[Eoas-seminar] MS Defense - Kaitlin Kitch

[eoas-seminar at lists.fsu.edu]

Hello,

Please join us for Kaitlin Kitch's MS Defense on Wednesday, October 29 @ 3:00 pm in Room EOAS 4067 and on Zoom.

Title: Investigating the Effects of a North Atlantic Marine Heatwave on the Extratropical Transition of Hurricane Sandy

Name: Kaitlin Kitch
Date: Wednesday, October 29, 2025 at 3:00 pm ET
Advisor: Rhys Parfitt
Location: EOAS 4067 and Zoom:
https://fsu.zoom.us/j/91323203640<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffsu.zoom.us%2Fj%2F91323203640&data=05%7C02%7Ceoas-seminar%40lists.fsu.edu%7Ce263def5b7dd40e7e1f908de1593a2fc%7Ca36450ebdb0642a78d1b026719f701e3%7C0%7C0%7C638971920984625720%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=L8cMMOMQ1lB7k3BZwjkRsmZq9Y%2F9sUuT13qJx8AdE9Q%3D&reserved=0>
Meeting ID: 913 2320 3640


Abstract:  Tropical cyclones (TCs) that undergo extratropical transition (ET) bring devastating impacts to the highly populated east coast of the United States.  The North Atlantic Ocean has also experienced several notable marine heatwaves (MHWs), which are becoming more frequent due to climate change.  ET is a challenge for forecasters, but an improved understanding of how pre-existing environmental conditions impact ET can better predictability.  Studies have shown a link between MHWs and increased TC intensity, but little work has been done to investigate the impacts of MHWs on ET.  This study uses the Weather Research and Forecasting model to simulate Hurricane Sandy in a typical October MHW.  Five simulations with five sensitivity tests are run with different magnitudes of the MHW sea surface temperature (SST) anomalies applied to the SST field to simulate warming and cooling.  The North Atlantic October MHW SST anomalies are composited and used to perturb the October 2012 SST field.  A MHW induces warming across the region, which is maximized in the Gulf Stream (GS), leading to an increase in SST gradients.  A MHW increases the sensible heat flux and sensible heat flux gradients along the GS, which appear to generate an increase in diabatic frontogenesis above.  Reducing the North Atlantic SSTs and gradients results in the opposite effects.  GS MHWs introduce competing effects because increased SSTs allow a TC to stay tropical longer, but increased SST gradients have been shown to promote frontal development and ET.  Cyclones in cooled simulations with SSTs decreased using the MHW anomaly magnitudes take a more easterly track and make landfall further north, delaying their passage over the GS.  Frontal development indicates a TC is undergoing ET.  Fronts associated with the cyclone in all simulations appear to strengthen and organize when they encounter the GS, which is especially reflected in the diabatic frontogenesis.  Storm-associated frontogenesis and frontolysis both appear stronger and peak earlier in the cyclones in warmed simulations as they encounter the GS earlier.  The timing of GS passage best aligns with the increase in diabatic frontogenesis.  Cyclones in cooled simulations begin ET earlier but take significantly longer to complete ET.  ET duration is similar between the control and MHW simulations but is significantly longer in the cooled simulations.  The increased SSTs and SST gradients associated with a North Atlantic MHW result in a relatively similar ET onset and duration, but decreasing the SSTs and SST gradients by subtracting the typical MHW anomalies from the SSTs delays ET onset and significantly increases ET duration.

Best,
Adea

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