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Soil Moisture Estimations Based on Airborne CAROLS L-Band Microwave Data
LATMOS, Route de Troux, 78280 Guyancourt, France
CESBIO (UPS/CNRS/IRD/CNES), 18 Avenue Edouard Belin, bpi 2801, 31401 Toulouse Cedex 9, France
INRA, EPHYSE, 71 Avenue Edouard Bourlaux, 33140 Villenave d’Ornon, France
MICINN, CDTI, Cid, 4, 28001 Madrid, Spain
CNRM-GAME, Météo-France, CNRS, URA 1357, 42 Avenue Gaspard Coriolis, 31057 Toulouse, France
* Author to whom correspondence should be addressed.
Received: 11 October 2011; in revised form: 24 November 2011 / Accepted: 24 November 2011 / Published: 2 December 2011
Abstract: The SMOS satellite mission, launched in 2009, allows global soil moisture estimations to be made using the L-band Microwave Emission of the Biosphere (L-MEB) model, which simulates the L-band microwave emissions produced by the soil–vegetation layer. This model was calibrated using various sources of in situ and airborne data. In the present study, we propose to evaluate the L-MEB model on the basis of a large set of airborne data, recorded by the CAROLS radiometer during the course of 20 flights made over South West France (the SMOSMANIA site), and supported by simultaneous soil moisture measurements, made in 2009 and 2010. In terms of volumetric soil moisture, the retrieval accuracy achieved with the L-MEB model, with two default roughness parameters, ranges between 8% and 13%. Local calibrations of the roughness parameter, using data from the 2009 flights for different areas of the site, allowed an accuracy of approximately 5.3% to be achieved with the 2010 CAROLS data. Simultaneously we estimated the vegetation optical thickness (t) and we showed that, when roughness is locally adjusted, MODIS NDVI values are correlated (R2 = 0.36) to t. Finally, as a consequence of the significant influence of the roughness parameter on the estimated absolute values of soil moisture, we propose to evaluate the relative variability of the soil moisture, using a default soil roughness parameter. The soil moisture variations are estimated with an uncertainty of approximately 6%.
Keywords: soil moisture; CAROLS; L-band; L-MEB; soil roughness
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Pardé, M.; Zribi, M.; Wigneron, J.-P.; Dechambre, M.; Fanise, P.; Kerr, Y.; Crapeau, M.; Saleh, K.; Calvet, J.-C.; Albergel, C.; Mialon, A.; Novello, N. Soil Moisture Estimations Based on Airborne CAROLS L-Band Microwave Data. Remote Sens. 2011, 3, 2591-2604.
Pardé M, Zribi M, Wigneron J-P, Dechambre M, Fanise P, Kerr Y, Crapeau M, Saleh K, Calvet J-C, Albergel C, Mialon A, Novello N. Soil Moisture Estimations Based on Airborne CAROLS L-Band Microwave Data. Remote Sensing. 2011; 3(12):2591-2604.
Pardé, Mickaël; Zribi, Mehrez; Wigneron, Jean-Pierre; Dechambre, Monique; Fanise, Pascal; Kerr, Yann; Crapeau, Marc; Saleh, Kauzar; Calvet, Jean-Christophe; Albergel, Clément; Mialon, Arnaud; Novello, Natalie. 2011. "Soil Moisture Estimations Based on Airborne CAROLS L-Band Microwave Data." Remote Sens. 3, no. 12: 2591-2604.