Surface soil moisture estimation over the AMMA Sahelian site in Mali using ENVISAT/ASAR data

Abstract

9This paper focuses on different methods for estimating soil moisture in a Sahelian environment by comparing ENVISAT/ASAR and ground data 10 at the same spatial scale. The analysis is restricted to Wide Swath data in order to take advantage of their high temporal repetitivity (about 3-4 days) 11 corresponding to a moderate spatial resolution (150 m). On the one hand, emphasis is put on the characterization of Surface Soil Moisture (SSM) at a 12 spatial scale compatible with the derivation of the backscattering coefficients, and a transfer function is developed for up-scaling local measurements 13 to the 1 km scale. On the other hand, three different approaches are used to normalize the angular variation of the observed backscattering coefficients. 14 The results show a strong linear relationship between the HH normalized backscattering coefficients and SSM. The best result is obtained when 15 restricting the ASAR data to low incidence angles and by taking into account vegetation effects using multi-angular radar data. For this case, the rms 16 error of the SSM retrieval is 2.8%. These results highlight the capabilities of the ASAR instrument to monitor SSM in a semiarid environment. 17

Soil moisture active and passive microwave products: intercomparison and evaluation over a Sahelian site

“…As pointed out by , the relative homogeneity of the Gourma meso-scale site is particularly suitable for remote sensing evaluation of land surface products. Several studies investigated the validation and evaluation of satellite products, including soil moisture, vegetation parameters, and albedo (Baup et al, 2007;Zribi and Decharme, 2009;Gruhier et al, 2008;Samain et al, 2008;de Rosnay et al, 2009a).…”

Mapping surface soil moisture over the Gourma mesoscale site (Mali) by using ENVISAT ASAR data

“…Indeed, the influence of the green vegetation can be either neglected or simply taken into account at low incidence angles and for low vegetation density (Leaf Area Index -LAI -<2 m 2 m −2 ) as proposed in Tansey et al, 1999 andMoran et al, 2000. At higher incidence angles, the vegetation effects on the radar signal can be corrected using the angular properties of the backscattering coefficient (Wagner et al, 2000;Baup et al, 2007a). Finally, the determination of SSM was found to be possible from ASAR data, for values higher than 4% (m 3 /m 3 ).…”

Evaluation of a Global Soil Moisture Product from Finer Spatial Resolution SAR Data and Ground Measurements at Irish Sites

“…In [26][27][28][29][30][31][32][33][34][35], the capability of ASAR backscattering to estimate the surface soil moisture has been demonstrated.…”