Atlantic Meridional Overturning Circulation (MOC)
Entry ID:
MOC
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Summary
On December 1st, 2005, Prof. Bryden and his team reported in Nature (Bryden et
al., 2005. Slowing of the Atlantic meridional overturning circulation at 25N.
Nature 438,
655-657:http://www.nature.com/nature/journal/v438/n7068/edsumm/e051201-11.html
) that the Atlantic meridional overturning circulation (MOC) seems to have
weakened by about 30% in the last ... decade or so.
The team analyzed measurements taken along a line at about 25N from the Bahamas
to Morocco in 2004, and compared these to measurements taken along
approximately this line in 1957, 1981, 1992 and 1998. The results suggest that
the Gulf Stream flow across 25N has remained nearly constant in this period,
but the MOC has slowed from about 20 Sv in 1957 to 14 Sv in 2004.
The evidence for the slow-down can be found both in the increase in southward
recirculation of warm water in the surface layer, and in a decrease in
southward transport of lower North Atlantic Deep Water between 3000 and 5000m
depth.
Some climate models have suggested that we could expect such a slowdown as a
result of global warming, and that this could cool northwest Europe by a few
degrees C, with the change happening relatively fast, perhaps over just a
decade. These measurements are evidence that the models could be right.
The five sections are just "snapshots" and cannot tell us for sure whether the
changes are a result of natural variability. Very little is known about how the
MOC varies seasonally or from year to year. To be sure that the observed change
is the result of a long-term trend rather than natural fluctuations we will
need to monitor flow across 25N continuously for about a decade.
In April 2004 Prof. Bryden's team deployed an array of instruments across the
Atlantic at 25 N. The array measures temperature, salinity, currents and
pressure. The first full year of measurements were collected in April 2005, and
analysis of this data is now underway.
See: http://www.noc.soton.ac.uk/rapid/sis/moc_monitor.php
Related URL
Link:
GET DATA
Description:
Access to graphs and documentation. Restricted access to data
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Geographic Coverage
Spatial coordinates
| N: 25.0 |
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S: 25.0 |
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E: -10.0 |
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W: -75.0 |
Data Set Citation
Dataset Creator:
Bryden, H., H. Longworth, S. Cunningham
Dataset Title:
Slowing of the Atlantic meridional overturning circulation at 25N.
Dataset Release Date:
1 December 2005
Dataset Publisher:
Nature
Issue Identification:
438, pp. 655-657
Online Resource:
http://www.noc.soton.ac.uk/rapid/sis/moc_monitor.php
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Temporal Coverage
Start Date:
1957-01-01
Stop Date:
2004-12-31
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Location Keywords
Science Keywords
ISO Topic Category
Platform
Instrument
Project
Access Constraints
Currently access to data restricted to RAPID investigators. Graphs and tables
are available.
Ancillary Keywords
Data Set Progress
Originating Center
Data Center
Personnel
HARRY
BRYDEN
Role:
INVESTIGATOR
Contact Address:
National Oceanography Centre
University of Southampton
Waterfront Campus
European Way
City:
Southampton
Postal Code:
SO14 3ZH
Country:
United Kingdom
HANNAH
LONGWORTH
Role:
INVESTIGATOR
Contact Address:
National Oceanography Centre
University of Southampton
Waterfront Campus
European Way
City:
Southampton
Postal Code:
SO14 3ZH
Country:
United Kingdom
STUART
CUNNINGHAM
Role:
INVESTIGATOR
Contact Address:
National Oceanography Centre
University of Southampton
Waterfront Campus
European Way
City:
Southampton
Postal Code:
SO14 3ZH
Country:
United Kingdom
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Publications/References
Bryden et al., 2005. Slowing of the Atlantic meridional overturning
circulation at 25°N. Nature 438, 655-657.
Creation and Review Dates
DIF Creation Date:
2005-12-22
Last DIF Revision Date:
2005-12-22
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Links
