April 1997

Four years of accurate TOPEX/POSEIDON (T/P) data have revealed yet again the ability of altimetry to measure dynamic and thermodynamic variations in the ocean. The data have also confirmed that satellite data, in situ data and numerical models need combining to isolate the signals, spread surface information down into the ocean, determine which dynamic or climatic processes are operating, and initialise predictive models.

The excellent operation of TOPEX/POSEIDON and the decision to go ahead with Jason make altimetry practically operational, although we still need long-term confirmation. Oceanographers also have routine access to surface temperature data, and data from XBTs, tide-gauges and Lagrangian currentmeters. It is time to build nu-merical modeling and routine assimilation tools for these data.

The building blocks for such tools exist: data processing and transmission systems, global numerical models, primitive equations at mesoscale resolution, increasingly realistic forcing models, multivariate assimilation methods, archiving systems, and so on. We must now integrate them, implement routine and even operational processing, set up regular diagnostic tests, and involve research teams who can take them on further.

The first to benefit from such tools will be oceanographers, who will enjoy optimally-analysed products and relatively realistic three-dimensional current fields and ocean transport offering regular quality over long periods. They will also have help in identifying problems, study areas and the potential applications of the new data. Climatologists will have tools enabling them to prepare second-generation climate models. Operational and commercial customers are interested in offshore mesoscale current fields at scales ranging from two weeks to a month.

The aim of the MERCATOR project is to build tools in France and Europe in the years to come. Our American colleagues are working on similar projects. I believe all this work is a vital ingredient for the oceanography - operational oceanography - of tomorrow.

Jean-François Minster (LEGOS/GRGS, Laboratoire CNES-CNRS-UPS, France)

Editorial board: Patrick Vincent (CNES), Frédérique Blanc (CLS)

Authors and other contributors: B. Andersen, S. Arnault, F. Blanc, P. Bonnefond, S. Bruinsma, A. J. Busalacchi, J. Dorandeu, P. Exertier, N. Ferry, M-P Gauthier, L. Gourdeau, P. Knudsen, T. Knudsen, M. Lefebvre, B. Legresy, J. Poitevin, P-Y Le Traon, J-F Minster, G.T Mitchum, R. Murtugudde, F. Ogor, D.T. Pham, F. Rémy, H. Roquet, J. Verron, P. Vincent.

English adaptation: N. Greenwood

Design: D. Ducros