Airborne Gravimetry Across the Seven Continents - Status and New Developments

Since the 1990's airborne gravimetry have been developed as a routine tool for both geophysics and geodesy, following closely the advances in precise kinematic GPS positioning. Long-range airborne gravimetry has to a large degree made the challenge of accurate gravity field modelling and geoid determination over large remote regions more realistic. Following the pioneering aerogravity survey of Greenland 1991-92, led by the US Naval Research Laboratory, the last three decades have seen major airborne surveys covering remote parts across the globe, both for support of global gravity field models and national geoids, as well as projects for rectifying existing gravity data and providing enhanced data over coastal or mountainous areas.

DTU Space has since the mid-1990's developed an effective aerogravity setup for small aircraft, and have carried out a large number of surveys, spanning major areas in the Arctic and Antarctica, as well as many projects for global models or national geoid models across all seven continents. Strapdown inertial sensors have usually been flown along with the used Lacoste and Romberg-style gravimeter systems, but only since 2013 (with the adaption of new iMAR IMU sensors) has the "draped" processing of gravimeter/IMU data given the full benefit of both sensors types, combining the long-term drift stability of platform gravimeters with the high linearity and turbulence tolerance of inertial sensors.

In the presentation the development and results of long-range gravimetry at DTU Space will be briefly outlined, followed by recent results, especially using a novel prototype iMAR temperature-stabilized unit, both in Arctic, temperate and tropical regions, showing how the system now can achieve the 1 mGal accuracy. We also report on recent applications in small ad-hoc aircraft (for marine coastal surveys for Danish/Swedish national 5 mm-geoid projects), as well as first gravimetry tests in medium-size drones.