Coherent Satellite Monitoring of the Water Cycle Over the Amazon. Part 1: Methodology and Initial Evaluation

Overview & Synopsis

Monitoring coherently the Amazon Water Cycle (WC) using satellite observations is crucial for climate and water resources studies. The SAtellite Water Cycle (SAWC) integration methodology is introduced to optimize the satellite datasets. In this paper, the WC budget is balanced simultaneously over 10 sub basins by constraining the horizontal water exchanges between them. Compared to an actual assimilation analysis, SAWC benefits from the use of water storage observations from Gravity Recovery and Climate Experiment. SAWC corrects the satellite evapotranspiration datasets that tend to under estimate the water limited evaporation over the central Amazon and to over estimate the energy limited evaporation over the northern Amazon. The SAWC precipitation estimates are evaluated against gauge measurements and show good overall results with a correlation varying from 0.94 to 0.99 and root mean square deviation between 16 and 41 mm/month (≃10% of precipitation estimate).