Crétaux Jean-François (LEGOS, France); Vuglinsky Valery (Hidrolare, Russia); Zawadzki Lionel (CLS, France)

The validation of lake water levels with in-situ data, needs the installation of permanent instruments over a large period. By using the lake water level data generated by several in-situ databases from a long-term monitoring (from 1992 to present), we determined the accuracy of lake water level estimated in Hydroweb from a wide spectrum of mission such as T/P, ENVISAT, SARAL, Jason-1, Jason-2 and Jason3 and Sentinel-3A. Some of them as the Jason missions operate in a Low Resolution Mode (LRM) and Sentinel-3A in a Synthetic Aperture Radar (SAR) mode. In-situ data is evaluated by averaging data over multiple fixed stations on a monthly basis. Altimeter data is performed averaging data along the track when the satellite overpass the lake. For this study, three indicators were estimated: Bias, RMS and Pearson coefficient. For all lakes the Pearson coefficient is higher than 0.9. In some cases, the bias is high an suggest that, even if the precision is good, the accuracy of the LWL products should be considered carefully by users. The data from Hydroweb is also compared to dataset from other altimetric based datasets as G-Realm and Dahiti.