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Warm Seclusion Extratropical Cyclones

Title: Warm Seclusion Extratropical Cyclones.
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Name(s): Maue, Ryan Nicholas, 1981-, author
Bourassa, Mark A., professor directing dissertation
Speer, Kevin G., university representative
Zou, Xiaolei, committee member
Misra, Vasubandhu, committee member
Hart, Robert E., committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: text
Issuance: monographic
Date Issued: 2010
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
Physical Form: online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The warm seclusion or mature stage of the extratropical cyclone lifecycle often has structural characteristics reminiscent of major tropical cyclones including eye-like moats of calm air at the barotropic warm-core center surrounded by hurricane force winds along the bent-back warm front. Many extratropical cyclones experience periods of explosive intensification or deepening (bomb) as a result of nonlinear dynamical feedbacks associated with latent heat release. Considerable dynamical structure changes occur during short time periods of several hours in which lower stratospheric and upper-tropospheric origin potential vorticity combines with ephemeral lower-tropospheric, diabatically generated potential vorticity to form a coherent, upright tower circulation. At the center, anomalously warm and moist air relative to the surrounding environment is secluded and may exist for days into the future. Even with the considerable body of research conducted during the last century, many questions remain concerning the warm seclusion process. The focus of this work is on the diagnosis, climatology, and synoptic-dynamic development of the warm seclusion and surrounding flank of intense winds. To develop a climatology of warm seclusion and explosive extratropical cyclones, current long-period reanalysis datasets are utilized along with storm tracking procedures and cyclone phase space diagnostics. Limitations of the reanalysis products are discussed with special focus on tropical cyclone diagnosis and the recent dramatic decrease in global accumulated tropical cyclone energy. A large selection of case studies is simulated with the Weather Research and Forecasting (WRF) mesoscale model using full-physics and "fake dry" adiabatic runs in order to capture the very fast warm seclusion development. Results are presented concerning the critical role of latent heat release and the combination of advective and diabatically generated potential vorticity in the generation of the coherent tower circulation characteristic of the warm seclusion. To motivate future research, issues related to predictability are discussed with focus on medium-range forecasts of varying extratropical cyclone lifecycles. Additional work is presented relating tropical cyclones and large-scale climate variability with special emphasis on the abrupt and dramatic decline in recent global tropical cyclone accumulated cyclone energy.
Identifier: FSU_migr_etd-2661 (IID)
Submitted Note: A Dissertation submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Summer Semester, 2010.
Date of Defense: May 28, 2010.
Keywords: Tropical Cyclone, Extratropical Cyclone, Climatology, Warm Seclusion
Bibliography Note: Includes bibliographical references.
Advisory Committee: Mark A. Bourassa, Professor Directing Dissertation; Kevin G. Speer, University Representative; Xiaolei Zou, Committee Member; Vasubandhu Misra, Committee Member; Robert E. Hart, Committee Member.
Subject(s): Meteorology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-2661
Owner Institution: FSU