Intercomparison between ALOS PALSAR and ENVISAT ASAR AP for soil moisture estimation capabilities in the REMEDHUS Area (SPAIN)

Carlos Perez-Gutierrez(3), Jesus Alvarez-Mozos(1), Jose Martinez-Fernandez(2) and Nilda Sanchez(2)

(1) Public University of Navarre, Los Tejos, Arrosadia s/n, 31006 Pamplona, Spain
(2) University of Salamanca, C/ Río Duero, 12. Parque Científico, 37185 Villamayor (Salamanca), Spain
(3) University of Salamanca, Avda. Hornos Caleros, 50, 05003 Avila, Spain


This work uses ALOS observations to retrieve soil moisture in the REMEDHUS network area in the northwest of Spain. Soil moisture estimations obtained from ALOS PALSAR and ENVISAT ASAR AP scenes are being compared with soil moisture measurements collected on soil moisture stations.

The REMEDHUS network is located in the semi-arid sector of the Duero Basin, Spain, (41,1º–41,5º N; 5,1º–5,7° W), covering a plain area of about 1300 km2. It has been operating 23 soil moisture stations since 1999, all of them situated over agricultural fields.

The different spatial resolution and microwave frequency between PALSAR and ASAR let to improve the detailed scale, and to compare the distribution of the soil moisture on the ground. Moreover, the polarimetric capabilities of ALOS PALSAR may provide improved approaches for the soil moisture retrieval. It is also interesting to compare the results obtained with L-band versus C-band observations.

Soil roughness is being used as ancillary data. Soil roughness is a parameter to be considered because it affects strongly the microwave backscattering. A multiscale description of soil roughness estimation is being analized. Hybrid techniques (close-range photogrammetry, terrestrial laser scanner devices and Digital Elevation Surfaces derived from ALOS PRISM’s triplets) are used to study the influence of micro- and macroroughness.

There are no definitive results until now. Several problems with ALOS acquisitions have been detected and there are no simultaneous scenes for both satellites in the same period. So no comparison dates with acquired ENVISAT ASAR were available. Catalogue ALOS PALSAR will be considered to compare with soil moisture real-time ground stations.

In our first phases, we detected that commercial software for remote sensing is getting problems to manage ALOS and non-commercial software packages are able but with limited functions yet.



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