Journal of geodesy . vol 90 n° 6Paru le : 01/06/2016 |
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Ajouter le résultat dans votre panierA systematic impact assessment of GRACE error correlation on data assimilation in hydrological models / Maike Schumacher in Journal of geodesy, vol 90 n° 6 (June 2016)
[article]
Titre : A systematic impact assessment of GRACE error correlation on data assimilation in hydrological models Type de document : Article/Communication Auteurs : Maike Schumacher, Auteur ; Jürgen Kusche, Auteur ; Petra Döll, Auteur Année de publication : 2016 Article en page(s) : pp 537 – 559 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bassin hydrographique
[Termes IGN] corrélation
[Termes IGN] données GRACE
[Termes IGN] erreur
[Termes IGN] filtre de Kalman
[Termes IGN] gravimétrie
[Termes IGN] Mississippi (fleuve)
[Termes IGN] modèle hydrographiqueRésumé : (auteur) Recently, ensemble Kalman filters (EnKF) have found increasing application for merging hydrological models with total water storage anomaly (TWSA) fields from the Gravity Recovery And Climate Experiment (GRACE) satellite mission. Previous studies have disregarded the effect of spatially correlated errors of GRACE TWSA products in their investigations. Here, for the first time, we systematically assess the impact of the GRACE error correlation structure on EnKF data assimilation into a hydrological model, i.e. on estimated compartmental and total water storages and model parameter values. Our investigations include (1) assimilating gridded GRACE-derived TWSA into the WaterGAP Global Hydrology Model and, simultaneously, calibrating its parameters; (2) introducing GRACE observations on different spatial scales; (3) modelling observation errors as either spatially white or correlated in the assimilation procedure, and (4) replacing the standard EnKF algorithm by the square root analysis scheme or, alternatively, the singular evolutive interpolated Kalman filter. Results of a synthetic experiment designed for the Mississippi River Basin indicate that the hydrological parameters are sensitive to TWSA assimilation if spatial resolution of the observation data is sufficiently high. We find a significant influence of spatial error correlation on the adjusted water states and model parameters for all implemented filter variants, in particular for subbasins with a large discrepancy between observed and initially simulated TWSA and for north–south elongated sub-basins. Considering these correlated errors, however, does not generally improve results: while some metrics indicate that it is helpful to consider the full GRACE error covariance matrix, it appears to have an adverse effect on others. We conclude that considering the characteristics of GRACE error correlation is at least as important as the selection of the spatial discretisation of TWSA observations, while the choice of the filter method might rather be based on the computational simplicity and efficiency. Numéro de notice : A2016-422 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0892-y Date de publication en ligne : 27/02/2016 En ligne : https://doi.org/10.1007/s00190-016-0892-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81314
in Journal of geodesy > vol 90 n° 6 (June 2016) . - pp 537 – 559[article]On the impact of airborne gravity data to fused gravity field models / Dimitrios Bolkas in Journal of geodesy, vol 90 n° 6 (June 2016)
[article]
Titre : On the impact of airborne gravity data to fused gravity field models Type de document : Article/Communication Auteurs : Dimitrios Bolkas, Auteur ; Georgia Fotopoulos, Auteur ; Alexander Braun, Auteur Année de publication : 2016 Article en page(s) : pp 561 – 571 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] fusion de données multisource
[Termes IGN] gravimétrie aérienne
[Termes IGN] gravimétrie terrestre
[Termes IGN] modèle de géopotentielRésumé : (auteur) In gravity field modeling, fused models that utilize satellite, airborne and terrestrial gravity observations are often employed to deal with erroneous terrestrially derived gravity datasets. These terrestrial datasets may suffer from long-wavelength systematic errors and inhomogeneous data coverage, which are not prevalent in airborne and satellite datasets. Airborne gravity acquisition plays an essential role in gravity field modeling, providing valuable information of the Earth’s gravity field at medium and short wavelengths. Thus, assessing the impact of airborne gravity data to fused gravity field models is important for identifying problematic regions. Six study regions that represent different gravity field variability and terrestrial data point-density characteristics are investigated to quantify the impact of airborne gravity data to fused gravity field models. The numerical assessments of these representative regions resulted in predictions of airborne gravity impact for individual states and provinces in the USA and Canada, respectively. Prediction results indicate that, depending on the terrestrial data point-density and gravity field variability, the expected impact of airborne gravity can reach up to 3mGal (in terms of standard deviation) in Canada and Alaska (over areas of 1∘×1∘). However, in the mainland US region, small changes are expected (0.2–0.4 mGal over areas of 1∘×1∘) due to the availability of high spatial resolution terrestrial data. These results can serve as a guideline for setting airborne gravity data acquisition priorities and for improving future planning of airborne gravity surveys. Numéro de notice : A2016-423 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0893-x Date de publication en ligne : 07/03/2016 En ligne : https://doi.org/10.1007/s00190-016-0893-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81316
in Journal of geodesy > vol 90 n° 6 (June 2016) . - pp 561 – 571[article]