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Nighttime polar cloud detection with MODIS / Y. Liu in Remote sensing of environment, vol 92 n° 2 (15/08/2004)
[article]
Titre : Nighttime polar cloud detection with MODIS Type de document : Article/Communication Auteurs : Y. Liu, Auteur ; J.R. Key, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 181 - 194 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Antarctique
[Termes IGN] Arctique
[Termes IGN] climat froid
[Termes IGN] climat terrestre
[Termes IGN] détection
[Termes IGN] dioxyde de carbone
[Termes IGN] données lidar
[Termes IGN] image Aqua-MODIS
[Termes IGN] image radar
[Termes IGN] image Terra-MODIS
[Termes IGN] luminance lumineuse
[Termes IGN] modèle de transfert radiatif
[Termes IGN] nuage
[Termes IGN] seuillage d'image
[Termes IGN] vapeur d'eauRésumé : (Auteur) Cloud detection is the first step in studying the role of polar clouds in the global climate system with satellite data. In this paper, the cloud detection algorithm for the Moderate Resolution Imaging Spectrometer (MODIS) is evaluated with model simulations and satellite data collocated with radar/lidar observations at three Arctic and Antarctic stations. Results show that the current MODIS cloud mask algorithm performs well in polar regions during the day but does not detect more than 40% of the cloud cover over the validation sights at night. Two new cloud tests utilizing the 7.2 um water vapor and 14.2 um carbon dioxide bands, one new clear-sky test using the 7.2 um band, and changes to the thresholds of several other tests are described. With the new cloud detection procedure, the misidentification of cloud as clear decreases from 44.2% to 16.3% at the two Arctic stations, and from 19.8% to 2.7% at the Antarctic station. Numéro de notice : A2004-333 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.06.004 En ligne : https://doi.org/10.1016/j.rse.2004.06.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26860
in Remote sensing of environment > vol 92 n° 2 (15/08/2004) . - pp 181 - 194[article]Mapping the atmospheric water vapor by integrating microwave radiometer and GPS measurements / P. Basili in IEEE Transactions on geoscience and remote sensing, vol 42 n° 8 (August 2004)
[article]
Titre : Mapping the atmospheric water vapor by integrating microwave radiometer and GPS measurements Type de document : Article/Communication Auteurs : P. Basili, Auteur ; S. Bonafoni, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 1657 - 1665 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse comparative
[Termes IGN] capteur imageur
[Termes IGN] données GPS
[Termes IGN] effet atmosphérique
[Termes IGN] image DMSP-SSM/I
[Termes IGN] image Météosat
[Termes IGN] interpolation
[Termes IGN] krigeage
[Termes IGN] Méditerranée, mer
[Termes IGN] précipitation
[Termes IGN] télédétection en hyperfréquence
[Termes IGN] vapeur d'eauRésumé : (Auteur) This paper deals with a procedure to generate maps of the Integrated Precipitable Water Vapor (IPWV) over the Mediterranean area by using estimates from a global positioning system (GPS) network over land and from the Special Sensor Microwave/Imager (SSM/I) over sea. In particular, we investigate the application of the Kriging geostatistical technique to obtain regularly spaced IPWV values. The horizontal spatial structure r water vapor retrieved by SSM/I is explored by computing-variograms that provide a measure of dissimilarity between pairs IPWV values for the region of interest. Because the water vapor density decreases with height, the GPS station elevation - accounted for in the interpolation procedure. In this respect, the potential of the Kriging with external drift relative to the linary Kriging is evaluated by applying a test based on the validation approach.The case studies are presented and qualitatively compared to the corresponding Meteosat infrared images. A quantitative comparison with an independent source of information, such as IPWV computed from radiosonde observations and from European Centre for Medium-Range Weather Forecasts only, is also performed. Numéro de notice : A2004-388 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2004.830943 En ligne : https://doi.org/10.1109/TGRS.2004.830943 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26915
in IEEE Transactions on geoscience and remote sensing > vol 42 n° 8 (August 2004) . - pp 1657 - 1665[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 065-04081 RAB Revue Centre de documentation En réserve L003 Disponible GPS water vapor project associated to the ESCOMPTE programme: description and first results of the field experiment / Olivier Bock in Physics and chemistry of the Earth (A/B/C), vol 29 n° 2-3 ([01/03/2004])
[article]
Titre : GPS water vapor project associated to the ESCOMPTE programme: description and first results of the field experiment Type de document : Article/Communication Auteurs : Olivier Bock , Auteur ; Erik Doerflinger, Auteur ; F. Masson, Auteur ; Andrea Walpersdorf, Auteur ; J. Van-Baelen, Auteur ; Jérôme Tarniewicz , Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 149 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] lidar Raman
[Termes IGN] radiosondage
[Termes IGN] tomographie par GPS
[Termes IGN] vapeur d'eauRésumé : (auteur) A dense network of 17 dual frequency GPS receivers has been operated for two weeks during June 2001 within a 20 km × 20 km area around Marseille, France, as part of the ESCOMPTE field campaign ([Cros et al., 2004. The ESCOMPTE program: an overview. Atmos. Res. 69, 241–279]; http://medias.obs-mip.fr/escompte). The goal of this GPS experiment was to provide GPS data allowing for tomographic inversions and their validation within a well-documented observing period (the ESCOMPTE campaign). Simultaneous water vapor radiometer, solar spectrometer, Raman lidar and radiosonde data are used for comparison and validation. In this paper, we highlight the motivation, issues and describe the GPS field experiment. Some first results of integrated water vapor retrievals from GPS and the other sensing techniques are presented. The strategies for GPS data processing and tomographic inversions are discussed. Numéro de notice : A2004-490 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.pce.2004.01.014 En ligne : https://doi.org/10.1016/j.pce.2004.01.014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103037
in Physics and chemistry of the Earth (A/B/C) > vol 29 n° 2-3 [01/03/2004] . - pp 149 - 157[article]GPS based determination of the integrated and spatially distributed water vapor in the troposphere / Marc Troller (2004)
Titre : GPS based determination of the integrated and spatially distributed water vapor in the troposphere Type de document : Thèse/HDR Auteurs : Marc Troller, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2004 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 67 Importance : 172 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-10-9 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] correction troposphérique
[Termes IGN] distribution spatiale
[Termes IGN] modèle atmosphérique
[Termes IGN] positionnement par GPS
[Termes IGN] propagation troposphérique
[Termes IGN] Suisse
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographie
[Termes IGN] traitement du signal
[Termes IGN] troposphère
[Termes IGN] vapeur d'eauIndex. décimale : 30.84 Applications de géodésie spatiale à l'atmosphère Résumé : (Auteur) Climate change and global warming have become a major challenge for the sustainable development of our Earth and its environment. Intensive research is carried out to understand atmospheric processes and their implications. In this content, water vapor plays a key role. It is an important component of the global energy balance and is involved in many chemical reactions. In microwave measurements, the tropospheric refractivity causes a delay in the arrival of the signal propagating through the atmosphere. This refraction effect is one of the limiting factors in accurate GPS positioning. The tropospheric path delay can be decomposed into a dry and wet part, where the latter part is coupled with the integrated precipitable water vapor above the GPS receiver.
On the one hand, the refraction effect has to be corrected for GPS measurements, on the other hand, it is a valuable signal to determine the spatial distribution of the water vapor. This study investigates both aspects. For the first part, two basic approaches are looked into: One method is based on meteorological measurements. Thereby, the integrated amount of water vapor and its temporal variation are the prime target. The other concept makes use of long-term GPS measurements. The arrival delay of the GPS signals are used, to estimate the integrated amount of water vapor. This result can then be the basis to determine its spatial distribution and temporal behavior. The investigation is based on a tomographic approach and forms the main content of part 2 of this work.
In part 1, an extension of the software package COMEDIE is developed and applied to determine tropospheric path delays. COMEDIE allows a four-dimensional modeling (in space and time) of the meteorological parameters air pressure, temperature and water vapor pressure using a collocation approach. Integrating the meteorological parameters, tropospheric path delays are obtained. Evaluations and comparisons in Switzerland show the performance of this method. An overall good agreement was achieved compared to GPS-estimated path delays. The accuracy depends on the season, and is in the range of 1-2 cm for the tropospheric path delay.
Continuous GPS measurements allow to estimate tropospheric path delays in the GPS processing. In a second approach of part 1, a method based on such GPS-estimated path delays is developed. It uses - like COMEDIE - a four-dimensional model and a collocation adjustment to estimate tropospheric path delays at desired locations. Evaluations are carried out in the area of Switzerland using the permanent GPS network AGNES. Long-term time series of cross-correlations are analyzed. An accuracy of 0.5 - 1.5 cm is obtained.
To resolve the GPS-estimated water vapor in the vertical, a tomographic approach is investigated in part 2 of this study. It is based on the assimilation of GPS double-difference observations. The wet refractivity field is determined applying a least-squares adjustment. To test the performance of the software, different weather conditions are simulated. Various stochastically constrained models are applied and discussed in terms of inversion stability. Results from real data gathered during a dedicated measurement campaign in the high density GPS network of the Big Island of Hawaii are analyzed. Compared to radiosondes, an accuracy of about 10 ppm (refractivity units) is achieved.
To compare the potential and limits of the investigated methods, independent data must be available. An extensive study is performed in the area of Switzerland to evaluate and compare all presented methods with each other. For the validation, data of the numerical weather model aLMo are used. Seven days of data in a high spatial distribution and on an hourly basis are investigated. The tropospheric path delays resulting from the various methods are compared and analyzed. An overall good agreement with the aLMo data was observed. To evaluate the spatial distribution of water vapor, 7680 refractivity profiles are determined with the tomographic method and compared with the numerical weather data. The analysis contains four tomographic approaches including different types of constraints. The results are statistically evaluated and compared. A correlation between the accuracy and the weather situation was found. Overall, an agreement of 5-7 ppm (refractivity units) was achieved compared to aLMo.
In conclusion, it can be stated that the determination of the integrated amount of water vapor in the troposphere was successfully performed. For the main geodetic application, the correction of GPS measurements, the estimation of path delays in the GPS processing is recommended, provided long-terrn GPS phase observations are available. For the determination of the spatial distribution and the temporal variation of the integrated amount of water vapor, modeling of the GPS-estimated path delays is a successful method. Moreover, the principal feasibility to resolve the vertical distribution of the water vapor applying the tomographic approach was demonstrated. However, further investigations concerning constraints or the introduction of additional information are required.Numéro de notice : 13264 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-004796376 Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-004796376 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-67.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54945 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 13264-01 30.84 Livre Centre de documentation Géodésie Disponible 13264-02 30.84 Livre Centre de documentation Géodésie Disponible 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)
[article]
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'eauRésumé : (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
in International Journal of Remote Sensing IJRS > vol 24 n° 19 (October 2003) . - pp 3821 - 3837[article]Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 080-03191 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Développement d'un lidar Raman pour le sondage de la vapeur d'eau et la correction des délais troposphériques en GPS / Olivier Bock in Bulletin d'information scientifique et technique de l'IGN, n° 74 (mars 2003)PermalinkRetrievals of low integrated water vapor using MIR and SSM/T-2 measurements / J.R. Wang in IEEE Transactions on geoscience and remote sensing, vol 41 n° 3 (March 2003)PermalinkCloud and aerosol properties, precipitable water, and profiles of temperature and water vapor from MODIS / M.D. King in IEEE Transactions on geoscience and remote sensing, vol 41 n° 2 (February 2003)PermalinkImpact of contextual information integration on pixel fusion / Sophie Fabre in IEEE Transactions on geoscience and remote sensing, vol 40 n° 9 (September 2002)PermalinkPermalinkSpatial and temporal distribution of atmospheric water vapor using space geodetic techniques / Lars Peter Kruse (2001)PermalinkSystème DORIS : applications scientifiques / Pascal Willis in XYZ, n° 73 (septembre - novembre 1997)PermalinkUtilisation de la méthode de positionnement satellitaire GPS pour la détermination précise des altitudes relatives et absolues / Erik Doerflinger (1997)PermalinkPermalinkAtmospheric water vapour over oceans from SSM-I measurements / P. Schluessel in International Journal of Remote Sensing IJRS, vol 11 n° 5 (May 1990)Permalink