[Eoas-seminar] Jacob Hair - Dissertation

[eoas-seminar at lists.fsu.edu]

Hi all,

Please join us for Jacob Hair's Dissertation on Thursday, October 29, 2026, at 3:00 PM in EOAS 1044.

Title: Examining the Role of the Fine-Scale Gulf Stream SST Gradient on the Development and Structure of Atmospheric Fronts

Name: Jacob Hair
Date: October 29, 2026
Time: 3:00 PM
Room: EOAS 1044
Major Professors: Dr. Robert Hart & Dr. Rhys Parfitt

Abstract: It is well established that western boundary currents (WBCs) can significantly influence the development of extratropical cyclones (ETCs). However, it remains challenging to disentangle the relative importance of absolute sea-surface temperature (SST) versus the various spatial scales of the SST gradient. This study isolates, for the first time, the role of the fine-scale (~ 25 km) Gulf Stream SST gradient in the development and structure of atmospheric fronts within ETCs by smoothing the fine-scale SST gradient in specified-SST simulations. We utilized two configurations of the Community Atmospheric Model Version 6, one having a 111 km global grid spacing, and the other a 14 km regional grid encompassing the North Atlantic and Gulf Stream regions. The SST is specified at a grid spacing of 0.1°.

Our results demonstrate that the fine-scale SST gradient does indeed perturb the localized atmospheric baroclinic environment through the sensible heat flux gradient during our wintertime experiments (February and March), as the sensible heat flux gradient is important in maintaining the near-surface baroclinicity. This acts to modify the near-surface air temperature gradient collocated in the region, which is diagnosed by the atmospheric diabatic frontogenesis. In other words, when an atmospheric front traverses a weakened (strengthened) fine-scale SST gradient, the atmospheric front is significantly weakened (strengthened)  through the diabatic processes. Our results suggest that when the fine-scale SST gradient is smoothed, there is a significant weakening in the frontogenesis, vertical velocities, and the forcing to the secondary ageostrophic circulation within the atmospheric warm front. Thus, it is argued that the fine-scale SST gradient reduction acts as a “bottom-up” perturbation that resonates through the atmospheric front, to then potentially influence larger-scale processes.

A high-resolution atmospheric model can better represent the influence of the fine-scale SST gradient on atmospheric fronts throughout the free troposphere. Thus, global climate and numerical weather prediction models with coarse atmospheric and/or ocean resolution that have the inability to resolve mesoscale frontal and diabatic processes can introduce errors that propagate throughout the free troposphere.

Best,
Adea



Adea Arrison

Sr. Academic Program Specialist

Department of Earth, Ocean & Atmospheric Science

[cid:0e63ab4f-a41f-4bc3-bf66-2b3961254b29]<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.eoas.fsu.edu%2F&data=05%7C02%7Ceoas-seminar%40lists.fsu.edu%7C68886cc86f92460dcab108df3421dd2b%7Ca36450ebdb0642a78d1b026719f701e3%7C0%7C0%7C639286992176244710%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=DP%2BQGTKvn7OGMA3OXnmihYDWS9FPdyxDZp%2F%2BSa%2FSaG8%3D&reserved=0>


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.fsu.edu/pipermail/eoas-seminar/attachments/20261027/7a4f53c2/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 3433 bytes
Desc: image.png
URL: <http://lists.fsu.edu/pipermail/eoas-seminar/attachments/20261027/7a4f53c2/attachment.png>