Preprints
https://doi.org/10.5194/egusphere-2023-1564
https://doi.org/10.5194/egusphere-2023-1564
13 Jul 2023
 | 13 Jul 2023

Surface factors controlling the volume of accumulated Labrador Sea Water

Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson

Abstract. We explore historical variability in the volume of Labrador Sea Water (LSW) using ECCO, an ocean state estimate configuration of the Massachusetts Institute of Technology general circulation model (MITgcm). The model’s adjoint, a linearization of the MITgcm, is set up to output the lagged sensitivity of the watermass volume to surface boundary conditions. This allows us to reconstruct the evolution of LSW volume over recent decades using historical surface wind stress, heat, and freshwater fluxes. Each of these boundary conditions contributes significantly to the LSW variability that we recover, but these impacts are associated with different geographical fingerprints and arise over a range of time lags. We show that the volume of LSW accumulated in the Labrador Sea exhibits a delayed response to surface wind stress and buoyancy forcing outside the convective interior of the Labrador Sea, at key locations in the North Atlantic Ocean. In particular, winds and surface density anomalies affect the North Atlantic Current’s (NAC) transport of warm and saline subtropical water masses that are precursors for the formation of LSW. This propensity for a delayed response of LSW to remote forcing allows us to predict a substantial fraction of LSW variability at least a year into the future. Our analysis also enables us to attribute LSW variability to different boundary conditions and to gain insight into the major mechanisms that drive volume anomalies in this deep watermass. We point out the important role of buoyancy loss and preconditioning along the NAC pathway, in the Iceland Basin, the Irminger Sea, and the Nordic Seas, processes which facilitate the formation of LSW both in the Irminger and in the Labrador Sea.

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Journal article(s) based on this preprint

11 Apr 2024
Surface factors controlling the volume of accumulated Labrador Sea Water
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson
Ocean Sci., 20, 521–547, https://doi.org/10.5194/os-20-521-2024,https://doi.org/10.5194/os-20-521-2024, 2024
Short summary
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1564', Anonymous Referee #1, 11 Aug 2023
    • AC1: 'Reply to RC1', Yavor Kostov, 27 Nov 2023
  • RC2: 'Comment on egusphere-2023-1564', Anonymous Referee #2, 13 Aug 2023
    • AC2: 'Reply to RC2', Yavor Kostov, 27 Nov 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1564', Anonymous Referee #1, 11 Aug 2023
    • AC1: 'Reply to RC1', Yavor Kostov, 27 Nov 2023
  • RC2: 'Comment on egusphere-2023-1564', Anonymous Referee #2, 13 Aug 2023
    • AC2: 'Reply to RC2', Yavor Kostov, 27 Nov 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Yavor Kostov on behalf of the Authors (30 Nov 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (08 Dec 2023) by Mehmet Ilicak
RR by Anonymous Referee #2 (20 Dec 2023)
RR by Anonymous Referee #1 (22 Dec 2023)
ED: Publish subject to minor revisions (review by editor) (05 Jan 2024) by Mehmet Ilicak
AR by Yavor Kostov on behalf of the Authors (02 Feb 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (08 Feb 2024) by Mehmet Ilicak
AR by Yavor Kostov on behalf of the Authors (17 Feb 2024)

Journal article(s) based on this preprint

11 Apr 2024
Surface factors controlling the volume of accumulated Labrador Sea Water
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson
Ocean Sci., 20, 521–547, https://doi.org/10.5194/os-20-521-2024,https://doi.org/10.5194/os-20-521-2024, 2024
Short summary
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson
Yavor Kostov, Marie-José Messias, Herlé Mercier, David P. Marshall, and Helen L. Johnson

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Short summary
We examine factors affecting variability in the volume of Labrador Sea Water (LSW), a deep watermass that is important for the uptake and storage of heat and carbon in the Atlantic Ocean. We find that LSW accumulated in the Labrador Sea exhibits a lagged response to remote conditions: surface wind stress, heat flux, and freshwater flux anomalies, especially along the pathways of the North Atlantic Current branches. We use our results to reconstruct and attribute historical changes in LSW volume.