Concentric Eyewall Formation in Typhoon Sinlaku (2008) - Part II: Axisymmetric Dynamical Processes
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Authors
Huang, Yi-Hsuan
Montgomery, Michael T.
Wu, Chun-Chieh
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Date of Issue
2012
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en_US
Abstract
In Part I of this study, the association between the secondary eyewall formation (SEF) and the broadening of the outer swirling wind in Typhoon Sinlaku (2008) was documented. The findings from Part I help lay the groundwork for the application of a newly proposed intensification paradigm to SEF. Part II presents a new model for SEF that utilizes this new paradigm and its axisymmetric view of the dynamics. The findings point to a sequence of structure changes that occur in the vortex’s outer-core region, culminating in SEF. The sequence begins with a broadening of the tangential winds, followed by an increase of the corre- sponding boundary layer (BL) inflow and an enhancement of convergence in the BL where the secondary eyewall forms. The narrow region of strong BL convergence is associated with the generation of supergradient winds in and just above the BL that acts to rapidly decelerate inflow there. The progressive strengthening of BL inflow and the generation of an effective adverse radial force therein leads to an eruption of air from the BL to support convection outside the primary eyewall in a favorable thermodynamic/kinematic environment. The results suggest that the unbalanced response in the BL serves as an important mechanism for initiating and sustaining a ring of deep convection in a narrow supergradient wind zone outside the primary eyewall. This progressive BL control on SEF suggests that the BL scheme and its coupling to the interior flow need to be adequately represented in numerical models to improve the prediction of SEF timing and preferred location.
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Article
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Part I may be found at https://doi.org/10.1175/MWR-D-11-00057.1
Part III may be found at http://hdl.handle.net/10945/60233
J. Atmos. Sci., 69 662-674
The article of record as published may be located at http://dx.doi.org/10.1175/JAS-D-11-0114.1
Part III may be found at http://hdl.handle.net/10945/60233
J. Atmos. Sci., 69 662-674
The article of record as published may be located at http://dx.doi.org/10.1175/JAS-D-11-0114.1
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Concentric Eyewall Formation in Typhoon Sinlaku (2008) - Part II: Axisymmetric Dynamical Processes, J. Atmos. Sci., 69: 662-674: 2012, Yi-Hsuan Huang, Michael T. Montgomery, and Chun-Chieh Wu
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.