LONG-TERM SEA LEVEL VARIABILITY FROM MULTI-SATELLITE ALTIMETRY IN THE EUROPEAN SEAS

摘要

The stability of the altimeter instruments and the accuracy of the corrections are very important for long-term sea level change determination from multi-mission altimetry. Dual-crossovers differences of ERS-2 and Topex in the interval 1995-2001 in the European seas show a time-dependence of the relative bias with a negative linear-term of a few mm/yr. The ionospheric correction, that has to be computed from a model for ERS-2, is responsible in the Mediterranean Sea for part of the linear-term, which is reduced from -10 to -4 mm/yr when the GIM correction is used instead of the Bent correction. Similar values are obtained in the other European Seas. The application of other corrections does not modify significantly the linear term of the dual-crossover differences. Comparison with tide gauge stations show that the linear-term of the tide gauge sea level measurements agrees better with Topex than with ERS-2 data.