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Monitoring seasonal snow dynamics using ground based high resolution photography (Austre Lovénbreen, Svalbard, 79°N) / Etienne Bernard in ISPRS Journal of photogrammetry and remote sensing, vol 75 (January 2013)
[article]
Titre : Monitoring seasonal snow dynamics using ground based high resolution photography (Austre Lovénbreen, Svalbard, 79°N) Type de document : Article/Communication Auteurs : Etienne Bernard , Auteur ; J.M. Friedt, Auteur ; F. Tolle, Auteur ; M. Laffly, Auteur ; C. Marlin, Auteur Année de publication : 2013 Article en page(s) : pp 92 - 100 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse diachronique
[Termes IGN] changement climatique
[Termes IGN] données localisées
[Termes IGN] glacier
[Termes IGN] image terrestre
[Termes IGN] neige
[Termes IGN] surveillance météorologique
[Termes IGN] SvalbardRésumé : (Auteur) Arctic glaciers are reliable indicators of global climate changes. However, monitoring snow and ice dynamics in Arctic regions is challenging: some fast but key events can be missed since they are short in time but significant in the hydrological budget. In the context of long term monitoring with high temporal and spatial resolutions of the snow cover dynamics, automated digital cameras were installed around the Austre Lovénbreen glacier basin (Spitsbergen, Norway, 79°N). Despite data losses due to rough weather conditions and control electronics failure, a dataset of 2411 pictures (out of an expected 3294) was gathered over a 1 year hydrological period to assess the snow coverage of the glacier as a function of time with daily resolution. 73% of the total number of expected images was thus recorded, with gaps associated with temporary electronics or data storage failure. The six camera stations oriented so as to observe the glacier itself provide a surface coverage of 96%. Furthermore, geometric corrections of the pictures, using reference ground control points located on the glacier through GPS receivers, yield a quantitative information from initially qualitative images. Projecting the resulting mosaic of the images gathered from six cameras on a GIS allows for the precise monitoring of ice-related processes, and especially the snow coverage evolution over time. This paper summarizes our current understanding of such dynamics, based on the analysis of daily mosaics of images allowing for the observation of both long term evolution on the seasonal scale and the short term events on a weekly scale. Such results demonstrated over one typical full hydrological season (April–October 2009) that snow coverage evolves following discrete steps, either due to water precipitation or warm events, with a snow coverage ranging from 100% (april) to 37% (September). Numéro de notice : A2013-035 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.11.001 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.11.001 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32173
in ISPRS Journal of photogrammetry and remote sensing > vol 75 (January 2013) . - pp 92 - 100[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 081-2013011 RAB Revue Centre de documentation En réserve L003 Disponible Near real-time estimation of water vapour in the troposphere using ground GNSS and the meteorological data / Jaroslaw Bosy in Annales Geophysicae, vol 30 n° 9 (September 2012)
[article]
Titre : Near real-time estimation of water vapour in the troposphere using ground GNSS and the meteorological data Type de document : Article/Communication Auteurs : Jaroslaw Bosy, Auteur ; J. Kaplon, Auteur ; Witold Rohm, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : 13 p. ; pp 1379 - 1391 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données météorologiques
[Termes IGN] EUPOS
[Termes IGN] modèle atmosphérique
[Termes IGN] Pologne
[Termes IGN] propagation troposphérique
[Termes IGN] surveillance météorologique
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographieRésumé : (Auteur) The near real-time (NRT) high resolution water vapour distribution models can be constructed based on GNSS observations delivered from Ground Base Augmentation Systems (GBAS) and ground meteorological data. Since 2008 in the territory of Poland, a GBAS system called ASGEUPOS (Active Geodetic Network) has been operating. This paper addresses the problems concerning construction of the NRT model of water vapour distribution in the troposphere near Poland. The first section presents all available GNSS and ground meteorological stations in the area of Poland and neighbouring countries. In this section, data feeding scheme is discussed, together with timeline and time resolution. The high consistency between measured and interpolated temperature value is shown, whereas some discrepancy in the pressure is observed. In the second section, the NRT GNSS data processing strategy of ASG-EUPOS network is discussed. Preliminary results show fine alignment of the obtained Zenith Troposphere Delays (ZTDs) with reference data from European Permanent Network (EPN) processing center. The validation of NRT troposphere products against daily solution shows 15mm standard deviation of obtained ZTD differences. The last section presents the first results of 2-D water vapour distribution above the GNSS network and application of the tomographic model to 3-D distribution of water vapour in the atmosphere. The GNSS tomography model, working on the simulated data from numerical forecast model, shows high consistency with the reference data (by means of standard deviation 4mmkm1 or 4 ppm), however, noise analysis shows high solution sensitivity to errors in observations. The discrepancy for real data preliminary solution (measured as a mean standard deviation) between reference NWP data and tomography data was on the level of 9mmkm1 (or 9 ppm) in terms of wet refractivity. Numéro de notice : A2012-749 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5194/angeo-30-1379-2012 Date de publication en ligne : 27/09/2012 En ligne : https://doi.org/10.5194/angeo-30-1379-2012 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33601
in Annales Geophysicae > vol 30 n° 9 (September 2012) . - 13 p. ; pp 1379 - 1391[article]Identification and modelling of sea level change contributors on GRACE satellite gravity data and their applications to climate monitoring / Bert Wouters (2010)
Titre : Identification and modelling of sea level change contributors on GRACE satellite gravity data and their applications to climate monitoring Type de document : Rapport Auteurs : Bert Wouters, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2010 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 73 Importance : 182 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-316-7 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] changement climatique
[Termes IGN] GRACE
[Termes IGN] Groenland
[Termes IGN] niveau moyen des mers
[Termes IGN] surveillance météorologiqueIndex. décimale : 30.83 Applications océanographiques de géodésie spatiale Résumé : (Auteur) Recently, the Intergovernmental Panel on Climate Change named sea level rise as one of the major challenges of the 21st century. Given the high population density of coastal regions, a small rise of the sea level will have a substantial impact on human society. However, the Earth's climate system is a complex matter arid model predictions of the sea level changes likely to be expected in the coming century currently show a wide spread. Clearly, a thorough understanding of present-day climate variability is imperative narrow this uncertainty band, which on its turn depends on the availability of accurate and detailed observations of our climate.
A valuable contribution to the expanding array of satellites dedicated to observations of the Earth System, are the Gravity Recovery and Climate Experiment (GRACE) satellites, launched in March 2002. This mission is dedicated to observing changes of the Earth's gravity field at (sub-)monthly intervals. At time-scales of a few years, these changes are mostly related to the redistribution of water on the Earth's surface. For example, a thinning of the Greenland ice sheet will manifest itself as a local negative anomaly in the gravity field, whereas the water that is added to the ocean will show up as a predominantly positive anomaly. The main objective of this dissertation is to study how the GRACE observations can be used to improve our knowledge of changes in the Earth's climate systems, and how the data should be processed in order to optimize quality and spatial resolution.
The GRACE data provided by the science teams consist of spherical harmonic coefficients. They show particular correlations between coefficients of identical order and even and odd degree, respectively, due to the mission's architecture and deficiencies in the background models used throughout the processing of the satellite measurements. These noise artifacts show up as striping patterns along the north-south direction in the monthly maps of surface mass changes, hampering the interpretation of the observations. In this dissertation, it is shown that empirical orthogonal function (EOF) analysis is an effective method to reduce the noise in the GRACE data. This statistical tool separates a data set into a number of characteristic (eigen) modes of variance, in combination with an index describing the amplitude of the mode in time, i.e. the principal components. The EOF analysis can be applied to the maps of surface mass changes, in which case the first few modes are related to the annual and long-term trend components. The fourth mode appears to be related to the El Nino/Southern Oscillation. The noise signals arc absorbed by the higher modes, which makes the leading modes largely stripe-free up to a resolution of approximately 400 kilometers.
A further reduction of the noise can be obtained by applying the EOF de-composition directly to the spherical harmonic coefficients, after grouping them following order. The principal components arc compared to a random process and, if the two arc statistically sufficiently alike, not used in the further data processing. A series of tests shows that this approach reduces the noise by 60-80 %, compared the non-filtered case. An important feature of this filter is that it does not alter the shape of the signal and causes less reduction its power, compared to other commonly used filter methods based on the approach of Swenson and Walir (2006).
Using the filtered data, changes in the mass content of the ocean have been studied. The GRACE satellites are capable of capturing seasonal changes in the ocean mass content accurately on a global scale. In combination with sea surface height observations made by satellite altimeter, the steric sea level component (related to changes in the heat and salinity content of the ocean) can be separated as well. A comparison with reference data sets shows that locally a coherent signal can be obtained at a (Gaussian) resolution of approximately 500 km over the oceans. These steric changes dominate the sea level in most of the oceans, but strong ocean bottom pressure fluctuations are observed in several areas, e.g., the Gulf of Carpentaria and the Gulf of Thailand. Estimates of long-term changes in the ocean mass and heat content arc a more challenging problem, and require a longer observation period and a better modeling of mass redistribution in the solid earth and the position of the center of mass of the Earth, two components to which the GRACE observations arc particularly sensitive.
It is found that the global spherical harmonic coefficients contain more information than previously acknowledged. This is demonstrated by using the GRACE data to obtain a picture of the mass balance of the Greenland ice sheet at a regional scale. From the research in this dissertations, it shows that Greenland lost 179 Gigaton each year on average between 2003 and 2008, causing a global mean rise of sea level by 0.5 mm/yr. Comparing the trend in the first few to that in the last few years shows a speed-up of the thinning, which corroborates the picture of an increasingly negative mass balance of the ice sheet since the mid 1990's as indicated by, for example, regional climate models and radar altimetry observations. The majority of the losses occur in the coastal regions in the southeastern sector. The northwestern coastal zones were approximately in balance up to the summer of 2005, but show strong negative trends since. Large year-to-year differences in the mass balance of the ice sheet are observed, with a record loss in the warm summer of 2007. A strong correlation between the GRACE observations in summer and satellite measurements of surface melt area extent is demonstrated. Also, good agreement is found with regional climate modeling data, highlighting the potential of the GRACE observations to validate and improve the numerical models.
A mass redistribution on land will cause a change in the shape of the global geoid. Sea level, when not acted upon by any other forcings, will adjust to this equipotential surface. Therefore, when water is exchanged between ocean and continents (and changes due to ocean dynamics are disregarded), sea level will not rise or fall uniformly, which is known as the so-called self-gravitation effect. Due to their global coverage, the GRACE observations of continental mass distribution are an excellent input to model this phenomenon. Strongest deviations from a uniform distribution are found off the coast of Alaska and in the Bay of Bengal, where differences of more than 100% are found on seasonal time-scales. In these regions, inclusion of the self-gravitation effect into numerical ocean model would result in a better agreement between modeled and observational data.
From the work presented in this dissertation, it shows that the GRACE satellites are an invaluable tool for the monitoring of our climate system. Statistically filtering of the data reveals a wealth of information. In combination with altimetry observations, the GRACE data allows the separation of mass and steric components in sea level on seasonal time scales. Given a longer observational period and an improved understanding of the processes in the solid earth, expected to come available soon thanks to ESA's GOCE missions, long-term trends in these components will be identifiable. Furthermore, the GRACE mission allows us to put a constraint on the contribution of the Greenland ice sheet to present-day sea level rise. The technique to recover these changes can easily be expanded to other regions, such as the Antarctic or the Alaskan glacier fields. The synergy between GRACE data, future missions such as Cryosat-2, which will map height variations of the cryosphere with an unprecedented accuracy, and regional climate models, uncovering the physical processes behind the observed changes, promises a leap forward in our understanding of the mass balance of the ice sheets. Finally, com-paring the modeled deviations from uniform sea level changes with in-situ data such as from tide-gauges, may lead to a direct validation of the aforementioned self-gravitation theory with present-day data.Numéro de notice : 10335 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Rapport de recherche DOI : sans En ligne : https://www.ncgeo.nl/downloads/73Wouters.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62396 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 10335-01 30.83 Livre Centre de documentation Géodésie Disponible Quantitative monitoring of a Saharan dust event with SEVIRI on Meteosat-8 / P. Zhang in International Journal of Remote Sensing IJRS, vol 28 n° 10 (May 2007)
[article]
Titre : Quantitative monitoring of a Saharan dust event with SEVIRI on Meteosat-8 Type de document : Article/Communication Auteurs : P. Zhang, Auteur ; J. Li, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 2181 - 2186 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Afrique du nord
[Termes IGN] géopositionnement
[Termes IGN] image MSG-SEVIRI
[Termes IGN] Sahara, désert du
[Termes IGN] surveillance météorologique
[Termes IGN] tempête de poussièreRésumé : (Auteur) An algorithm has been developed to quantitatively retrieve dust properties (identification, optical thickness, particle radius, and dust density) from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) aboard Meteosat-8, the first of the Meteosat Second Generation (MSG). Two SEVIRI thermal infrared (IR) window channels (10.8 um and 12 um) were used to monitor the dust event of 3 March 2004 over the Sahara in northern Africa. The identification and evolution of dust are well depicted by SEVIRI data with high spatial resolution (approximately 3 km) and high temporal resolution (15 minutes). This demonstrates the capability of a geostationary advanced imager to monitor dust events over land, their migration and the corresponding air quality. Copyright Taylor & Francis Numéro de notice : A2007-289 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160600975337 En ligne : https://doi.org/10.1080/01431160600975337 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28652
in International Journal of Remote Sensing IJRS > vol 28 n° 10 (May 2007) . - pp 2181 - 2186[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 080-07061 RAB Revue Centre de documentation En réserve L003 Exclu du prêt Inondations : les maires moins seuls / M. Mayo in Géomètre, n° 2033 (janvier 2007)
[article]
Titre : Inondations : les maires moins seuls Type de document : Article/Communication Auteurs : M. Mayo, Auteur Année de publication : 2007 Article en page(s) : pp 46 - 47 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Cartographie thématique
[Termes IGN] aide à la décision
[Termes IGN] cartographie des risques
[Termes IGN] commune
[Termes IGN] crue
[Termes IGN] dommage matériel
[Termes IGN] Gard (30)
[Termes IGN] gestion de crise
[Termes IGN] Hérault (34)
[Termes IGN] inondation
[Termes IGN] plan de prévention des risques
[Termes IGN] pluie
[Termes IGN] prévision météorologique
[Termes IGN] protection de l'environnement
[Termes IGN] risque naturel
[Termes IGN] surveillance hydrologique
[Termes IGN] surveillance météorologique
[Termes IGN] temps réel
[Termes IGN] Vaucluse (84)Résumé : (Auteur) La gestion de crise est au coeur des préoccupations des élus, comme en témoigne le succès de l'offre Predict, qui favorise la mise en oeuvre des plans communaux de sauvegarde. Et de nouvelles pistes se dessinent... Copyright Géomètre Numéro de notice : A2007-006 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28372
in Géomètre > n° 2033 (janvier 2007) . - pp 46 - 47[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 063-07011 RAB Revue Centre de documentation En réserve L003 Disponible Monitoring glacier elevation and volume changes with digital photogrammetry and GIS at Gepatschferner glacier, Austria / A. Keutterling in International Journal of Remote Sensing IJRS, vol 27 n°18 - 19 - 20 (October 2006)PermalinkLandsat-7 long-term acquisition plan radiometry: evolution over the time / B. Markham in Photogrammetric Engineering & Remote Sensing, PERS, vol 72 n° 10 (October 2006)PermalinkHeat and drought 2003 in Europe: a climate synthesis / Martine Rebetez in Annals of Forest Science, Vol 63 n° 6 (september 2006)PermalinkApplication of three satellite techniques in support of precipitation forecasts of a NWP [numerical weather prediction] model / H. Feidas in International Journal of Remote Sensing IJRS, vol 26 n° 24 (December 2005)PermalinkAssessment of ASTER land cover and MODIS data at multiple scales for ecological characterization of an arid urban center / W.L. Stefanov in Remote sensing of environment, vol 99 n° 1-2 (15 November 2005)PermalinkSnow cover monitoring in Alpine regions using ENVISAT optical data / M. Pepe in International Journal of Remote Sensing IJRS, vol 26 n° 21 (November 2005)PermalinkNOAA operational hydrological products derived from the Advanced Microwave Sounding Unit / R.R. Ferraro in IEEE Transactions on geoscience and remote sensing, vol 43 n° 5 (May 2005)PermalinkRapid response for cloud monitoring through Meteosat VIS-IR and NOAA-A/TOVS image fusion: civil application. A first approach to MSG-SEVIRI / C. Casanova in International Journal of Remote Sensing IJRS, vol 26 n° 8 (April 2005)PermalinkMonitoring surface soil moisture in post-harvest rice areas using C-band radar imagery in NorthEast Thailand / S. Kaojarern in Geocarto international, vol 19 n° 3 (September - November 2004)PermalinkGlobal fire monitoring: use of MODIS near-real-time satellite data / D.J. Davies in GIM international, vol 18 n° 4 (April 2004)Permalink