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Understanding measured sea level rise by data assimilation

Manfred Wenzel(1) and Jens Schroeter(1)

(1) AWI, Bussestr. 24, 27570 Bremerhaven, Germany


Work at AWI that is related to altimetric measurements focusses on the estimation of the global oceans circulation, its sea level change and finally its mass budget. This presentation will shortly review the findings achieved so far.

Sea surface elevations as measured by the altimeter are 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 associated to heat and salt anomalies in the ocean. This finally allowed to estimate the temporally variing oceanic mass budget from sea surface elevations.


Workshop presentation

Full paper


                 Last modified: 07.10.03