A Numerical Study on the Effects of Environmental Flow on Tropical Storm Genesis

Tuleya, Robert E.; Kurihara, Yoshio

doi:10.1175/1520-0493(1981)109<2487:ansote>2.0.co;2

Cited by 69 publications

(61 citation statements)

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“…In addition to these factors, vertical shear of the environmental flow is considered an important factor that can limit both the intensification and intensity of a TC (Wu and Cheng, 1999;Emanuel, 2004;Wang and Wu, 2004). Tropical cyclones are influenced by environmental, vertical wind shear at all stages of their life cycle (Gray, 1968;McBride and Zehr, 1981;Tuleya and Kurihara, 1981;Merrill, 1988). Wind shear causes asymmetry in eyewall convection, the upshear (downshear) side intensifies (weakens).…”

Section: Sensitivity To Cumulus Parameterization Schemes (Cps)supporting

confidence: 89%

Impact of cloud parameterization on the numerical simulation of a super cyclone

2012

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Abstract. This study examines the role of parameterization of convection and explicit moisture processes on the simulated track, intensity and inner core structure of Orissa super cyclone (1999) in Bay of Bengal (north Indian Ocean). Sensitivity experiments are carried out to examine the impact of cumulus parameterization schemes (CPS) using MM5 model (Version 3.7) in a two-way nested domain (D1 and D2) configuration at horizontal resolutions (45-15 km). Three different cumulus parameterization schemes, namely Grell (Gr), Betts-Miller (BM) and updated Kain Fritsch (KF2), are tested. It is noted that track and intensity both are very sensitive to CPS and comparatively, KF2 predicts them reasonably well. Particularly, the rapid intensification phase of the super cyclone is best simulated by KF2 compared to other CPS. To examine the effect of the cumulus parameterization scheme at high resolution (5 km), the three-domain configuration (45-15-5 km resolution) is utilized. Based on initial results, KF2 scheme is used for both the domains (D1 and D2). Two experiments are conducted: one in which KF2 is used as CPS and another in which no CPS is used in the third domain. The intensity is well predicted when no CPS is used in the innermost domain. The sensitivity experiments are also carried out to examine the impact from microphysics parameterization schemes (MPS). Four cloud microphysics parameterization schemes, namely mixed phase (MP), Goddard microphysics with Graupel (GG), Reisner Graupel (RG) and Schultz (Sc), are tested in these experiments. It is noted that the tropical cyclone tracks and intensity variation have considerable sensitivity to the varying cloud microphysical parameterization schemes. The MPS of MP and Sc could very well capture the rapid intensification phase. The final intensity is well predicted by MP, which is overestimated by Sc. The MPS of GG and RG underestimates the intensity.

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Section: Sensitivity To Cumulus Parameterization Schemes (Cps)supporting

confidence: 89%

Impact of cloud parameterization on the numerical simulation of a super cyclone

2012

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“…It therefore needs help from the parent wave. The protective kinematics of the Kelvin cat's eye (moving with the wave at its critical latitude) implies a reduction of dry air intrusions from outside (Tuleya and Kurihara, 1981) and a tendency for the heat released by cumulus convection to be retained in the comoving frame (Krishnamurti et al, 1994). The observation by Krishnamurti et al is incorporated in a third hypothesis below.…”

Section: Three New Hypotheses Regarding the Wave-vortex Hybridmentioning

confidence: 99%

Tropical cyclogenesis in a tropical wave critical layer: easterly waves

2009

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Abstract. The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by Correspondence to: T. J. Dunkerton (tim@nwra.com) the resolved flow, (ii) containment of moisture entrained by the developing gyre and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. The entire sequence is likened to the development of a marsupial infant in its mother's pouch. These ideas are formulated in three new hypotheses describing the flow kinematics and dynamics, moist thermodynamics and wave/vortex interactions comprising the "marsupial paradigm". A survey of 55 named tropical storms in 1998-2001 reveals that actual critical layers sometimes resemble the ideal east-west train of cat's eyes, but are usually less regular, with one or more recirculation regions in the co-moving frame. It is shown that the kinematics of isolated protovortices carried by the wave also can be visualized in a fra...

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“…The loss of heat in the core would lead to a hydrostatic adjustment to a higher minimum pressure and thus a weaker TC. Through the following decades, there was little talk in the literature about the venting hypothesis as most TC researchers were more concerned with shear's effects on TC track (Shapiro, 1992;Flatau et al, 1994;Wang & Holland, 1996), TC structure (Bender, 1997), and with specifying the effect of different types of shear on TC intensity (Tuleya & Kurihara, 1981;Merrill, 1998), rather than how exactly shear produced these effects. However, as mentioned, general explanations as to how these processes occurred generally focused on dynamical processes (Jones, 1995), midlevel warming (DeMaria, 1996), and asymmetries between surface fluxes and moisture convergence (Peng et al, 1999).…”

Section: The Venting Hypothesismentioning

confidence: 73%

“…This has been confirmed repeatedly even in the last 5 years (Paterson et al, 2005;Zeng et al, 2007Zeng et al, , 2008Garner et al, 2009;Hendricks et al, 2009). While small amounts of vertical shear have been seen as beneficial to TC development (Tuleya & Kurihara, 1981;Paterson et al, 2005), shears above 8-12m/s (DeMaria Kaplan, 1999;Wong and Chan, 2004;Paterson et al, 2005) have proven deleterious to TC intensity and structure. The question is how this works.…”

Section: Resultsmentioning

confidence: 99%

“…This asymmetry, he noted, was deadly for TC growth in that it renders the concentration of heat through the entire troposphere quite difficult (Gray, 1968). In stark contradiction to the findings of Gray (1968) and the community in general, Tuleya and Kurihara (1981) found that small (nonzero) levels of vertical shear, or moderate easterly www.intechopen.com shear, were beneficial to TC development. They performed their study using an 11-level primitive equation model in which simple environmental flows were superposed on a shallow perturbation resembling an easterly wave.…”

Section: Early Workmentioning

confidence: 99%

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