This project was supported by the National Oceanic and Atmospheric Administration and the Office of Naval Research.
In a collaborative experiment between the University of Rhode
Island and
the Bedford Institute of Oceanography, a line of inverted echo sounders,
bottom pressure sensors, and current meter
moorings were deployed across the North Atlantic Current along
WOCE line ACM6. The
purpose was to determine the structure and transport of the North
Atlantic
Current at a location where historical hydrographic studies indicated
that
a short line of moored instruments could consistently capture all of
the
North Atlantic Current transport. The moorings were in place from
August
1993 through February 1995.
Eight current meter moorings with up to 7 levels instrumented (400,
700,
1500, 2500, 3500, 4000~m, and at 100~m above the bottom) were deployed
to
directly measure the current within all the major water mass components
at the upper, intermediate, deep, and near-bottom levels. The vertical
spacing
was chosen to define the NAC and deep western boundary current (DWBC)
flow,
and to provide the data for full-water-column integrations of
transport.
The lateral spacing of the moorings was chosen to resolve the dominant
lateral
scales and features of the NAC and western boundary currents at
intermediate
and deep levels along the sloping topography. The mooring spacing at
offshore
sites was 60~km, decreasing to about 30~km at the onshore sites.
Six inverted echo sounders equipped with pressure gauges (PIES) were
deployed
along the same transect. Three of the six PIES sites were located at
the
same sites as the current moorings and two were at midpoints. The sixth
PIES site extended the transect beyond the current meter moorings.
Since
baroclinic velocity is determined from horizontal gradients of dynamic
height
measured by the IESs, the calculated velocities apply to the half-way
points
between the PIESs. The four recovered PIESs provided full-water-column
profiles
of temperature and relative velocity daily over the 19-month time
period.
Absolute velocities were obtained by combining these relative velocity
profiles
with absolute bottom velocities determined from the bottom pressure and
deep current measurements.
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Last Updated: May 14, 2018
URL: http://po.gso.uri.edu/dynamics/NAC/