Descripteur
Documents disponibles dans cette catégorie (5)
Ajouter le résultat dans votre panier Affiner la recherche Interroger des sources externesEtendre la recherche sur niveau(x) vers le bas
Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe / Monica Campanelli in Atmospheric measurement techniques, vol 11 n° 1 (January 2018)
Titre : Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe Type de document : Article/Communication Auteurs : Monica Campanelli, Auteur ; Alessandra Mascitelli, Auteur ; Paolo Sano, Auteur ; Henri Diémoz, Auteur ; Victor Estellés, Auteur ; Stefano Federico, Auteur ; Anna Maria Iannarelli, Auteur ; Francesca Fratarcangeli, Auteur ; Augusto Mazzoni, Auteur ; Eugenio Realini, Auteur ; Mattia Crespi, Auteur ; Olivier Bock Année de publication : 2018 Projets : 1-Pas de projet / Article en page(s) : pp 81 - 94 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Aoste (val d')
[Termes IGN] constante
[Termes IGN] coordonnées GPS
[Termes IGN] données météorologiques
[Termes IGN] données spatiotemporelles
[Termes IGN] étalonnage d'instrument
[Termes IGN] photomètre
[Termes IGN] précipitation
[Termes IGN] retard troposphérique zénithal
[Termes IGN] Rome
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] Valence (Espagne)
[Termes IGN] water vapour radiometerRésumé : (Auteur) The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NET-work (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the agreement with the GPS (considered the reference one) from a % bias of 5.76 to 0.52. Numéro de notice : A2018-053 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-81-2018 Date de publication en ligne : 09/01/2018 En ligne : http://dx.doi.org/10.5194/amt-11-81-2018 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89371
in Atmospheric measurement techniques > vol 11 n° 1 (January 2018) . - pp 81 - 94[article]
Titre : On the long-term stability of microwave radiometers using noise diodes for calibration Type de document : Article/Communication Auteurs : S.T. Brown, Auteur ; Shailen Desai, Auteur ; W. Lu, Auteur ; A.B. Tanner, Auteur Année de publication : 2007 Article en page(s) : pp 1908 - 1920 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] Advanced Microwave Radiometer
[Termes IGN] bruit (théorie du signal)
[Termes IGN] capteur spatial
[Termes IGN] diode
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] radiomètre à hyperfréquence
[Termes IGN] température de luminance
[Termes IGN] water vapour radiometerRésumé : (Auteur) Results are presented from the long-term monitoring and calibration of the National Aeronautics and Space Administration Jason Microwave Radiometer (JMR) on the Jason-1 ocean altimetry satellite and the ground-based Advanced Water Vapor Radiometers (AWVRs) developed for the Cassini Gravity Wave Experiment. Both radiometers retrieve the wet tropospheric path delay (PD) of the atmosphere and use internal noise diodes (NDs) for gain calibration. The JMR is the first radiometer to be flown in space that uses NDs for calibration. External calibration techniques are used to derive a time series of ND brightness for both instruments that is greater than four years. For the JMR, an optimal estimator is used to find the set of calibration coefficients that minimize the root-mean-square difference between the JMR brightness temperatures and the on-Earth hot and cold references. For the AWVR, continuous tip curves are used to derive the ND brightness. For the JMR and AWVR, both of which contain three redundant NDs per channel, it was observed that some NDs were very stable, whereas others experienced jumps and drifts in their effective brightness. Over the four-year time period, the ND stability ranged from 0.2% to 3% among the diodes for both instruments. The presented recalibration methodology demonstrates that long-term calibration stability can be achieved with frequent recalibration of the diodes using external calibration techniques. The JMR PD drift compared to ground truth over the four years since the launch was reduced from 3.9 to $-$0.01 mm/year with the recalibrated ND time series. The JMR brightness temperature calibration stability is estimated to be 0.25 K over ten days. Copyright IEEE Numéro de notice : A2007-170 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2006.888098 En ligne : https://doi.org/10.1109/TGRS.2006.888098 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28533
in IEEE Transactions on geoscience and remote sensing > vol 45 n° 7 Tome 1 (July 2007) . - pp 1908 - 1920[article]Réservation
Réserver ce documentExemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 065-07071A RAB Revue Centre de documentation En réserve 3L Disponible Spatial and temporal distribution of atmospheric water vapor using space geodetic techniques / Lars Peter Kruse (2001)
Titre : Spatial and temporal distribution of atmospheric water vapor using space geodetic techniques Type de document : Thèse/HDR Auteurs : Lars Peter Kruse, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2001 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 61 Importance : 128 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-03-1 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] atmosphère terrestre
[Termes IGN] distribution spatiale
[Termes IGN] données GPS
[Termes IGN] modèle atmosphérique
[Termes IGN] temps réel
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographie
[Termes IGN] troposphère
[Termes IGN] vapeur d'eau
[Termes IGN] water vapour radiometerRésumé : (Auteur) This work investigates methodological aspects of the Global Positioning System (GPS) to validate its potential as a remote sensing tool for monitoring atmospheric water vapor. GPS estimates of integral precipital water vapor (IPWV) are compared with simultaneous measurements of collocated Water Vapor Radiometers (WVR), as well as atmospheric refraction models for validation of GPS for meteorological applications.
Based on a one year data set of continuous GPS estimates and WVR observations at ETH Zurich a standard deviation of 1.54 mm and an offset of 0.54 mm IPWV is found between the two techniques. The analysis of several dedicated observation campaigns carried out at different sites in Europe and on Hawaii revealed offsets between GPS estimates and WVR observations.
The instrumental methods are also compared with a numerical model of the troposphere using ground meteorological observations and radiosondes from the station Payerne of the Swiss meteorological network (ANETZ). The modeling results, obtained with a software package performing four-dimensional interpolations by collocation yield a standard deviation of 2.88 mm and a bias of 2.23 mm IPWV with respect to the GPS derived time series of IPWV. Furthermore a clear seasonal dependency of the GPS - WVR differences is recognized. Mainly the periods dominated by strong fluctuations of water vapor during summer and autumn months degrade the agreement between the two techniques.
Because of the high correlation between GPS estimated tropospheric parameters and the height component, potential error sources are investigated.
The accuracy of GPS-derived IPWV in near real-time for consideration in weather forecasting is degraded due to insufficient satellite orbit quality. Investigations on the impact of implementing predicted orbit information on GPS water vapor retrievals showed that the accuracy degrades by a factor of about 2 compared to results obtained with final precise orbits as released by the International GPS Service (IGS) about two weeks after the observations.
Finally the potential of GPS for resolving three-dimensional distributions of tropospheric water vapor by means of the tomographic technique is investigated and applied within this work. For this purpose a software package called AWATOS (Atmospheric WAter vapor TOmography Software) was developed. In order to validate the tomographic approach a dedicated field experiment was carried out on the Big Island of Hawaii, USA. Tomographic results based on the extremely dense Continuous GPS (CGPS) network in the Mt. Kilauea and Mauna Loa volcano area are presented. They are compared to other independent techniques, such as radiosondes, Water Vapor Radiometers, and a high resolution solar spectrometer.Numéro de notice : 13061 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-003884306 Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-003884306 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-61.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54862 Réservation
Réserver ce documentExemplaires (2)
Code-barres Cote Support Localisation Section Disponibilité 13061-02 30.84 Livre Centre de documentation Géodésie Disponible 13061-01 30.84 Livre Centre de documentation Géodésie Disponible Satellite-Earth range measurements : Correction of the excess path length due to atmospheric water vapour by ground based microwave radiometry / Gunnar Elgered (1985)
Titre : Satellite-Earth range measurements : Correction of the excess path length due to atmospheric water vapour by ground based microwave radiometry Type de document : Rapport Auteurs : Gunnar Elgered, Auteur ; B. Ronnang, Auteur ; E. Winberg, Auteur ; J. Askne, Auteur Editeur : Göteborg [Suède] : Chalmers University of Technology Année de publication : 1985 Collection : Research report num. 147 Importance : 112 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rayonnement électromagnétique
[Termes IGN] hyperfréquence
[Termes IGN] propagation ionosphérique
[Termes IGN] propagation troposphérique
[Termes IGN] radiomètre à hyperfréquence
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] water vapour radiometerRésumé : (Auteur) This report deals with the excess delay of radio waves penetrating the neutral atmosphere of the earth, especially the delay due to water vapour, and reviews the state of the art of sounding techniques and instrumentation, in particular microwave radiometry. The physical background of the water vapour radiometer (WVR) method is presented and seven different types of WVR are described in detail. The expected accuracies of wet path delays vary with the local climate as well as with instrumental errors and the operating frequencies of the WVR. It is shown that errors in the wet path delay for zenith observations range from O.M to 0.9 cm rms for optimum WVR frequencies and instrumental errors of 0.5 K rms. Two different WVR designs - one with high accuracy and one with low cost (but less accurate) - are proposed for the ESA POPSAT system. Numéro de notice : 18239 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Rapport Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=41451 Réservation
Réserver ce documentExemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 18239-01 24.30 Livre Centre de documentation Physique Disponible
