposphere is critical for increasing the mass flux and vorticity just above the boundary layer, but it is necessary yet insufficient because the spinup is strongly governed by boundary layer dynamics.

© 2019 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: Yaping Wang, wangyap1990@gmail.com

Abstract

Idealized simulations are conducted using the Cloud Model version 1 (CM1) to explore the mechanism of tropical cyclone (TC) genesis from a preexisting midtropospheric vortex that forms in radiative–convective equilibrium. With lower-tropospheric air approaching near saturation during TC genesis, convective cells become stronger, along with the intensifying updrafts and downdrafts and the larger area coverage of updrafts relative to downdrafts. Consequently, the low-level vertical mass flux increases, inducing vorticity amplification above the boundary layer. Of interest is that while surface cold pools help organize lower-tropospheric updrafts, genesis still proceeds, only slightly delayed, if subcloud evaporation cooling and cold pool intensity are drastically reduced. More detrimental is the disruption of near saturation through the introduction of weak vertical wind shear. The lower-tropospheric dry air suppresses the strengthening of convection, leading to weaker upward mass flux and much slower near-surface vortex spinup. We also find that surface spinup is similarly inhibited by decreasing surface drag despite the existence of a nearly saturated column, whereas larger drag accelerates spinup. Increased vorticity above the boundary layer is followed by the emergence of a horizontal pressure gradient through the depth of the boundary layer. Then the corresponding convergence resulting from the gradient imbalance in the frictional boundary layer causes vorticity amplification near the surface. It is suggested that near saturation in the lower troposphere is critical for increasing the mass flux and vorticity just above the boundary layer, but it is necessary yet insufficient because the spinup is strongly governed by boundary layer dynamics.

© 2019 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: Yaping Wang, wangyap1990@gmail.com
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  • Abarca, S. F., and M. T. Montgomery, 2013: Essential dynamics of secondary eyewall formation. J. Atmos. Sci., 70, 32163230, https://doi.org/10.1175/JAS-D-12-0318.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bell, M. M., and M. T. Montgomery, 2010: Sheared deep vortical convection in pre-depression Hagupit during TCS08. Geophys. Res. Lett., 37, L06802, https://doi.org/10.1029/2009GL042313.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bister, M., and K. A. Emanuel, 1997: The genesis of Hurricane Guillermo: TEXMEX analyses and a modeling study. Mon. Wea. Rev., 125, 26622682, https://doi.org/10.1175/1520-0493(1997)125<2662:TGOHGT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Böing, S. J., H. J. Jonker, A. P. Siebesma, and W. W. Grabowski, 2012: Influence of the subcloud layer on the development of a deep convective ensemble. J. Atmos. Sci., 69, 26822698, https://doi.org/10.1175/JAS-D-11-0317.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bryan, G. H., and J. M. Fritsch, 2002: A benchmark simulation for moist nonhydrostatic numerical models. Mon. Wea. Rev., 130, 29172928, https://doi.org/10.1175/1520-0493(2002)130<2917:ABSFMN>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bryan, G. H., and H. Morrison, 2012: Sensitivity of a simulated squall line to horizontal resolution and parameterization of microphysics. Mon. Wea. Rev., 140, 202225, https://doi.org/10.1175/MWR-D-11-00046.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chou, M. D., and M. J. Suarez, 1999: A solar radiation parameterization (CLIRAD-SW) for atmospheric studies. NASA Tech. Memo. NASA/TM-1990-104606, 51 pp.

  • Davis, C. A., 2015: The formation of moist vortices and tropical cyclones in idealized simulations. J. Atmos. Sci., 72, 34993516, https://doi.org/10.1175/JAS-D-15-0027.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Davis, C. A., and T. J. Galarneau Jr., 2009: The vertical structure of mesoscale convective vortices. J. Atmos. Sci., 66, 686704, https://doi.org/10.1175/2008JAS2819.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Freismuth, T. M., B. Rutherford, M. A. Boothe, and M. T. Montgomery, 2016: Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment? Atmos. Chem. Phys., 16, 85118519, https://doi.org/10.5194/acp-16-8511-2016.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gjorgjievska, S., and D. J. Raymond, 2014: Interaction between dynamics and thermodynamics during tropical cyclogenesis. Atmos. Chem. Phys., 14, 30653082, https://doi.org/10.5194/acp-14-3065-2014.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hendricks, E. A., M. T. Montgomery, and C. A. Davis, 2004: The role of “vortical” hot towers in the formation of Tropical Cyclone Diana (1984). J. Atmos. Sci., 61, 12091232, https://doi.org/10.1175/1520-0469(2004)061<1209:TROVHT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hong, S. Y., Y. Noh, and J. Dudhia, 2006: A new vertical diffusion package with an explicit treatment of entrainment processes. Mon. Wea. Rev., 134, 23182341, https://doi.org/10.1175/MWR3199.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Houze, R. A., Jr., W. C. Lee, and M. M. Bell, 2009: Convective contribution to the genesis of Hurricane Ophelia (2005). Mon. Wea. Rev., 137, 27782800, https://doi.org/10.1175/2009MWR2727.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • James, R. P., and P. M. Markowski, 2010: A numerical investigation of the effects of dry air aloft on deep convection. Mon. Wea. Rev., 138, 140161, https://doi.org/10.1175/2009MWR3018.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kilroy, G., and R. K. Smith, 2013: A numerical study of rotating convection during tropical cyclogenesis. Quart. J. Roy. Meteor. Soc., 139, 12551269, https://doi.org/10.1002/qj.2022.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kilroy, G., R. K. Smith, and M. T. Montgomery, 2017a: A unified view of tropical cyclogenesis and intensification. Quart. J. Roy. Meteor. Soc., 143, 450462, https://doi.org/10.1002/qj.2934.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kilroy, G., M. T. Montgomery, and R. K. Smith, 2017b: The role of boundary-layer friction on tropical cyclogenesis and subsequent intensification. Quart. J. Roy. Meteor. Soc., 143, 25242536, https://doi.org/10.1002/qj.3104.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kilroy, G., R. K. Smith, and M. T. Montgomery, 2018: The role of heating and cooling associated with ice processes on tropical cyclogenesis and intensification. Quart. J. Roy. Meteor. Soc., 144, 99114, https://doi.org/10.1002/qj.3187.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lewellen, D. C., and W. S. Lewellen, 2007: Near-surface intensification of tornado vortices. J. Atmos. Sci., 64, 21762194, https://doi.org/10.1175/JAS3965.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Montgomery, M. T., and R. K. Smith, 2014: Paradigms for tropical cyclone intensification. Aust. Meteor. Oceanogr. J., 64, 3766, https://doi.org/10.22499/2.6401.005.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Montgomery, M. T., M. E. Nicholls, T. A. Cram, and A. B. Saunders, 2006: A vortical hot tower route to tropical cyclogenesis. J. Atmos. Sci., 63, 355386, https://doi.org/10.1175/JAS3604.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Montgomery, M. T., V. S. Nguyen, J. Persing, and R. K. Smith, 2009: Do tropical cyclones intensify by WISHE? Quart. J. Roy. Meteor. Soc., 135, 16971714, https://doi.org/10.1002/qj.459.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Montgomery, M. T., R. K. Smith, and S. V. Nguyen, 2010: Sensitivity of tropical-cyclone models to the surface drag coefficient. Quart. J. Roy. Meteor. Soc., 136, 19451953, https://doi.org/10.1002/qj.702.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nguyen, S. V., R. K. Smith, and M. T. Montgomery, 2008: Tropical cyclone intensification and predictability in three dimensions. Quart. J. Roy. Meteor. Soc., 134, 563582, https://doi.org/10.1002/qj.235.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nolan, D. S., 2007: What is the trigger for tropical cyclogenesis? Aust. Meteor. Mag., 56, 241266.

  • Peng, K., R. Rotunno, and G. Bryan, 2018: Evaluation of a time-dependent model for the intensification of tropical cyclones. J. Atmos. Sci., 75, 21252138, https://doi.org/10.1175/JAS-D-17-0382.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Persing, J., M. T. Montgomery, J. McWilliams, and R. K. Smith, 2013: Asymmetric and axisymmetric dynamics of tropical cyclones. Atmos. Chem. Phys., 13, 12 29912 341, https://doi.org/10.5194/acp-13-12299-2013.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., 2012: Balanced thermal structure of an intensifying tropical cyclone. Tellus, 64A, 19181, https://doi.org/10.3402/tellusa.v64i0.19181.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., and S. L. Sessions, 2007: Evolution of convection during tropical cyclogenesis. Geophys. Res. Lett., 34, L06811, https://doi.org/10.1029/2006GL028607.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., and C. López-Carrillo, 2011: The vorticity budget of developing Typhoon Nuri (2008). Atmos. Chem. Phys., 11, 147163, https://doi.org/10.5194/acp-11-147-2011.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., and M. J. Herman, 2012: Frictional convergence, atmospheric convection, and causality. Atmósfera, 25, 253267.

  • Raymond, D. J., S. L. Sessions, and C. López-Carrillo, 2011: Thermodynamics of tropical cyclogenesis in the Northwest Pacific. J. Geophys. Res., 116, D18101, https://doi.org/10.1029/2011JD015624.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reasor, P. D., M. T. Montgomery, and L. F. Bosart, 2005: Mesoscale observations of the genesis of Hurricane Dolly (1996). J. Atmos. Sci., 62, 31513171, https://doi.org/10.1175/JAS3540.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ritchie, E. A., and G. J. Holland, 1997: Scale interactions during the formation of Typhoon Irving. Mon. Wea. Rev., 125, 13771396, https://doi.org/10.1175/1520-0493(1997)125<1377:SIDTFO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sanger, N. T., M. T. Montgomery, R. K. Smith, and M. M. Bell, 2014: An observational study of tropical cyclone spinup in Supertyphoon Jangmi (2008) from 24 to 27 September. Mon. Wea. Rev., 142, 328, https://doi.org/10.1175/MWR-D-12-00306.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schmidt, C., and R. K. Smith, 2016: Tropical cyclone evolution in a minimal axisymmetric model revisited. Quart. J. Roy. Meteor. Soc., 142, 15051516, https://doi.org/10.1002/qj.2753.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Simpson, J., E. Ritchie, G. J. Holland, J. Halverson, and S. Stewart, 1997: Mesoscale interactions in tropical cyclone genesis. Mon. Wea. Rev., 125, 26432661, https://doi.org/10.1175/1520-0493(1997)125<2643:MIITCG>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sippel, J. A., J. W. Nielsen-Gammon, and S. E. Allen, 2006: The multiple-vortex nature of tropical cyclogenesis. Mon. Wea. Rev., 134, 17961814, https://doi.org/10.1175/MWR3165.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Smith, R. K., and M. T. Montgomery, 2012: Observations of the convective environment in developing and non-developing tropical disturbances. Quart. J. Roy. Meteor. Soc., 138, 17211739, https://doi.org/10.1002/qj.1910.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Smith, R. K., M. T. Montgomery, and V. S. Nguyen, 2009: Tropical cyclone spin-up revisited. Quart. J. Roy. Meteor. Soc., 135, 13211335, https://doi.org/10.1002/qj.428.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, Y., Y. Huang, and X. Cui, 2018: Impact of mid- and upper-level dry air on tropical cyclone genesis and intensification: A modeling study of Durian (2001). Adv. Atmos. Sci., 35, 15051521, https://doi.org/10.1007/s00376-018-8039-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, Z., 2012: Thermodynamic aspects of tropical cyclone formation. J. Atmos. Sci., 69, 24332451, https://doi.org/10.1175/JAS-D-11-0298.1.

  • Zawislak, J., and E. J. Zipser, 2014: Analysis of the thermodynamic properties of developing and nondeveloping tropical disturbances using a comprehensive dropsonde dataset. Mon. Wea. Rev., 142, 12501264, https://doi.org/10.1175/MWR-D-13-00253.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, D. L., Y. Liu, and M. K. Yau, 2001: A multiscale numerical study of Hurricane Andrew (1992). Part IV: Unbalanced flows. Mon. Wea. Rev., 129, 92107, https://doi.org/10.1175/1520-0493(2001)129<0092:AMNSOH>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, J. A., and F. D. Marks, 2015: Effects of horizontal diffusion on tropical cyclone intensity change and structure in idealized three-dimensional numerical simulations. Mon. Wea. Rev., 143, 39813995, https://doi.org/10.1175/MWR-D-14-00341.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
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