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Communication Dans Un Congrès Année : 2020

G-SWAF a 10 years dataset of global water dynamics from L-Band microwave: from concept to applications

Résumé

Monitoring of in-land waters has gained a big interest in the last decade due to the high stacks related to water resources and the increased availability of satellite-based Earth Observation (EO) data for the detection of water surfaces. L-band passive microwave while providing deca-Kilometric spatial resolution observations is able to monitor water surfaces at high temporal resolution (<3days) under dense vegetated areas globally. Here, we present the algorithms basis of the latest 10 years dataset of Global Surface WAter Fraction (G-SWAF) available at www.catds.fr (Al Bitar et al. 2020). G-SWAF is based on multi-angular and dual-pole observation from the Soil Moisture and Ocean Salinity satellite. Level3 Angle binned Horizontal (HH) and Vertical (VV) polarization, Top of Atmosphere (TOA) Brightness Temperatures (TB) (Al Bitar et al. 2017) at 32.5 to 52.5 incidence angles are used to retrieve the surface water fractions. The retrieval is based on minimizing the quadratic difference between the modeled and the observed TB. Surface emission for forest is considered from spatio-temporal observations while the TB for water surfaces is modeled using radiative transfer principals. We present the validation and comparison of the G-SWAF product against water surfaces from microwave (SWAMP, GIEMS), SAR (ALOS-PALSAR), optical (MODIS), and altimetry (Jason2, Sentinel-3) (Parrens et al. 2017, Fatra et al. 2020). Fusion of the SWAF data with digital elevation models (SRTM, MERIT) and optical data (GSW) provides enhanced 1km resolution surface water maps (SWAF-HR) (Parrens et al. 2020). Several applications are also illustrated showing the added value of the G-SWAF product. Namely, the forcing of hydrodynamic models (MGB,SWAT) in tropical basins, a first EO based quantification of denitrification in the Amazon river (Guilerne et al. 2020, Martinez, et al. 2020), the monitoring of the floods in the Congo River Basin (Fatras et al. 2020), In the last section, we show how the combination of the G-SWAF with altimetric data can provide monitoring of water volumes in densely vegetated areas in preparation of the SWOT mission.
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Dates et versions

hal-04528311 , version 1 (01-04-2024)

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  • HAL Id : hal-04528311 , version 1

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Al Bitar Ahmad, Marie Parrens, Jeremy Guilhen, Ayan Fleischmann, Sabine Sauvage, et al.. G-SWAF a 10 years dataset of global water dynamics from L-Band microwave: from concept to applications. EO for Water Cycle Science, ESA, Nov 2020, London, United Kingdom. ⟨hal-04528311⟩
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