Coherent Circulation Changes in the Deep North Atlantic From 16°N and 26°N Transport Arrays
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The meridional overturning circulation (MOC) has been measured by boundary arrays in the Atlantic since 2000. Over the past decade of measurements, however, the reported tendencies in overturning circulation strength have differed between 16°N and 26°N. Here we investigate these differences by diagnosing their origin in the observed hydrography, finding that both arrays show deep waters (below 1,100 dbar) at the western boundary becoming fresher and less dense. The associated change in geopotential thickness is about 0.15 m 2 s−2 between 2004–2009 and 2010–2014, with the shift occurring between 2009 and 2010 and earlier at 26°N than 16°N. In the absence of a similar density change on the east of the Atlantic, this middepth reduction in water density at the west would drive an increase in the shear between the upper and lower layers of North Atlantic Deep Water of about 2.6 Sv at 26°N and 3.9 Sv at 16°N. These transport anomalies result in an intensifying tendency in the MOC estimate at 16°N, but at 26°N, the method of correcting the geostrophic reference level results in an opposing (reducing) tendency of the MOC. The results indicate that both arrays are observing coherent, low‐frequency changes, but that there remain discrepancies in the methods of addressing the geostrophic reference level for boundary arrays measuring ocean circulation.
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Since 2000, a mooring array has been maintained at 16N that includes velocity measurements covering the DWBC east of Guadeloupe and additional geostrophic moorings measuring the deep flow between the continental slope and the mid-Atlantic ridge.
“Since 2000, a mooring array has been maintained at 16 • N that includes velocity measurements covering the DWBC east of Guadeloupe and additional geostrophic moorings measuring the deep flow between the continental slope and the mid-Atlantic ridge (Send et al., 2011;Frajka-Williams et al., 2018).”
From The tropical atlantic observing system (2019) · cites this paper as Frajka-Williams et al., 2018
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Foltz, G. R., Brandt, P., Richter, I., Rodríguez-Fonseca, B., Hernandez, F., Dengler, M., Rodrigues, R. R., Schmidt, J. O., Yu, L., Lefevre, N., et al. (2019) · Frontiers in Marine Science · doi:10.3389/fmars.2019.00206 · Cited by 150 · see citing works
“Since 2000, a mooring array has been maintained at 16◦N that includes velocity measurements covering the DWBC east of Guadeloupe and additional geostrophic moorings measuring the deep flow between the continental slope and the mid-Atlantic ridge (Send et al., 2011; Frajka-Williams et al., 2018).”
Background
- Authors
- Frajka‐Williams, E., Lankhorst, M., Koelling, J., & Send, U.
- Affiliations
- Ocean and Earth Science University of Southampton Southampton UK
- Scripps Institution of Oceanography (US)
- Venue
- Journal of Geophysical Research: Oceans
- Publisher
- American Geophysical Union (AGU)
- Published
- 2018-05
- Volume
- 123
- Issue
- 5
- Pages
- 3427-3443
- ISSN
- 2169-9275 (ISSN-L)
- 2169-9291
- OpenAlex
- W2801369357
- Cited by
- 33
- References
- 1
- Citations by year
- 2026: 4 · 2025: 1 · 2024: 2 · 2023: 10 · 2022: 2 · 2021: 5 · 2020: 2 · 2019: 4 · 2018: 3
- FWCI
- 2.25
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Journal of Geophysical Research Oceans (publishedVersion, cc-by)
- NERC Open Research Archive (Natural Environment Research Council) (acceptedVersion)
- ePrints Soton (University of Southampton) (acceptedVersion)
- Funders
- National Aeronautics and Space Administration (NNX16AO39H)
- Natural Environment Research Council
- National Science Foundation (OCE1332978)
- National Oceanic and Atmospheric Administration
- Bundesministerium für Bildung und Forschung
- Topics
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Oceanographic and Atmospheric Processes
- Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine and coastal ecosystems
- Keywords
- North Atlantic meridional overturning circulation, North Atlantic Deep Water, hydrographic changes
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