Deep convection in elliptical and polygonal eyewalls of tropical cyclones: Deep Convection of Polygonal Eyewalls
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Authors
Kuo, Hung-Chi
Cheng, Wei-Yi
Yang, Yi-Ting
Hendricks, Eric A.
Peng, Melinda S.
Subjects
Advisors
Date of Issue
2017
Date
December, 2016, Journal of Geophysical Research: Atmospheres
Publisher
American Geophysical Union (AGU)
Language
Abstract
In observations, tropical cyclones with cyclonically rotating elliptical eyewalls are often characterized by wave number 2 (WN2) deep convection located at the edge of the major axis. A simple modeling framework is used to understand this phenomenon, where a nondivergent barotropic model (NBM) is employed to represent the elliptical vortex in the free atmosphere, and an asymmetric slab boundary layer (SBL) model is used to simulate the frictional boundary layer (BL) underneath the free atmosphere. The interaction is one way in that the overlying cyclonic flow drives the BL, but the BL pumping does not feed back to the overlying flow. The nonlinear-balanced pressure field from the NBM drives the winds in the SBL model, which then causes BL convergence and pumping near the eyewall. The strong updrafts at the edge of the major axis for the elliptic vortex in the BL are induced by the larger convergent radial wind from the asymmetric distribution of the pressure fields of the free atmosphere with noncircular vortex. The large radial inflow maintains the supergradient wind at the edge of the elliptical vortex. The results emphasize the cyclonic rotation of the WN2 feature of strong updrafts at the top of the BL from the local shock-like BL radial wind structure. Similar radial profiles and strong BL top updrafts occur at the edges of higher-order polygonal eyewalls with the magnitude of the peak updraft decreasing as the wave number structure of the vortex increases.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.1002/2016JD025317
Series/Report No
Department
Meteorology
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Sponsors
This work was supported by Ministry of Science and Technology in Taiwan under grants MOST 104-2111- M-002-002-MY3, MOST 104-2625-M- 002-006, and MOST-105-2119-M-002- 035 and the Naval Research Laboratory under grant N62909-15-1-2008.
Funder
This work was supported by Ministry of Science and Technology in Taiwan under grants MOST 104-2111- M-002-002-MY3, MOST 104-2625-M- 002-006, and MOST-105-2119-M-002- 035 and the Naval Research Laboratory under grant N62909-15-1-2008.
Format
Citation
Kuo, Hung-Chi, et al. "Deep convection in elliptical and polygonal eyewalls of tropical cyclones." Journal of Geophysical Research: Atmospheres 121.24 (2016).
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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.