Southern Ocean polynyas and dense water formation in a high-resolution, coupled Earth system model
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Published:2023-07-11
Issue:7
Volume:17
Page:2681-2700
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
Jeong HyeinORCID, Turner Adrian K.ORCID, Roberts Andrew F.ORCID, Veneziani MilenaORCID, Price Stephen F.ORCID, Asay-Davis Xylar S.ORCID, Van Roekel Luke P.ORCID, Lin Wuyin, Caldwell Peter M., Park Hyo-Seok, Wolfe Jonathan D., Mametjanov Azamat
Abstract
Abstract. Antarctic coastal polynyas produce dense shelf water, a primary source of Antarctic Bottom Water that contributes to the global overturning
circulation. This paper investigates Antarctic dense water formation in the high-resolution version of the Energy Exascale Earth System Model
(E3SM-HR). The model is able to reproduce the main Antarctic coastal polynyas, although the polynyas are smaller in area compared to
observations. E3SM-HR also simulates several occurrences of open-ocean polynyas (OOPs) in the Weddell Sea at a higher rate than what the last
50 years of the satellite sea ice observational record suggests, but similarly to other high-resolution Earth system model simulations. Furthermore,
the densest water masses in the model are formed within the OOPs rather than on the continental shelf as is typically observed. Biases related to
the lack of dense water formation on the continental shelf are associated with overly strong atmospheric polar easterlies, which lead to a strong
Antarctic Slope Front and too little exchange between on- and off-continental shelf water masses. Strong polar easterlies also produce excessive
southward Ekman transport, causing a build-up of sea ice over the continental shelf and enhanced ice melting in the summer season. This, in turn,
produces water masses on the continental shelf that are overly fresh and less dense relative to observations. Our results indicate that high
resolution alone is insufficient for models to properly reproduce Antarctic dense water; the large-scale polar atmospheric circulation around
Antarctica must also be accurately simulated.
Funder
Biological and Environmental Research
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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