Séminaire
During the last decades, Earth Observations (EO) have increasingly been used to study global hydrology. However, using EO to analyze the water cycle is still a challenge, at the regional as at the global scale: EO suffer from numerous systematic and/or random errors and they are often not coherent with each other (Pellet and Aires. 2018). In particular, they generally do not close the water cycle budget. It is however possible to optimally merge several datasets for each component of the terrestrial water cycle to close this budget at the basin scale, using only EO and no model assimilation (Aires et al. 2014; Munier et al. 2015). Once a reference dataset is obtained to describe the water cycle in a hydrologically coherent way, it is possible to design a simple calibration of each satellite dataset to reduce the overall budget residual, over long time series, and with the original EO spatial resolution. In this presentation, I will introduce these merging techniques and illustrate them with 3 applications. (1) When considering enough basins and associated river discharges to constrain a closed domain such as the Mediterranean region, it is possible to develop a dedicated integration technique that closes simultaneously the terrestrial, oceanic and atmospheric water cycle budgets (Pellet et al. 2019). (2) This approach has opened new perspectives to generate long-term estimate of the missing Total Water Storage Change (TWSC) in large Asian river basins (Pellet et al. 2019, in review). (3) It is also possible to introduce the hydrological dependency of sub-basins in the closure of the terrestrial Water cycle over large river catchment to infer the GroundWater Fluxes between these dependent sub-basins. This will be investigated over the Amazon.
References :
• Pellet, V.,F. Aires, S. Munier, F. Papa, long-term estimate of the water storage change in the large Himalayan river basins from water budget closure (in review), HESS, 2019
• Pellet, V., F. Aires, S. Munier, Optimisation of satellite observations to study the water cycle over the Mediterranean region, HESS, 2019.
• Pellet, V., and F. Aires, Analyzing the Mediterranean water cycle via satellite data integration, Pure Appl. Geophys,
https://doi.org/10.1007/s00024-018-1912-zpp
. 1-29, 2018.
• Munier, S., F. Aires, S. Schlaffer, C. Prigent, F. Papa, P. Maisongrande, and M. Pan, Combining datasets of satellite retrieved products. Part II: Evaluation on the Mississippi Basin and closure correction model, J. Geophys. Res., 10/2014, DOI: 10.1002/2014JD021953, 2015.
• Aires, F. Combining datasets of satellite retrieved products. Part I: Methodology and water budget closure, J. of Hydrometeor., 10.1175/JHM-D-13-0148.1, 2014.
thomas.thiebault@upmc.fr