Two Methods for Quality Assessment of GOCE Gradients

The first ESA Earth Explorer Core Mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) entered the operational measurement phase in September 2009. Before gravity field processing, the quality of the GOCE gradients in the measurement bandwidth (5-100mHz), MBW, has to be assessed. Here, two procedures have been developed in Hanover, the mutual comparison and analysis of observed gradients in satellite track cross-overs and the application of terrestrial gravity data which are upward continued and transformed into reference gradients for the GOCE gradiometer measurements. First the gravity gradients are filtered, where the longer wavelength signals below the MBW are replaced by global geopotential model (GPM) information. The filtered time series is used as input signal for both validation methods.