Sea surface elevations as measured by the altimeter together with hydrographic measurements are assimilated into a global OGCM that has a free surface, i.e. that conserves mass rather than volume. The combination of both types of measurements appeared to be necessary to get a reasonable estimate of the oceanic circulation.Furthermore referencing the altimeter data to the GRACE geoid improves the modelling of anomalies.Further improvement in estimating sea level change was achieved by including the steric effects (thermosteric AND halosteric) into the modelled sea surface elevation, because local sea level trends vary substatial in space anmd time. They are closely associatedto heat and salt anomalies in the ocean. This finally allowed to estimate the temporally variing oceanic mass budget from sea surface elevations.