Short-time-scale processes in a mature hurricane as a response to sea surface fluctuations

Kosuke Ito, Yoichi Ishikawa, Yoshiaki Miyamoto, Toshiyuki Awaji

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

To clarify the effect of fluctuations in surface stress and heat fluxes on the intensity of a mature-state hurricane, a sensitivity analysis is performed by using a cloud-permitting nonhydrostatic axisymmetric adjoint model. The response function of our experiment is tangential velocity at the top of the boundary layer in the eyewall. As a result of an integration backward to 4 min prior to the specified time, a dipole pattern appears in the sensitivity fields with respect to the vertical velocity, the potential temperature, and the mixing ratio of water vapor. A positive (negative) sensitivity is found in the hurricane interior (exterior) relative to the verification region. It exhibits an increase of tangential velocity 4 min after the introduction of positive (negative) perturbations in potential temperature or in the mixing ratio of water vapor in the interior (exterior). These sensitivities are not related to the changes in the central pressure field. With further backward integration, the sensitivity signals reach down to the surface and are located in the exterior region of the hurricane. While the sensitivity with respect to surface friction (heat flux) is strongly negative (positive) within a certain radius, the sensitivity can be positive (negative) beyond that radius. This means that both stronger friction and a reduction in moist air supply in the exterior region of the hurricane can serve to strengthen the maximum tangential velocity. To the authors' knowledge, this effect has not been explained in previous studies.

Original languageEnglish
Pages (from-to)2250-2272
Number of pages23
JournalJournal of the Atmospheric Sciences
Volume68
Issue number10
DOIs
Publication statusPublished - 2011 Oct 1
Externally publishedYes

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hurricane
sea surface
timescale
potential temperature
mixing ratio
heat flux
water vapor
friction
pressure field
sensitivity analysis
boundary layer
perturbation
air
experiment
effect

Keywords

  • Atmosphere-ocean interaction
  • Hurricanes
  • Sensitivity studies

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Short-time-scale processes in a mature hurricane as a response to sea surface fluctuations. / Ito, Kosuke; Ishikawa, Yoichi; Miyamoto, Yoshiaki; Awaji, Toshiyuki.

In: Journal of the Atmospheric Sciences, Vol. 68, No. 10, 01.10.2011, p. 2250-2272.

Research output: Contribution to journalArticle

Ito, Kosuke ; Ishikawa, Yoichi ; Miyamoto, Yoshiaki ; Awaji, Toshiyuki. / Short-time-scale processes in a mature hurricane as a response to sea surface fluctuations. In: Journal of the Atmospheric Sciences. 2011 ; Vol. 68, No. 10. pp. 2250-2272.
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