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Role of Diabatic Potential Vorticity during Hurricane Genesis

Title: Role of Diabatic Potential Vorticity during Hurricane Genesis.
Name(s): Ramaswamy, Leela, author
Krishnamurti, T. N., professor directing thesis
Barcilon, Albert I., committee member
Ruscher, Paul H., 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: 2003
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: This study explores potential vorticity budgets from the complete Ertel's potential vorticity equation during hurricane genesis. The data sets for these experiments are derived from a high-resolution hurricane forecast that provided reasonable simulation on hurricane genesis. The budgets sort out the relative contribution from the horizontal advection of PV (i.e., related to the conservation of PV in isentropic coordinates), vertical advection of PV (a diabatic contribution), differential heating along the vertical, differential heating along the horizontal, and the frictional contributions. This is aimed to sort out the role of conservation versus non-conservation of PV during the formative stage of a hurricane. The main findings of this study are that conservation of PV was not adequate to explain the large increase in PV during genesis of the storm. The vertical differential of heating made by far the most significant contributions to the changes of PV during the length of the forecast. This term contributed to a net generation of PV over a region of stable air with cyclonic vorticity and increased heating with height. The term is akin to the vortex stretching term in the vorticity equation and is the diabatic stretching of the vortex tube. The effect that convergence has on vorticity in pressure coordinates is entirely analogous to the effect that the diabatic stretching term has on PV in isentropic coordinates. The vertical advection of PV and the horizontal differential of heating each made smaller contributions to changes in PV, but neither was a significant contributor as compared to the other terms. Our analysis includes parcel trajectories along which the PV components (adiabatic and diabatic) of the complete equation are calculated at intervals of every three hours. These were also cast on isentropic surfaces to assess the role of the nonlinear advection of PV and of the diabatic contributions. In the inner rain area of the hurricane a jump in the value of diabatic PV was noted (related to the vertical differential of heating) that was roughly several times larger than that of the nonlinear advection of PV (the latter relates to the conservation of PV while the former is a measure of the non-conservation).
Identifier: FSU_migr_etd-2138 (IID)
Submitted Note: A Thesis Submitted to the Department of Meteorology in Partial Fulfillment of the Requirements for the Degree of Master of Science.
Degree Awarded: Fall Semester, 2003.
Date of Defense: September 25, 2003.
Keywords: Vortices, Vortex, Hurricane, Diabatic
Bibliography Note: Includes bibliographical references.
Advisory Committee: T. N. Krishnamurti, Professor Directing Thesis; Albert I. Barcilon, Committee Member; Paul H. Ruscher, Committee Member.
Subject(s): Meteorology
Persistent Link to This Record:
Owner Institution: FSU

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Ramaswamy, L. (2003). Role of Diabatic Potential Vorticity during Hurricane Genesis. Retrieved from