[G02-2] Gravimetry

[G02-2-01] Closing the GOCE polar gap in Antarctica from airborne gravity and derived gravity gradients

^○Rene Forsberg¹, Arne Olesen¹, Tom Jordan², Fausto Ferraccioli², Kenichi Matsuoka³, Hasan Yildiz⁴ (1.DTU-Space, Lyngby, Denmark, 2.Bristish Antarctic Survey, Cambridge, UK, 3.Norwegian Polar Institute, Tromso, Norway, 4.General Command of Mapping, Ankara, Turkey)

GOCE has mapped the global gravity field with hitherto unprecedented accuracy and resolution, except for the polar gaps north and south of latitude 83.3 degree. While the Arctic gap has been filled since a decade by Arctic Gravity Project data, filling the Antarctic polar gap has been a major challenge. An ESA-supported airborne gravity survey was carried out to do this in a major, challenging field campaign 2015/16. This “Polar Gap project" used a Twin-Otter aircraft equipped with several gravity sensors (spring gravimeter and iMAR IMU), magnetometers, ice penetrating radar, and scanning lidar, to collect a complete suite of airborne remote sensing data over the essentially unmapped region of the polar gap. The PolarGap logistics involved two deep interior field camps, as well as flights the Amundsen-Scott South Pole station, thanks to a special arrangement with NSF. In the talk we outline the Antarctic field operations, and show final results of the campaign, including performance of the gravity sensors, the gravity reference network, and the comparison to the limited existing gravity data in the region. We also show results of computations of gravity field gradients at altitude, computed by least-squares collocation, and compared to GOCE gradients along the outer rim of the polar gap. Examples of other acquired geophysical and lidar data are also given, including discoveries of hitherto unknown major subglacial valleys and mountains in the survey region.