Reliability¶

In general, the TSS Mahrs is reliable, meaning “present and reporting ‘good’ values”. The Mahrs has a QC message that is recorded and used by UHDAS. On the one occasion when the Mahrs was reset, it took an hour to settle. The status message correctly indicated that there was a problem with the data:

Accuracy¶

The ADCP data processing includes a calibration calculation made using times when the ship accelerates (stops, starts, or turns). This cruise provides an unusually high number of watertrack calibration points. The watertrack calibration points (green), which are a measure of Mahrs error, show the strong latitude-dependence of the heading error. In gray, the Mahrs-POSMV difference is also plotted. It shows a latitude-dependent difference between the POSMV and the Mahrs.

This latitude-dependent error must be corrected in the ADCP data processing, but it is unknown what level of error remains after taking out the obvious trend.