Ocean Dynamic Topography from GPS - Galathea-3 First results

From August 14, 2006–April 24, 2007 the Danish expedition called Galathea-3 circumnavigated the globe. The Danish Technical University, DTU space, participated in the expedition with two experiments on-board. From Perth in Australia to Copenhagen Denmark measurements of the exact position and movements of the ship and also the sea surface height were carried out with high accuracy using a combination of GPS, INS, and laser. The aim of this experiment was to measure the position of the GPS antenna on the ship to decimetre accuracy and try to transfer this height to estimates of the sea surface height as accurate as possible using lasers and INS, and to investigate the accuracy and feasibility of sea surface height observations in this way. In this presentation the setup of the experiment will be described along with the first results in retrieving the mean dynamic topographic signal related to permanent currents in the ocean. Comparison with the DNSC08 mean dynamic topography derived from satellite altimetry across the Gulf Stream yields agreement on the 20 cm level, which is a very satisfactory preliminary result calling for further refinement of the technique.