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Data-driven gap filling and spatio-temporal filtering of the GRACE and GRACE-FO records / Louis-Marie Gauer in Journal of geophysical research : Solid Earth, vol 128 n° 5 (May 2023)  

Public [article]  inJournal of geophysical research : Solid Earth > vol 128 n° 5 (May 2023) . - n° e2022JB025561 Titre : Data-driven gap filling and spatio-temporal filtering of the GRACE and GRACE-FO records Type de document : Article/Communication Auteurs : Louis-Marie Gauer, Auteur ; Kristel Chanard , Auteur ; Luce Fleitout, Auteur Année de publication : 2023 Projets : TOSCA HYDROGEODESY / Article en page(s) : n° e2022JB025561 Note générale : bibliographie This study was supported by the CNES-TOSCA HYDROGEODESY project. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données GRACE [Termes IGN] filtrage spatiotemporel [Termes IGN] traitement de données localisées [Termes IGN] valeur aberrante Résumé : (auteur) Gravity Recovery And Climate Experiment and Follow On (GRACE/-FO) global monthly measurements of Earth's gravity field have led to significant advances in quantifying mass transfer. However, a significant temporal gap between missions hinders evaluating long-term mass variations. Moreover, instrumental and processing errors translate into large non-physical North-South stripes polluting geophysical signals. We use Multichannel Singular Spectrum Analysis (M-SSA) to overcome both issues by exploiting spatio-temporal information of Level-2 GRACE/-FO solutions, filtered using the DDK7 decorrelation and a new complementary filter, built based on the residual noise between fully processed data and a parametric fit to observations. Using an iterative M-SSA on Equivalent Water Height (EWH) time series processed by Center of Space Research, GeoForschungsZentrum, Institute of Geodesy at Graz University of Technology, and Jet Propulsion Laboratory, we replace missing data and outliers to obtain a combined evenly sampled solution. Then, we apply M-SSA to retrieve common signals between each EWH time series and its same-latitude neighbors to further reduce residual spatially uncorrelated noise. Comparing GRACE/-FO M-SSA solution with Satellite Laser Ranging and Swarm low-degree Earth's gravity field and hydrological model demonstrates its ability to satisfyingly fill missing observations. Our solution achieves a noise level comparable to mass concentration (mascon) solutions over oceans (3.0 mm EWH), without requiring a priori information nor regularization. While short-wavelength signals are challenging to capture using highly filtered spherical harmonics or mascons solutions, we show that our technique efficiently recovers localized mass variations using well-documented mass transfers associated with reservoir impoundments. Numéro de notice : A2023-096 Affiliation des auteurs : UMR IPGP-Géod (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2022JB025561 En ligne : https://doi.org/10.1029/2022JB025561 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103213 [article]

Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX / Alex V. Conrad in Navigation : journal of the Institute of navigation, vol 70 n° 1 (Spring 2023)  

Public [article]  inNavigation : journal of the Institute of navigation > vol 70 n° 1 (Spring 2023) . - n° 565 Titre : Improved GPS-based single-frequency orbit determination for the CYGNSS spacecraft using GipsyX Type de document : Article/Communication Auteurs : Alex V. Conrad, Auteur ; Penina Axelrad, Auteur ; Bruce J. Haines, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 565 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales [Termes IGN] données GRACE [Termes IGN] étalonnage d'instrument [Termes IGN] mesurage de phase [Termes IGN] orbite précise [Termes IGN] orbitographie [Termes IGN] récepteur monofréquence [Termes IGN] trajet multiple Résumé : (auteur) This paper presents methods for the precise orbit determination (POD) of a satellite in the CYGNSS constellation based on available single-frequency GPS code and carrier measurements. The contributions include the development and evaluation of procedures for single-frequency POD with GipsyX, improvement of CYGNSS orbit knowledge, and an assessment of its final accuracy. Ionospheric effects are mitigated using the GRAPHIC processing method, and spacecraft multipath effects are calibrated with an azimuth/elevation-dependent antenna calibration map. The method is demonstrated using comparable data from the GRACE mission, from which we infer the expected accuracy of the CYGNSS results. Processing more than 170 days of data from each mission, a 1σ CYGNSS orbit accuracy of 2.8 cm radial, 2.4 cm cross-track, and 6 cm in-track is demonstrated. We expect that achieving this level of performance will expand the set of future scientific investigations that can be undertaken using satellites equipped with single-frequency GNSS. Numéro de notice : A2023-141 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.33012/navi.565 Date de publication en ligne : 20/10/2022 En ligne : https://doi.org/10.33012/navi.565 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102708 [article]

Ground deformation monitoring of the eruption offshore Mayotte / Aline Peltier in Comptes rendus : Géoscience Sciences de la planète, vol 354 n° S2 (2022)  

Public [article]  inComptes rendus : Géoscience Sciences de la planète > vol 354 n° S2 (2022) . - pp 1 - 23 Titre : Ground deformation monitoring of the eruption offshore Mayotte Titre original : Suivi des déformations liées à l’éruption au large de Mayotte Type de document : Article/Communication Auteurs : Aline Peltier, Auteur ; Sébastien Saur , Auteur ; Valérie Ballu, Auteur ; François Beauducel, Auteur ; Pierre Briole, Auteur ; Kristel Chanard , Auteur ; et al., Auteur ; Perrine Rouffiac , Auteur ; Pierre Valty , Auteur Année de publication : 2022 Article en page(s) : pp 1 - 23 Note générale : bibliographie REVOSIMA (Réseau de surveillance volcanologique et sismologique de Mayotte) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] coordonnées GNSS [Termes IGN] déformation de la croute terrestre [Termes IGN] données GRACE [Termes IGN] Mayotte [Termes IGN] séisme Résumé : (auteur) En mai 2018, l’île de Mayotte a été touchée par une crise sismique sans précédent, suivie en juillet 2018 par des déplacements de surface à terre anormaux. En cumulé, du 1er juillet 2018 au 31 décembre 2021, les déplacements horizontaux étaient d’environ 21 à 25 cm vers l’est, et la subsidence d’environ 10 à 19 cm. L’étude des données GNSS à terre, et leur modélisation couplée aux données des capteurs de pression en mer, ont permis de conclure à une origine magmatique de la crise sismique avec la déflation d’une source profonde à l’est de Mayotte, confirmée en mai 2019 par la découverte d’une éruption sous-marine, à 50 km au large de Mayotte ([Feuillet et al., 2021]). Malgré une géométrie de réseau non optimale et des récepteurs éloignés de la source, les données GNSS ont permis de suivre la dynamique profonde du transfert magmatique, via la surveillance des flux volumiques. Numéro de notice : A2022-917 Affiliation des auteurs : IGN+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article DOI : 10.5802/crgeos.176 Date de publication en ligne : 19/12/2022 En ligne : https://doi.org/10.5802/crgeos.176 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102409 [article]

On study of the Earth topography correction for the GRACE surface mass estimation / Fan Yang in Journal of geodesy, vol 96 n° 12 (December 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 12 (December 2022) . - n° 95 Titre : On study of the Earth topography correction for the GRACE surface mass estimation Type de document : Article/Communication Auteurs : Fan Yang, Auteur ; Zhicai Luo, Auteur ; Hao Zhou, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 95 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] données GRACE [Termes IGN] formule de Stokes [Termes IGN] géoïde gravimétrique [Termes IGN] itération [Termes IGN] masse de la Terre [Termes IGN] topographie Résumé : (auteur) Traditional conversion from gravity Stokes coefficients into the surface mass, e.g., in the GRACE(-FO) applications, presumes the Earth as a perfect sphere that is apparently against the reality. Recent studies manage to correct the conversion by considering the Earth’s oblateness, in another word, the Earth is treated as an ellipsoid. However, the Earth’s geometry is far more complicated due to the topography, so that neither a sphere nor an ellipsoid is exact. Evidences from recent studies and this one demonstrate that any geometrical approximation of the Earth shape like a presumed sphere will inevitably lead to a bias in the surface mass estimation from GRACE gravity fields, resulting in a possible misinterpretation of geophysical signals that may occur in polar regions or mountain areas. In this context, we propose an iterative scaling factor method to numerically realize a more accurate surface mass estimate, considering a more realistic geometry of the Earth including its oblateness, topography and geoid undulation. Verified with a series of simulations, the proposed method is found to be efficient (less than four iterations), reliable (after a broad range of tests) and universally accurate (reducing at least 80% of the bias). Relative to our method, the mean linear trend in 2002–2015 estimated from GRACE under an ideal spherical Earth is found to be underestimated by about 3.1% and 5.5% over Greenland and West Antarctica, respectively. Among the trend underestimation, the topography-related contribution takes up − 0.5% (0.79 Gt/yr, the negative sign denotes an overestimation) and − 0.4% (0.34 Gt/yr), respectively. Although the value is small, it is a systematic bias worth considering, for example, it is greater than the influence (0.3 Gt/yr on the trend estimation over West Antarctica) by switching atmospherical de-aliasing products from RL05 to RL06. Besides, the topography-induced bias rapidly increases to 2.7% (0.26 mm/yr) at mountain Himalayas, which is even larger than the ellipsoid-induced bias (0.19 mm/yr). Based on the results obtained so far, the topography-induced bias is found to be roughly one order of magnitude smaller than GRACE’s present measurement error; nevertheless, it will be relevant once the GRACE is improved toward its baseline accuracy. In particular, the topography correction should be considered for NGGM that expects to map the Earth gravity field in an unprecedented accuracy and spatial resolution. Numéro de notice : A2022-878 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s00190-022-01683-0 Date de publication en ligne : 02/12/2022 En ligne : https://doi.org/10.1007/s00190-022-01683-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102189 [article]

Impact assessment of the seasonal hydrological loading on geodetic movement and seismicity in Nepal Himalaya using GRACE and GNSS measurements / Devendra Shashikant Nagale in Geodesy and Geodynamics, vol 13 n° 5 (September 2022)  

Public [article]  inGeodesy and Geodynamics > vol 13 n° 5 (September 2022) . - pp 445 - 455 Titre : Impact assessment of the seasonal hydrological loading on geodetic movement and seismicity in Nepal Himalaya using GRACE and GNSS measurements Type de document : Article/Communication Auteurs : Devendra Shashikant Nagale, Auteur ; Suresh Kannaujiya, Auteur ; Param K. Gautam, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 445 - 455 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] coefficient de corrélation [Termes IGN] déformation de la croute terrestre [Termes IGN] données GNSS [Termes IGN] données GRACE [Termes IGN] International Terrestrial Reference Frame [Termes IGN] mousson [Termes IGN] Népal [Termes IGN] pondération [Termes IGN] série temporelle [Termes IGN] sismicité [Termes IGN] surcharge hydrologique [Termes IGN] variation saisonnière Résumé : (auteur) The Himalayan terrain is an epitome of ongoing convergence and geodetic deformation where both tectonic and non-tectonic forces prevail. In this study, the Gravity Recovery and Climate Experiment (GRACE) and Global Positioning System (GPS) datasets are used to assess the impact of seasonal loading on deformation with seismicity in Nepal. The recorded GPS data from 21 Global Navigation Satellite System (GNSS) stations during 2017–2020 are processed with respect to ITRF14 and the Indian reference frame, and the Center for Space Research (CSR) mascon RL06 during 2002–2020 is adopted to estimate the terrestrial water storage (TWS) change over the Ganga-Brahmaputra River basin. The results indicate that the hydrological loading effect or TWS change shows high negative, high positive, and moderately positive values in pre-monsoon, co-monsoon, and post-monsoon months, respectively. The detrended GPS data of both horizontal and vertical components correlate with the seasonal TWS change using the Pearson correlation coefficient at each GNSS site. In addition, the correlation coefficient has been interpolated using inverse distance weighting to investigate the regional TWS influence on geodetic displacement. In the north component, the correlation coefficient ranges from −0.6 to 0.6. At the same time, the TWS is positively correlated with geodetic displacement (0.82) in the east component, and the correlation coefficient is negative (−0.69) in the vertical component. The negative correlation signifies an inverse relationship between seasonal TWS variation and geodetic displacements. The strain rate is estimated, which shows higher negative values in pre-monsoon than in post-monsoon. Similarly, the effect of seismicity is 47.90% for pre-monsoon, 15.97% for co-monsoon, and 17.56% for post-monsoon. Thus we can infer that the seismicity decreases with the increase of seasonal hydrological loading. Furthermore, the effect of strain is much higher in pre-monsoon than in post-monsoon since the impact of co-monsoon continues to persist on a small scale in the post-monsoon season. Numéro de notice : A2022-762 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2022.02.006 Date de publication en ligne : 20/05/2022 En ligne : https://doi.org/10.1016/j.geog.2022.02.006 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101780 [article]

Detecting preseismic signals in GRACE gravity solutions: Application to the 2011 Tohoku Mw 9.0 earthquake / Isabelle Panet in Journal of geophysical research : Solid Earth, vol 127 n° 8 (August 2022)  

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Comparison between Gaussian and decorrelation filters of GRACE-based RL05 temporal gravity solutions over Egypt / Basem Elsaka in Survey review, vol 54 n° 384 (May 2022)  

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Deep mass redistribution prior to the 2010 Mw 8.8 Maule (Chile) Earthquake revealed by GRACE satellite gravity / Marie Bouih in Earth and planetary science letters, vol 584 (15 April 2022)  

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Estimation of the height datum geopotential value of Hong Kong using the combined Global Geopotential Models and GNSS/levelling data / Panpan Zhang in Survey review, vol 54 n° 383 (March 2022)  

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Understanding the geodetic signature of large aquifer systems: Example of the Ozark plateaus in central United States / Stacy Larochelle in Journal of geophysical research : Solid Earth, vol 127 n° 3 (March 2022)  

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Applications and challenges of GRACE and GRACE follow-on satellite gravimetry / Jianli Chen in Surveys in Geophysics, vol 43 n° 1 (February 2022)  

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Seasonal variations of vertical crustal motion in Australia observed by joint analysis of GPS and GRACE / Hao Wang in Geomatics and Information Science of Wuhan University, vol 47 n° 2 (February 2022)  

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Les journées de la Recherche IGN 2021 / Anonyme in Géomatique expert, n° 135 (septembre 2021)

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Assessment of degree-2 order-1 gravitational changes from GRACE and GRACE Follow-on, Earth rotation, satellite laser ranging, and models / Jianli Chen in Journal of geodesy, vol 95 n° 4 (April 2021)  

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What have we learnt from Icesat on Greenland ice sheet change and what to expect from Icesat 2 / Blaženka Bukač in Geodetski vestnik, vol 65 n° 1 (March - May 2021)  

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