The Governing Dynamics of the Secondary Eyewall Formation of Typhoon Sinlaku (2008)

Sun, Yongqiang; Jiang, Yuxin; Tan, Benkui; Zhang, Fuqing

doi:10.1175/jas-d-13-044.1

Cited by 44 publications

(57 citation statements)

References 52 publications

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“…SW82 and the subsequent studies [e.g., Smith et al , 2005; Bui et al ., ; Rozoff et al ., ; Sun et al ., ] showed that the vertical transverse circulation induced by heating and momentum forcing may be appropriately diagnosed via the Sawyer‐Eliassen equation,

\begin{matrix} left \\ \frac{\partial}{\partial r} [- g \frac{\partial \overset{true¯}{χ}}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial r} - \frac{\partial (\overset{true¯}{χ} \overset{true¯}{C})}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial z}] + \frac{\partial}{\partial z} [(\overset{true¯}{ξ} \overset{true¯}{χ} (\overset{true¯}{ς} + f) + \overset{true¯}{C} \frac{\partial \overset{true¯}{χ}}{\partial r}) \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial z} - \frac{\partial (\overset{true¯}{χ} \overset{true¯}{C})}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial r}] \\ = g \frac{\partial}{\partial r} ({\overset{χ}{true}}^{2} \overset{true¯}{Q}) + \frac{\partial}{\partial z} (\overset{true¯}{C} {\overset{χ}{true}}^{2} \overset{true¯}{Q}) - \frac{\partial}{\partial z} (\overset{true¯}{χ} \overset{true¯}{ξ} {\overset{F}{true}}_{λ}), \end{matrix}

…”

Section: Resultsmentioning

confidence: 99%

The role of outer rainband convection in governing the eyewall replacement cycle in numerical simulations of tropical cyclones

Zhu

2014

J. Geophys. Res. Atmos.

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Eyewall replacement cycles (ERCs) are frequently observed during the evolution of intensifying tropical cyclones (TCs). Although intensely studied in recent years, the underlying mechanisms of ERCs are still not well understood, and a timely accurate forecast of ERCs remains to be a challenge. To advance our understanding of ERCs and provide insights into the improvement of numerical forecast of ERCs, a series of three-dimensional full physics simulations is performed using the Weather Research and Forecasting (WRF) model to investigate ERCs in TC-like vortices on an f plane. The simulated ERC in the control experiment possesses key features similar to those observed in real TCs including the formation and development of a secondary tangential wind maximum associated with the outer eyewall. The Sawyer-Eliassen diagnoses and tangential momentum budget analyses are performed to investigate the mechanisms underlying the secondary eyewall formation (SEF) and ERC. The simulations show the crucial roles of outer rainband heating in governing the formation and development of the secondary tangential wind maximum and demonstrate that the outer rainband convection must reach a critical strength relative to the eyewall convection before SEF and ERC can occur. The diagnoses reveal a positive feedback among low-level convection, acceleration of tangential winds and convergence of radial flow in the upper boundary layer, and surface evaporation that leads to the development of outer rainband convection and formation of secondary eyewall, and a mechanism for the demise of inner eyewall that involves the interaction between the transverse circulations induced by eyewall and outer rainband convection.

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\begin{matrix} left \\ \frac{\partial}{\partial r} [- g \frac{\partial \overset{true¯}{χ}}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial r} - \frac{\partial (\overset{true¯}{χ} \overset{true¯}{C})}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial z}] + \frac{\partial}{\partial z} [(\overset{true¯}{ξ} \overset{true¯}{χ} (\overset{true¯}{ς} + f) + \overset{true¯}{C} \frac{\partial \overset{true¯}{χ}}{\partial r}) \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial z} - \frac{\partial (\overset{true¯}{χ} \overset{true¯}{C})}{\partial z} \frac{1}{r ρ_{o}} \frac{\partial \overset{true¯}{ψ}}{\partial r}] \\ = g \frac{\partial}{\partial r} ({\overset{χ}{true}}^{2} \overset{true¯}{Q}) + \frac{\partial}{\partial z} (\overset{true¯}{C} {\overset{χ}{true}}^{2} \overset{true¯}{Q}) - \frac{\partial}{\partial z} (\overset{true¯}{χ} \overset{true¯}{ξ} {\overset{F}{true}}_{λ}), \end{matrix}

…”

Section: Resultsmentioning

confidence: 99%

The role of outer rainband convection in governing the eyewall replacement cycle in numerical simulations of tropical cyclones

Zhu

2014

J. Geophys. Res. Atmos.

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“…Other models propose wave-mean flow interaction associated primarily with vortex Rossby waves and their modification to the storm inner-core region (Montgomery and Kallenbach 1997;Martinez et al 2010a,b;Menelaou et al 2012;Qiu et al 2010;Abarca and Corbosiero 2011) or the generation and accumulation of convectively induced potential vorticity anomalies and the absence of vortex Rossby wave activity (Judt and Chen 2010). Sun et al (2013) proposed that SEF arises from a feedback between inward-moving rainbands, the balanced response to their source of heat, and unbalanced dynamics. Wang et al (2013) proposed that a ''net'' radial force in the boundary layer is relevant in the process and Qiu and Tan (2013) emphasized the role of the asymmetric boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Departures from Axisymmetric Balance Dynamics during Secondary Eyewall Formation

Abarca

Montgomery

2014

Journal of the Atmospheric Sciences

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Departures from axisymmetric balance dynamics are quantified during a case of secondary eyewall formation. The case occurred in a three-dimensional mesoscale convection-permitting numerical simulation of a tropical cyclone, integrated from an initial weak mesoscale vortex in an idealized quiescent environment. The simulation exhibits a canonical eyewall replacement cycle. Departures from balance dynamics are quantified by comparing the azimuthally averaged secondary circulation and corresponding tangential wind tendencies of the mesoscale integration with those diagnosed as the axisymmetric balanced response of a vortex subject to diabatic and tangential momentum forcing. Balance dynamics is defined here, following the tropical cyclone literature, as those processes that maintain a vortex in axisymmetric thermal wind balance.The dynamical and thermodynamical fields needed to characterize the background vortex for the SawyerEliassen inversion are obtained by azimuthally averaging the relevant quantities in the mesoscale integration and by computing their corresponding balanced fields. Substantial differences between azimuthal averages and their homologous balance-derived fields are found in the boundary layer. These differences illustrate the inappropriateness of the balance assumption in this region of the vortex (where the secondary eyewall tangential wind maximum emerges). Although the balance model does broadly capture the sense of the forced transverse (overturning) circulation, the balance model is shown to significantly underestimate the inflow in the boundary layer. This difference translates to unexpected qualitative differences in the tangential wind tendency. The main finding is that balance dynamics does not capture the tangential wind spinup during the simulated secondary eyewall formation event.

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“…Mesoscale numerical models continue to be an invaluable tool to study the dynamical and thermodynamical processes relating to the evolution of the hurricane vortex. Numerical studies on rainband formation and structure [e.g., Akter and Tsuboki , ; Li and Wang , ; Yu and Tsai , ; Tang et al ., ], secondary eyewall formation [e.g., Terwey and Montgomery , ; Judt and Chen , ; Huang et al ., ; Rozoff et al ., ; Abarca and Montgomery , ; Qiu and Tan , ; Sun et al ., ; Wang et al ., ], and land effects on intensity, structure, and track [e.g., Kimball , ; Wu et al ., , ; Huang et al ., ] are just a few recent examples. In each of the above named situations, convective processes are vital and heavily studied.…”

Section: Introductionmentioning

confidence: 99%

Objective convective updraft identification and tracking: Part 1. Structure and thermodynamics of convection in the rainband regions of two hurricane simulations

Terwey

Rozoff

2014

JGR Atmospheres

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To better understand the life cycles of convective elements in numerical model simulations, a convective updraft tracking algorithm, dubbed the Statistical and Programmable Objective Updraft Tracker (SPOUT), is developed. SPOUT identifies updraft cores in horizontal slices through a given model data set, links these cores in three dimensions to form vertically coherent updrafts, and then tracks updrafts in time via estimates of the mean local advection. SPOUT is evaluated in idealized hurricane simulations from both the Regional Atmospheric Modeling System (RAMS) and Weather Research and Forecasting (WRF). In both simulations, SPOUT indicates most updrafts live less than 60 min, but some can persist for over 2 h. Updrafts are typically manifested as shallow cumulus, cumulus congestus, and deep cumulonimbus. Overall, there is reasonable agreement between the vigor of convection and the amount of localized conditional convective instability. Also, the majority of updrafts attain a tilted structure that is in accordance with the localized vertical wind shear. Nonetheless, there are striking differences between models, with the higher-resolution WRF simulation producing around twice as many updrafts as RAMS. Moreover, the WRF updrafts are significantly weaker. This paper highlights the utility of SPOUT for studying convective life cycles in high-resolution numerical simulations and provides some basic features of convection in two hurricane simulations.

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The Governing Dynamics of the Secondary Eyewall Formation of Typhoon Sinlaku (2008)

Cited by 44 publications

References 52 publications

The role of outer rainband convection in governing the eyewall replacement cycle in numerical simulations of tropical cyclones

The role of outer rainband convection in governing the eyewall replacement cycle in numerical simulations of tropical cyclones

Departures from Axisymmetric Balance Dynamics during Secondary Eyewall Formation

Objective convective updraft identification and tracking: Part 1. Structure and thermodynamics of convection in the rainband regions of two hurricane simulations

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