Application of doppler satellite observations to the study of ice-flow in East Antarctica-Problems peculiar to doppler surveys in high latitudes

Doppler satellite survey techniques are presently being applied to the study of the shape and movement of the Antarctic Ice Sheet.  Glaciologists of the Antarctic Division of the Australian Department of Science are using JMR-1 Doppler receivers to record signals from the US Navy Navigation Satellites, NAVSATS, at a large number of sites in East Antarctica.  Geodetic coordinates are calculated using both the onboard and precise ephemeris information, and the movement of the ice sheet is given by the rate of change of the coordinate values with time.

Typically, two or three days are required to observe sufficient passes at each site to obtain optimum accuracy for the coordinate solutions.  Because useable field-time in Antarctica is limited, techniques which can minimise the observation interval, and meaningfully use data from shorter observation periods are most valuable.  A technique is suggested whereby the motion of the station is modelled as part of the solution.  During analysis of results significant differences have been noted between coordinates calculated using the onboard and precise ephemeris.  In the poler regions where all passes of all NAVSATS are visible at a station, an inherent imbalance of the data set will result from a normal observing program.