Statistical Models and Latest Results in the Determination of the Absolute Bias for the Radar Altimeters of Jason Satellites using the Gavdos Facility

The dedicated calibration site for satellite radar altimeters in Gavdos, Greece, has been operational as of 2004. The island of Gavdos is located along a repeating ground track of Jason satellites, adjacent to Envisat, where the altimeter and radiometer do not experience significant land intrusion. In this article, the models and techniques for calculating the satellite altimeter bias, as well as the software tool called TUCalibrit, are presented. In summary, over cycles 209-259 for Jason-1 and cycles 1-40 for Jason-2, the altimeter biases have been estimated as B(J1) = + 103.6 mm +/- 4.7 mm and B(J2) = + 181.9 mm +/- 6.7 mm, respectively.