Summary

The Cape Roberts Tide Gauge that was refurbished in November & December 2002 with new data logging equipment failed recording in March 2003 due to a component failure in the new Campbell CR10X data logger. LINZ and USGS surveyors visited Cape Roberts on 10 November for a programmed tide gauge calibration and determined that the instrument had failed. I visited Cape Roberts the following day and determined that the data logger had failed and was not repairable in the field. The logger was returned to Scott Base for evaluation and the calibration postponed until replacement equipment could be installed and to coincide with another spring tide period on 24 November. The installation was checked, restarted and the calibration successfully completed during the period 22-26 November. Also planned this season was a submarine levelling of the transducer last done in 1993 by drilling through the ice foot 3+ m thick above the transducer with video camera and levelling probe. At this time the transducer was obscured due to extremely thick submarine anchor ice and the levelling not completed.

The failed logger was returned to New Zealand for repair under warranty and a replacement logger borrowed from the Crary Lab at McMurdo.

Future work and recommendations

• The Cape Roberts Tide Gauge should be visited in October prior to the annual survey calibration to recover stored data and determine that the installation is continuing to function.
• Repaired equipment should be reinstalled in the 2004-05 season and the installation checked.
• Annual survey calibration should be carried out during a spring tide period preferably in November or early December when access to the near shore fast sea ice is still possible.
• The submarine transducer levelling is still required. The anchor ice problem could be initially assessed with video camera but if present in thick quantities that may not be possible to clear with a mini hot water drill. Levelling may be postponed until January when the anchor ice is more likely to have been reduced in the late summer. This can be carried out independently of the annual GPS survey calibration.