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Retrieval of atmospheric water vapour using a ground-based single-channel microwave radiometer / P. Jarlemark in International Journal of Remote Sensing IJRS, vol 24 n° 19 (October 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 19 (October 2003) . - pp 3821 - 3837 Titre : Retrieval of atmospheric water vapour using a ground-based single-channel microwave radiometer Type de document : Article/Communication Auteurs : P. Jarlemark, Auteur ; Gunnar Elgered, Auteur Année de publication : 2003 Article en page(s) : pp 3821 - 3837 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] atmosphère terrestre [Termes IGN] erreur moyenne quadratique [Termes IGN] filtre de Kalman [Termes IGN] radiomètre à hyperfréquence [Termes IGN] vapeur d'eau Résumé : (Auteur) Estimates of the amount of atmospheric water vapour derived from algorithms for a ground-based single-channel (21.OGHz) microwave radiometer have been investigated. Ten datasets covering 44 days were used to derive the methods and two other sets (in total 32 days) were used to assess the quality of these. It is shown how the rms estimation error can be reduced by recognizing the rapid variations in sky brightness temperatures during periods when cloud liquid is present. Data was either discarded, guided by the variability, or an adaptive Kalman filter was applied with different parameter values for different degrees of variability. The resulting estimates were compared to the estimates obtained from a dual-channel algorithm (2t.0 and 31.4GHz), which were used as reference. The amount of water vapour was represented as the 'wet delay', the excess radio path length due to the atmospheric water vapour. Applying the Kalman filter to the single-frequency estimates reduced the wet delay rms error from 20 mm to 9 and 14 mm for the two datasets. Further reduction of the rms error was achieved by the removal of data in periods with high variability; discarding about 40% of the data led to rms errors of 5 and 7 mm for the two datasets. Numéro de notice : A2003-281 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116021000023952 En ligne : https://doi.org/10.1080/0143116021000023952 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22576 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03191	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Fully polarimetric airborne SAR and ERS SAR observations of snow: implications for selection of Envisat ASAR modes / T. Guneriussen in International Journal of Remote Sensing IJRS, vol 24 n° 19 (October 2003)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 24 n° 19 (October 2003) . - pp 3839 - 3854 Titre : Fully polarimetric airborne SAR and ERS SAR observations of snow: implications for selection of Envisat ASAR modes Type de document : Article/Communication Auteurs : T. Guneriussen, Auteur ; H. Johnsen, Auteur Année de publication : 2003 Article en page(s) : pp 3839 - 3854 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] atmosphère terrestre [Termes IGN] bande C [Termes IGN] bande L [Termes IGN] données polarimétriques [Termes IGN] glace [Termes IGN] image EMISAR [Termes IGN] image Envisat-ASAR [Termes IGN] image ERS-SAR [Termes IGN] manteau neigeux [Termes IGN] montagne [Termes IGN] neige [Termes IGN] polarimétrie radar Résumé : (Auteur) Snow cover has a substantial impact on processes involved in the interaction between atmosphere and surface, and the knowledge of snow parameters is important in both climatology and weather forecasting. With the upcoming launch of Advanced Synthetic Aperture Radar (ASAR) instruments on Envisat, enhanced snow-mapping capabilities are foreseen. In this paper fully polarimetric C- and L-band airborne SAR data, ERS SAR and auxiliary data from various snow conditions in mountainous areas are analysed in order to determine the optimum ASAR modes for snow monitoring. The data used in this study are from the Norwegian part of the snow and ice experiment within the European Multi-sensor Airborne Campaign (EMAC'95) acquired in the Kongsfjellet area, located in Norway, 66°N, 14°E. Fully polarimetric C- and L-band SAR data from ElectroMagnetic Institute SAR (EMISAR), an airborne instrument operated by the Danish Center for Remote Sensing (DCR), were acquired in March, May, and July 1995. In addition, several ERS SAR, airborne photos, field and auxiliary data were acquired. A larger separation between wet snow and bare ground in EMISAR C-VV polarisation data was found at high incidence angle (55°) compared to lower incidence angle (45°). Crosspolarized observations from bare ground, dry and wet snow in the incidence angle range 35° to 65° are below the specified Envisat ASAR noise floor of -20-22 dB. The backscattering angular dependency for wet snow and bare ground derived from EMISAR C-VV and ERS SAR data corresponds well, and agrees to some extent with volume and surface scattering model results. The C-band is more sensitive to variation in snow properties than the L-band. Numéro de notice : A2003-282 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116021000053319 En ligne : https://doi.org/10.1080/0143116021000053319 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22577 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-03191	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt