Towards a new free air anomaly map of the Antarctic Peninsula

Since 1959 the British Antarctic Survey (BAS) has undertaken reconnaissance gravity surveys of the Antarctic Peninsula. Approximately 1500 on-rock and about 600 on-snow station values were measured. Continuing climatic, topographical and logistic constraints resulted in an uneven distribution of stations, with a concentration of measurements on the coast and very few on the ice covered spine of the peninsula. An even sampling of the gravity field over two thirds of the Antarctic Peninsula has now been obtained from a BAS airborne gravity survey over areas with sparse land station coverage. A total of 10,700 line km of data were flown during the 1996/97 season using a modified LaCoste and Romberg S meter deployed in a Twin Otter aircraft. The free air anomaly field was recovered with an accuracy of 5 mGals for along line wavelengths greater than 9 km and gridded wavelengths greater than 20 km. Ice thickness and topographical data were recorded from simultaneous radio echo soundings.