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Record 1 of 6680
Genesis of Pre-Hurricane Felix (2007). Part 1; The Role of the Easterly Wave Critical Layer
External Online Source: doi:10.1175/2009JAS3420.1
Author and Affiliation:
Wang, Zhuo(Illinois Univ. at Urbana-Champaign, Urbana, IL, United States)
Montgomery, M. T.(Naval Postgraduate School, Monterey, CA, United States)
Dunkerton, T. J.(Naval Postgraduate School, Monterey, CA, United States)
Abstract: The formation of pre Hurricane Felix (2007) in a tropical easterly wave is examined in a two-part study using the Weather Research and Forecasting (WRF) model with a high-resolution nested grid configuration that permits the representation of cloud system processes. The simulation commences during the wave stage of the precursor African easterly-wave disturbance. Here the simulated and observed developments are compared, while in Part II of the study various large-scale analyses, physical parameterizations, and initialization times are explored to document model sensitivities. In this first part the authors focus on the wave/vortex morphology, its interaction with the adjacent intertropical convergence zone complex, and the vorticity balance in the neighborhood of the developing storm. Analysis of the model simulation points to a bottom-up development process within the wave critical layer and supports the three new hypotheses of tropical cyclone formation proposed recently by Dunkerton, Montgomery, and Wang. It is shown also that low-level convergence associated with the ITCZ helps to enhance the wave signal and extend the "wave pouch" from the jet level to the top of the atmospheric boundary layer. The region of a quasi-closed Lagrangian circulation within the wave pouch provides a focal point for diabatic merger of convective vortices and their vortical remnants. The wave pouch serves also to protect the moist air inside from dry air intrusion, providing a favorable environment for sustained deep convection. Consistent with the authors' earlier findings, the tropical storm forms near the center of the wave pouch via system-scale convergence in the lower troposphere and vorticity aggregation. Components of the vorticity balance are shown to be scale dependent, with the immediate effects of cloud processes confined more closely to the storm center than the overturning Eliassen circulation induced by diabatic heating, the influence of which extends to larger radii.
Publication Date: Jun 01, 2010
Document ID:
20120002760
(Acquired Feb 29, 2012)
Subject Category: METEOROLOGY AND CLIMATOLOGY
Document Type: Journal Article
Publication Information: America Meteorological Society Journal of the Atmospheric Sciences (ISSN 0022-4928); Volume 67; Issue 6; 1711-1729
Publisher Information: American Meteorological Society, Washington, DC, United States
Contract/Grant/Task Num: NNH04CC63C; NNG07HU171; NSF ATM-0733380; NSF ATM-0715426; NSF ATM-0851554; N001408WR20129
Financial Sponsor: NASA; Washington, DC, United States
Office of Naval Research; Arlington, VA, United States
National Science Foundation; Arlington, VA, United States
Organization Source: Illinois Univ. at Urbana-Champaign; Urbana, IL, United States
Description: 19p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ATMOSPHERIC BOUNDARY LAYER; CLOUD PHYSICS; CYCLONES; HURRICANES; LAGRANGIAN FUNCTION; TROPICAL STORMS; VORTICES; CONVECTION; HEAT TRANSFER; WEATHER FORECASTING; INTRUSION; MORPHOLOGY; PARAMETERIZATION; SIMULATION; TROPICAL REGIONS
Availability Source: Other Sources
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Last Modified: February 29, 2012
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