Impact of ocean model resolution on understanding the delayed warming of the Southern Ocean

Currently available historical climate change simulations indicate a relatively delayed Southern Ocean warming, particularly poleward of the Antarctic Circumpolar Current (ACC) compared much of the rest of the globe. However, even this simulated delayed warming is inconsistent with observational est...

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Bibliographic Details
Published in:Environmental Research Letters
Main Authors: Simge I Bilgen, Ben P Kirtman
Format: Article in Journal/Newspaper
Language:English
Published: IOP Publishing 2020
Subjects:
delayed warming
greenhouse gas forcing
eddy resolving and eddy parameterized models
Southern Ocean climate
Southern Ocean SST trends
Environmental technology. Sanitary engineering
TD1-1066
Environmental sciences
GE1-350
Science
Q
Physics
QC1-999
Antarctic
Southern Ocean
The Antarctic
Antarc*
Online Access:https://doi.org/10.1088/1748-9326/abbc3e
https://doaj.org/article/a276976ad93849bea5032a32e929fbb9
Description
Summary:Currently available historical climate change simulations indicate a relatively delayed Southern Ocean warming, particularly poleward of the Antarctic Circumpolar Current (ACC) compared much of the rest of the globe. However, even this simulated delayed warming is inconsistent with observational estimates which show a cooling trend poleward of the ACC for the period 1979–2014. A fully coupled model run at two resolutions, i.e. ocean eddy parameterized and ocean eddy resolving, driven by historical and fixed CO2 concentration is used to investigate forced trends south of the ACC. We analyze the 1961–2005 Southern Ocean surface and upper ocean temperatures trends simulated by the model and observational estimates to understand the observed trends in the SO. At both resolutions, the models successfully reproduce the observed warming response for the northern flank of the ACC. The eddy resolving simulations, however, are able to reproduce the observed near Antarctic cooling in contrast to the eddy parameterized simulation which shows a warming trend. The cause of this inconsistency between the observations and the ocean eddy parameterized climate models is still a matter of debate, and we show here results that suggest resolved ocean meso-scale processes may be an integral part of capturing the observed trends in the Southern Ocean.

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