Tidal corrections of the ERS-1 satellite altimeter data in the Mediterranean sea

Abstract

Two tidal models for the Mediterranean Sea are recently available. From these models tidal heights have been computed and used to correct the altimeter data of the first 10 ERM's of ERS-I. Comparisons of the statistics of the differences between ERS-I and OSU9I before and after the tida! correction do not present a significant improvement. In terms of the standard deviation (sd) of the aforementioned differences a small de crease is observed for most of the ERM's, but there are also cases in which the sd increases. Significant information was obtained by analyzing the power spectrum at main tidal frequencies during the stacking procedure of the altimeter data. Another test carried out in our study was the comparison of the results of the crossover analysis of the ERS-I data in the Mediterranean before and after the tidal correction. The very small decrease (at the order of several mm) of the rms of the crossover differences after the tidal correction could be inperpreted either as ineffectiveness of the model or as an indication that the tidal signal in the Mediterranean is weak enough and for this reason could be ignored in several applications.