Isentropic analysis of a simulated hurricane

Agnieszka A. Mrowiec, Olivier M. Pauluis, Fuqing Zhang

Research output: Contribution to journalArticle

Abstract

Hurricanes, like many other atmospheric flows, are associated with turbulent motions over a wide range of scales. Here the authors adapt a new technique based on the isentropic analysis of convective motions to study the thermodynamic structure of the overturning circulation in hurricane simulations. This approach separates the vertical mass transport in terms of the equivalent potential temperature of air parcels. In doing so, one separates the rising air parcels at high entropy from the subsiding air at low entropy. This technique filters out oscillatory motions associated with gravity waves and separates convective overturning from the secondary circulation. This approach is applied here to study the flow of an idealized hurricane simulation with the Weather Research and Forecasting (WRF) Model. The isentropic circulation for a hurricane exhibits similar characteristics to that of moist convection, with a maximum mass transport near the surface associated with a shallow convection and entrainment. There are also important differences. For instance, ascent in the eyewall can be readily identified in the isentropic analysis as an upward mass flux of air with unusually high equivalent potential temperature. The isentropic circulation is further compared here to the Eulerian secondary circulation of the simulated hurricane to show that the mass transport in the isentropic circulation is much larger than the one in secondary circulation. This difference can be directly attributed to the mass transport by convection in the outer rainband and confirms that, even for a strongly organized flow like a hurricane, most of the atmospheric overturning is tied to the smaller scales.

Original languageEnglish (US)
Pages (from-to)1857-1870
Number of pages14
JournalJournal of the Atmospheric Sciences
Volume73
Issue number5
DOIs
StatePublished - May 1 2016

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hurricane
mass transport
convection
air
potential temperature
entropy
rainband
analysis
gravity wave
entrainment
simulation
thermodynamics
filter
weather

Keywords

  • Circulation/Dynamics
  • Cloud resolving models
  • Hurricanes
  • Isentropic analysis
  • Lagrangian circulation/transport
  • Mathematical and statistical techniques
  • Models and modeling

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Isentropic analysis of a simulated hurricane. / Mrowiec, Agnieszka A.; Pauluis, Olivier M.; Zhang, Fuqing.

In: Journal of the Atmospheric Sciences, Vol. 73, No. 5, 01.05.2016, p. 1857-1870.

Research output: Contribution to journalArticle

Mrowiec, Agnieszka A. ; Pauluis, Olivier M. ; Zhang, Fuqing. / Isentropic analysis of a simulated hurricane. In: Journal of the Atmospheric Sciences. 2016 ; Vol. 73, No. 5. pp. 1857-1870.
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