[Eoas-seminar] Reminder: Physical Oceanography seminar "The Southern Ocean in a Warming Climate" by Qian Li - Monday April 15 at 1:30pm in EOAS 6042

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________________________________
From: Eric Chassignet <echassignet at fsu.edu>
Sent: Thursday, April 11, 2024 4:26 PM
To: eoas-seminar at lists.fsu.edu <eoas-seminar at lists.fsu.edu>
Cc: seminar at coaps.fsu.edu <seminar at coaps.fsu.edu>
Subject: Physical Oceanography seminar "The Southern Ocean in a Warming Climate" by Qian Li - Monday April 15 at 1:30pm in EOAS 6042

Please join us for a seminar by Physical Oceanography candidate Qian Li Monday April 15 at 1:30pm in EOAS 6042.

The Southern Ocean in a Warming Climate

In a warming climate, the Antarctic ice sheet has been losing mass to the ocean at an accelerating rate. The Antarctic sea ice extent has taken a regime shift from relatively gradual increases to rapid decreases. Concurrently, the Southern Ocean circulation has been changing. Yet, the mechanisms controlling the long-term polar ice-ocean interaction remain unclear.

In this talk, I will first use a high-resolution (~0.1°) global ocean–sea-ice model to show the critical importance of Antarctic meltwater in influencing future trends in the abyssal ocean overturning circulation and properties. Rapid melting freshens the surface ocean and strengthens the stratification, preventing the formation of dense shelf water and Antarctic Bottom Water (AABW). A slowdown in the sinking of AABW results in warming and ageing of the abyssal ocean, with implications for global ocean biogeochemistry and climate that could last for centuries. Second, in the framework of residual-mean theory, I will show a two-time-scale response of the Southern Ocean overturning circulation to westerly winds. The essentially white-noise forcing by westerly winds triggers high-frequency fluctuations of the ocean’s overturning circulation. The oceanic eddy-driven component, instead, responds on decadal timescales, leading to the ocean heat transport convergence into the seasonal ice zone and a decadal decrease in sea ice extent. It suggests that the rapid decline in Antarctic sea ice observed in recent years may be part of natural variability and not necessarily associated with anthropogenic climate change.

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Eric Chassignet
Professor and Director
Center for Ocean-Atmospheric Prediction Studies (COAPS)
Florida State University
2000 Levy Avenue, Building A, Suite 292
P.O. Box 3062741
Tallahassee, FL  32306-2741

Office : (1) 850-645-7288
COAPS  : (1) 850-644-3846
Cell   : (1) 850-524-0033 (urgent matters only)
FAX    : (1) 850-644-4841
E-mail : echassignet at fsu.edu
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