Rigorous Fusion of Gravity Field into Stationary Ocean Models

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In RIFUGIO we considered the altimetric sea surface as a sum of geoid heights represented in terms of spherical harmonics and the mean dynamic topography parameterized by a finite element method. With this combined model we avoid the inversion and smoothing processes which are necessary in the step-by-step approaches and estimate the normal equations of the mean dynamic topography in a straightforward way. Subsequently, these normal equations have been used in stationary ocean models to weight the model data misfit in a least-squares sense. Prototypes of those rigorously combined models were developed for our main study area the North Atlantic ocean and assimilated into the 3D-inverse model IFEOM. A detailed analysis of numerical effects arising during the data combination will be necessary. The main goal of RIFUGIO+ is the assessment of this rigorous data assimilation and the tuning and refinement of our method. In addition we want to increase the spatial resolution of our model by the integration of GOCE geoid models and multi-mission altimetry. An important aspect is the question whether the ocean models in this study can improve estimates of the mean dynamic topography. In a detailed redundancy analysis we will study the impact of the new data on the ocean model and thus feedback information into determining gravity field solutions.