A new Taiwanese geoid model based upon airborne, satellite and terrestrial gravimetric data

Abstract

A new airborne gravity survey was conducted over Taiwan in 2004-2005. The survey results in conjunction with existing terrestrial, marine and satellite altimetry data are used for creating a consistent 2´x2´ grid of gravity anomalies referred to the Earth’s surface. For this, the gravity anomalies observed at the flight level are downward continued to the topographic surface. After the gridding, to solve the boundary value problem (BVP) by Stokes’s formula, the surface gravity anomalies are continued further to the sea level. The inverse of Poisson’s integral formula is used at these steps. The effects of topographic masses are estimated by applying Helmert’s second condensation method. A modified Stokes’s formula is used for evaluating the short wavelength geoid contribution, whereas the long wavelength geoid information stems from a recent GRACE-based geopotential model. The effect (in terms of geoidal heights) of inclusion the airborne data exceeds one metre over the mountainous part of Taiwan.