Increased sensitivity of tropical cyclogenesis to wind shear in higher SST environments

David S. Nolan, Eric D. Rappin

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

A new method for evaluating the sensitivity of tropical cyclone (TC) genesis to environmental parameters involves the simulation of tropical cyclone development with a cloud-resolving model in environments of radiative-convective equilibrium (RCE) generated by the same model. This method is extended to allow for the incorporation of mean wind shear into the RCE states, thus providing much more realistic and relevant simulations of TC genesis. The "finite-amplitude" nature of tropical cyclogenesis is reproduced, with cyclogenesis resulting only when the initial vortex strength is sufficient, which in turn depends on the environmental parameters. For fixed thermodynamic parameters, the required initial vortex strength necessary for genesis increases with the mean wind shear. However, an unexpected result has been obtained, that increasing sea surface temperature (SST) does not allow TC genesis to overcome greater shear. In fact, the opposite trend is found, that shear is more effective in suppressing TC genesis when the SST is higher. This increased sensitivity can be explained by several factors, such as the higher altitude of the developing mid-level vortex, stronger downdrafts, and increased static stability, all of which allow the shear to be more effective in disrupting the developing cyclone.

Original languageEnglish (US)
Article numberL14805
JournalGeophysical Research Letters
Volume35
Issue number14
DOIs
StatePublished - Jul 28 2008

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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