Scientific Endeavours & Achievements.

The first stage of this seasons field programme was to drill a hole in the coastal rock using the "portable" Winkie diamond coring drill belonging to DSIR Antarctic. This season the ice foot (above free water) was thicker than usual (5.5m) and a large amount of ice had been pushed against the shore and incorporated into the overthickened ice foot. These unusual ice conditions prevented the use of video camera modified to work under the ice which we intended to use to establish the best site for the transducer hole. Instead five holes were drilled in the ice foot to establish the ice thickness and where free water occcurred. The site choosen for drilling was within 5m of the previous tide gauge site and required a hole to be drilled 45⁰ from the verticle. This was accomplished succesfully in 2 days of drilling with breakthrough occurring at approximately 12.8m. Sea water with a small quantity of Calcium chloride (50kg) was used for drilling fluid and will have no lasting effect on the near shore environment. All equipment was removed after drilling leaving only the transducer cable protected in a polyethylene pipe and steel support cable anchored at the hole.

The transducer is located in a cage at the end of a 32mm low denisty polyethylene pipe lining the drilled hole. The transducer cable became frozen within the hole as expected within a few hours. Two days later the transducer was removed and rechecked by unfreezing the cable with about 51 of isopropal alcohol poured into the plastic liner pipe. This shows that it will be possible to remove the transducer for replacement if it becomes faulty in the future and it should also be possible to adjust the liner pipe and transducer cage at a later date by unfreezing the liner pipe with a submersible heating element.

The water level transducer in connected via a 32m suspended cable to the data logger/meteorological instrumentation on a rock promintory at the eastern end of Cape Roberts. New gell cell batteries were installed and the met. instruments replaced and checked this season. The system is currently programmed to record a 10 minute average of water depth each hour with hourly averages of wind speed and direction, air temperature and solar radiation. Memory storage has been increased so that data can be recorded for a full year.

In the 1991/92 season it will be necessary to accurately relevel, and reclibrate the water depth transducer for connection to the tidegauge bench mark and to Cape Roberts trig. Installation and operation of the tide gauge/met. instrumentation at Cape Roberts has been jointly sponsored by the Antarctic Research Centre, Victoria University of Wellington, the N.Z. Meteorological Service and the Department of Survey and Land Information (DOSLI). This seasons programme was carried out as DOSLI event # K193 and DSIR Antarctic provided logistic support, drill equipment and drilling expertise for the transducer installation.