Dynamics and predictability of secondary eyewall formation in sheared tropical cyclones

Fuqing Zhang, Dandan Tao, Y. Qiang Sun, Jeffrey D. Kepert

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

This study examines the predictability and dynamics of tropical cyclone (TC) secondary eyewall formation (SEF), eyewall replacement cycles (ERC), and intensity changes under moderate environmental shear through convection-permitting ensemble simulations. Even with the same environmental shear, the TC intensity changes during formation, rapid intensification, and SEF/ERC can be extremely sensitive to small, unobservable, random initial condition uncertainties, or computer's truncation error due to the chaotic nature of moist convection. Through composite analysis of five ensemble members with similar clear SEF/ERC and diagnostics with a nonlinear boundary layer (BL) model, we identify several key factors in the SEF/ERC process: (1) fast expansion of outer wind fields and changing inertial stability through shear-induced peripheral convection outside of the primary eyewall, (2) downward building and axisymmetrization of the primary (outer) rainband due to enhanced inertial stability and positive feedback between BL and outer convection, (3) establishment of the secondary eyewall along with moat formation that is facilitated by compensating subsidence from the primary eyewall, and (4) weakening and eventual replacement of the original primary eyewall by the strengthening secondary eyewall. It is also seen from the partial ERC cases that the preexisting rainband can be of great importance to the later development of SEF. Diagnosis with the nonlinear BL model shows that the location and relative strengths of the diagnosed frictional updrafts closely match those in the ensemble simulation of the ERC case, suggesting that the boundary layer convergence substantially influences the location of the convection in both eyewalls there.

Original languageEnglish (US)
Pages (from-to)89-112
Number of pages24
JournalJournal of Advances in Modeling Earth Systems
Volume9
Issue number1
DOIs
StatePublished - Mar 1 2017

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tropical cyclone
replacement
Boundary layers
convection
boundary layer
rainband
Subsidence
updraft
Convection
wind field
Feedback
simulation
subsidence
Composite materials

All Science Journal Classification (ASJC) codes

  • Global and Planetary Change
  • Environmental Chemistry
  • Earth and Planetary Sciences(all)

Cite this

Zhang, Fuqing ; Tao, Dandan ; Sun, Y. Qiang ; Kepert, Jeffrey D. / Dynamics and predictability of secondary eyewall formation in sheared tropical cyclones. In: Journal of Advances in Modeling Earth Systems. 2017 ; Vol. 9, No. 1. pp. 89-112.
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Dynamics and predictability of secondary eyewall formation in sheared tropical cyclones. / Zhang, Fuqing; Tao, Dandan; Sun, Y. Qiang; Kepert, Jeffrey D.

In: Journal of Advances in Modeling Earth Systems, Vol. 9, No. 1, 01.03.2017, p. 89-112.

Research output: Contribution to journalArticle

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