Sea-level variations in the Baltic Sea: Consistency of geodetic observations and oceanographic models

Altimetric sea-surface heights from the ERS-1, ERS-2 and TOPEX/Poseidon missions as well as tide gauge observations in the Baltic Sea area were used for comparisons with the output of a high resolution oceanographic model. The general agreement of the in-situ sea-level measurements and the sea-surface heights obtained from the model was investigated. Special attention was paid to the analysis of the temporal and spatial sea-level variability as well as sea-level extrema (high/low fill level, extreme sea-surface slopes). The observed and modelled sea-surface heights show a high correlation (above 0.8). Extreme situations appear also as extremes in the model., yet the magnitudes of the variations are slightly underestimated by the model. Another aspect to be considered is the stationary sea surface. The mean sea-surface topography determined from satellite altimetry in combination with a regional geoid model was compared to the mean sea-surface topography that was derived from the oceanographic model. The well-known general behaviour of the Baltic Sea mean sea-surface is reflected in both solutions. However, a detailed comparison and the determination of features of small dimensions demands further investigations.