Extreme air–sea interaction over the North Atlantic subpolar gyre during the winter of 2013–2014 and its sub-surface legacy
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
Exceptionally low North American temperatures
and record-breaking precipitation over the British
Isles during winter 2013–2014 were interconnected
by anomalous ocean evaporation over the North Atlantic
subpolar gyre region (SPG). This evaporation (or oceanic
latent heat release) was accompanied by strong sensible
heat loss to the atmosphere. The enhanced heat loss over
the SPG was caused by a combination of surface westerly
winds from the North American continent and northerly
winds from the Nordic Seas region that were colder,
drier and stronger than normal. A distinctive feature of the air–sea exchange was that the enhanced heat loss spanned
the entire width of the SPG, with evaporation anomalies
intensifying in the east while sensible heat flux anomalies
were slightly stronger upstream in the west. The immediate
impact of the strong air–sea fluxes on the ocean–atmosphere
system included a reduction in ocean heat content of
the SPG and a shift in basin-scale pathways of ocean heat
and atmospheric freshwater transport. Atmospheric reanalysis
data and the EN4 ocean data set indicate that a longerterm
legacy of the winter has been the enhanced formation
of a particularly dense mode of Subpolar Mode Water
(SPMW)—one of the precursors of North Atlantic Deep
Water and thus an important component of the Atlantic
Meridional Overturning Circulation. Using particle trajectory
analysis, the likely dispersal of newly-formed SPMW
is evaluated, providing evidence for the re-emergence of
anomalously cold SPMW in early winter 2014/2015.
and record-breaking precipitation over the British
Isles during winter 2013–2014 were interconnected
by anomalous ocean evaporation over the North Atlantic
subpolar gyre region (SPG). This evaporation (or oceanic
latent heat release) was accompanied by strong sensible
heat loss to the atmosphere. The enhanced heat loss over
the SPG was caused by a combination of surface westerly
winds from the North American continent and northerly
winds from the Nordic Seas region that were colder,
drier and stronger than normal. A distinctive feature of the air–sea exchange was that the enhanced heat loss spanned
the entire width of the SPG, with evaporation anomalies
intensifying in the east while sensible heat flux anomalies
were slightly stronger upstream in the west. The immediate
impact of the strong air–sea fluxes on the ocean–atmosphere
system included a reduction in ocean heat content of
the SPG and a shift in basin-scale pathways of ocean heat
and atmospheric freshwater transport. Atmospheric reanalysis
data and the EN4 ocean data set indicate that a longerterm
legacy of the winter has been the enhanced formation
of a particularly dense mode of Subpolar Mode Water
(SPMW)—one of the precursors of North Atlantic Deep
Water and thus an important component of the Atlantic
Meridional Overturning Circulation. Using particle trajectory
analysis, the likely dispersal of newly-formed SPMW
is evaluated, providing evidence for the re-emergence of
anomalously cold SPMW in early winter 2014/2015.
Date Issued
2015-09-05
Date Acceptance
2015-08-25
Citation
Climate Dynamics, 2015, 46 (11), pp.4027-4045
ISSN
1432-0894
Publisher
Springer Verlag (Germany)
Start Page
4027
End Page
4045
Journal / Book Title
Climate Dynamics
Volume
46
Issue
11
Copyright Statement
The final publication is available at Springer via http://dx.doi.org/10.1007/s00382-015-2819-3
Subjects
Science & Technology
Physical Sciences
Meteorology & Atmospheric Sciences
North Atlantic Ocean
Air-sea fluxes
Ocean heat content
Subpolar Mode Water
Winter 2013-2014
MERIDIONAL OVERTURNING CIRCULATION
SURFACE HEAT
THERMOHALINE CIRCULATION
OCEAN TEMPERATURE
VARIABILITY
SYSTEM
FLUXES
0401 Atmospheric Sciences
0405 Oceanography
Publication Status
Published