Gravity and Geoid in the Mediterranean from a Common Adjustment of ERS-1 and TOPEX Altimeter Data

From the separate processing and crossover analysis of repeat ERS-1 and TOPEX altimeter data in the Mediterranean basin was assessed that the TOPEX data are characterized by higher accuracy than that of ERS-1 and other previous missions data. It is also known from the coverage of both missions that the resolution of ERS-1 data is superior to that of the TOPEX data, since the distance across track in TOPEX mission is about four times the corresponding distance in ERS-1 mission. Moreover, numerical tests carried out to recover the gravity anomalies in the Mediterranean sea showed that the prediction results are affected by the data accuracy in the case of ERS-1 and by the poor coverage in the case of TOPEX. Therefore, taking into account the advantages and drawbacks of both missions we carried out a common adjustment of both altimeter data sources in order to improve the prediction accuracy of gravity anomalies and geoid heights in the Mediterranean sea.