Bottom-Anchored
Mooring
In April 2006,
the fifth NPEO bottom-anchored mooring was recovered
and a sixth deployed, each anchored more than 4000 meter
deep to the abyssal
plain
near the North Pole. Measurements
include ice thickness and drift, water temperature and salinity,
and current speed and direction, from near the surface to great
depths. (Diagram) Each
instrument records internally for at least one year. Data from
the first five years' moorings was successfully recovered and
is being analyzed. Other automated measurements
were added beginning in 2005,
including
concentrations
of nutrients
and a variety of other biological tracers.
Measurement
of the precise ocean depth is critical to ensure the Upward
Looking Sonar
at the top of the mooring is just 50 meters beneath the drifting
ice. Recovery
of each mooring from beneath the ice is a logistically complex
operation, requiring the ability to return to a precise location
and, in most cases, divers to go beneath the ice.
The intent is
to maintain each year's mooring at the same position. However,
slight differences are operationally unavoidable, because of
the ice drift during the one-to-three day period between the
release of the old mooring and actual deployment of the new
one. Closeness to the Pole accounts for the wild-appearing
changes in longitude.
Mooring |
Deployed |
Recovered |
Latitude |
Longitude |
Depth |
NP-01 |
10 April 2001 |
22 April 2002 |
89° 33.412'
N |
66° 38.820'
E |
4293m |
NP-02 |
23
April 2002 |
24 April 2003 |
89° 27.457'
N |
53° 31.258'
E |
4297m |
NP-03 |
25
April 2003 |
19
April 2004 |
89° 23.336'
N |
46° 07.156'
E |
4301m |
NP-04 |
21
April 2004 |
20
April 2005 |
89° 27.288'
N |
54° 19.744'
E |
4295m |
NP-05 |
22
April 2005 |
22
April 2006 |
89° 15.172'
N |
64° 41.509'
E |
4305m |
NP-06 |
24
April 2006 |
11
April 2008 |
89° 20.810'N |
77° 07.208'E |
4315m |
NP-08 |
17
April 2008 |
-
current - |
89° 31.527'N |
84° 22.488'E |
4304m |
Data from the
first three mooring years may
be obtained via
FTP at this website.
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