Laurent Testut (LIENSs - CNRS/University of La Rochelle, France); Alvaro Santamaría-Gómez (LIENSs - CNRS/University of La Rochelle, France); Guy Wöppelmann (LIENSs - CNRS/University of La Rochelle, France)

For more than two decades, in situ data from tide gauges have been used to calibrate and validate the altimeter instruments onboard satellites. In addition to the length and intrinsic quality of the tide gauge time series, the choice of a calibration site depends on the additional criteria such as the geometrical configuration between the satellite track, the coast and the tide gauge location (which includes information on the distance, the angle, the sequence of passage, i.e ascending or descending), a good correlation between tide gauge and satellite altimetry sea-surface height observations, a proper knowledge of the vertical land motion that affect the tide gauge site…
Based on geometrical criteria only, the aim of this study is to evaluate the optimal distribution of tide gauges for calibrating the main satellite altimetry missions, with a particular interest in the sites that could be used for more than one mission and sites where a tide gauge and/or permanent GPS installation is needed.