• The poor coverage of the marine gravity data for certain areas;
• The inhomogeneous quality of the marine gravity data (bias, precision);
• The data reduction is not as efficient as achieved over land.
Marine gravity data is not available for large parts of the Mediterranean and consequently the gravimetric geoid solution is significantly less accurate there. Gravity inferred from altimetry data, or a mean sea surface corrected for mean dynamic topography (i.e., an ‘oceanographic’ geoid model), can be used to fill the gaps. However, ocean dynamic signal may contaminate
the derived gravity or geoid, which is why a pure gravimetric solution is preferred in an ideal world. The effect on the geoid solution of using several altimeter-based datasets, such as DTU10, DTU15 and UCSD V24 gravity, using simple gap filling, weighted combinations with the gravimetric data, and combination through collocation, will be evaluated and quantified. The combined models are compared with the gravimetric geoid solution as well as with the oceanographic geoid. The (local) errors and increased uncertainty due to the data gaps, and the subsequent effect on the ocean mean dynamic topography and geostrophic currents, can be estimated via the results of all comparisons. All models are equally compared to drifter-inferred current velocities, which constitutes an independent quality evaluation. This type of evaluation leads to a very detailed quality assessment of the models, notably as a function of patial scale.
|Number of pages||1|
|Publication status||Published - 2018|
|Event||25 years of progress in radar altimetry symposium - , Portugal|
Duration: 24 Sep 2018 → 29 Sep 2018
|Conference||25 years of progress in radar altimetry symposium|
|Period||24/09/2018 → 29/09/2018|