Geodetic aspects of long term sea level variations in European seas from altimetry and tide gauge data

The classical method for monitoring the sea level variations at continental margins, using tide gauge records, gives the relative sea level changes with respect to the earth crust. Absolute sea level measurements are possible from tide gauge records when the geocentric coordinates of the station are known. The altimetry data allow the monitoring of the absolute sea level changes. We investigate the seasonal, annual and interannual variations from satellite altimeter data of the ERS-1, ERS-2 and Topex-Poseidon missions. The altimetry data used cover a time interval of five years, from 1992 to 1996, the secular trend cannot be evidenced on this short interval of time. The regions considered are the European semi-closed basins: the Mediterranean Sea, the North Sea and the Baltic Sea. The agreement with the absolute sea level variations obtained from tide gauge data, as well as the correlation with air temperature and air pressure at the tide gauge stations are investigated.