Shipboard Acoustic Doppler Current Profiler Data
The Oleander has been collecting velocity data during its weekly roundtrips
between Bermuda and New Jersey since the Fall of 1992.
- These sections
provide exceptional resolution of the
upper ocean velocity field: 8 meters in the vertical and 2.4 km in
the horizontal (5 minute averaging at 16 Kt vessel speed).
- Since 1995 a differential GPS receiver has corrected for the effects of
deliberate degrading of GPS navigation (selective availability;
Since 1995 we also operate a heading GPS
system (3D-GPS) which allows us to correct the gyro compass error
directly to a heading accuracy of ± 0.1°.
(An error of 1° introduces a 0.14 m/s error
in cross-track velocity with a vessel speed of 16 Kts.)
Under good operating conditions we think the velocities are accurate at the
± 0.03 m/s level.
- At the beginning of every month
an XBT survey occurs across the shelf,
the Slope Sea and the Gulf Stream on the outbound leg and some
additional XBTs in the Sargasso Sea on the return leg.
- The horizontal
resolution of the XBTs varies and depends upon location. In the Gulf
Stream profiles are taken about every 25 km.
- The once a month sampling means that only one out of eight crossings will have
XBTs and depending upon the weather the concurrent ADCP data may or
may not be very useful. Thus the number of sections with simultaneous
good XBT and ADCP coverage of the core of the Gulf Stream is
significantly less than the total number of sections available for