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Combination of GRACE monthly gravity fields on the normal equation level / Ulrich Meyer in Journal of geodesy, vol 93 n° 9 (September 2019)
[article]
Titre : Combination of GRACE monthly gravity fields on the normal equation level Type de document : Article/Communication Auteurs : Ulrich Meyer, Auteur ; Yoomin Jean, Auteur ; A. Kvas, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 1645 - 1658 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse de variance
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GRACE
[Termes IGN] filtrage du bruit
[Termes IGN] gravimétrie spatiale
[Termes IGN] mesure de la qualité
[Termes IGN] série temporelleRésumé : (Auteur) A large number of time-series of monthly gravity fields derived from GRACE data provide users with a wealth of information on mass transport processes in the system Earth. The users are, however, left alone with the decision which time-series to analyze. Following the example of other well-known combination services provided by the geodetic community, the prototype of a combination service has been developed within the frame of the project EGSIEM (2015–2017) to combine the different time-series with the goal to provide a unique and superior product to the user community. Four associated analysis centers (ACs) of EGSIEM, namely AIUB, GFZ, GRGS and IfG, generated monthly gravity fields which were then combined using the different normal equations (NEQs). But the relative weights determined by variance component estimation (VCE) on the NEQ level do not lead to an optimal combined product due to the different processing strategies applied by the individual ACs. We therefore resort to VCE on the solution level to derive relative weights that are representative of the noise levels of the individual solutions. These weights are then applied in the combination on the NEQ level. Prior to combination, empirical scaling factors that are based on pairwise combinations of NEQs are derived to balance the impact of the NEQs on the combined solution. We compare the processing approaches of the different ACs and introduce quality measures derived either from the differences w.r.t. the monthly means of the individual gravity fields or w.r.t. a deterministic signal model. After combination, the gravity fields are validated by comparison to the official GRACE SDS RL05 time-series and the individual contributions of the associated ACs in the spectral and the spatial domain. While the combined gravity fields are comparable in signal strength to the individual time-series, they stand out by their low noise level. In terms of noise, they are in 90% of all months as good or better than the best individual contribution from IfG and significantly less noisy than the official GRACE SDS RL05 time-series. Numéro de notice : A2019-507 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01274-6 Date de publication en ligne : 02/07/2019 En ligne : https://doi.org/10.1007/s00190-019-01274-6 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93792
in Journal of geodesy > vol 93 n° 9 (September 2019) . - pp 1645 - 1658[article]Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data / Joanna Kuczynska-Siehien in Journal of applied geodesy, vol 13 n° 3 (July 2019)
[article]
Titre : Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data Type de document : Article/Communication Auteurs : Joanna Kuczynska-Siehien, Auteur ; Dimitrios Piretzidis, Auteur ; Michael G. Sideris, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 229 – 243 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse diachronique
[Termes IGN] analyse spectrale
[Termes IGN] données GLDAS
[Termes IGN] données GRACE
[Termes IGN] gravimètre absolu
[Termes IGN] inondation
[Termes IGN] levé gravimétrique
[Termes IGN] modèle numérique de surface
[Termes IGN] Pologne
[Termes IGN] risque naturel
[Termes IGN] sécheresse
[Termes IGN] surveillance hydrologique
[Termes IGN] variation temporelleRésumé : (auteur) This study deals with the analysis of temporal gravity variations in central Poland, deduced from multiple sources and covering the period from 2002–2016. The gravity data sets used comprise GRACE monthly solutions, GLDAS land surface models and absolute gravimeter measurements from the FG-5 gravimeter located in Józefosław, Poland. All data are corrected using standard processing methods in order to include the same gravity effects. After removing the annual and semi-annual components from all data using least-squares spectral analysis and seasonal-trend decomposition, the deseasoned time series are derived and examined for signatures of extreme hydrological events. The signatures of several severe drought and flood conditions affecting Poland and central Europe are identified. A complementary correlation analysis is performed to assess the level of agreement between different data sources. A higher correlation is shown when the analysis is restricted in the 2009–2012 period that includes the 2010 extreme flood and 2011 increased precipitation events, both affecting Poland. Numéro de notice : A2019-286 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0003 Date de publication en ligne : 20/04/2019 En ligne : https://doi.org/10.1515/jag-2019-0003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93121
in Journal of applied geodesy > vol 13 n° 3 (July 2019) . - pp 229 – 243[article]On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state / Alexey Androsov in Journal of geodesy, vol 93 n° 2 (February 2019)
[article]
Titre : On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state Type de document : Article/Communication Auteurs : Alexey Androsov, Auteur ; Lars Nerger, Auteur ; Reiner Schnur, Auteur ; Alberta Albertella, Auteur ; Reiner Rummel, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 141 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] assimilation des données
[Termes IGN] circulation océanique
[Termes IGN] données altimétriques
[Termes IGN] données CHAMP
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] filtre de Kalman
[Termes IGN] geoïde marin
[Termes IGN] géoïde terrestre
[Termes IGN] hauteurs de mer
[Termes IGN] modèle de simulation
[Termes IGN] modèle océanographique
[Termes IGN] océanographie dynamique
[Termes IGN] salinité
[Termes IGN] température de surface de la merRésumé : (auteur) General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation. Numéro de notice : A2019-076 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1151-1 Date de publication en ligne : 12/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1151-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92190
in Journal of geodesy > vol 93 n° 2 (February 2019) . - pp 141 - 157[article]Climate variability and climate change impacts on land surface, hydrological processes and water management / Yongqiang Zhang (2019)
Titre : Climate variability and climate change impacts on land surface, hydrological processes and water management Type de document : Monographie Auteurs : Yongqiang Zhang, Éditeur scientifique ; Hongxia Li, Éditeur scientifique ; Paolo Reggiani, Éditeur scientifique Editeur : Bâle [Suisse] : Multidisciplinary Digital Publishing Institute MDPI Année de publication : 2019 Importance : 460 p. Format : 17 x 25 cm ISBN/ISSN/EAN : 978-3-03921-508-9 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] changement climatique
[Termes IGN] Chine
[Termes IGN] données GRACE
[Termes IGN] dynamique de la végétation
[Termes IGN] gestion de l'eau
[Termes IGN] gestion durable
[Termes IGN] hydrologie
[Termes IGN] image Landsat
[Termes IGN] inondation
[Termes IGN] modèle de régression
[Termes IGN] modèle hydrographique
[Termes IGN] occupation du sol
[Termes IGN] sécheresse
[Termes IGN] utilisation du solRésumé : (éditeur) During the last several decades, Earth´s climate has undergone significant changes due to anthropogenic global warming, and feedbacks to the water cycle. Therefore, persistent efforts are required to improve our understanding of hydrological processes and to engage in efficient water management strategies that explicitly consider changing environmental conditions. The twenty-four contributions in this book have broadly addressed topics across four major research areas: (1) Climate and land-use change impacts on hydrological processes, (2) hydrological trends and causality analysis faced in hydrology, (3) hydrological model simulations and predictions, and (4) reviews on water prices and climate extremes. The broad spectrum of international contributions to the Special Issue indicates that climate change impacts on water resources analysis attracts global attention. We hope that the collection of articles presented here can provide scientists, policymakers and stakeholders alike with insights that support sustainable decision-making in the face of climate change and increasingly scarce environmental resources. Note de contenu : 1- Climate variability and climate change Impacts on Land Surface, Hydrological Processes and Water Management
2- Human-Induced Alterations to Land Use and Climate and Their Responses for Hydrology and Water Management in the Mekong River Basin
3- Quantifying the impacts of climate change, coal mining and soil and water conservation on streamflow in a Coal mining concentrated watershed on the Loess Plateau, China
4- A statistical–distributed model of average annual runoff for water resources assessment in DPR Korea
5- Climate change and intense irrigation growth in Western Bahia, Brazil: The urgent need for hydroclimatic monitoring
6- Influence of power operations of cascade hydropower stations under climate change and human activities and revised optimal operation strategies: A case study in the Upper Han River, China
7- Comparative study of two state-of-the-art semi-distributed hydrological models
8- The use of large-scale climate indices in monthly reservoir inflow forecasting and its application on time series and artificial intelligence models
9- Land use and climate change effects on surface runoff variations in the upper Heihe
River Basin
10- Meteorological factors affecting pan evaporation in the Haihe River Basin, China
11- Effects of the three gorges project on runoff and related benefits of the key regions along main branches of the Yangtze River
12- Analysis of the recent trends of two climate parameters over two eco-regions of Ethiopia
13- Evaluating future flood scenarios using CMIP5 climate projections
14- Analyzing the impacts of climate variability and land surface changes on the annual
water–energy balance in the Weihe River Basin of China
15- Quantifying the impact of climate change and human activities on streamflow in a semi-arid watershed with the Budyko Equation incorporating dynamic vegetation information
16- Spatiotemporal variation of snowfall to precipitation ratio and its implication on water resources by a regional climate model over Xinjiang, China
17- Observed trends of climate and river discharge in Mongolia’s Selenga Sub-Basin of the Lake Baikal basin
18- Multiple linear regression models for predicting nonpoint-source pollutant discharge from a highland agricultural region
19- Analysis of natural streamflow variation and its influential factors on the Yellow River from 1957 to 2010
20- The effects of litter layer and topsoil on surface runoff during simulated rainfall in Guizhou Province, China: A plot scale case study
21- Integrating field experiments with modeling to evaluate the freshwater availability at ungauged sites: A case study of Pingtan Island (China)
22- Assessing the influence of the three gorges dam on hydrological drought using GRACE data
23- Explaining water pricing through a water security lens
24- Compound extremes in hydroclimatology: A reviewNuméro de notice : 28538 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Monographie DOI : 10.3390/books978-3-03921-508-9 En ligne : https://doi.org/10.3390/books978-3-03921-508-9 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97368 Reconciling upper mantle seismic velocity and density structure below ocean basins / Isabelle Panet (2019)
Titre : Reconciling upper mantle seismic velocity and density structure below ocean basins Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Barbara Romanowicz, Auteur ; Marianne Greff-Lefftz, Auteur Editeur : Saint-Mandé : Institut national de l'information géographique et forestière - IGN (2012-) Année de publication : 2019 Projets : 1-Pas de projet / Conférence : AGU 2019 Fall Meeting 09/12/2019 13/12/2019 San Francisco Californie - Etats-Unis programme sans actes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données bathymétriques
[Termes IGN] données GRACE
[Termes IGN] fond marin
[Termes IGN] geoïde marin
[Termes IGN] géophysique interne
[Termes IGN] Indien (océan)
[Termes IGN] manteau terrestre
[Termes IGN] Pacifique (océan)
[Termes IGN] structure géologique
[Termes IGN] vitesse de déplacementRésumé : (auteur) Imaging the spatial pattern of mantle flows and constraining their mass is one of the keys to understand the character of mantle convection inside the Earth, and its interactions with plate motions. The horizontal planform of the flows, their heterogeneity and mass transport at depth, are reflected in variations of the gravity field and seismic velocities, as well as deformations of the Earth's surface. Over ocean basins, these observables show an elusive medium-scale structure. A 1500-2000 km wavelength directional fabric following the present-day absolute plate motion is present in the Pacific Ocean in GRACE satellite gravity data (Hayn et al., 2012), while 2000-km wavelength slow shear velocity anomalies sharing a similar orientation are found in seismic tomography at upper mantle depths below the oceans (SEMUM2, French et al., 2013). Today, the dynamic processes at the origin of these observations remain unresolved.
Here, we develop a joint analysis of satellite gravity and bathymetry data together with the SEMUM2 seismic tomography model, in order to advance our understanding of upper to mid-mantle flows below the oceans. First, we enhance and reconstruct the medium-scale gravity and seafloor topography signals aligned with the present-day plate motion from an analysis of the rates of gravity vector variations and seafloor slopes. Then, we compare the obtained signals with the spatial distribution of shear velocity anomalies at depth. We show that slow velocity anomalies coincide with geoid lows, depressions in the seafloor topography, and mass excess in the mantle, in the Pacific ocean and part of the Indian ocean. We first consider a purely thermal interpretation of the seismic velocity variations, associated with medium-scale convective rolls in the upper to mid-mantle, a process able to only explain the observed geometry of anomalies. Investigating whether the needed mass excess arises from lithospheric or deeper sources, such as at the level of the 660-km interface, we conclude that it lies more likely within the slow velocity anomalies themselves, suggesting hot and dense structures. We finally discuss the possible meaning and implications of these results.Numéro de notice : C2019-058 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96896 PermalinkA Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation / Daniel Koenig in Journal of geodesy, vol 92 n° 11 (November 2018)PermalinkMigrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data / Isabelle Panet in Nature geoscience, vol 11 n° 5 (May 2018)PermalinkToward a global horizontal and vertical elastic load deformation model derived from GRACE and GNSS station position time series / Kristel Chanard in Journal of geophysical research : Solid Earth, vol 123 n° 4 (April 2018)PermalinkConstraints on transient viscoelastic rheology of the asthenosphere from seasonal deformation / Kristel Chanard in Geophysical research letters, vol 45 n° 5 (15 March 2018)PermalinkBruit de scintillation dans les séries temporelles de positions GNSS : origines et conséquences / Paul Rebischung (2018)PermalinkContribution actuelle de la calotte Antarctique à la variation du niveau marin / Clémence Chupin (2018)PermalinkDéformation saisonnière de la Terre : observations, modélisations et implications / Kristel Chanard (2018)PermalinkHydrological excitation of polar motion by different variables from the GLDAS models / Malgorzata Winska in Journal of geodesy, vol 91 n° 12 (December 2017)PermalinkOn the estimation of physical height changes using GRACE satellite mission data – A case study of Central Europe / Walyeldeen Godah in Geodesy and cartography, vol 66 n° 2 (December 2017)Permalink