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Article Dans Une Revue Science of Remote Sensing Année : 2023

Towards soil moisture profile estimation in the root zone using L- and P-band radiometer observations: A coherent modelling approach

Résumé

Precision irrigation management and crop water stress assessment rely on accurate estimation of root zone soil moisture. However, only the top 5 cm soil moisture can be estimated using the two current passive microwave satellite missions, Soil Moisture and Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP), which operate at L-band (wavelength of-21 cm). Since the contributing depth of the soil to brightness temperature increases with observation wavelength, it is expected that a P-band (wavelength of-40 cm) radiometer could potentially provide soil moisture information from deeper layers of the soil profile. Moreover, by combining both L-and P-bands, it is hypothesized that the soil moisture profile can be estimated even beyond their individual observation depths. The aim of this study was to demonstrate the potential of combined L-band and P-band radiometer observations to estimate the soil moisture profile under flat bare soil using a stratified coherent forward model. Brightness temperature observations at L-band and P-band from a tower based experimental site across a dry (April 2019) and a wet (March 2020) period, covering different soil moisture profile shapes, were used in this study. Results from an initial synthetic study showed that the performance of a combined L-band and P-band approach was better than the performance of using either band individually, with an average depth over which reliable soil moisture profile information could be estimated (i.e. with a target root mean square error (RMSE) of less than 0.04 m3/m3) being 20 cm for linear and 15 cm for second-order polynomial functions. Other functions were also tested but found to have a poorer performance. Applying the method to the tower-based brightness temperature achieved an average estimation depth of 28 cm (20 cm) and 5 cm (5 cm) during the dry and wet periods respectively when using a second-order polynomial (linear) function. These findings highlight the opportunity of a satellite mission with L-band and P-band observations to accurately estimate the soil moisture profile to as deep as 30 cm globally.
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hal-04620196 , version 1 (21-06-2024)

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Foad Brakhasi, Jeffrey Walker, Nan Ye, Xiaoling Wu, Xiaoji Shen, et al.. Towards soil moisture profile estimation in the root zone using L- and P-band radiometer observations: A coherent modelling approach. Science of Remote Sensing, 2023, 7, pp.100079. ⟨10.1016/j.srs.2023.100079⟩. ⟨hal-04620196⟩
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