Assimilation of Altimetric Data into an Eddy-Permitting Model of the North Atlantic

• Published in: Progress in Oceanography
• Main Authors: Killworth, P., Dieterich, C., LeProvost, C., Oschlies, Andreas, Willebrand, Jürgen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2001
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/4451/; https://oceanrep.geomar.de/id/eprint/4451/1/Killworth.pdf; https://doi.org/10.1016/S0079-6611(01)00009-X

This paper shows that the mean flow of an eddy-permitting model can be altered by assimilation of surface height variability, providing that information about the mean sea surface is included, using an adaption of a statistical–dynamical method devised by Oschlies and Willebrand. We show that for a restricted depth range (about 1000 m), dynamical knowledge can make up for the null space present in surface data whose temporal extent may be too short to distinguish between vertical modes. The lack of an accurate geoid has meant that most assimilation methods, while representing variability well, have been unable to modify the mean flow to any extent. However, we show that by including several approximate forms for the mean sea surface, the mean interior flow in the upper kilometer can be rapidly adjusted towards reality by the assimilation, with the location of major current systems moved by hundreds of kilometers.