Sea level anomalies (PO.DAAC version of TOPEX/Poseidon and Jason-1) are assimilated into the model using a Kalman filter (Fukumori, 2002). The assimilation corrects model errors associated with inaccuracies in time-varying wind forcing (NCEP product). The filter estimates consist of large-scale adiabatic adjustments of the model state. As of 5th April, 2009, this simulation is no longer updated. Also note that the last several months of 2005 was incorrectly forced by NCEP operational products, which happened as a result of accenditally transfer of input forcing files from Zhangfan in April 2006. See this link for model description.