Satellite Altimeter Data Assimilation in the Occam Global Ocean Model

Abstract

Assimilation of satellite altimeter data into ocean models offers the best prospect for testing the ability of ocean models to correctly represent near surface circulation and to extrapolate observations of that circulation in space and time. This will ultimately lead to real time prediction of ocean circulation and of sea surface temperature which will contribute to improving weather and climate forecasts.

The relative scarcity of observations of the ocean, even when satellite data are considered, places special importance on the choice of numerical model in any oceanographic data assimilation system. The 1/4 degree OCCAM global ocean model used here represents the state of the art. This model has been combined with a new approach to assimilating altimeter data developed at Edinburgh, in which emphasis is placed on preserving sub-surface water mass properties.

The basic altimeter assimilation scheme has been tested successfully in an idealised, ‘twin’ experiment. Further experiments are now underway assimilating TOPEX/POSEIDON altimeter data into the OCCAM model. Early results of a model run assimilating altimeter sea surface height data from 1993 are presented.