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ADCP Configurations and Calibrations
Explorer of the Seas transducer depth: 8.5 meters
OS38
Narrowband profile mode, single ping ensembles, fifty-five 24 meter bins with a 16 meter blanking distance
Maximum profiling depth: 1320 meters
OS150
Narrowband profile mode, single ping ensembles, fifty-five 8 meter bins with a 6 meter blanking distance
Maximum profiling depth: 440 meters
ADCP Calibrations and Transducer Misalignments
In order to obtain ocean velocities from the ADCP it is necessary to
accurately remove the ship velocity from the measured velocities.
Because the ship velocity is typically an order of magnitude greater
than the ocean velocity, if it is removed at the incorrect angle the
resultant errors are large. For the first five years of ADCP
measurements from Explorer of the
Seas, heading data was obtained from a Sperry Navigat 2100 fibre-optic
gyrocompass, with estimated errors up to 0.5 degrees (see previous
section on errors). With this level of heading accuracy we were limited
to estimating a single calibration angle, which includes components
resulting from gyrocompass bias and transducer misalignment. Hence, for
cruises prior to March 2006, a single calibration angle (different for
OS38 and OS150 instruments) has been applied to all cruises.
In March 2006 a Thalles ADU5 GPS antenna array was installed on
Explorer of the Seas, allowing time-dependent heading correction
estimates for more accurate ocean velocities.