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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2018-17
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 Feb 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
An improved perspective in the representation of soil moisture: potential added value of SMOS disaggregated 1 km resolution product
Samiro Khodayar1, Amparo Coll2, and Ernesto Lopez-Baeza2 1Institute of Meteorology and Climate Research (IMK-TRO), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
2University of Valencia, Spain. Earth Physics and Thermodynamics Department. Climatology from Satellites Group
Abstract. This study uses the synergy of multiresolution soil moisture (SM) satellite estimates from the Soil Moisture Ocean Salinity (SMOS) mission, a dense network of ground-based SM measurements, and a Soil Vegetation Atmosphere Transfer (SVAT) model, SURFEX (Externalized Surface) – module ISBA (Interactions between Soil-Biosphere-Atmosphere), to examine, i) the comparison and suitability of different operational SMOS SM products to provide realistic information on the water content of the soil as well as the added value of the newly released SMOS Level 4 3.0 all weather disaggregated ~ 1 km SM (SMOS_L43.0), and ii) its potential impact for improving uncertainty associated to SM initialization in land surface modelling. Three different data products from SMOS-L3 (~ 25 km), L2 (~ 15 km), and disaggregated L4 3.0 (~ 1 km) are investigated. In situ SM observations over the Valencia Anchor Station (VAS; SMOS Calibration/Validation (Cal/Val) site in Europe) are used for comparison. The SURFEX-ISBA model is used to simulate point-scale surface SM (SSM) and, in combination with high-quality atmospheric information data, namely ECMWF and the SAFRAN meteorological analysis system, to obtain a representative SSM mapping over the VAS. The sensitivity to SSM initialization, particularly to realistic initialization with SMOS_L43.0 to simulate the spatial and temporal distribution of SSM is assessed. Results demonstrate: (a) all SMOS products correctly capture the temporal patterns, but, the spatial patterns are not accurately reproduced by the coarser resolutions probably in relation to the contrast with point-scale in situ measurements. (b) The potential of SMOS-L43.0 product is pointed out to adequately characterize SM spatio-temporal variability reflecting patterns consistent with intensive point scale SSM samples on a daily time scale. The restricted temporal availability of this product dictated by the revisit period of the SMOS satellite compromises the averaged SSM representation for longer periods than a day. (c) A seasonal analysis points out improved consistency during December-January-February and September-October-November in contrast to significantly worse correlations in March-April-May (in relation to the growing vegetation) and June-July-August (in relation to low SSM values < 0.1 m3/m3 and low spatial variability). (d) Perturbation simulations with the SURFEX-ISBA SVAT (Soil-Vegetation-Atmosphere Transfer) model demonstrate the impact of the initial SSM scenarios on its temporal evolution. (e) The combined use of the SURFEX-ISBA SVAT model with the SAFRAN system, initialized with SMOS-L43.0 1 km disaggregated data is proven to be a suitable tool to produce regional SM maps with high accuracy which could be used as initial conditions for model simulations, flood forecasting, crop monitoring and crop development strategies, among others.

Citation: Khodayar, S., Coll, A., and Lopez-Baeza, E.: An improved perspective in the representation of soil moisture: potential added value of SMOS disaggregated 1 km resolution product, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-17, in review, 2018.
Samiro Khodayar et al.
Samiro Khodayar et al.
Samiro Khodayar et al.

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