Summary:¶

1. The Mahrs has a calibration problem or some other reason that caused a large latitude-dependent error (almost 1 degree over this cruise)
2. The POSMV has many heading glitches, as indicated by the large number of “heading accuracy” excursions away from baseline. These glitches are difficult to remove correctly, and when done so, result in the loss of 30%-55% of the headings.
3. Even after a reasonable effort at removing bad headings, the remaining data still show a latitude-dependent error of about 0.5deg over the cruise. A healthy POSMV should not have this error.
4. POSMVs can be fixed: The Ka`imimoana is an example of a ship where the POSMV went from bad to worse, and resources were eventually allocated to fix the instrument.

Finally, the Ron Brown is about to head west and take on the maintainance of the TAO buoys. There is an existing body of shipboard ADCP data, mostly taken from the Ka`imimoana, which forms the foundation of a valuable time series of Equatorial Pacific zonal ocean currents. For this reason it would be very beneficial if the POSMV on the Brown could be fixed.