Rapid export of waters formed by convection near the Irminger Sea's western boundary
Rapid export of waters formed by convection near the Irminger Sea's western boundary
The standard view of the overturning circulation emphasizes the role of convection, yet for waters to contribute to overturning, they must not only be transformed to higher densities but also exported equatorward. From novel mooring observations in the Irminger Sea (2014–2016), we describe two water masses that are formed by convection and show that they have different rates of export in the western boundary current. Upper Irminger Sea Intermediate Water appears to form near the boundary current and is exported rapidly within 3 months of its formation. Deep Irminger Sea Intermediate Water forms in the basin interior and is exported on longer time scales. The subduction of these waters into the boundary current is consistent with an eddy transport mechanism. Our results suggest that light intermediate waters can contribute to overturning as much as waters formed by deeper convection and that the export time scales of both project onto overturning variability.
North Atlantic, convection, eddy processes, high latitude, overturning, subpolar circulation
Le Bras, I. A.‐A.
70b94548-a7f7-49ec-abac-187cf69ba232
Straneo, F.
025f7b0c-2d8f-48a7-9d1d-148a947b903c
Holte, J.
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Jong, M. F.
cac6fc64-acd5-4e56-a17a-61770a350a01
Holliday, N. P.
c4ef99c7-1be1-4148-ae23-0c678aa4f8f2
16 February 2020
Le Bras, I. A.‐A.
70b94548-a7f7-49ec-abac-187cf69ba232
Straneo, F.
025f7b0c-2d8f-48a7-9d1d-148a947b903c
Holte, J.
64587317-034f-4cf3-bc65-ff318c131950
Jong, M. F.
cac6fc64-acd5-4e56-a17a-61770a350a01
Holliday, N. P.
c4ef99c7-1be1-4148-ae23-0c678aa4f8f2
Le Bras, I. A.‐A., Straneo, F., Holte, J., Jong, M. F. and Holliday, N. P.
(2020)
Rapid export of waters formed by convection near the Irminger Sea's western boundary.
Geophysical Research Letters, 47 (3), [e2019GL085989].
(doi:10.1029/2019GL085989).
Abstract
The standard view of the overturning circulation emphasizes the role of convection, yet for waters to contribute to overturning, they must not only be transformed to higher densities but also exported equatorward. From novel mooring observations in the Irminger Sea (2014–2016), we describe two water masses that are formed by convection and show that they have different rates of export in the western boundary current. Upper Irminger Sea Intermediate Water appears to form near the boundary current and is exported rapidly within 3 months of its formation. Deep Irminger Sea Intermediate Water forms in the basin interior and is exported on longer time scales. The subduction of these waters into the boundary current is consistent with an eddy transport mechanism. Our results suggest that light intermediate waters can contribute to overturning as much as waters formed by deeper convection and that the export time scales of both project onto overturning variability.
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Bras1_et_al-2020-Geophysical_Research_Letters
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Accepted/In Press date: 14 January 2020
e-pub ahead of print date: 15 January 2020
Published date: 16 February 2020
Additional Information:
Funding Information:
We gratefully acknowledge the U.S. National Science Foundation: This work was supported by Grants OCE-1258823 and OCE-1756272. M. F. d J. was supported by NIOZ and EU Horizon 2020 project Blue-Action (Grant 727852). N. P. H. was supported by NERC program UK OSNAP (NE/K010875/1), UK OSNAP-Decade (NE/T00858X/1), and ACSIS (National Capability). The U.S. Cape Farewell OSNAP data reported here are available from this site (doi:10.7924/r4fb50z9b). The UK data are available here (doi:10.5285/8c232969-11cd-3e52-e053-6c86abc07963). OOI data were obtained from the NSF Ocean Observatories Initiative Data Portal, http://ooinet.oceanobservatories.org, downloaded on 9 August 2017. EN4 data were downloaded from https://www.metoffice.gov.uk/hadobs/en4/download-en4-2-1.html on 26 October 2018. The Argo float mixed layer climatology shown in the supporting information is described in Holte et al. () and was downloaded from mixedlayer.ucsd.edu on 20 November 2019. We thank M. Spall, R. Pickart, and A. Pacini for helpful scientific discussions, and F. Li and M.S. Lozier for providing the gridded velocity field across the OSNAP line (doi:10.7924/r4z60gf0f). The data presented in this manuscript would not have come about without the hard work of the entire OSNAP team, especially all scientists, technical staff, and crew who went to sea to collect these data.
Publisher Copyright:
©2020. The Authors.
Keywords:
North Atlantic, convection, eddy processes, high latitude, overturning, subpolar circulation
Identifiers
Local EPrints ID: 438095
URI: http://eprints.soton.ac.uk/id/eprint/438095
ISSN: 0094-8276
PURE UUID: dc316e25-164d-4187-91d1-866e3882e082
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Date deposited: 28 Feb 2020 17:31
Last modified: 15 Apr 2024 17:09
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Author:
I. A.‐A. Le Bras
Author:
F. Straneo
Author:
J. Holte
Author:
M. F. Jong
Author:
N. P. Holliday
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