Vorticity-Based Detection of Tropical Cyclogenesis

• Other Authors: Hite, Michelle M. (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Meteorology; Oceanography; Atmospheric sciences
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-4027

Ocean wind vectors from the SeaWinds scatterometer on QuikSCAT and GOES imagery are used to develop an objective technique that can detect and monitor tropical disturbances associated with the early stages of tropical cyclogenesis in the Atlantic basin. The technique is based on identification of surface vorticity and wind speed signatures that exceed certain threshold magnitudes, with vorticity averaged over an appropriate spatial scale. The threshold values applied herein are determined from the precursors of 15 tropical cyclones during the 1999-2004 Atlantic hurricane seasons using research-quality QuikSCAT data. Tropical disturbances are found for these cases within a range of 19 hours to 101 hours before classification as tropical cyclones by the National Hurricane Center (NHC). The 15 cases are further subdivided based upon their origination source (i.e., easterly wave, upper-level cut-off low, stagnant frontal zone, etc). Primary focus centers on the cases associated with tropical waves, since these waves account for approximately 63% of all Atlantic tropical cyclones. The detection technique illustrates the ability to track these tropical disturbances from near the coast of Africa. Analysis of the pre-tropical cyclone (TC) tracks for these cases depict stages, related to wind speed and precipitation, in the evolution of an easterly wave to tropical cyclone. === A Thesis submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science. === Spring Semester, 2006. === November 22, 2005. === Quikscat, Seawinds, Tropical Disturbance, Tropical Cyclogenesis, Vorticity === Includes bibliographical references. === James J. O’Brien, Professor Directing Thesis; Mark A. Bourassa, Committee Member; Paul D. Reasor, Committee Member.