Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

Montgomery, Michael T.; Wang, Zhuo; Dunkerton, Timothy J.

doi:10.5194/acp-10-10803-2010

Cited by 54 publications

(50 citation statements)

References 36 publications

(43 reference statements)

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“…In this paper, we will test the applicability of the marsupial paradigm using satellite and numerical model analyses for the case of Hurricane Sandy. This study distinguishes itself from previous work by first showing that the parent wave of Hurricane Sandy is weak and thus did not form a completely protected environment Wang et al 2010a). We then demonstrate that cyclogenesis still occurred because the location of the wave pouch opening is adjacent to a favorable external environment, characterized by abundant moisture and cyclonic vorticity.…”

Section: Introductioncontrasting

confidence: 42%

“…The cat's-eye within the wave critical layer is thus dubbed the ''wave's pouch.'' Previous work using observations (Montgomery et al 2010aRutherford and Montgomery 2012) and numerical simulations Wang et al 2010a,b) have documented the applicability of the marsupial paradigm to the tropical cyclogenesis problem on both the synoptic and mesoscales for EW cases. In this paper, we will test the applicability of the marsupial paradigm using satellite and numerical model analyses for the case of Hurricane Sandy.…”

Section: Introductionmentioning

confidence: 99%

“…In many cases, to increase lead time for hurricane warnings, an accurate forecast of genesis is required (as a warning would be necessary prior to the formation of a hurricane). For the past several years, the authors have produced real-time tropical cyclogenesis forecasts based on the dynamical concepts inherent in the marsupial paradigm (Montgomery et al 2010a;Wang et al 2009Wang et al , 2012. A review of these forecasts for the case of Hurricane Sandy is presented.…”

Section: Introductionmentioning

confidence: 99%

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Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

Lussier¹,

L.²,

Blake³

et al. 2014

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The tropical cyclogenesis sequence of Hurricane Sandy is examined. It is shown that genesis occurs within a recirculating Kelvin cat's-eye flow of a westward-propagating tropical wave. The cat's-eye flow is able to provide a protective environment for the mesoscale vortex to grow and is characterized by gradual column moistening and increased areal coverage of deep cumulus convection. These findings are generally consistent with a recently proposed tropical cyclogenesis sequence referred to as the ''marsupial paradigm.'' Sandy's cyclogenesis provides a useful illustration of the marsupial paradigm within a partially open recirculating region, with the opening located south of the pouch center. It is suggested that the opening acts to enhance the genesis process because it is adjacent to an environment characterized by warm, moist air, conditions favorable for tropical cyclogenesis. From a dynamical perspective, accretion of low-level cyclonic vorticity filaments into the developing vortex from several sources (the South American convergence zone, an easterly wave located west of the pre-Sandy wave, and cyclonic vorticity generated along Hispaniola) is documented. Organization and growth of the nascent storm is enhanced by this accretion of cyclonic vorticity. A Lagrangian trajectory analysis is used to assess potential contributions to Sandy's spinup from a Caribbean gyre and the easterly wave that formed Hurricane Tony. This analysis indicates that these features are outside of the Lagrangian flow boundaries that define the pre-Sandy wave and do not directly contribute to spinup of the vortex. Finally, the effectiveness of forecasts from the U.S. and European operational numerical weather prediction models is discussed for this case.

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Section: Introductioncontrasting

confidence: 42%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

Lussier¹,

L.²,

Blake³

et al. 2014

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“…The role of VHTs in the intensification of the larger-scale vortex circulation has been the subject of recent numerical and theoretical investigations, (Hendricks et al, 2004;Montgomery et al, 2006;Nguyen et al, 2008;Shin and Smith, 2008;Nguyen et al, 2011;Montgomery et al, 2010;Fang and Zhang, 2010;Levina and Montgomery, 2010). From a mean-field viewpoint associated with an azimuthal average around the system center of circulation, VHTs have been implicated in two mechanisms for spinning up the mean vortex Montgomery and Smith, 2012):…”

Section: Role Of Vhts In the Spin Up Of The Mean Circulationmentioning

confidence: 99%

Lagrangian coherent structures in tropical cyclone intensification

2012

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Abstract. Recent work has suggested that tropical cyclones intensify via a pathway of rotating deep moist convection in the presence of enhanced fluxes of moisture from the ocean. The rotating deep convective structures possessing enhanced cyclonic vorticity within their cores have been dubbed Vortical Hot Towers (VHTs). In general, the interaction between VHTs and the system-scale vortex, as well as the corresponding evolution of equivalent potential temperature (θ e ) that modulates the VHT activity, is a complex problem in moist helical turbulence.To better understand the structural aspects of the threedimensional intensification process, a Lagrangian perspective is explored that focuses on the coherent structures seen in the flow field associated with VHTs and their vortical remnants, as well as the evolution and localized stirring of θ e . Recently developed finite-time Lagrangian methods are limited in the three-dimensional turbulence and shear associated with the VHTs. In this paper, new Lagrangian techniques developed for three-dimensional velocity fields are summarized and we apply these techniques to study VHT and θ e phenomenology in a high-resolution numerical tropical cyclone simulation. The usefulness of these methods is demonstrated by an analysis of particle trajectories.We find that VHTs create a locally turbulent mixing environment. However, associated with the VHTs are hyperbolic structures that span between adjacent VHTs or adjacent vortical remnants and represent coherent finite-time transport barriers in the flow field. Although the azimuthally-averaged inflow is responsible for the inward advection of boundary layer θ e , attracting Lagrangian coherent structures are coincident with pools of high boundary layer θ e . Extensions of boundary layer coherent structures grow above the boundary layer during episodes of convection and remain with the convective vortices. These hyperbolic structures form initially as boundaries between VHTs. As vorticity aggregates into a ring-like eyewall feature, the Lagrangian boundaries merge into a ring outside of the region of maximal vorticity.

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“…1 The new cyclogenesis model and accompanying scientific hypotheses were established observationally in the Atlantic and eastern Pacific sectors by DMW09. The new models find additional support in idealized numerical modeling simulations (Wang et al, 2010a, b;Montgomery et al, 2010a;Nicholls and Montgomery, 2013), recent case studies in the field in the western North Pacific during the Tropical Cyclone Structure Experiment 2008 (TCS08, Montgomery et al, 2010b;Lussier III, 2010;Montgomery et al, 2012;Raymond and López-Carrillo, 2011;Lussier III et al, 2014), in the Atlantic during the Pre-Depression Investigation of Cloud Systems in the Tropics (PREDICT) campaign in 2010 Smith and Montgomery, 2012;Ahijevych, 2012, 2013), in NASA's ongoing Hurricane and Severe Storm (HS3) missions (2012)(2013)(2014)(2015)(2016) and the case of Hurricane Sandy (Lussier III et al, 2015). The field data afford a resolved view of horizontal and vertical structure in the wave pouch and its immediate surroundings, valuable for system centering, circulation magnitude, vortic-8512 T. M. Freismuth et al: Why did the storm ex-Gaston (2010) fail to redevelop?…”

Section: Introductionmentioning

confidence: 99%

Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment?

et al. 2016

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Abstract. An analysis is presented of the failed redevelopment of ex-Gaston during the 2010 PREDICT field campaign based on the European Centre for Medium Range Weather Forecast (ECMWF) analyses. We analyze the dynamics and kinematics of ex-Gaston to investigate the role of dry, environmental air in the failed redevelopment. The flow topology defined by the calculation of particle trajectories shows that ex-Gaston's pouch was vulnerable to dry, environmental air on all days of observations. As early as 12:00 UTC 2 September 2010, a dry layer at and above 600 hPa results in a decrease in the vertical mass flux and vertical relative vorticity. These findings support the hypothesis that entrained, dry air near 600 hPa thwarted convective updraughts and vertical mass flux, which in turn led to a reduction in vorticity and a compromised pouch at these middle levels. A compromised pouch allows further intrusion of dry air and quenching of subsequent convection, therefore hindering vorticity amplification through vortex tube stretching. This study supports recent work investigating the role of dry air in moist convection during tropical cyclogenesis.

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Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

Cited by 54 publications

References 36 publications

Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

Lagrangian coherent structures in tropical cyclone intensification

Why did the storm ex-Gaston (2010) fail to redevelop during the PREDICT experiment?

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