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Error assessment of the initial near real-time METOP ASCAT surface soil moisture product / S. Hahn in IEEE Transactions on geoscience and remote sensing, vol 50 n° 7 Tome 1 (July 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 7 Tome 1 (July 2012) . - pp 2556 - 2565 Titre : Error assessment of the initial near real-time METOP ASCAT surface soil moisture product Type de document : Article/Communication Auteurs : S. Hahn, Auteur ; T. Melzer, Auteur ; W. Wagner, Auteur Année de publication : 2012 Article en page(s) : pp 2556 - 2565 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] analyse comparative [Termes IGN] artefact [Termes IGN] bande C [Termes IGN] diffusomètre [Termes IGN] humidité du sol [Termes IGN] image ERS [Termes IGN] image MetOp-ASCAT [Termes IGN] modèle d'erreur [Termes IGN] série temporelle Résumé : (Auteur) Since December 2008, the European Organisation for the Exploitation of Meteorological Satellites has been operationally distributing a global 25-km surface soil moisture product derived from the Advanced Scatterometer (ASCAT) onboard the meteorological operational platform (METOP) satellite METOP-A. Soil moisture is retrieved by using the semiempirical change detection method originally developed by the Vienna University of Technology (TU Wien) for the Active Microwave Instrument (AMI) flown on the European Remote Sensing (ERS) satellites ERS-1 and ERS-2. With the launch of the first of the three Meteorological Operational Platforms (METOP-A) in October 2006, ASCAT onboard METOP-A inherits and continues the role of his predecessor AMI. The original soil moisture retrieval algorithm (TU Wien model) was expected to be almost directly applicable for ASCAT with only minor changes, since the configuration and technical design is similar to the ERS scatterometers. Since the TU Wien model requires a robust historic long-term reference of scattering parameters, the initial near real-time METOP ASCAT soil moisture product had to rely on the model parameters derived from over 15 years of ERS-1/2. However, the combination of ASCAT backscatter measurements and ERS-1/2 historic long-term reference introduced some artifacts in the soil moisture product. The objectives of this paper were to analyze and investigate the impact of the ERS-1/2 historic long-term reference on the soil moisture retrieval. An error model has been developed to quantify the effects of the two main error sources: differences in spatial resolution and absolute calibration. The results of the study show that a simple model is able to describe the artifacts in the initial near real-time METOP ASCAT soil moisture product, which frequently occur in areas characterized by sharp backscatter contrasts. The expected overestimation of soil moisture using ERS-1/2 model parameters due to a calibration bias between AMI- and ASCAT could be modeled as well. Numéro de notice : A2012-352 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2012.2183877 Date de publication en ligne : 27/02/2012 En ligne : https://doi.org/10.1109/TGRS.2012.2183877 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31798 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2012071A	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Detection of large-scale forest canopy change in pan-tropical humid forests 2000–2009 with the seawinds Ku-band scatterometer / S. Frolking in IEEE Transactions on geoscience and remote sensing, vol 50 n° 7 Tome 1 (July 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 7 Tome 1 (July 2012) . - pp 2603 - 2617 Titre : Detection of large-scale forest canopy change in pan-tropical humid forests 2000–2009 with the seawinds Ku-band scatterometer Type de document : Article/Communication Auteurs : S. Frolking, Auteur ; Toni Hagen, Auteur ; M. Palace, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 2603 - 2617 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Afrique tropicale [Termes IGN] analyse diachronique [Termes IGN] bande Ku [Termes IGN] Brésil [Termes IGN] canopée [Termes IGN] détection de changement [Termes IGN] diffusomètre [Termes IGN] forêt équatoriale [Termes IGN] Malaisie Résumé : (Auteur) We analyzed the 10-year record (1999-2009) of SeaWinds Ku-band microwave backscatter from humid tropical forest regions in South America, Africa, and Indonesia/Malaysia. While backscatter was relatively stable across much of the region, it declined by 1-2 dB in areas of known large-scale deforestation, and increased by up to 1-2 dB in areas of secondary forest or plantation forest growth and in major metropolitan areas. The reduction in backscatter over 142 18.5 km * 18.5 km blocks of tropical forest was correlated with gross forest cover loss (as determined from Landsat data analysis) (R = -0.78); this correlation improved when restricted to humid tropical forest blocks in South America with high initial forest cover (R = -0.93, n = 22). This study shows that scatterometer-based analyses can provide an important geophysical data record leading to robust identification of the spatial patterns and timing of large-scale change in tropical forests. The coarse spatial resolution of SeaWinds ( ~ 10 km) makes it unsuitable for mapping deforestation at the scale of land-use activity. However, due to a combination of instrument stability, sensitivity to canopy change and insensitivity to atmospheric effects, and straight-forward data processing, Ku-band scatterometery can provide a fully independent assessment of large-scale tropical forest canopy dynamics which may complement the interpretation of higher resolution optical remote sensing. Numéro de notice : A2012-353 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2011.2182516 Date de publication en ligne : 06/02/2012 En ligne : https://doi.org/10.1109/TGRS.2011.2182516 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31799 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2012071A	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Analysis of C-band scatterometer moisture estimations derived over a semiarid region / R. Amri in IEEE Transactions on geoscience and remote sensing, vol 50 n° 7 Tome 1 (July 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 7 Tome 1 (July 2012) . - pp 2630 - 2638 Titre : Analysis of C-band scatterometer moisture estimations derived over a semiarid region Type de document : Article/Communication Auteurs : R. Amri, Auteur ; Mehrez Zribi, Auteur ; Zohra Lili-Chabaane, Auteur ; W. Wagner, Auteur Année de publication : 2012 Article en page(s) : pp 2630 - 2638 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Afrique du nord [Termes IGN] bande C [Termes IGN] humidité du sol [Termes IGN] image MetOp-ASCAT [Termes IGN] image radar [Termes IGN] MetOp [Termes IGN] sécheresse [Termes IGN] zone semi-aride Résumé : (Auteur) Spatial and temporal variations of soil moisture strongly affect flooding, erosion, solute transport, and vegetation productivity. Their characterization offers numerous possibilities for the improvement of our understanding of complex land-surface-atmosphere interactions. In this paper, soil moisture dynamics at the soil's surface (the first centimeters) and in its root zone (at depths down to 1 m) are investigated using 25 x 25 km2 scale data (Advanced Scatterometer (ASCAT)/METorological OPerational (METOP) scatterometer), for a semiarid region in North Africa. Our study highlights the quality of the surface and root-zone soil moisture products, derived from ASCAT data recorded over a two-year period. Surface soil moisture tends to be highly variable because it is strongly influenced by atmospheric conditions (rain and evaporation). On the other hand, root-zone moisture is considerably less variable. A statistical drought-monitoring index, referred to as the “moisture anomaly index,” is derived from ASCAT and European Remote Sensing (ERS) time series. This index was tested with ERS and ASCAT products during the 1991-2010 study period. A strong correlation is found between the proposed index and the standardized precipitation index. Numéro de notice : A2012-354 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2012.2186458 Date de publication en ligne : 12/03/2012 En ligne : https://doi.org/10.1109/TGRS.2012.2186458 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31800 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2012071A	RAB	Revue	Centre de documentation	En réserve L003	Disponible