We review the procedures and challenges that must be considered when using geoid data derived from the Gravity and steady-state Ocean Circulation Explorer (GOCE) mission in order to constrain the circulation and water mass representation in an ocean general circulation model. It covers the combination of the geoid information with time-mean sea level information derived from satel- lite altimeter data, to construct a mean dynamic topogra- phy (MDT), and considers how this complements the time- varying sea level anomaly, also available from the satellite altimeter. We particularly consider the compatibility of these different fields in their spatial scale content, their temporal representation, and in their error covariances. These consid- erations are very important when the resulting data are to be used to estimate ocean circulation and its corresponding er- rors.
We describe the further steps needed for assimilating the resulting dynamic topography information into an ocean cir- culation model using three different operational forecasting and data assimilation systems. We look at methods used for assimilating altimeter anomaly data in the absence of a suit- able geoid, and then discuss different approaches which have been tried for assimilating the additional geoid information. We review the problems that have been encountered and the lessons learned in order the help future users. Finally we present some results from the use of GRACE geoid informa- tion in the operational oceanography community and discuss the future potential gains that may be obtained from a new GOCE geoid.