[Eoas-seminar] MS Defense - Tekoe

[eoas-seminar at lists.fsu.edu]

Good afternoon all!

Please join us for Abraham Tekoe's MS Defense on Tuesday, March 10th from 3-5 PM in EOA 1044.

Title: Efficiency of Tropical Cyclogenesis in Large-Scale Circulations: Climatology of Monsoon Gyres and Tropical Cyclogenesis in the Western North Pacific

Name:  Abraham Tekoe
Date:  March 10th  3:00-5:00 PM
Major Professor:  Chelsea Nam
Location:  EOA 1044

Abstract: Monsoon gyres (MGs) are large-scale cyclonic circulation systems embedded within the western North Pacific monsoon trough and are often associated with tropical cyclone (TC) formation. Despite their importance as precursors to tropical cyclogenesis, the factors controlling the timing of TC formation within MG environments remain poorly understood. This study examines how the structure and horizontal scale of MGs influence the evolution of embedded disturbances and the timing of TC genesis during 1980-2024. An objective detection algorithm was developed using ERA5 reanalysis data to identify MG events, and each gyre was analyzed using a normalized coordinate framework to compare environments across gyres of different sizes. Convective activity was diagnosed using GridSat-B1 infrared satellite data, while TC formation was identified using IBTrACS best-track records. Results show that MGs are strongly linked to TC formation, with about 91% of detected gyres producing at least one tropical cyclone. However, the timing of genesis varies systematically with gyre size: larger gyres tend to produce TCs later than smaller ones. Thermodynamic conditions such as sea surface temperature and humidity are generally favorable across cases, suggesting that dynamical processes-particularly vortex consolidation and vertical alignment-play a more important role in determining when genesis occurs. A detailed case study of Invest 95W (Typhoon Tapah 2019) illustrates how TC formation can be delayed within very large MG environments. Overall, the results support a two-scale framework in which monsoon gyres provide a favorable background environment, while the timing of tropical cyclogenesis depends primarily on the dynamical evolution of embedded vortices.

Best,
Adea

Adea Arrison
Sr. Academic Program Specialist
Department of Earth, Ocean & Atmospheric Science
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