Geoid and Sea Surface Topography from satellite and ground data - A review and new proposals

The present work aims to provide a review of the application of least squares collocation for heterogeneous data combination in studies related to the determination of the geoid and the sea surface topography. First, an outline of the observation equations used in LSC is presented with a derivation of the final geoid height estimates. The application of LSC for mean dynamic topography determination is then presented, together with the implementation of the Multiple Input Multiple Output System Theory for geoid determination. In the same section, a brief outline of the similarities and differences between the two methods is also given. The next section is devoted to the application of LSC in data combination schemes when GOCE observables, i.e., potential and its second order derivatives, are available. It should be noted that within the context of this paper, whenever GOCE observables are mentioned they refer to simulation datasets. Results acquired by the authors towards the determination of geoid models over both land and sea are also presented, while a detailed discussion on the improvement that GOCE data provide is given. The last section is devoted to the presentation of a new method for altimetric sea surface height data analysis and the determination of sea surface topography covariance functions based on second order kriging. Results based on both simulated data and real altimetric sea surface heights are presented using both the traditional LSC approach and second order kriging.