Assimilation of altimeter data in the ECMWF ocean analysis system
Arthur Vidard(1) , Magdalena A. Balmaseda(1) , and David L. T. Anderson(1)
RG2 9AX Reading,
The operational ocean analysis system at ECMWF has been recently
upgraded; among other changes it includes the ability to assimilate both salinity data and sea level anomalies derived from altimeter in addition
The altimeter data is used to correct temperature and salinity using
the Cooper and Haines (1996) scheme. As part of the process of developing the new system, several ways of merging this
information with the assimilation of subsurface data were explored and
their respective merits compared. Additionally, attempts were made to use grace derived mean seal levels to reconstruct the total mean sea level. Although not used in the ECMWF operational system where only anomalies are assimilated, the relevance of this approach is discussed.
An ocean reanalysis was carried out from 1959 and has now reach real time. It assimilates subsurface data from 1959 and altimeter data from 1993. Results from this analysis are presented and compared with subsurface only assimilation runs.