LINZ Does its Share of Antarctic Housekeeping

21 January 2009

For almost six weeks in late 2008, two data analysts from LINZ were busy completing an annual work programme in Antarctica, with a focus on supporting conservation efforts.

“Antarctica is a place of collaboration,” says Data Analyst (Hydrographic) Glen Rowe. “What we do helps many other groups complete their work, which is great.”

Annual tasks completed included surveying historic sites and calibrating sea level gauges. Other work was done in support of current projects, such as science taking place to understand local ecosystems.

GPS receiver (foreground) in the Darwin/Hatherton Glacier region, Antarctica. (Click image for expanded view).

Putting the picture in place

Mapping control was carried out in the Darwin/Hatherton Glacier region. Accurate positioning ties were made between images of the area, captured by the ALOS PRISM satellite, and ground features identified in the images, by using Global Positioning System (GPS) receivers.

This mapping assists the Latitudinal Gradient Project, operating along Antarctica’s Victoria Land coast. The project studies the region’s complex ecosystems and the effects of environmental change on them.

Vector topographic data from the 2007-08 season and orthophotos taken during the 2006-07 season of the Darwin/Hatherton Glacier region are available to download. Data from the recent survey will be available later this year.

Data Analyst (Geodetic) Dave Collett surveying Shackleton's historic hut at Cape Royds, Antarctica. (Click image for expanded view).

Surveying history

Two historic sites, Captain Robert Scott’s hut at Cape Evans and Sir Ernest Shackleton’s hut at Cape Royds, were surveyed to determine any vertical movement due to ice build-up beneath them. The huts have been monitored on behalf of the Antarctic Heritage Trust (AHT) for the past twenty years. No more than a centimetre of movement has been observed over this time. Any significant movement would be managed by the AHT.

Additional features were surveyed at Scott’s hut to establish the relative positioning of artifacts in the ice surrounding the hut. Conservation work on Scott’s hut is being carried out by the AHT, who have already completed similar conservation work at the Shackleton site.

An old survey beacon being removed from Mount Boreas in the McMurdo Dry Valleys, Antarctica. (Click image for expanded view).

Housekeeping in the Dry Valleys

Several survey beacons installed in the 1980s were removed from the McMurdo Dry Valleys, an Antarctic Specially Managed Area. The removal of old beacons has been ongoing over the past several years.

The beacons—oil drums bolted or welded two high and weighted with rocks—were no longer necessary due to improvements in technology, such as GPS, and posed aesthetic and environmental problems.

Data Analyst (Hydrographic) Glen Rowe drilling sea ice beside a GPS receiver at Cape Roberts, Antarctica. (Click image for expanded view).

Keeping up with the tides

Sea level gauges (tide gauges) at Cape Roberts and Scott Base were calibrated to ensure the long-term accuracy of the data they collect. The Cape Roberts gauge was installed in 1990 as part of a drilling project by Victoria University of Wellington, with the support of LINZ’s predecessor the Department of Survey and Land Information (DOSLI). LINZ took over full ownership of the gauge when the university’s interests ended.

The Scott Base gauge was installed in 2000 by the National Institute of Water and Atmospheric Research in conjunction with Antarctica New Zealand.

Calibrating the gauges involved comparing their data with that collected by GPS receivers. Holes were dug in the snow to reach the floating sea ice beneath, which forms around the Antarctic coast. The GPS receivers were placed on the sea ice and the ice was drilled to measure the distance from the GPS to sea-level. The GPS receivers were then left for several days to record changes in their vertical position as the tides moved.

Sea level data from the Cape Roberts gauge is available to download.