The observed North Atlantic Meridional Overturning Circulation, its Meridional Coherence and Ocean Bottom Pressure

Elipot, Shane; Frajka-Williams, Eleanor ORCID: https://orcid.org/0000-0001-8773-7838; Hughes, Chris W. ORCID: https://orcid.org/0000-0002-9355-0233; Willis, Joshua. 2014 The observed North Atlantic Meridional Overturning Circulation, its Meridional Coherence and Ocean Bottom Pressure. Journal of Physical Oceanography, 44 (2). 517-537. https://doi.org/10.1175/JPO-D-13-026.1

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Abstract/Summary

Analyses of meridional transport time series from the RAPID MOC array at 26°N and from Argo float and altimetry data at 41°N reveal that, at semi-annual and longer time scales, the contribution from the western boundary dominates the variability of the North Atlantic Meridional Overturning Circulation (MOC), defined as the transport in the upper 1000 m of the ocean. Since the variability of the western boundary contribution is associated with a geostrophic overturning, it is reected in independent estimates of transports from gradient of ocean bottom pressure (OBP) relative to and below 1000 m on the continental slope of the western boundary at three nominal latitudes (26°N, 39°N and 42.5°N). Time series of western meridional transports relative to and below 1000 m derived from OBP gradient, or equivalently derived from transport shear profile, exhibit approximately the same phase relationship between 26°N and 39–42.5°N as the western contribution to the geostrophic MOC time series do: the western geostrophic MOC at 41°N precedes the MOC at 26°N by approximately a quarter of an annual cycle, resulting in a zero correlation at this time scale. This study therefore demonstrates how OBP gradients on basin boundaries can be used to monitor the MOC and its meridional coherence.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1175/JPO-D-13-026.1
ISSN:	0022-3670
Date made live:	19 Sep 2013 15:12 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/503290

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1175/JPO-D-13-026.1

ISSN:

0022-3670

Date made live:

19 Sep 2013 15:12 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/503290