Quality assessment of water level retrieved by the successive altimetry missions in the Congo basin
Event: 2016 Ocean Surface Topography Science Team Meeting
Session: Science III: Two decades of continental water's survey from satellite altimetry - From nadir low-resolution mode to SAR altimetry, new perspectives for hydrology
Presentation type: Type Poster
We present the largest ever built database of water stages in the Congo bassin by processing the ENVISAT, SARAL Jason 2-3 missions, reaching a total of 350+ Virtual Stations spaning over 1 to 2 decades. In bassins such as the Congo basin, where almost no gauge exist and can be used to assess the quality of such altimetry series, other ways than this external validation methods have to be developped. There, we took advantage of the orbit characteristics to develop an internal validation of ENVISAT, SARAL, Jason-2 and Jason-3 series. We looked at crossings that occur 1- over a river (i.e. wthin 20 km) and 2- at short time differences. For the ENVISAT/SARAL orbit, we found that such crossings occur at 1.5 day of interval for ~ 30 locations. At 2 locations, the Jason orbit makes a crossing over the Congo river at the same day. Making the conservative asumption that the water level did not change significantly between the two passes of a same cycle, we computed the rms difference throughtout the series. We used ICE-1 retracking for the ENVISAT, SARAL and Jason-3 series, and PISTACH/ICE3-retracking for Jason-2. We present the results for each mission.