Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas

Evans, Dafydd Gwyn; Holliday, N. Penny; Bacon, Sheldon; Le Bras, Isabela

doi:https://doi.org/10.5194/os-19-745-2023

Articles | Volume 19, issue 3

https://doi.org/10.5194/os-19-745-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-19-745-2023

© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 3

Research article

|

02 Jun 2023

Research article |

| 02 Jun 2023

Mixing and air–sea buoyancy fluxes set the time-mean overturning circulation in the subpolar North Atlantic and Nordic Seas

Dafydd Gwyn Evans, N. Penny Holliday, Sheldon Bacon, and Isabela Le Bras

Data sets

ERA5 monthly averaged data on single levels from 1940 to present H. Hersbach, B. Bell, P. Berrisford, G. Biavati, A. Horányi, J. Muñoz Sabater, J. Nicolas, C. Peubey, R. Radu, I. Rozum, D. Schepers, A. Simmons, C. Soci, D. Dee, and J.-N. Thépaut https://doi.org/10.24381/cds.f17050d7

NCEP Climate Forecast System Version 2 (CFSv2) Monthly Products S. Saha, S. Moorthi, X. Wu, J. Wang, S. Nadiga, P. Tripp, D. Behringer, Y. Hou, H. Chuang, M. Iredell, M. Ek, J. Meng, R. Yang, M. P. Mendez, H. van den Dool, Q. Zhang, W. Wang, M. Chen, and E. Becker https://doi.org/10.5065/D69021ZF

JRA-55: Japanese 55-year Reanalysis, Monthly Means and Variances Japan Meteorological Agency/Japan https://doi.org/10.5065/D60G3H5B

EN4: quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates S. A. Good, M. J. Martin, and N. A. Rayner https://www.metoffice.gov.uk/hadobs/en4/download.html

Multi Observation Global Ocean 3D Temperature Salinity Height Geostrophic Current and MLD S. Guinehut, A.-L. Dhomps, G. Larnicol, and P.-Y. Le Traon https://doi.org/10.48670/moi-00052

Global Ocean Ensemble Physics Reanalysis CMEMS https://doi.org/10.48670/moi-00024

ECCO Ocean Temperature and Salinity - Monthly Mean llc90 Grid (Version 4 release 4) I.Fenty and O. Wang https://doi.org/10.5067/ECL5M-OTS44

ECCO Ocean Velocity - Monthly Mean llc90 Grid (Version 4 release 4) I.Fenty and O. Wang https://doi.org/10.5067/ECL5M-OVE44

ECCO Gent-McWilliams Ocean Bolus Velocity - Monthly Mean llc90 Grid (Version 4 release 4) I.Fenty and O. Wang https://doi.org/10.5067/ECL5M-BOL44

ECCO Ocean and Sea-Ice Surface Freshwater Fluxes - Monthly Mean llc90 Grid (Version 4 release 4) I.Fenty and O. Wang https://doi.org/10.5067/ECL5M-FRE44

ECCO Ocean and Sea-Ice Surface Heat Fluxes - Monthly Mean llc90 Grid (Version 4 release 4) I.Fenty and O. Wang https://doi.org/10.5067/ECL5M-HEA44

Meridional Overturning Circulation Observed by the Overturning in the Subpolar North Atlantic Program (OSNAP) Array Y. Fu, M. S. Lozier, T. C. Biló, A. S. Bower, S. A. Cunningham, F. Cyr, M. F. de Jong, B. deYoung, L. Drysdale, N. Fraser, N. Fried, H. H. Furey, G. Han, P. Handmann, N. P. Holliday, J. Holte, M. E. Inall, W. E. Johns, S. Jones, J. Karstensen, F. Li, A. Pacini, R. S. Pickart, D. Rayner, F. Straneo, and I. Yashayaev https://doi.org/10.35090/gatech/70342

Short summary

This study investigates the processes that form dense water in the high latitudes of the North Atlantic to determine how they affect the overturning circulation in the Atlantic. We show for the first time that turbulent mixing is an important driver in the formation of dense water, along with the loss of heat from the ocean to the atmosphere. We point out that the simulation of turbulent mixing in ocean–climate models must improve to better predict the ocean's response to climate change.