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Hurricane formation in diabatic Ekman turbulence
Author(s) -
Schecter David A.,
Dunkerton Timothy J.
Publication year - 2009
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.405
Subject(s) - diabatic , ekman transport , climatology , tropical cyclone , turbulence , environmental science , meteorology , ekman layer , atmospheric sciences , geology , physics , mechanics , oceanography , boundary layer , upwelling , adiabatic process , thermodynamics
This article investigates the emergence of hurricanes from chaotic swirling motions in a three‐layer model of the tropical troposphere that includes basic parametrizations of cumulus convection and air‐‐sea interaction. The chaotic flow is referred to as diabatic Ekman turbulence (DET), in order to emphasize that cumulus convection and Ekman pumping are critical to its behaviour. The time required for hurricane formation in DET is examined over a broad range of sea‐surface temperatures, tropical latitudes and surface exchange coefficients for moist entropy and momentum. The mean trends are sensible, but for a given set of parameters, the genesis time can vary significantly with subtle changes to the initial turbulence. Moreover, hurricanes do not always form. In the event that a tropical depression develops into a hurricane, the process is highly asymmetric. Intensification involves a shear‐flow instability, the production of mesovortices and contraction of the basic circulation. Despite the complex evolution, the intensification rate is largely consistent with the expectations of a quasi‐linear stability analysis. Properties of mature hurricanes and the nature of their fluctuations are discussed in the context of the model. Copyright © 2009 Royal Meteorological Society