• Alvey, G. R., III, J. Zawislak, and E. Zipser, 2015: Precipitation properties observed during tropical cyclone intensity change. Mon. Wea. Rev., 143, 44764492, https://doi.org/10.1175/MWR-D-15-0065.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bhatia, K. T., and D. S. Nolan, 2013: Relating the skill of tropical cyclone intensity forecasts to the synoptic environment. Wea. Forecasting, 28, 961980, https://doi.org/10.1175/WAF-D-12-00110.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, B., C. A. Davis, and Y. Kuo, 2018: Effects of low-level flow orientation and vertical shear on the structure and intensity of tropical cyclones. Mon. Wea. Rev., 146, 24472467, https://doi.org/10.1175/MWR-D-17-0379.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, B., C. A. Davis, and Y. Kuo, 2019: An idealized numerical study of shear-relative low-level mean flow on tropical cyclone intensity and size. J. Atmos. Sci., 76, 23092334, https://doi.org/10.1175/JAS-D-18-0315.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, H., and S. G. Gopalakrishnan, 2015: A study on the asymmetric rapid intensification of Hurricane Earl (2010) using the HWRF system. J. Atmos. Sci., 72, 531550, https://doi.org/10.1175/JAS-D-14-0097.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, S. S., J. A. Knaff, and F. D. Marks, 2006: Effects of vertical wind shear and storm motion on tropical cyclone rainfall asymmetries deduced from TRMM. Mon. Wea. Rev., 134, 31903208, https://doi.org/10.1175/MWR3245.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Corbosiero, K. L., and J. Molinari, 2002: The effects of vertical wind shear on the distribution of convection in tropical cyclones. Mon. Wea. Rev., 130, 21102123, https://doi.org/10.1175/1520-0493(2002)130<2110:TEOVWS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • DeHart, J. C., R. A. Houze Jr., and R. F. Rogers, 2014: Quadrant distribution of tropical cyclone inner-core kinematics in relation to environmental shear. J. Atmos. Sci., 71, 27132732, https://doi.org/10.1175/JAS-D-13-0298.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • DeMaria, M., 1996: The effect of vertical shear on tropical cyclone intensity change. J. Atmos. Sci., 53, 20762088, https://doi.org/10.1175/1520-0469(1996)053<2076:TEOVSO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • DeMaria, M., and J. Kaplan, 1994: A Statistical Hurricane Intensity Prediction Scheme (SHIPS) for the Atlantic basin. Wea. Forecasting, 9, 209220, https://doi.org/10.1175/1520-0434(1994)009<0209:ASHIPS>2.0.CO;2.

    • Crossref
    • 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, https://doi.org/10.1175/1520-0469(1989)046<3077:NSOCOD>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Dunion, J. P., 2011: Rewriting the climatology of the tropical North Atlantic and Caribbean Sea atmosphere. J. Climate, 24, 893908, https://doi.org/10.1175/2010JCLI3496.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Emanuel, K., and F. Zhang, 2017: The role of inner-core moisture in tropical cyclone predictability and practical forecast skill. J. Atmos. Sci., 74, 23152324, https://doi.org/10.1175/JAS-D-17-0008.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Finocchio, P. M., and S. J. Majumdar, 2017a: A statistical perspective on wind profiles and vertical wind shear in tropical cyclone environments of the Northern Hemisphere. Mon. Wea. Rev., 145, 361378, https://doi.org/10.1175/MWR-D-16-0221.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Finocchio, P. M., and S. J. Majumdar, 2017b: The predictability of idealized tropical cyclones in environments with time-varying vertical wind shear. J. Adv. Model. Earth Syst., 9, 28362862, https://doi.org/10.1002/2017MS001168.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Finocchio, P. M., D. S. Nolan, and M. Iskandarani, 2016: Idealized tropical cyclone responses to the height and depth of environmental vertical wind shear. Mon. Wea. Rev., 144, 21552175, https://doi.org/10.1175/MWR-D-15-0320.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Frank, W. M., and E. A. Ritchie, 1999: Effects of environmental flow upon tropical cyclone structure. Mon. Wea. Rev., 127, 20442061, https://doi.org/10.1175/1520-0493(1999)127<2044:EOEFUT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Frank, W. M., and E. A. Ritchie, 2001: Effects of vertical wind shear on the intensity and structure of numerically simulated hurricanes. Mon. Wea. Rev., 129, 22492269, https://doi.org/10.1175/1520-0493(2001)129<2249:EOVWSO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gu, J., Z. Tan, and X. Qiu, 2015: Effects of vertical wind shear on inner-core thermodynamics of an idealized simulated tropical cyclone. J. Atmos. Sci., 72, 511530, https://doi.org/10.1175/JAS-D-14-0050.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gu, J., Z. Tan, and X. Qiu, 2018: The evolution of vortex tilt and vertical motion of tropical cyclones in directional shear flows. J. Atmos. Sci., 75, 35653578, https://doi.org/10.1175/JAS-D-18-0024.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gu, J., Z. Tan, and X. Qiu, 2019: Intensification variability of tropical cyclones in directional shear flows: Vortex tilt–convection coupling. J. Atmos. Sci., 76, 18271844, https://doi.org/10.1175/JAS-D-18-0282.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hong, S.-Y., and J.-O. J. Lim, 2006: The WRF single-moment 6-class microphysics scheme (WSM6). J. Korean Meteor. Soc., 42, 129151.

  • 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
  • Jiménez, P. A., J. Dudhia, J. F. González-Rouco, J. Navarro, J. P. Montávez, and E. García-Bustamante, 2012: A Revised scheme for the WRF surface layer formulation. Mon. Wea. Rev., 140, 898918, https://doi.org/10.1175/MWR-D-11-00056.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jones, S. C., 1995: The evolution of vortices in vertical shear. I: Initially barotropic vortices. Quart. J. Roy. Meteor. Soc., 121, 821851, https://doi.org/10.1002/qj.49712152406.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Marks, F. D., and L. K. Shay, 1998: Landfalling tropical cyclones: Forecast problems and associated research opportunities. Bull. Amer. Meteor. Soc., 79, 305323, https://doi.org/10.1175/1520-0477(1998)079<0305:LTCFPA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Miyamoto, Y., and T. Takemi, 2013: A transition mechanism for the spontaneous axisymmetric intensification of tropical cyclones. J. Atmos. Sci., 70, 112129, https://doi.org/10.1175/JAS-D-11-0285.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mlawer, E. J., S. J. Taubman, P. D. Brown, M. J. Iacono, and S. A. Clough, 1997: Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated-k model for the longwave. J. Geophys. Res., 102, 16 66316 682, https://doi.org/10.1029/97JD00237.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Molinari, J., and D. Vollaro, 2010: Rapid intensification of a sheared tropical storm. Mon. Wea. Rev., 138, 38693885, https://doi.org/10.1175/2010MWR3378.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Molinari, J., D. Vollaro, and K. L. Corbosiero, 2004: Tropical cyclone formation in a sheared environment: A case study. J. Atmos. Sci., 61, 24932509, https://doi.org/10.1175/JAS3291.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Molinari, J., P. Dodge, D. Vollaro, K. L. Corbosiero, and F. Marks, 2006: Mesoscale aspects of the downshear reformation of a tropical cyclone. J. Atmos. Sci., 63, 341354, https://doi.org/10.1175/JAS3591.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nguyen, L. T., and J. Molinari, 2012: Rapid intensification of a sheared, fast-moving hurricane over the Gulf Stream. Mon. Wea. Rev., 140, 33613378, https://doi.org/10.1175/MWR-D-11-00293.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nguyen, L. T., R. Rogers, J. Zawislak, and J. A. Zhang, 2019: Assessing the influence of convective downdrafts and surface enthalpy fluxes on tropical cyclone intensity change in moderate vertical wind shear. Mon. Wea. Rev., 147, 35193534, https://doi.org/10.1175/MWR-D-18-0461.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nolan, D. S., 2011: Evaluating environmental favorableness for tropical cyclone development with the method of point-downscaling. J. Adv. Model. Earth Syst., 3, M08001, https://doi.org/10.1029/2011MS000063.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Nolan, D. S., Y. Moon, and D. P. Stern, 2007: Tropical cyclone intensification from asymmetric convection: Energetics and efficiency. J. Atmos. Sci., 64, 33773405, https://doi.org/10.1175/JAS3988.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Onderlinde, M. J., and D. S. Nolan, 2014: Environmental helicity and its effects on development and intensification of tropical cyclones. J. Atmos. Sci., 71, 43084320, https://doi.org/10.1175/JAS-D-14-0085.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Onderlinde, M. J., and D. S. Nolan, 2016: Tropical cyclone–relative environmental helicity and the pathways to intensification in shear. J. Atmos. Sci., 73, 869890, https://doi.org/10.1175/JAS-D-15-0261.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Onderlinde, M. J., and D. S. Nolan, 2017: The tropical cyclone response to changing wind shear using the method of time-varying point-downscaling. J. Adv. Model. Earth Syst., 9, 908931, https://doi.org/10.1002/2016MS000796.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rappin, E. D., and D. S. Nolan, 2012: The effect of vertical shear orientation on tropical cyclogenesis. Quart. J. Roy. Meteor. Soc., 138, 10351054, https://doi.org/10.1002/qj.977.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reasor, P. D., and M. T. Montgomery, 2015: Evaluation of a heuristic model for tropical cyclone resilience. J. Atmos. Sci., 72, 17651782, https://doi.org/10.1175/JAS-D-14-0318.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reasor, P. D., M. T. Montgomery, and L. D. Grasso, 2004: A new look at the problem of tropical cyclones in vertical shear flow: Vortex resiliency. J. Atmos. Sci., 61, 322, https://doi.org/10.1175/1520-0469(2004)061<0003:ANLATP>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Riemer, M., and F. Laliberté, 2015: Secondary circulation of tropical cyclones in vertical wind shear: Lagrangian diagnostic and pathways of environmental interaction. J. Atmos. Sci., 72, 35173536, https://doi.org/10.1175/JAS-D-14-0350.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rios-Berrios, R., 2020: Impacts of radiation and cold pools on the intensity and vortex tilt of weak tropical cyclones interacting with vertical wind shear. J. Atmos. Sci., 77, 669689, https://doi.org/10.1175/JAS-D-19-0159.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rios-Berrios, R., and R. D. Torn, 2017: Climatological analysis of tropical cyclone intensity changes under moderate vertical wind shear. Mon. Wea. Rev., 145, 17171738, https://doi.org/10.1175/MWR-D-16-0350.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rios-Berrios, R., R. D. Torn, and C. A. Davis, 2016: An ensemble approach to investigate tropical cyclone intensification in sheared environments. Part II: Ophelia (2011). J. Atmos. Sci., 73, 15551575, https://doi.org/10.1175/JAS-D-15-0245.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rios-Berrios, R., C. A. Davis, and R. D. Torn, 2018: A hypothesis for the intensification of tropical cyclones under moderate vertical wind shear. J. Atmos. Sci., 75, 41494173, https://doi.org/10.1175/JAS-D-18-0070.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rogers, R., P. Reasor, and S. Lorsolo, 2013: Airborne Doppler observations of the inner-core structural differences between intensifying and steady-state tropical cyclones. Mon. Wea. Rev., 141, 29702991, https://doi.org/10.1175/MWR-D-12-00357.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rotunno, R., and K. A. Emanuel, 1987: An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci., 44, 542561, https://doi.org/10.1175/1520-0469(1987)044<0542:AAITFT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ryglicki, D. R., and R. E. Hart, 2015: An investigation of center-finding techniques for tropical cyclones in mesoscale models. J. Appl. Meteor. Climatol., 54, 825846, https://doi.org/10.1175/JAMC-D-14-0106.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Schecter, D. A., M. T. Montgomery, and P. D. Reasor, 2002: A theory for the vertical alignment of a quasigeostrophic vortex. J. Atmos. Sci., 59, 150168, https://doi.org/10.1175/1520-0469(2002)059<0150:ATFTVA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Simpson, R. H., and H. Riehl, 1958: Mid-tropospheric ventilation as a constraint on hurricane development and maintenance. Proc. Tech. Conf. on Hurricanes, Miami, FL, Amer. Meteor. Soc., D4.1–D4.10.

  • Stevenson, S. N., K. L. Corbosiero, M. DeMaria, and J. L. Vigh, 2018: A 10-year survey of tropical cyclone inner-core lightning bursts and their relationship to intensity change. Wea. Forecasting, 33, 2336, https://doi.org/10.1175/WAF-D-17-0096.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Stoelinga, M. T., 2009: A users’ guide to RIP version 4.5: A program for visualizing mesoscale model output. UCAR, accessed 30 July 2015, http://www2.mmm.ucar.edu/wrf/users/docs/ripug.htm.

  • Tang, B., and K. Emanuel, 2010: Midlevel ventilation’s constraint on tropical cyclone intensity. J. Atmos. Sci., 67, 18171830, https://doi.org/10.1175/2010JAS3318.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Velden, C. S., and J. Sears, 2014: Computing deep-tropospheric vertical wind shear analyses for tropical cyclone applications: Does the methodology matter? Wea. Forecasting, 29, 11691180, https://doi.org/10.1175/WAF-D-13-00147.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, Y., and C. Wu, 2004: Current understanding of tropical cyclone structure and intensity changes—A review. Meteor. Atmos. Phys., 87, 257278, https://doi.org/10.1007/s00703-003-0055-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, Y., Y. Rao, Z. Tan, and D. Schönemann, 2015: A statistical analysis of the effects of vertical wind shear on tropical cyclone intensity change over the western North Pacific. Mon. Wea. Rev., 143, 34343453, https://doi.org/10.1175/MWR-D-15-0049.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wu, L., and S. A. Braun, 2004: Effects of environmentally induced asymmetries on hurricane intensity: A numerical study. J. Atmos. Sci., 61, 30653081, https://doi.org/10.1175/JAS-3343.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, F., and D. Tao, 2013: Effects of vertical wind shear on the predictability of tropical cyclones. J. Atmos. Sci., 70, 975983, https://doi.org/10.1175/JAS-D-12-0133.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
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The Role of Low-Level Flow Direction on Tropical Cyclone Intensity Changes in a Moderate-Sheared Environment

Tsung-Yung LeeaDepartment of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan

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Chun-Chieh WuaDepartment of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan

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Rosimar Rios-BerriosbNational Center for Atmospheric Research, Boulder, Colorado

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Abstract

The impact of low-level flow (LLF) direction on the intensification of intense tropical cyclones under moderate deep-layer shear is investigated based on idealized numerical experiments. The background flow profiles are constructed by varying the LLF direction with the same moderate deep-layer shear. When the maximum surface wind speed of the simulation without background flow reaches 70 kt (36 m s−1), the background flow profiles are imposed. After a weakening period in the first 12 h, the members with upshear-left-pointing LLF (fast-intensifying group) intensify faster between 12 and 24 h than those members (slow-intensifying group) with downshear-right-pointing LLF. The fast-intensifying group experiences earlier development of inner-core structures after 12 h, such as potential vorticity below the midtroposphere, upper-level warm core, eyewall axisymmetrization, and radial moist entropy gradient, while the inner-core features of the slow-intensifying group remain relatively weak and asymmetric. The FI group experiences smaller tilt increase and stronger midlevel PV ring development. The upshear-left convection during 6–12 h is responsible for the earlier development of the inner core by reducing ventilation, providing axisymmetric heating, and benefiting the eyewall development. The LLF of the fast-intensifying group enhances surface heat fluxes in the downshear side, resulting in higher energy supply to the upshear-left convection from the boundary layer. In all, this study provides new insights on the impact of LLF direction on intense storms under moderate shear by modulating the surface heat fluxes and eyewall convection.

© 2021 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: Chun-Chieh Wu, cwu@as.ntu.edu.tw

Abstract

The impact of low-level flow (LLF) direction on the intensification of intense tropical cyclones under moderate deep-layer shear is investigated based on idealized numerical experiments. The background flow profiles are constructed by varying the LLF direction with the same moderate deep-layer shear. When the maximum surface wind speed of the simulation without background flow reaches 70 kt (36 m s−1), the background flow profiles are imposed. After a weakening period in the first 12 h, the members with upshear-left-pointing LLF (fast-intensifying group) intensify faster between 12 and 24 h than those members (slow-intensifying group) with downshear-right-pointing LLF. The fast-intensifying group experiences earlier development of inner-core structures after 12 h, such as potential vorticity below the midtroposphere, upper-level warm core, eyewall axisymmetrization, and radial moist entropy gradient, while the inner-core features of the slow-intensifying group remain relatively weak and asymmetric. The FI group experiences smaller tilt increase and stronger midlevel PV ring development. The upshear-left convection during 6–12 h is responsible for the earlier development of the inner core by reducing ventilation, providing axisymmetric heating, and benefiting the eyewall development. The LLF of the fast-intensifying group enhances surface heat fluxes in the downshear side, resulting in higher energy supply to the upshear-left convection from the boundary layer. In all, this study provides new insights on the impact of LLF direction on intense storms under moderate shear by modulating the surface heat fluxes and eyewall convection.

© 2021 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: Chun-Chieh Wu, cwu@as.ntu.edu.tw
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