GPS survey of 11 points for the David Glacier and its Drygalski Ice Tongue

During the survey the GPS antennas were fixed, by adapters for classical tribach, directly on the top of the aluminum pipes permitting in this way a solid and reliable autocentering positioning of the antennas. On the basis of the reliable results obtained with this kind of benchmark the GPS measurements were repeated in successive years, to investigate if seasonal or yearly variations occur on the flow speed. The same approach was used also to obtain information about Priestley and Reeves Glaciers.

Currently the numbers of points systematically measured are 11 for the David Glacier and its Drygalski Tongue, 3 for the Priestley Glacier and Nansen Ice Sheet, 2 for the Reeves Glacier. In two successive days during the 1993/1994 expedition, 24-hour-long measurements using the GPS continuous kinematic technique were performed on five points of the David Glacier and its Drygalski Ice Tongue. At the same time two other GPS receivers were located, the first on a fixed reference station , the second on the fast ice close to Terra Nova Bay Station.

The purpose of these measurements was to record the response of floating Drygalski Ice Tongue to the ocean tide, in order to individuate the position of the grounding line and the hydrostatic equilibrium of floating area. Measurements of the same points have been repeated in 1992/1993, 1993/1994, 1994/1995 and 1995/1996.Data have been processed by Geotracer v.2.25 software.