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Utilizing calibrated GPS reflected signals to estimate soil reflectivity and dielectric constant: results from SMEX02 / S.J. Katzberg in Remote sensing of environment, vol 100 n° 1 (15/01/2006)  

Public [article]  inRemote sensing of environment > vol 100 n° 1 (15/01/2006) . - pp 17 - 28 Titre : Utilizing calibrated GPS reflected signals to estimate soil reflectivity and dielectric constant: results from SMEX02 Type de document : Article/Communication Auteurs : S.J. Katzberg, Auteur ; O. Torres, Auteur ; et al., Auteur Année de publication : 2006 Article en page(s) : pp 17 - 28 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] bande L [Termes IGN] constante diélectrique [Termes IGN] données de terrain [Termes IGN] étalonnage géométrique [Termes IGN] humidité du sol [Termes IGN] Iowa (Etats-Unis) [Termes IGN] réflectance de surface [Termes IGN] réflectivité [Termes IGN] réflexion spéculaire [Termes IGN] signal GPS [Termes IGN] Soil Moisture Experiment [Termes IGN] sol arable [Termes IGN] télédétection en hyperfréquence Résumé : (Auteur) Extensive reflected GPS data was collected using a GPS reflectometer installed on an HC130 aircraft during the Soil Moisture Experiment 2002 (SMEX02) near Ames, Iowa. At the same time, widespread surface truth data was acquired in the form of point soil moisture profiles, areal sampling of near-surface soil moisture, total green biomass and precipitation history, among others. Previously, there have been no reported efforts to calibrate reflected GPS data sets acquired over land. This paper reports the results of two approaches to calibration of the data that yield consistent results. It is shown that estimating the strength of the reflected signals by either (1) assuming an approximately specular surface reflection or (2) inferring the surface slope probability density and associated normalization constants give essentially the saine results for the conditions encountered in SMEX02. The corrected data is converted to surface reflectivity and then to dielectric constant as a test of the calibration approaches. Utilizing the extensive in-situ soil moisture related data, this paper also presents the results of comparing the GPS-inferred relative dielectric constant with the Wang - Schmugge model frequently used to relate volume moisture content to dielectric constant. It is shown that the calibrated GPS reflectivity estimates follow the expected dependence of permittivity with volume moisture, but with the following qualification: The soil moisture value governing the reflectivity appears to come from only the top 1 - 2 cm of soil, a result consistent with results found for other microwave techniques operating at L-band. Nevertheless, the experimentally derived dielectric constant is generally lower than predicted. Possible explanations are presented to explain this result. Numéro de notice : A2006-014 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2005.09.015 En ligne : https://doi.org/10.1016/j.rse.2005.09.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27741 [article]