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Slantwise convection in the Irminger Sea

Le Bras, Isabela Alexander-Astiz and Callies, Jörn and Straneo, Fiamma and Carrilho Biló, Tiago and Holte, James and Johnson, Helen Louise (2022) Slantwise convection in the Irminger Sea. . (Unpublished)

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The subpolar North Atlantic is a site of significant carbon dioxide, oxygen, and heat exchange with the atmosphere. This exchange, which regulates transient climate change and prevents large-scale hypoxia throughout the North Atlantic, is thought to be mediated by vertical mixing in the ocean's surface mixed layer. Here we present observational evidence that waters deeper than the conventionally defined mixed layer are affected directly by atmospheric forcing. When northerly winds blow along the Irminger Sea's western boundary current, the Ekman response pushes denser water over lighter water and triggers slantwise convection. We estimate that this down-front wind forcing is four times stronger than air--sea heat flux buoyancy forcing and can mix waters to several times the conventionally defined mixed layer depth. Slantwise convection is not included in most large-scale ocean models, which likely limits their ability to accurately represent subpolar water mass transformations and deep ocean ventilation.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper ItemOSNAP mooring data!/dataset/reanalysis-era5-single-levelsRelated ItemERA5 reanalysis hourly data!/dataset/reanalysis-era5-single-levels-monthly-meansRelated ItemERA5 monthly wind stress fields shown in Figure 1 ItemMonthly sea surface height (anomaly) data ItemJournal Article
Le Bras, Isabela Alexander-Astiz0000-0003-0952-1446
Callies, Jörn0000-0002-6815-1230
Straneo, Fiamma0000-0002-1735-2366
Carrilho Biló, Tiago0000-0002-4007-5862
Holte, James0000-0002-3451-7572
Johnson, Helen Louise0000-0003-1873-2085
Additional Information:Attribution 4.0 International (CC BY 4.0). ILB, FS, TCB, and JH gratefully acknowledge the US National Science Foundation (NSF): this work was supported by grants OCE-1258823, OCE-1756272, OCE-1948335, and OCE-2038481. JC gratefully acknowledges NSF support through grant OCE-1924354. HLJ was supported by the SNAP-DRAGON program (UK Natural Environment Research Council grant number NE/T013494/1). We gratefully acknowledge the many scientists and mariners who went to sea to collect the observational data, and Bob Pickart in particular. Data Availability. OSNAP mooring data used in this study are available at under “US East Cape Farewell Slope Array”. ERA5 reanalysis hourly data was downloaded from!/dataset/reanalysis-era5-single-levels. Hourly wind stress and heat flux fields were downloaded on June 18, 2020 and hourly sea level pressure data was downloaded on July 13,4472021. ERA5 monthly wind stress fields shown in Figure 1 were downloaded on August 4, 2020 from!/dataset/reanalysis-era5-single-levels-monthly-means. Monthly sea surface height (anomaly) data (Figure 1) are Ssalto/Duacs altimeter products distributed by Aviso+ with support from Cnes and by the Copernicus Marine and Environment Monitoring Service (CMEMS). They were downloaded on August 31, 2020 from
Funding AgencyGrant Number
Natural Environment Research Council (NERC)NE/T013494/1
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Copernicus Marine and Environment Monitoring ServiceUNSPECIFIED
Record Number:CaltechAUTHORS:20220725-414674000
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115813
Deposited By: George Porter
Deposited On:27 Jul 2022 15:09
Last Modified:18 Oct 2022 21:26

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