Developing use of altimetry for climate studies

Project Information

DUACS

Grant agreement ID: ENV4960357

Project closed

Start date 1 February 1997

End date 31 January 2000

Funded under

• Specific programme of research and technological development in the field of environment and climate, 1994-1998

Total cost No data

EU contribution No data

Coordinated by

COLLECTE LOCALISATION SATELLITES SA
France

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Exploitable results

Experiment with altimeter data assimilation into cooled ocean-atmosphere models used for climate forecasts.

During the 3 years of the project, the climate groups have carefully analyzed the altimeter data, information content and gained considerable experience in the analysis and assimilation of such data. They found by comparing model and tide gauge sea level observations and TAO thermal data, that the altimeter data were of high quality with respect to interannual variability, as required for seasonal forecasting. Most of the ocean analyses and comparisons were based on the Homogeneous Historical data set (HH). This is expected to be the most accurate data as most calibration effort has been devoted to this product. Most of the DUACS partners used this data stream both for model data intercomparisons and for ocean analyses. It is less appropriate for near real time seasonal forecasting, however, and DUACS, for the first time delivered multi-satellite sea level observations in near real time (NRT). It was found that the NRT data set was also of hi-h quality and could be used in nearreal-time ocean analysis systems. Finally all climate groups found that assimilation of altimeter data had a beneficial impact on ocean analyses and seasonal climate forecast skill compared to control forecasts which did not use altimeter data. The techniques used for assimilation of altimeter data were based on current generation techniques. The most commonly used technique of preserving water mass is generally sound but needs flurther development. The enhancement of computer power now makes it feasible to envisage' using, next generation assimilation techniques based on the 4D variational approach which has proved so successful in meteorology, or some form.of Kalman filter. The DUACS group therefore believes that such techniques shall be adapted in the future for assimilation of altimeter data.