Mean Sea Level and Sea Level Variation Studies in the Black Sea and the Aegean

Abstract

An analysis on the use of ERS1, ERS2 and TOPEX/Poseidon (T/P) data for the determination of a Mean Sea Surface (MSS) model in the Black Sea and the Aegean is presented. From all three satellites, the Exact Repeat Mission (ERM) data have been used spanning over a period of 12 years. The sea surface heights were edited for blunder detection and removal while an inter-comparison between the T/P data has been preformed as well. During the latter, a T/P validation data set was formed by stacking all 9 year of avail-able T/P SSHs. Then, the differences between each year and the validation data set were estimated to identify patterns of sea level change during the period covered by the T/P data. This analysis was followed by the combination of the ERS1/2 and T/P data to form an MSS model. Three different gridding algorithms, i.e., ordinary weighted least squares, least squares collocation and interpolation using splines in tension were tested to determine the most appropriate. The gridded outputs were compared against the KMS2001 MSS model, which was used as a ground truth data set. Furthermore, T/P monthly, seasonal and annual SSHs have been compared with the best of the MSS model determined to identify patterns in sea level variation. Additionally, a comparison of the MSS model with gravimetric quasigeoid heights at tide gauge (TG) stations across the Black Sea was conducted to assess their agreement and determine corrector surfaces for the transformation between altimetric and gravimetric geoid models.