Assessment of recent tidal models in the Mediterranean Sea

Abstract

Ocean tides especially in closed sea areas can deviate considerably from the theoretical values due to unequal water depths and to the fact that the continents impede the movement of water. Satellite altimetry enabled the development of improved tidal models event in closed sea areas, by assimilating altimeter data into hydrodynamic models. The Mediterranean Sea due to its morphology is an ideal test field for the assessment of tidal models, based on this technique. An attempt to assess the recent tidal models TPXO.6, GOT00.2 and NAO.99b was based on (a) an inter-comparison of tidal heights computed from the three models at different time moments on the same 15′ × 15′ grid covering the Mediterranean and (b) on the comparison of the statistics of a crossover analysis of nearly 2.3 years of JASON-1 altimeter data (Cycle 1-86), before and after the tidal correction, using the three tidal models. The inter-comparison in terms of mean value and standard deviation of the differences between the tidal heights on the 15′ × 15′ grid resulted in mean values up to 3 mm and standard deviations ranging from 16 to 26 mm. However, maximum values of differences exceed several dm. On the other hand, the statistics of the crossover analysis showed a 17% decrease of the standard deviation of the JASON-1 crossover differences after the tidal correction. These results show a good agreement between the three tidal models. © Springer-Verlag Berlin Heidelberg 2007.