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Proceedings Paper

Continuous data assimilation for downscaling large-footprint soil moisture retrievals
Author(s): Muhammad U. Altaf; Raghavendra B. Jana; Ibrahim Hoteit; Matthew F. McCabe
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Paper Abstract

Soil moisture is a key component of the hydrologic cycle, influencing processes leading to runoff generation, infiltration and groundwater recharge, evaporation and transpiration. Generally, the measurement scale for soil moisture is found to be different from the modeling scales for these processes. Reducing this mismatch between observation and model scales in necessary for improved hydrological modeling. An innovative approach to downscaling coarse resolution soil moisture data by combining continuous data assimilation and physically based modeling is presented. In this approach, we exploit the features of Continuous Data Assimilation (CDA) which was initially designed for general dissipative dynamical systems and later tested numerically on the incompressible Navier-Stokes equation, and the Benard equation. A nudging term, estimated as the misfit between interpolants of the assimilated coarse grid measurements and the fine grid model solution, is added to the model equations to constrain the model’s large scale variability by available measurements. Soil moisture fields generated at a fine resolution by a physically-based vadose zone model (HYDRUS) are subjected to data assimilation conditioned upon coarse resolution observations. This enables nudging of the model outputs towards values that honor the coarse resolution dynamics while still being generated at the fine scale. Results show that the approach is feasible to generate fine scale soil moisture fields across large extents, based on coarse scale observations. Application of this approach is likely in generating fine and intermediate resolution soil moisture fields conditioned on the radiometerbased, coarse resolution products from remote sensing satellites.

Paper Details

Date Published: 25 October 2016
PDF: 10 pages
Proc. SPIE 9998, Remote Sensing for Agriculture, Ecosystems, and Hydrology XVIII, 99981O (25 October 2016); doi: 10.1117/12.2241042
Show Author Affiliations
Muhammad U. Altaf, King Abdullah Univ. of Science and Technology (Saudi Arabia)
Raghavendra B. Jana, King Abdullah Univ. of Science and Technology (Saudi Arabia)
Ibrahim Hoteit, King Abdullah Univ. of Science and Technology (Saudi Arabia)
Matthew F. McCabe, King Abdullah Univ. of Science and Technology (Saudi Arabia)


Published in SPIE Proceedings Vol. 9998:
Remote Sensing for Agriculture, Ecosystems, and Hydrology XVIII
Christopher M. U. Neale; Antonino Maltese, Editor(s)

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