Error evaluation for regional geoid computation using varying integration cap sizes in a synthetic environment

Abstract

A modified Stokes’ function with different maximum integration radii is applied to synthetic gravity data for quasigeoid solutions. The spectral combination method is used. The synthetic environment comprises a geopotential model and regional terrestrial gravity data, both including (uncorrelated and correlated) noise, and permits a closedloop validation in all points. Due to the enhanced synthetic data set including noise, the computation results are closer to reality than simulations neglecting noise. The closed-loop differences meet the error estimates from error assessment based on degree variances. Main objective of the investigations is the study of the effect of varying integration cap sizes on the quasigeoid heights. Based on the same modified kernel function, the 1st and 2nd zero-crossing are chosen as constant cut-off distance, moreover a Meissl modified kernel is used based on a cut-off at the 1st minimum of the kernel and finally a fixed integration area with varying cut-off radii is used. The cut-off at the 2nd zero-crossing and the integration using a fixed input area show the best results. In the synthetic environment a quasigeoid can be derived with an accuracy of 1 cm and 13 cm (resolution about 15 km) based on regional gravity data with 1 mgal uncorrelated and 5 mgal correlated noise, respectively, and a high-resolution GPM (GRACE model, EGM96).