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Wei Zhong, Da-Lin Zhang, and Han-Cheng Lu

–gravity waves (IGWs; e.g., Willoughby 1978 ; Xu 1983 ). However, radar observations indicate that internal IGWs often propagate at speeds that are much faster than those of spiral rainbands. Thus, more research interest has shifted since the 1990s to the vortex–Rossby wave (VRW) theory of MacDonald (1968) , who drew an analogy between the movement of spiral rainbands and the propagation of Rossby waves around a rotating planet. Guinn and Schubert (1993) hypothesized that during the intensifying stage

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Zhuo Wang, M. T. Montgomery, and T. J. Dunkerton

and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm. Atmos. Chem. Phys. Discuss. , 9 , 26143 – 26197 . Noh , Y. , W-G. Cheon , S-Y. Hong , and S. Raasch , 2003 : Improvement of the K -profile model for the planetary boundary layer based on large eddy simulation data. Bound.-Layer Meteor. , 107 , 401 – 427 . Nolan , D. S. , 2007 : What is the trigger for tropical cyclogenesis? Aust. Meteor. Mag. , 56 , 241

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Edward K. Vizy and Kerry H. Cook

wave, Tropical Storm Debby, so those parameters were selected for use here. Parameterizations chosen include the Purdue–Lin microphysics scheme, new Kain–Fritsch cumulus convection scheme; Monin–Obukhov surface layer scheme; unified National Centers for Environmental Prediction (NCEP), Oregon State, Air Force, Hydrologic Research Laboratory of the National Weather Service (NOAH) land surface model ( Chen and Dudhia 2001 ); the NCAR CAM radiation parameterization; and the Yonsei University planetary

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Wallace Hogsett and Da-Lin Zhang

different stages of storm development. They found that the KE budgets are determined primarily by the mean flow, although the contribution of eddies is not negligible. Wang (2002a) also examined the inner-core energetics of a simulated TC vortex and found that the maximum eddy KE, located in the lower levels near the radius of maximum wind (RMW), appears to be associated with vortex–Rossby waves (VRWs). Although VRWs have been hypothesized to be active in the inner core of TCs ( Montgomery and

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Scott A. Braun, Michael T. Montgomery, Kevin J. Mallen, and Paul D. Reasor

form within regions of pre-existing cyclonic relative vorticity in the lower troposphere—for example, easterly waves, a monsoon trough, or the active part of the Madden–Julian oscillation ( Roundy and Frank 2004 ). Tropical storms are generally spawned from mesoscale convective system (MCS) precursors within the pre-existing region of cyclonic vorticity noted above ( Velasco and Fritsch 1987 ; Gray 1998 ). Midlevel convergence into large stratiform precipitation regions within MCSs, along with

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Chanh Q. Kieu and Da-Lin Zhang

global models in predicting TC tracks indicate that the large-scale circulation is the key parameter in determining where TCG may occur. It is well known that the large-scale conditions conducive for TCG over different ocean basins include weak vertical wind shear ( Gray 1968 ; McBride and Zehr 1981 ; DeMaria 1996 ), warm sea surface temperature (SST) and deep moist layers ( Emanuel 2000 ), well-organized angular momentum fluxes ( Challa and Pfeffer 1990 ), easterly waves ( Molinari et al. 2000

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Zhaoxia Pu, Xuanli Li, and Juanzhen Sun

remarks are made in section 5 . 2. Description of Hurricane Dennis and Doppler radar data a. A brief overview of Hurricane Dennis (2005) According to Beven (2005) , Hurricane Dennis developed from a tropical wave near the coast of Africa on 29 June 2005. It became a tropical storm on 5 July, reached hurricane strength early on 7 July, and then rapidly intensified into category 4 strength before making landfall near Puntadel Ingles in southeastern Cuba around 0300 UTC 8 July. Dennis weakened to a

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Robert Rogers

change. Montgomery and Kallenbach (1997) showed that vortex Rossby waves intensify the axisymmetric primary circulation by axisymmetrizing convectively generated potential vorticity perturbations near the radius of maximum winds. Mesovortices are other asymmetric features that have been identified as being important for TC intensity change by mixing momentum, vorticity, and high-entropy air between the eye and eyewall ( Schubert et al. 1999 ; Kossin and Schubert 2001 ; Montgomery et al. 2002

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Syed Ismail, Richard A. Ferrare, Edward V. Browell, Gao Chen, Bruce Anderson, Susan A. Kooi, Anthony Notari, Carolyn F. Butler, Sharon Burton, Marta Fenn, Jason P. Dunion, Gerry Heymsfield, T. N. Krishnamurti, and Mrinal K. Biswas

limit (∼30°N and 38°W) of National Oceanic and Atmospheric Administration (NOAA) research aircraft that were conducting coordinated Saharan Air Layer Experiment (SALEX) research missions from Barbados ( Zipser et al. 2009 ). The study of African easterly waves (AEWs; Thorncroft and Hoskins 1994a , b ) and the potential development of AEWs into major Atlantic hurricanes is of great interest because nearly 85% of intense (or major) hurricanes have their origins as AEWs ( Landsea 1993 ). Seven AEWs

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Chanh Q. Kieu and Da-Lin Zhang

one? To what extent do the convectively generated PV fluxes in the ITCZ assist the deepening of Eugene, especially after its migration into an environment with strong vertical shear and colder sea surface temperature (SST)? What are the roles of the frictional convergence in the planetary boundary layer (PBL) in determining the genesis of Eugene? Is the bottom-up development of Eugene valid in general or is it just a result of the vortex merger? These questions will be addressed through a series

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