CoAuthors

Frédéric Frappart (GET-OMP, LEGOS-OMP, France); José Darrozes (GET-OMP, France); Vincent Marieu (EPOC-OASU, France); Guillaume Ramillien (GET-OMP, France); Pascal Bonnefond (Observatoire de Paris - SYRTE, France); Florence Birol (LEGOS-OMP, France)

Accurate monitoring of sea-level variations using satellite altimetry requires a precise determination of the error budget of the altimeter measurements. Calibration of the altimetry missions is crucial for estimating sea surface height (SSH) bias and assessing the error balance of the altimetry measurement system. Long-term monitoring of the performances of radar altimeters are performed at permanent calibration facilities such as or Calibration/Validation (Cal/Val) sites in Corsica, Western Mediterranean Sea, at Harvest platform, Eastern Pacific Ocean, in Gavdos, Eastern Mediterranean Sea, and Bass Strait, between Australia and Tasmania. In this study, local absolute calibrations are performed under the altimeter groundtrack using tide gauge records located along the French coast of the Bay Biscay, from the Spanish border to La Rochelle, using data from the following altimetry missions:ERS-2 (REAPER product), Jason-1, ENVISAT, Jason-2 and SARAL. Bias, RMSE and correlation were estimated between altimetry-derived SSH and tide gauges. Different combinations of corrections were tested (bi-frequency and MWR, bi-frequency and model, model and MWR, model and model for the ionosphere and wet troposphere corrections respectively). The domain of validity of the corrections with reference to the distance to the coast was also assessed.