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Genesis of Pre-Hurricane Felix (2007)This is the second of a two-part study examining the simulated formation of Atlantic Hurricane Felix (2007) in a cloud-representing framework. Here several open issues are addressed concerning the formation of the storm's warm core, the evolution and respective contribution of stratiform versus convective precipitation within the parent wave's pouch, and the sensitivity of the development pathway reported in Part I to different model physics options and initial conditions. All but one of the experiments include ice microphysics as represented by one of several parameterizations, and the partition of convective versus stratiform precipitation is accomplished using a standard numerical technique based on the high-resolution control experiment. The transition to a warm-core tropical cyclone from an initially cold-core, lower tropospheric wave disturbance is analyzed first. As part of this transformation process, it is shown that deep moist convection is sustained near the pouch center. Both convective and stratiform precipitation rates increase with time. While stratiform precipitation occupies a larger area even at the tropical storm stage, deep moist convection makes a comparable contribution to the total rain rate at the pregenesis stage, and a larger contribution than stratiform processes at the storm stage. The convergence profile averaged near the pouch center is found to become dominantly convective with increasing deep moist convective activity there. Low-level convergence forced by interior diabatic heating plays a key role in forming and intensifying the near-surface closed circulation, while the midlevel convergence associated with stratiform precipitation helps to increase the midlevel circulation and thereby contributes to the formation and upward extension of a tropospheric-deep cyclonic vortex. Sensitivity tests with different model physics options and initial conditions demonstrate a similar pregenesis evolution. These tests suggest that the genesis location of a tropical storm is largely controlled by the parent wave's critical layer, whereas the genesis time and intensity of the protovortex depend on the details of the mesoscale organization, which is less predictable. Some implications of the findings are discussed.
Document ID
20120002780
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
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)
Date Acquired
August 25, 2013
Publication Date
June 1, 2010
Publication Information
Publication: Journal of the Atmospheric Sciences
Publisher: American Meteorite Lab.
Volume: 67
Issue: 6
Subject Category
Meteorology And Climatology
Report/Patent Number
ISSN 0022-4928
Funding Number(s)
CONTRACT_GRANT: NSF ATM-0715426
CONTRACT_GRANT: NSF ATM-0851554
CONTRACT_GRANT: NNG07HU171
CONTRACT_GRANT: NNH04CC63C
CONTRACT_GRANT: NSF ATM-0733380
CONTRACT_GRANT: N001408WR20129
Distribution Limits
Public
Copyright
Other

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