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Considering combined or separated roughness and vegetation effects in soil moisture retrievals

hal.structure.identifierCentre d'études spatiales de la biosphère [CESBIO]
dc.contributor.authorPARRENS, Marie
hal.structure.identifierInteractions Sol Plante Atmosphère [UMR ISPA]
dc.contributor.authorWIGNERON, Jean-Pierre
hal.structure.identifierCentre d'études spatiales de la biosphère [CESBIO]
dc.contributor.authorRICHAUME, Philippe
hal.structure.identifierCentre d'études spatiales de la biosphère [CESBIO]
dc.contributor.authorAHMAD, Al Bitar
hal.structure.identifierCentre d'études spatiales de la biosphère [CESBIO]
dc.contributor.authorMIALON, Arnaud
hal.structure.identifierInteractions Sol Plante Atmosphère [UMR ISPA]
dc.contributor.authorFERNÁNDEZ-MORÁN, Roberto
hal.structure.identifierInteractions Sol Plante Atmosphère [UMR ISPA]
dc.contributor.authorAL-YAARI, Amen
hal.structure.identifierNASA Goddard Space Flight Center [GSFC]
dc.contributor.authorO’NEILL, Peggy
hal.structure.identifierCentre d'études spatiales de la biosphère [CESBIO]
dc.contributor.authorKERR, Yann H.
dc.date.accessioned2024-04-08T12:06:26Z
dc.date.available2024-04-08T12:06:26Z
dc.date.issued2017
dc.identifier.issn1569-8432
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/196403
dc.description.abstractEnFor more than six years, the Soil Moisture and Ocean Salinity (SMOS) mission has provided multi angular and full-polarization brightness temperature (TB) measurements at L-band. Geophysical products such as soil moisture (SM) and vegetation optical depth at nadir (τnad) are retrieved by an operational algorithm using TB observations at different angles of incidence and polarizations. However, the quality of the retrievals depends on several surface effects, such as vegetation, soil roughness and texture, etc. In the microwave forward emission model used in the retrievals (L-band Microwave Emission Model, L-MEB), soil roughness is modelled with a semi-empirical equation using four main parameters (Qr, Hr, Nrp, with p = H or V polarizations). At present, these parameters are calibrated with data provided by airborne studies and in situ measurements made at a local scale that is not necessarily representative of the large SMOS footprints (43 km on average) at global scale. In this study, we evaluate the impact of the calibrated values of Nrp and Hr on the SM and τnad retrievals based on SMOS TB measurements (SMOS Level 3 product) over the Soil Climate Analysis Network (SCAN) network located in North America over five years (2011–2015). In this study, Qr was set equal to zero and we assumed that NrH = NrV. The retrievals were performed by varying Nrp from −1 to 2 by steps of 1 and Hr from 0 to 0.6 by steps of 0.1. At satellite scale, the results show that combining vegetation and roughness effects in a single parameter provides the best results in terms of soil moisture retrievals, as evaluated against the in situ SM data. Even though our retrieval approach was very simplified, as we did not account for pixel heterogeneity, the accuracy we obtained in the SM retrievals was almost systematically better than those of the Level 3 product. Improved results were also obtained in terms of optical depth retrievals. These new results may have key consequences in terms of calibration of roughness effects within the algorithms of the SMOS (ESA) and the SMAP (NASA) space missions.
dc.language.isoen
dc.publisherElsevier
dc.subjectSMOS
dc.subjectsoil moisture
dc.subject.enL-band
dc.subject.ensoil roughness
dc.subject.enretrievals
dc.subject.enoptical vegetation depth
dc.title.enConsidering combined or separated roughness and vegetation effects in soil moisture retrievals
dc.typeArticle de revue
dc.identifier.doi10.1016/j.jag.2016.11.001
dc.subject.halSciences de l'ingénieur [physics]/Traitement du signal et de l'image
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre
bordeaux.journalInternational Journal of Applied Earth Observation and Geoinformation
bordeaux.page73-86
bordeaux.volume55
bordeaux.hal.laboratoriesInteractions Soil Plant Atmosphere (ISPA) - UMR 1391*
bordeaux.institutionBordeaux Sciences Agro
bordeaux.institutionINRAE
bordeaux.peerReviewedoui
hal.identifierhal-02620186
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-02620186v1
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