ESTIMATION OF THE SEA STATE BIAS EFFECT ON THE ALTIMETRIC MEASUREMENTS USING A PARAMETRIC MODEL

The sea state bias (SSB) which affect the altimetric measurements on the sea surface is estimated using empirical parametric model (BM4), calibrated by the analysis of the altimeter data. This model is a simple linear function that links the SSB with the significant wave height (SWH), the wind speed (U) and the backscatter coefficient (σ 0). The knowledge of the backscatter coefficient determined by altimetric signal processing allows to determine the significant wave height and the wind speed. The use of Topex/Poseidon and Jason-1 altimetric data to calculate the sea state bias with the BM4 model and the comparison of the results obtained with the SSB value transmitted in the message of each satellite allowed us the validation of the methodological approach developed. The proximity of the results obtained with Topex/Poseidon data is sufficient for the most altimetric applications as the determination of the mean sea level which was calculated on the western Mediterranean Sea during a period of 72 cycles. Concerning Jason-1, the difference of the results in the determination of the SSB can be explained by the nature of the instruments on board and also the type of model used