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High-resolution change estimation of soil moisture using L-band radiometer and Radar observations made during the SMEX02 experiments / U. Narayan in IEEE Transactions on geoscience and remote sensing, vol 44 n° 6 (June 2006)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 44 n° 6 (June 2006) . - pp 1545 - 1554 Titre : High-resolution change estimation of soil moisture using L-band radiometer and Radar observations made during the SMEX02 experiments Type de document : Article/Communication Auteurs : U. Narayan, Auteur ; V. Lakshmi, Auteur ; Thomas J. Jackson, Auteur Année de publication : 2006 Article en page(s) : pp 1545 - 1554 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] bande L [Termes IGN] coefficient de rétrodiffusion [Termes IGN] détection de changement [Termes IGN] humidité du sol [Termes IGN] image AIRSAR [Termes IGN] image ALOS [Termes IGN] Iowa (Etats-Unis) [Termes IGN] limite de résolution radiométrique [Termes IGN] radiomètre à hyperfréquence [Termes IGN] rugosité du sol [Termes IGN] simulation numérique [Termes IGN] Soil Moisture Experiment [Termes IGN] température de luminance Résumé : (Auteur) The soil moisture experiments held during June-July 2002 (SMEX02) at lowa demonstrated the potential of the L-band radiometer (PALS) in estimation of near surface soil moisture under dense vegetation canopy conditions. The L-band radar was also shown to be sensitive to near surface soil moisture. However, the spatial resolution of a typical satellite L-band radiometer is of the order of tens of kilometers, which is not sufficient to serve the full range of science needs for land surface hydrology and weather modeling applications. Disaggregation schemes for deriving subpixel estimates of soil moisture from radiometer data using higher resolution radar observations may provide the means for making available global soil moisture observations at a much finer scale. This paper presents a simple approach for estimation of change in soil moisture at a higher (radar) spatial resolution by combining L-band copolarized radar backscattering coefficients and L-band radiometric brightness temperatures. Sensitivity of AIRSAR L-band copolarized channels has been demonstrated by comparison with in situ soil moisture measurements as well as PALS brightness temperatures. The change estimation algorithm has been applied to coincident PALS and AIRSAR datasets acquired during the SMEX02 campaign. Using AIRSAR data aggregated to a 100-m resolution, PALS radiometer estimates of soil moisture change at a 400-m resolution have been disaggregated to 100-m resolution. The effect of surface roughness variability on the change estimation algorithm has been explained using integral equation model (IEM) simulations. A simulation experiment using synthetic data has been performed to analyze the performance of the algorithm over a region undergoing gradual wetting and dry down. Copyright IEEE Numéro de notice : A2006-260 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2006.871199 En ligne : https://doi.org/10.1109/TGRS.2006.871199 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27987 [article]

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Retrieval of soil moisture from passive and active L/S band sensor (PALS) observations during the soil moisture experiment in 2002 (SMEX) / U. Narayan in Remote sensing of environment, vol 92 n° 4 (30 September 2004)  

Public [article]  inRemote sensing of environment > vol 92 n° 4 (30 September 2004) . - pp 483 - 496 Titre : Retrieval of soil moisture from passive and active L/S band sensor (PALS) observations during the soil moisture experiment in 2002 (SMEX) Type de document : Article/Communication Auteurs : U. Narayan, Auteur ; V. Lakshmi, Auteur ; E. Njoku, Auteur Année de publication : 2004 Article en page(s) : pp 483 - 496 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] bande L [Termes IGN] bande S [Termes IGN] bande spectrale [Termes IGN] capteur actif [Termes IGN] capteur passif [Termes IGN] Glycine max [Termes IGN] humidité du sol [Termes IGN] Iowa (Etats-Unis) [Termes IGN] maïs (céréale) [Termes IGN] Passive and Active L and S band Sensor [Termes IGN] régression [Termes IGN] Soil Moisture Experiment [Termes IGN] teneur en eau de la végétation [Termes IGN] transfert radiatif Résumé : (Auteur) The Soil Moisture Experiments in 2002 (SMEX02) were conducted in Iowa between June 25th and July 12th, 2002. A major aim of the experiments was examination of existing algorithms for soil moisture retrieval from active and passive microwave remote sensors under high vegetation water content conditions. The data obtained from the passive and active L and S band sensor (PALS) along with physical variables measured by in situ sampling have been used in this study to demonstrate the sensitivity of the instrument to soil moisture and perform soil moisture retrieval using statistical regression and physical modeling techniques. The land cover conditions in the region studied were predominantly soybean and corn crops with average vegetation water contents ranging from 0 to ~ 5 kg/m2. The PALS microwave sensitivity to soil moisture under these vegetation conditions was investigated for both passive and active measurements. The performance of the PALS instrument and retrieval algorithms has been analyzed, indicating soil moisture retrieval errors of approximately 0.04 g/g gravimetric soil moisture. Statistical regression techniques have been shown to perform satisfactorily with soil moisture retrieval error of around 0.05 g/g gravimetric soil moisture. The retrieval errors were higher for the corn than for the soybean fields due to the higher vegetation water content of the corn crops. However, the algorithms performed satisfactorily over the full range of vegetation conditions. Numéro de notice : A2004-414 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.05.018 En ligne : https://doi.org/10.1016/j.rse.2004.05.018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26941 [article]