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Using real polar ground gravimetry data to solve the GOCE polar gap problem in satellite-only gravity field recovery / Biao Lu in Journal of geodesy, Vol 94 n°3 (March 2020)  

Public [article]  inJournal of geodesy > Vol 94 n°3 (March 2020) Titre : Using real polar ground gravimetry data to solve the GOCE polar gap problem in satellite-only gravity field recovery Type de document : Article/Communication Auteurs : Biao Lu, Auteur ; Christoph Förste, Auteur ; Franz Barthelmes, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] anomalie de pesanteur [Termes descripteurs IGN] Antarctique [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] champ de gravitation [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] Earth Gravity Model 2008 [Termes descripteurs IGN] filtrage d'information [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] modèle de géopotentiel [Termes descripteurs IGN] zone polaire Résumé : (auteur) With the successful completion of European Space Agency (ESA)’s PolarGAP campaign, ground gravity data are now available for both polar regions. Therefore, it is now possible to solve the GOCE polar gap problem in satellite-only gravity field recovery by using additional polar ground gravity data instead of some regularization methods. However, ground gravimetry data need to be filtered to remove the short-wavelength information beyond a certain harmonic degree to avoid spectral leakage when inferring satellite-only gravity field models. For the Arctic, the ArcGP data set was successfully applied when inferring the high-resolution gravity field model EGM2008 which could be used for this filtering there. For Antarctica, a combination of latest airborne gravimetry data from ESA’s PolarGap campaign and some previous gravity data was recently published which was irregularly distributed in space and still had some small gaps within the GOCE south polar gap. Therefore, we proposed a point mass modeling method for this filtering which was similar to the way using EGM2008 for such filtering to the ground gravity data in the Arctic. Furthermore, a variance component estimation was applied to combine the normal equations from the different sources to build a global gravity field model called IGGT_R1C. Then, this model’s accuracy was evaluated by comparison with other gravity field models in terms of difference degree amplitudes, gravity anomaly differences as well as external checking by obit adjustment and gravity data in the GOCE polar gap areas. This gravity field model performed well globally according to these checking results; especially, the RMS of the residuals between the filtered gravity data and that calculated from IGGT_R1C was the smallest (2.6 mGal in the Arctic and 5.4 mGal in Antarctica) compared with that of the relevant satellite-only gravity field models, e.g., GOCO05s. Therefore, the disturbing impact of the GOCE polar data gap problem could be solved by adding the polar ground gravity data. Numéro de notice : A2020-155 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01361-z date de publication en ligne : 25/02/2020 En ligne : https://doi.org/10.1007/s00190-020-01361-z Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94805 [article]

Precise DEM extraction from Svalbard using 1936 high oblique imagery / Luc Girod in Geoscientific instrumentation methods and data systems, vol 7 n° 4 ([01/10/2018])    

Public [article]  inGeoscientific instrumentation methods and data systems > vol 7 n° 4 [01/10/2018] . - pp 277 - 288 Titre : Precise DEM extraction from Svalbard using 1936 high oblique imagery Type de document : Article/Communication Auteurs : Luc Girod, Auteur ; Niels Ivar Nielsen, Auteur ; Frédérique Couderette, Auteur ; Christopher Nuth, Auteur ; Andreas Kääb, Auteur Année de publication : 2018 Article en page(s) : pp 277 - 288 Note générale : bibliographie The study was funded by the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013)/ERC grant agreement no. 320816 and the ESA projects Glaciers_cci (4000109873/14/I-NB), DUE GlobPermafrost (4000116196/15/IN-B), and CCI_Permafrost (4000123681/18/I-NB). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes descripteurs IGN] image aérienne oblique [Termes descripteurs IGN] MicMac [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] photographie aérienne oblique [Termes descripteurs IGN] Python (langage de programmation) [Termes descripteurs IGN] structure-from-motion [Termes descripteurs IGN] Svalbard [Termes descripteurs IGN] zone polaire Résumé : (auteur) Stretching time series further in the past with the best possible accuracy is essential to the understanding of climate change impacts and geomorphological processes evolving on decadal-scale time spans. In the first half of the twentieth century, large parts of the polar regions were still unmapped or only superficially so. To create cartographic data, a number of historic photogrammetric campaigns were conducted using oblique imagery, which is easier to work with in unmapped environments as collocating images is an easier task for the human eye given a more familiar viewing angle and a larger field of view. Even if the data obtained from such campaigns gave a good baseline for the mapping of the area, the precision and accuracy are to be considered with caution. Exploiting the possibilities arising from modern image processing tools and reprocessing the archives to obtain better data is therefore a task worth the effort. The oblique angle of view of the data is offering a challenge to classical photogrammetric tools, but the use of modern structure-from-motion (SfM) photogrammetry offers an efficient and quantitative way to process these data into terrain models. In this paper, we propose a good practice method for processing historical oblique imagery using free and open source software (MicMac and Python) and illustrate the process using images of the Svalbard archipelago acquired in 1936 by the Norwegian Polar Institute. On these data, our workflow provides 5 m resolution, high-quality elevation data (SD 2 m for moderate terrain) as well as orthoimages that allow for the reliable quantification of terrain change when compared to more modern data. Numéro de notice : A2018-661 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/gi-7-277-2018 date de publication en ligne : 15/10/2018 En ligne : http://dx.doi.org/10.5194/gi-7-277-2018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93842 [article]

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Reducing leakage error in GRACE-observed long-term ice mass change: a case study in West Antarctica / J. L. Chen in Journal of geodesy, vol 89 n° 9 (september 2015)  

Public [article]  inJournal of geodesy > vol 89 n° 9 (september 2015) . - pp 925 - 940 Titre : Reducing leakage error in GRACE-observed long-term ice mass change: a case study in West Antarctica Type de document : Article/Communication Auteurs : J. L. Chen, Auteur ; C. R. Wilson, Auteur ; Jin Li, Auteur ; Zizhan Zhang, Auteur Année de publication : 2015 Article en page(s) : pp 925 - 940 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] Antarctique [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] force de gravitation [Termes descripteurs IGN] harmonique sphérique [Termes descripteurs IGN] iceberg [Termes descripteurs IGN] masse [Termes descripteurs IGN] zone polaire Résumé : (auteur) Spatial leakage is a major limitation for quantitative interpretation of satellite gravity measurements from the gravity recovery and climate experiment (GRACE). Using synthetic data to simulate ice mass changes in the Amundsen Sea Embayment and Antarctic Peninsula, we analyze quantitatively the effects of a limited range of spherical harmonics (SH) coefficients and additional filtering, which in combination can significantly attenuate signal amplitudes. We present details of a forward modeling algorithm and show that it is capable of removing these biases from GRACE estimates. Examples show how to implement the method by constraining locations of presumed mass changes, or leaving these locations unspecified within a continental region. Our analysis indicates that leakage effects from far-field mass signals (e.g., terrestrial water storage change and glacial melting over other continents) on Antarctic mass rate estimates appear to be negligible. However, leakage from long-term ocean bottom pressure change in the surrounding Antarctic Circumpolar Current regions may bias Antarctic mass rate estimates by up to 20 Gigatonne per year (Gt/year). Experiments based on proxy GRACE measurement noise indicate that the effects of GRACE spatial noise on estimated Antarctic mass rates via constrained and unconstrained forward modelings are ∼5 and 15 Gt/year, respectively. Numéro de notice : A2015-877 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern En ligne : http://link.springer.com/article/10.1007/s00190-015-0824-2/fulltext.html Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79407 [article]

Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe / C. Lee in Journal of geodesy, vol 85 n° 12 (December 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 12 (December 2011) . - pp 921 - 929 Titre : Validation of international reference ionosphere models using in situ measurements from GRACE K-band ranging system and CHAMP planar Langmuir probe Type de document : Article/Communication Auteurs : C. Lee, Auteur ; S. Han, Auteur ; Dieter Bilitza, Auteur ; J. Chung, Auteur Année de publication : 2011 Article en page(s) : pp 921 - 929 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] atmosphère solaire [Termes descripteurs IGN] bande K [Termes descripteurs IGN] données CHAMP [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] International Reference Ionosphere [Termes descripteurs IGN] modèle ionosphérique [Termes descripteurs IGN] teneur totale en électrons [Termes descripteurs IGN] zone équatoriale [Termes descripteurs IGN] zone polaire Résumé : (Auteur) The in situ measurements of electron contents from GRACE K-band (dual-frequency) ranging system and CHAMP planar Langmuir probe were used to validate the international reference ionosphere (IRI) models. The comparison using measurements from year 2003 to 2007 shows a general agreement between data and the model outputs. The improvement in the newer IRI model (IRI-2007) is evident with the measurements from the GRACE satellites orbiting at the higher altitude. We present the comparison between the models and data comprehensively for various cases in solar activity, local time, season, and latitude. The IRI models do not well predict the electron density in the years 2006 and later, when the solar activity is extremely low. The IRI models generally overestimate the electron density during local winter while they underestimate during local summer. In the equatorial region, the large difference at local sunrise lasts for all years and all seasons. The IRI models do not perform well in predicting the anomaly in the polar region such as the Weddell Sea Anomaly. These discrepancies are likely due to smoothed (12-month averaged) solar activity indices used in the IRI models and due to insufficient spherical harmonic representation not able to capture small spatial scales. In near future, further improvement on the IRI models is expected by assimilating those in situ satellite data by implementing higher resolution (spatial and temporal) parameterizations. Numéro de notice : A2011-503 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0442-6 date de publication en ligne : 30/11/2019 En ligne : https://doi.org/10.1007/s00190-011-0442-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31397 [article]

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Mapping the North : the updated North Circumpolar Region map by the atlas of Canada / R.E. Kramers in Cartographica, vol 45 n° 3 (September 2010)  

Public [article]  inCartographica > vol 45 n° 3 (September 2010) . - pp 201 - 210 Titre : Mapping the North : the updated North Circumpolar Region map by the atlas of Canada Type de document : Article/Communication Auteurs : R.E. Kramers, Auteur ; A. Murray, Auteur Année de publication : 2010 Article en page(s) : pp 201 - 210 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] Arctique, océan [Termes descripteurs IGN] atlas régional [Termes descripteurs IGN] bathymétrie [Termes descripteurs IGN] Canada [Termes descripteurs IGN] image Terra-MODIS [Termes descripteurs IGN] modèle numérique de terrain [Termes descripteurs IGN] relief [Termes descripteurs IGN] relief sous-marin [Termes descripteurs IGN] révision cartographique [Termes descripteurs IGN] système d'information géographique [Termes descripteurs IGN] zone polaire Résumé : (Auteur) For more than 100 years the Atlas of Canada, published by Natural Resources Canada, has told the story of Canada through geographical and historical maps reflecting the country's social, environmental, and economic diversity. The Atlas' original North Circumpolar Region map was published in 1990; revisions followed in 1996, 1997, and 2004. The latest edition, published in 2008 for the International Polar Year, reflects significant progress in data collection, data integration, and cartographic methods. The revision process presented a number of challenges that led to innovative cartographic and technical solutions. This article focuses on some of the objectives, challenges, and methods associated with undersea and terrestrial relief, bathymetry, drainage features, sea ice, glaciers, and ice shelves. Numéro de notice : A2010-369 Thématique : GEOMATIQUE Nature : Article DOI : 10.3138/carto.45.3.201 date de publication en ligne : 01/08/2010 En ligne : https://doi.org/10.3138/carto.45.3.201 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30563 [article]

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Sea ice monitoring by L-band SAR: an assessment based on literature and comparisons of JERS-1 and ERS-1 imagery / W. Dierking in IEEE Transactions on geoscience and remote sensing, vol 44 n° 4 (April 2006)

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Gravity, geoïd and geodynamics 2000 GGG2000, IAG international symposium, Banff, Alberta, Canada, July 31 - August 4, 2000 / Michael G. Sideris (2004)

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vol 23 n° 21 - November 2002 - Sixth circumpolar symposium on remote sensing of the polar environments, [actes], Yellowknife, 12 - 14 June 2000 (Bulletin de International Journal of Remote Sensing IJRS) / Remote sensing and photogrammetry society

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Observing our environment from space / G. Begni (2002)

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Modelling permafrost temperature response to variations in meteorological data / F. Caline (2000)

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Merging AVHRR and SMMR data for remote sensing of ice and cloud in polar regions / J.A. Maslanik in International Journal of Remote Sensing IJRS, vol 10 n° 10 (October 1989)

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Cloud track winds in the polar regions from sequences of AVHRR images / J. Turner in International Journal of Remote Sensing IJRS, vol 10 n°4-5 (May 1989)

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Proceedings of the NIPR symposium on Antarctic geosciences / Y. Yoshida (1987)

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Proceedings of the twenty-first international symposium on remote sensing of environment, Ann Arbor, (Michigan), 26-30 October 1987, 1. Volume 1 / Environmental research institute of Michigan (1986)

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Proceedings of the twenty-first international symposium on remote sensing of environment, Ann Arbor, (Michigan), 26-30 October 1987, 2. Volume 2 / Environmental research institute of Michigan (1986)

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