Observed poleward heat transport by mesoscale eddies in the deep Southern Ocean

Liu, Tongya, Zhai, Xiaoming, He, Qingyou, Hogg, Andrew McC. and Chen, Dake (2026) Observed poleward heat transport by mesoscale eddies in the deep Southern Ocean. Nature Communications. ISSN 2041-1723 (In Press)

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Abstract

Mesoscale eddies in the Southern Ocean can extend from the surface to the deep ocean and play a crucial role in both regional and global heat budgets. However, sparse in situ observations have limited prior estimates of eddy meridional heat transport (EMHT) to the near surface, leaving deep ocean processes poorly understood. Here, we present the first observational quantification of deep eddy kinetic energy (EKE) and EMHT using Argo data. Our results show that deep EMHT reaches at least the same order of magnitude as the surface transport, despite deep EKE being only one fifth of surface levels. Float observations and sensitivity experiments reveal that, in contrast to the relatively short-range cross-frontal transport observed near the surface, deep EMHT extends the meridional movement of subtropical warm waters by over ten degrees of latitude closer to Antarctica than that driven by mean flows alone, with about 60% occurring in eddy hotspot regions of the Indian Ocean sector. These findings provide new observational evidence for the role of mesoscale eddies in modulating deep Southern Ocean heat redistribution and their potential impact on Antarctic climate.

Item Type:	Article
Additional Information:	Data availability: All data used in this study are publicly available. The META3.1exp dataset is available at https://www.aviso.altimetry.fr/en/data/products/value-added-products/global-mesoscale-eddytrajectory-product/meta3-1-exp-dt.html. The surface drifter data are available at https://www.aoml.noaa.gov/phod/gdp/hourly_data.php. The Argo velocity data can be found at https://library.ucsd.edu/dc/collection/bb6630688j. The Argo profile data are available at https://argo.ucsd.edu/data/argo-data-products/. The WOA23 dataset can be accessed at https://www.ncei.noaa.gov/products/world-ocean-atlas. The B-SOSE data can be downloaded from https://sose.ucsd.edu/BSOSE6_iter122_solution.html. The satellite altimetry data can be found at https://www.aviso.altimetry.fr/en/data/products/. The OISST dataset is available at https://www.ncei.noaa.gov/products/climate-data-records/sea-surface-temperature-optimum interpolation. The mooring records are available from the following repositories: WHOI 835 from https://cmrecords.net/quick/southern/agulret/agulret.html, SAZ47-2010 and SAZ47-2015 from https://thredds.aodn.org.au/thredds/catalog/IMOS/DWM/SOTS/catalog.html, and Drake M7 from https://www.seanoe.org/data/00500/61186/. Code availability: The MITgcm model is available at https://mitgcm.org/source-code/.
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	LivePure Connector
Date Deposited:	31 Jul 2026 10:23
Last Modified:	31 Jul 2026 10:23
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103955
DOI:	issn:2041-1723

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