An Intercomparison of Parametric Models of Sea State Bias for the TOPEX, Poseidon and Jason-1 Altimeters

The ‘BM4’ four-parameter (Gaspar et al., Journal of Geophysical Research, 1994) empirical model of sea state bias based on wind stress and significant wave height (SWH) is applied in both crossover and collinear analyses of all available TOPEX, Poseidon and Jason-1 data provided by the Radar Altimeter Database System at Delft University of Technology. The relative biases are - 2%, -5% and -4% of SWH for TOPEX, Poseidon and Jason-1 respectively. Estimates of the uncertainties on the lower-order coefficients are large and unhelpful. For each altimeter, crossover analyses resulted in a greater proportion of the variance in sea surface height differences explained by the calculated model than collinear analyses. From the available Jason-1 data, the calculated crossover model performs as well as the sea state bias model provided with the data.