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A phase-altimetric simulator : studying the sensitivity of Earth-reflected GNSS signals to ocean topography / Aaron Maximilian Semmling in IEEE Transactions on geoscience and remote sensing, vol 54 n° 11 (November 2016)
[article]
Titre : A phase-altimetric simulator : studying the sensitivity of Earth-reflected GNSS signals to ocean topography Type de document : Article/Communication Auteurs : Aaron Maximilian Semmling, Auteur ; Vera Leister, Auteur ; Jan Saynisch, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 6791 - 6802 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] altimétrie
[Termes IGN] analyse de sensibilité
[Termes IGN] océanographie spatiale
[Termes IGN] positionnement par GNSS
[Termes IGN] réflectométrie par GNSS
[Termes IGN] signal GNSS
[Termes IGN] surface de la merRésumé : (Auteur) This paper presents a simulation study on Global Navigation Satellite System (GNSS) reflections focusing on a phase altimetric method for ocean topography retrieval. It examines carrier phase residuals of Earth-reflected GNSS signals in preparation for the GNSS Reflectometry Radio Occultation and Scatterometry experiment aboard the International Space Station (GEROS-ISS). The residuals' sensitivity to ocean topography (maximum of 2-m amplitude variation of global sea level) is shown. A trigonometric approach to determine the specular reflection point is proposed. Reflection events are simulated assuming different low Earth orbit receivers and GNSS-type transmitters. Suitable events for phase altimetry are assumed between 5° and 30° elevation lasting between 10 and 15 min with ground tracks length of > 3000 km. Typical along-track footprints (1 s integration time) have a length of about 5 km. Within the assumed elevation range the coherent footprint ellipse has a major axis between 1 and 6 km. A Master-Slave sampling is proposed to approximate large-scale delay and Doppler variations of the reflected signal (Slave channel) relative to the direct signal (Master channel). Slave residuals of an example event are simulated to retrieve a small-scale phase delay for ocean topography inversion. The signal-to-noise ratio restricts the quality of the topography results. Height precision on sub-decimeter level for 30-dB SNR is degraded up to a meter level for 20-dB SNR. Ionosphere-free linear combination allows keeping the precision level. Troposphere refraction degrades precision particularly at the low elevation limit. Precision improves toward higher elevations. The tolerance to ocean roughness decreases in the same way. Numéro de notice : A2016-918 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2591065 En ligne : http://dx.doi.org/10.1109/TGRS.2016.2591065 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83147
in IEEE Transactions on geoscience and remote sensing > vol 54 n° 11 (November 2016) . - pp 6791 - 6802[article]A statistical model and simulator for ocean-reflected GNSS signals / James L. Garrison in IEEE Transactions on geoscience and remote sensing, vol 54 n° 10 (October 2016)
[article]
Titre : A statistical model and simulator for ocean-reflected GNSS signals Type de document : Article/Communication Auteurs : James L. Garrison, Auteur Année de publication : 2016 Article en page(s) : pp 6007 - 6019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] atmosphère terrestre
[Termes IGN] modélisation
[Termes IGN] positionnement par GNSS
[Termes IGN] réflectométrie par GNSS
[Termes IGN] surface de la merRésumé : (auteur) Global Navigation Satellite Systems Reflectometry (GNSS-R) methods sense ocean roughness by cross correlating scattered GNSS signals with a locally generated replica of the transmitted signal. The resulting delay-Doppler map (DDM) is related to surface slope statistics through established scattering models. DDM samples are correlated in time and between delay and Doppler coordinates, limiting the number of independent samples available to reduce measurement error. Performance predictions for future GNSS-R missions depend on a model with sufficient fidelity to represent these statistics. A previously developed model for the correlation in time and a new model for the correlation between delays are used to create a GNSS-R signal simulator. A change of variables reduces these models to the numerically efficient form of a single integral and a convolution. Independent normally distributed white noise is passed through a filter bank implementing these models to generate an ensemble of synthetic noisy measurements having realistic correlation in time and between delay bins. Correlation between Doppler bins, however, is not represented by this model. The output of this simulator is compared to 1-D (delay-only) DDMs collected during a 2009 airborne experiment in the North Atlantic, with winds from 5 to 25 m/s. Good agreement is found in the variance, time correlation, and covariance matrix. The probability density functions show reasonable agreement. A bias between the synthetic and observed data was found to result from a bias in the wind/roughness retrieval. Agreement was worse for the low-wind (5.8 m/s) example, perhaps due to a component of specular reflection. One application of this simulator is in generating synthetic DDMs, maintaining accurate representation of statistics following nonlinear processing (e.g., incoherent averaging). The simulator presents a numerically efficient method for generating large statistically significant ensembles of DDMs under identical conditions. Numéro de notice : A2016-866 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2579504 En ligne : http://dx.doi.org/ 10.1109/TGRS.2016.2579504 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82903
in IEEE Transactions on geoscience and remote sensing > vol 54 n° 10 (October 2016) . - pp 6007 - 6019[article]A conventional value for the geoid reference potential W0 / L. Sánchez in Journal of geodesy, vol 90 n° 9 (September 2016)
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Titre : A conventional value for the geoid reference potential W0 Type de document : Article/Communication Auteurs : L. Sánchez, Auteur ; Robert Cunderlik, Auteur ; N. Dayoub, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 815 - 835 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] force de gravitation
[Termes IGN] géoïde terrestre
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] surface de la mer
[Termes IGN] télémétrie laser sur satelliteRésumé : (auteur) W0 is defined as the potential value of a particular level surface of the Earth’s gravity field called the geoid. Since the most accepted definition of the geoid is understood to be the equipotential surface that coincides with the worldwide mean ocean surface, a usual approximation of W0 is the averaged potential value WS at the mean sea surface. In this way, the value of W0 depends not only on the Earth’s gravity field modelling, but also on the conventions defining the mean sea surface. W0 computations performed since 2005 demonstrate that current published estimations differ by up to −2.6 m2 s−2 (corresponding to a level difference of about 27 cm), which could be caused by the differences in the treatment of the input data. The main objective of this study is to perform a new W0 estimation relying on the newest gravity field and sea surface models and applying standardised data and procedures. This also includes a detailed description of the processing procedure to ensure the reproducibility of the results. The following aspects are analysed in this paper: (1) sensitivity of the W0 estimation to the Earth’s gravity field model (especially omission and commission errors and time-dependent Earth’s gravity field changes); (2) sensitivity of the W0 estimation to the mean sea surface model (e.g., geographical coverage, time-dependent sea surface variations, accuracy of the mean sea surface heights); (3) dependence of the W0 empirical estimation on the tide system; and (4) weighted computation of the W0 value based on the input data quality. Main conclusions indicate that the satellite-only component (n=200) of a static (quasi-stationary) global gravity model is sufficient for the computation of W0. This model should, however, be based on a combination of, at least, satellite laser ranging (SLR), GRACE and GOCE data. The mean sea surface modelling should be based on mean sea surface heights referring to a certain epoch and derived from a standardised multi-mission cross-calibration of several satellite altimeters. We suggest that the uncertainties caused by geographically correlated errors, including shallow waters in coastal areas and sea water ice content at polar regions should be considered in the computation of W0 by means of a weighed adjustment using the inverse of the input data variances as a weighting factor. This weighting factor should also include the improvement provided by SLR, GRACE and GOCE to the gravity field modelling. As a reference parameter, W0 should be time-independent (i.e., quasi-stationary) and it should remain fixed for a long-term period (e.g., 20 years). However, it should have a clear relationship with the mean sea surface level (as this is the convention for the realisation of the geoid). According to this, a suitable recommendation is to adopt a potential value obtained for a certain epoch as the reference value W0 and to monitor the changes of the mean potential value at the sea surface WS. When large differences appear between W0 and WS (e.g., >±2 m2 s−2), the adopted W0 may be replaced by an updated (best estimate) value. In this paper, the potential value obtained for the epoch 2010.0 (62,636,853.4 m2 s−2) is recommended as the present best estimate for the W0 value. It differs −2.6 m2 s−2 from the so-called IERS W0 value (62,636,856.0 m2 s−2), which corresponds to the best estimate available in 1998. Numéro de notice : A2016-655 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0913-x En ligne : http://dx.doi.org/10.1007/s00190-016-0913-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81857
in Journal of geodesy > vol 90 n° 9 (September 2016) . - pp 815 - 835[article]La mission Topex-Poséidon d'altimétrie spatiale / Anonyme in Géomètre, n° 2139 (septembre 2016)
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Titre : La mission Topex-Poséidon d'altimétrie spatiale Type de document : Article/Communication Auteurs : Anonyme, Auteur Année de publication : 2016 Article en page(s) : pp 43 - 43 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altimétrie satellitaire par radar
[Termes IGN] courant marin
[Termes IGN] fond marin
[Termes IGN] lever bathymétrique
[Termes IGN] océanographie spatiale
[Termes IGN] positionnement par DORIS
[Termes IGN] précision centimétrique
[Termes IGN] surface de la mer
[Termes IGN] TOPEX-PoseidonRésumé : (Auteur) [Introduction] Suite à des - brèves mais prometteuses - missions pionnières au début des années 1980, la première grande mission d'océanographie spatiale a été une mission commune CNES-NASA, nommée Topex-Poséidon, et son succès a été tel qu'elle a été suivie par Jason-1, Jason-2, puis maintenant Jason-3, afin que ces mesures ne s'interrompent pas. Numéro de notice : A2016-672 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81919
in Géomètre > n° 2139 (septembre 2016) . - pp 43 - 43[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 036-2016081 RAB Revue Centre de documentation En réserve L003 Disponible The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques / Philip L. Woodworth in Journal of geodesy, vol 89 n° 8 (August 2015)
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Titre : The status of measurement of the Mediterranean mean dynamic topography by geodetic techniques Type de document : Article/Communication Auteurs : Philip L. Woodworth, Auteur ; Médéric Gravelle, Auteur ; Marta Marcos, Auteur ; Guy Wöppelmann , Auteur ; Chris W. Hughes, Auteur Année de publication : 2015 Article en page(s) : pp 811 - 827 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] données marégraphiques
[Termes IGN] géoïde local
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] Méditerranée, mer
[Termes IGN] océanographie dynamique
[Termes IGN] océanographie spatiale
[Termes IGN] positionnement par GPS
[Termes IGN] surface de la merRésumé : (auteur) We review the measurement of the mean dynamic topography (MDT) of the Mediterranean using ellipsoidal heights of sea level at discrete tide gauge locations, and across the entire basin using satellite altimetry, subtracting estimates of the geoid obtained from recent models. This ‘geodetic approach’ to the determination of the MDT can be compared to the independent ‘ocean approach’ that involves the use of in situ oceanographic measurements and ocean modelling. We demonstrate that with modern geoid and ocean models there is an encouraging level of consistency between the two sets of MDTs. In addition, we show how important geodetic MDT information can be in judging between existing global ocean circulation models, and in providing insight for the development of new ones. The review makes clear the major limitations in Mediterranean data sets that prevent a more complete validation, including the need for improved geoid models of high spatial resolution and accuracy. Suggestions are made on how a greater amount of reliable geo-located tide gauge information can be obtained in the future. Numéro de notice : A2015-423 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-015-0817-1 Date de publication en ligne : 01/05/2015 En ligne : https://doi.org/10.1007/s00190-015-0817-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77009
in Journal of geodesy > vol 89 n° 8 (August 2015) . - pp 811 - 827[article]The impact of the dynamic sea surface topography on the quasi-geoid in shallow coastal waters / D.C. Slobbe in Journal of geodesy, vol 88 n° 3 (March 2014)PermalinkEffects of atmospheric stability and wind fetch on microwave sea echoes / Yunhua Wang in IEEE Transactions on geoscience and remote sensing, vol 52 n° 2 (February 2014)PermalinkTowards a 1 mGal accuracy and 1 min resolution altimetry gravity field / Lifeng Bao in Journal of geodesy, vol 87 n° 10-12 (October - December 2013)PermalinkRéflectométrie GNSS : modélisation des trajets des signaux réfléchis à la surface de la mer / Nicolas Roussel in XYZ, n° 135 (juin - août 2013)PermalinkVariabilité de surface océanique à partir des données des altimètres Topex, Jason-1 et Jason-2 / M. Haddad in Bulletin des sciences géographiques, n° 28 (juin 2013)PermalinkThe Harvest experiment LIDAR system : Water level measurement device comparison for Jason-1 and Jason-2/OSTM calibration / S. Washburn in Marine geodesy, vol 34 n° 3-4 (July - december 2011)Permalinkvol 34 n° 3-4 - July - december 2011 - Special issue on OSTM/Jason-2. Calibration/validation- part2 (Bulletin de Marine geodesy) / G. BornPermalinkSea surface topography and marine geoid by airborne laser altimetry and shipborne ultrasound altimetry / Philippe Limpach (2010)PermalinkA kinematic GPS methodology for sea surface mapping, Vanuatu / Marie-Noëlle Bouin in Journal of geodesy, vol 83 n° 12 (December 2009)PermalinkImproving resolution and accuracy of mean sea surface from kinematic GPS, Vanuatu subduction zone / Marie-Noëlle Bouin in Journal of geodesy, vol 83 n° 11 (November 2009)Permalink