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Combining weather prediction and remote sensing data for the calculation of evapotranspiration rates: application to Denmark / E. Boegh in International Journal of Remote Sensing IJRS, vol 25 n° 13 (July 2004)
[article]
Titre : Combining weather prediction and remote sensing data for the calculation of evapotranspiration rates: application to Denmark Type de document : Article/Communication Auteurs : E. Boegh, Auteur ; H. Soegaard, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 2553 - 2574 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] correction atmosphérique
[Termes IGN] Danemark
[Termes IGN] erreur moyenne quadratique
[Termes IGN] évapotranspiration
[Termes IGN] humidité de l'air
[Termes IGN] image NOAA-AVHRR
[Termes IGN] prévision météorologique
[Termes IGN] trajectographie (positionnement)Résumé : (Auteur) Evapotranspiration rates in Denmark were estimated using Advanced Very High Resolution Radiometer (AVHRR) satellite data and weather conditions predicted by a high-resolution weather forecast model (HIRLAM). The predictions were used both for atmospheric correction of satellite data and for remote sensing based calculation of net radiation, sensible heat fluxes and evapotranspiration rates. Climate predictions at 12 GMT were used as proxies for the atmospheric conditions at the time of the afternoon satellite passage (12.30-14.30 GMT). The air temperature at the time of the satellite passage was retrieved with a rms error of 1.9ºC, and the rms error of the retrieved air humidity was 204 Pa. The evapotranspiration results were significantly influenced by the spatial distribution of weather conditions. Due to the encirclement of Denmark by sea shorelines, sea breezes extending more than 30 km inland were responsible for the intrusion of cooler air temperatures which increased the sensible heat fluxes and suppressed the evapotranspiration rates. The predictions were linearly related to eddy-covariance flux measurements representing agricultural land, beech forest and conifer forest, but the relationships were also characterized by a large degree of scattering. The results are discussed in relation to inaccuracies and future perspectives. Numéro de notice : A2004-260 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160310001647984 En ligne : https://doi.org/10.1080/01431160310001647984 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26787
in International Journal of Remote Sensing IJRS > vol 25 n° 13 (July 2004) . - pp 2553 - 2574[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-04111 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Evaporing estimation in the Yellow River basin, China using integrated NDVI data / R. Sun in International Journal of Remote Sensing IJRS, vol 25 n° 13 (July 2004)
[article]
Titre : Evaporing estimation in the Yellow River basin, China using integrated NDVI data Type de document : Article/Communication Auteurs : R. Sun, Auteur ; X. Gao, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 2523 - 2534 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse diachronique
[Termes IGN] bassin hydrographique
[Termes IGN] Chine
[Termes IGN] distribution spatiale
[Termes IGN] évapotranspiration
[Termes IGN] Fleuve jaune (Chine)
[Termes IGN] humidité de l'air
[Termes IGN] indice d'humidité
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] production agricole
[Termes IGN] ressources en eau
[Termes IGN] sécheresseRésumé : (Auteur) It is important to estimate land surface evapotranspiration (ET) for water resources evaluation, drought monitoring and crop production simulation. In this paper, a relationship between annual ET, integrated Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) and Relative Moisture Index (RMI) was established. Based on this relationship, the spatial distribution and dynamic change of annual ET were estimated for the Yellow River Basin, China from 1982 to 2000. Our analyses involved the use of integrated NDVI data, monthly mean air temperature, and precipitation. Our results showed that the integrated AVHRR NDVI can be used to effectively estimate annual ET in the Yellow River Basin, with an accuracy over 90% for the whole basin. Numéro de notice : A2004-259 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116032000160471 En ligne : https://doi.org/10.1080/0143116032000160471 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26786
in International Journal of Remote Sensing IJRS > vol 25 n° 13 (July 2004) . - pp 2523 - 2534[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-04111 RAB Revue Centre de documentation En réserve L003 Exclu du prêt 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 Exemplaires(2)
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 GPS Tomography and Remote Sensing Techniques for Water Vapor Determination in the ESCOMPTE Campaign / Beat Bürki (2004)
contenu dans Celebrating a decade of the International GPS Service, Workshop & Symposium 2004 / Michael Meindl (2004)
Titre : GPS Tomography and Remote Sensing Techniques for Water Vapor Determination in the ESCOMPTE Campaign Type de document : Article/Communication Auteurs : Beat Bürki, Auteur ; Simon Lutz, Auteur ; Marc Troller, Auteur ; Alexander Somieski, Auteur ; Andrea Walpersdorf, Auteur ; Erik Doerflinger, Auteur ; Alain Geiger, Auteur ; Olivier Bock , Auteur ; et al., Auteur Editeur : Berne : Université de Berne Année de publication : 2004 Conférence : IGS 2004, international symposium, Celebrating a decade of the International GPS Service Symposium 01/03/2004 05/03/2004 Berne Suisse Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] positionnement par GPS
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographieRésumé : (Auteur) The hierarchy of reference frames used in the IGS and the procedures and rationale for realizing them are reviewed. The Conventions of the IERS lag developments in the IGS in a number of important respects. Recommendations are offered for changes in the IERS Conventions to recognize geocenter motion (as already implemented by the IGS) and to enforce greater model consistency in order to achieve higher precision for combined reference frame products. Despite large improvements in the internal consistency of IGS product sets, defects remain which should be addressed in future developments. If the IGS is to remain a leader in this area, then a comprehensive, long-range strategy should be formulated and pursued to maintain and enhance the IGS reference frame, as well as to improve its delivery to users. Actions should include the official designation of a high-performance reference tracking network whose stations are expected to meet the highest standards possible. Numéro de notice : C2004-016 Affiliation des auteurs : LAREG+Ext (1991-2011) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=65027 Remote sensing of atmospheric water vapor with the Global Positioning System / John Joseph Braun (2004)
Titre : Remote sensing of atmospheric water vapor with the Global Positioning System Type de document : Thèse/HDR Auteurs : John Joseph Braun, Auteur ; Judith Curry, Directeur de thèse Editeur : Boulder [Etats-Unis] : University of Colorado Année de publication : 2004 Importance : 158 p. Format : 21 x 30 cm Note générale : bibliographie
A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Aerospace Engineering SciencesLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] Etats-Unis
[Termes IGN] teneur en vapeur d'eauRésumé : (auteur) Signals from the Global Positioning System (GPS) are used to retrieve the integrated amount of water vapor along the path between a transmitting satellite and a receiving station. This integrated quantity is called slant water vapor (SW). Measurements of SW allow for an improved assessment of the spatial distribution of water vapor within the atmosphere. This technique is developed and validated through simulations and comparisons to similar measurements from a pointing microwave water vapor radiometer. Absolute accuracy of zenith scaled SW is found to be 1.5 mm with a relative precision that is better than 0.5 mm. Dual and single frequency GPS stations are used to measure SW. Previously, only dual frequency GPS stations have been used for atmospheric remote sensing. The use of single frequency stations, which are significantly less expensive than dual frequency ones, allows for a denser placement of stations. The effects of the ionosphere on single frequency GPS observations are eliminated using global ionosphere models and double difference processing with short station separation. Networks of GPS stations are deployed in the Southern Great Plains of the United States. Combining SW measurements from all stations within a dense network allows for an estimation of the three dimensional distribution of water vapor above the network. This tomographic technique is improved by including vertical profiles from radiosondes. The retrieval of SW is utilized during the International H20 Project 2002 (IHOP_2002). Significant water vapor structure is observed within the atmospheric boundary layer, including dryline convergence and horizontal convective rolls. Tomography results computed during squall line passage indicate elevated levels of water vapor in the free troposphere prior to the onset of rainfall. A statistical analysis of the results obtained during IHOP_2002 show coherent water vapor structure across horizontal lengths ranging from less than 1 to almost 100 kilometers. A significant diurnal cycle of atmospheric water vapor variability is also found. Numéro de notice : 14872 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Aerospace Engineering Sciences : University of Colorado : 2004 DOI : sans En ligne : https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/3n203z351 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75928 Mesoscale meteorological modeling / R.A. Pielke (2002)PermalinkEffect of small-scale atmospheric inhomogeneity on positioning accuracy with GPS / Olivier Bock in Geophysical research letters, vol 28 n° 11 (1 June 2001)PermalinkStudy of external path delay correction techniques for high accuracy height determination with GPS / Olivier Bock in Physics and chemistry of the Earth, Part A: Solid Earth and Geodesy, vol 26 n° 3 ([01/03/2001])PermalinkSpatial and temporal distribution of atmospheric water vapor using space geodetic techniques / Lars Peter Kruse (2001)PermalinkMeteorology for scientists and engineers / R.B. Stull (2000)PermalinkThermodynamics of atmospheres and oceans / J.A. Curry (1999)PermalinkPermalinkUsing DORIS for determining the tropospheric delay : implications on climatology and meteorology / Pascal Willis (1998)PermalinkModèle de nuage pour la restitution de paramètres microphysiques à partir de données satellitaires micro-ondes / Nathalie Dejour (1997)PermalinkAn introduction to numerical weather prediction techniques / T.N. Krishnamurti (1996)Permalink