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Influence of Helicity on Regulating Diabatic Potential Vorticity in Isolated Convective Storms

Title: The Influence of Helicity on Regulating Diabatic Potential Vorticity in Isolated Convective Storms.
Name(s): Jo, Enoch, author
Chagnon, Jeffery M., professor directing thesis
Fuelberg, Henry E., committee member
Hart, Robert E. (Robert Edward), committee member
Florida State University, degree granting institution
College of Arts and Sciences, degree granting college
Department of Earth, Ocean, and Atmospheric Science, degree granting department
Type of Resource: text
Genre: Text
Master Thesis
Issuance: monographic
Date Issued: 2017
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (59 pages)
Language(s): English
Abstract/Description: Severe supercell thunderstorms exhibit rotation which aids in organization and maintenance of the storms. The effects of helicity and diabatic heating on the structure of potential vorticity (PV) in a supercell thunderstorm is examined through simple theoretical analysis using the linearized form of the Boussinesq system of equations and using sensitivity experiments in the Weather Research and Forecasting (WRF) model. The linear analysis shows that in the presence of helicity, a region of diabatic heating will favor one PV pole, resulting in storm rotation. In an environment with no helicity, a PV dipole will straddle the region of diabatic heating. The amplitude of the diabatically generated PV is regulated by the ratio H/U^2 where H is the helicity and U is the component of wind directed parallel to the background horizontal vorticity. This theoretical analysis of PV informs the design of five different idealized WRF experiments which demonstrate the role of helicity and latent heating in storm organization under differing environmental wind conditions. The WRF sensitivity tests confirm that a larger (smaller) H/U^2 results in more (less) storm rotation. This thesis offers a new PV perspective on the origin of storm scale rotation in convective environments and highlights the role of microphysical processes and latent heating in storm rotation.
Identifier: FSU_SUMMER2017_Jo_fsu_0071N_14088 (IID)
Submitted Note: A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Summer Semester 2017.
Date of Defense: July 10, 2017.
Keywords: Helicity, Latent Heating, Potential Vorticity, Storm Rotation, WRF
Bibliography Note: Includes bibliographical references.
Advisory Committee: Jeffrey Chagnon, Professor Directing Thesis; Henry Fuelberg, Committee Member; Robert Hart, Committee Member.
Subject(s): Meteorology
Persistent Link to This Record:
Owner Institution: FSU

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Jo, E. (2017). The Influence of Helicity on Regulating Diabatic Potential Vorticity in Isolated Convective Storms. Retrieved from