Recent dynamic ocean topography models and their comparison

Regarding the rapidly growing satellite altimetry database and corresponding products worldwide, an investigation of different mean dynamic ocean topography (MDT) models was assessed to be important for further use in geodetic applications. The efficiency and quality of different MDT models are discussed in view of adopted geoids as reference surfaces. The models used are: 1) The ECCO model based on hydrology and altimetry data, 2) The combined MDT Rio-05 constructed in CSL AVISO (2005) from data for the period 1993-1999, 3) The combined MDT CNES-CLS09 model at the grid points 15’x15’ based on altimetry and hydrology data for the period 1993-2007 (CSL AVISO, 2009), 4) The DNSC08MDT solution of mean dynamic topography (Danish National Space Center) obtained from the geometrical differences between the DNSC08 mean sea surface and the EGM2008 geoid model. The concluding results of the investigation are: 1) statistics of all mean dyamic topography models leads to the approximately same standard deviations about 70 cm and range from -2 m to 2 m; 2) all differences among various MDT models give much smaller standard deviations about 6 – 15 cm; 3) all such differences among various MDT give larger mean deviation, which can be explained by different geoid models or reference surfaces adopted for each solution; 4) better agreement provides MDT CNES-CLS09 and DNSC08MDT models. As a result, we prefer MDT CNES-CLS09 and DNSC08MDT solutions since their noise level corresponds to an estimated accuracy of modern satellite altimetry data.