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Journal of Southern Hemisphere Earth Systems Science Journal of Southern Hemisphere Earth Systems Science SocietyJournal of Southern Hemisphere Earth Systems Science Society
A journal for meteorology, climate, oceanography, hydrology and space weather focused on the southern hemisphere
RESEARCH ARTICLE (Open Access)

Vacillation Cycles in WRF Simulations of Hurricane Katrina

M. Reif, M.J. Reeder and M.C.N. Hankinson

Australian Meteorological and Oceanographic Journal 64(2) 123 - 132
Published: 2014

Abstract

The intensification of hurricane Katrina (2005) in non-hydrostatic simulations with the WRF model is compared to a hydrostatic simulation conducted in a previous study with the Australian Bureau of Meteorology’s Tropical Cyclone Limited Area Prediction System (TCLAPS). During the intensification both simulations exhibit inner-core vacillation cycles between highly asymmetric and more symmetric phases in the low-level potential vorticity (PV) and vertical velocity, although their evolution and structure are more complex in WRF. Although in WRF the lowlevel PV vacillates between symmetric and more asymmetric stages, similar to the hydrostatic TCLAPS simulation, no fully monopolar structure develops in asymmetric phases; the PV maintains its ring-like structure during the intensification. The asymmetric phases in WRF are characterised by isolated PV anomalies breaking from the eyewall and propagating towards the centre. While stirring high PV into the centre episodically, these isolated PV anomalies cause a stepwise drop in central pressure.

https://doi.org/10.1071/ES14012

© Commonwealth of Australia represented by the Bureau of Meterology 2014. This is an open access article distributed under the Creative Commons Attribution-NonCommerical-NoDerivatives 4.0 International License (CC BY-NC-ND).

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