This is a short post about an ongoing project of drilling and monitoring the sea ice off Davis Station.
Every week during the winter, the sea ice thickness is measured at seven waypoints as part of an ongoing monitoring programme (AAS #2500) with Dr Petra Heil at the University of Tasmania as the projects leader. This information is fed into a larger study of the sea ice characteristics around the Antarctic.
This winter the Weather Bureau wants this project to be part of our duties. So both Daleen (Bureau of Meteorology Technical engineer/observer) and I (Senior Bureau of Meteorology Observer) went out with Ladge (Senior Science engineer) and Lotter (this winters Science Engineer) to learn the method of drilling and monitoring of sea ice.
To have consistency in the project – 7 drill sites have been determined and several measurements are taken at each of these sites every week.
The auger (drill) is 2 metres long, though more sections can be added. Once a hole is drilled right through the ice – a string with an attachment is lowered down the hole and once it is through the attachment is opened and anchors at the bottom of the ice. The depth of the ice is then measure off the string. A second string tied to the attachment is pulled so it folds and can be pulled up through the hole.
When the ice returns in late March or early April we start the measurements and monitoring. The 7 waypoints (measuring sites) are found by their GPS coordinates. A cane is then embedded in the ice so the site is easily located for the next reading in a week’s time.
All the measurements were fairly consistent with the ice thickness between 1.4 metres to 1.7 metres thick.
On route to the waypoints we passed close by some beautiful ice bergs embedded in the ice.
The sea ice was breaking out several kilometres from Station. As we drove further out we could not see the outer marker and we knew that the open water would not be to far ahead. So we stopped and Lotter climbed on top of the hägglund to try and spot the last waypoint cane.
Lotter couldn’t locate the cane, but he could see the open water so it was considered that the last waypoint was in the ocean. During the months of November and December the sea ice eventually breaks out completely.
We turned around and headed back to station.
Apart from the measurements a long term record of the sea ice depth and consistency -it is also vital for operational and recreational safe travel over the winter months as well as use of heavy equipment during the station re-supply.
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Until next time……