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

摘要

The stability of the altimeter instruments and theaccuracy of the corrections are very important for longtermsea level change determination from multi-missionaltimetry. Dual-crossovers differences of ERS-2 andTopex in the interval 1995-2001 in the European seasshow a time-dependence of the relative bias with anegative linear-term of a few mm/yr. The ionosphericcorrection, that has to be computed from a model forERS-2, is responsible in the Mediterranean Sea for partof the linear-term, which is reduced from –10 to –4mm/yr when the GIM correction is used instead of theBent correction. Similar values are obtained in the otherEuropean Seas. The application of other correctionsdoes not modify significantly the linear term of thedual-crossover differences. Comparison with tide gaugestations show that the linear-term of the tide gauge sealevel measurements agrees better with Topex than withERS-2 data.