Regional gravimetric geoid calculations in the north sea test area

Abstract

The present paper reports on results obtained with research work related to the SEASAT‐A North Sea project. In the North Sea test area, a regional gravimetric geoid of high precision and resolution (50 km) has been calculated, using a combination of the present available terrestrial gravity data and the GEM 8 earth model. The accuracy of this geoid has been estimated by comparing it with the astrogeodetic geoid calculated for the adjoining land areas, and with the GEOS‐3 altimetric geoid for the German Bay. It is found that in the region of good gravity coverage (6' x 10' mean anomalies), geoid height differences can be derived with an accuracy of ±0.2 ... 0.6 m, depending on the point distance (50. . .500 km). Gravimetric deflections of the vertical have an accuracy of ±0.5?... 1.0? in this range. These results correspond to the accuracy obtainable by astrogeodetic methods in flat areas and by GEOS‐3 satellite altimetry. The accuracy of geoid differences decreases to ±0.7. . .1.0 m (range 50...1,000 km) if only 1^o × 1^o mean anomalies exist in the calculation area.