Investigations on the Quality of the GOCE Level 1b Gradiometer Data around the Magnetic Poles

English Abstract:

The latest Canadian Geoid Model was developed based on the combination of GOCE, GRACE, terrestrial and altimetry data. It is observed that the GOCE data have improved the Canadian geoid up to a few centimetres in some regions. Our preliminary investigations on the GOCE Level 1b gradiometer data have shown that GOCE data processing methodology still needs improvements. It is found that GOCE gravity gradients along the satellite track are affected by unknown external sources over Northern Canada and Greenland. These effects can disturb the gravity signal up to three times the expected noise level. In this study, we have attempted to understand the reasons behind these disturbances present in the gradients by using external and GOCE-independent space weather datasets. Solar satellites ACE (Advanced Composition Explorer) and WIND derived interplanetary magnetic and electric field data and magnetic activity data observed by the terrestrial CARISMA (Canadian Array for Real-time Investigations of Magnetic Activity) stations are used for this purpose. We found that GOCE was affected by the increasing short-term solar activity and its corresponding effects around the polar cusp regions. We have investigated both, the GOCE and magnetic activity observations in time, spectral and spatial domain and attempted to eliminate these disturbances from GOCE observations. We believe that any improvement on GOCE data processing can help scientists improve the quality of the global and regional geoid models as well as the processing of other missions’ datasets.