An airborne gravity survey of Nepal was carried out December 2010 in a cooperation between DTU-Space, Nepal Survey Department, and NGA, USA. The entire country was flown with survey lines spaced 6 nm with a King Air aircraft, with a varying flight altitude from 4 to 10 km. The survey operations were a major challenge due to excessive jet streams at altitude as well as occasional excessive mountain waves. Despite the large 400 mGal+ range of gravity anomaly changes from the Indian plains to the Tibetan Plateau, results appear accurate to a few mGal, with proper evaluation from cross-overs complicated by the varying flight altitudes. Using a downward continuation scheme based on least-squares collocation, a new geoid of Nepal is made by Fourier methods. The new geoid shows large changes to EGM08, illustrating the impact of the new data. The new geoid is compared to limited GPS-levelling data as well as recent GPS-heights of Mt. Everest. The new airborne data also provide an independent validation of GOCE gravity field results at the local ~100 km resolution scale.
International Association of Geodesy Symposia: Earth on the Edge: Science for a Sustainable Planet Earth on the Edge: Science for a Sustainable Planet Proceedings of the Iag General Assembly, Melbourne, Australia, June 28 - July 2, 2011, 2014, p. 521-527