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The gravitational effect of ocean tide loading at high latitude coastal stations in Norway / D.I. Lysaker in Journal of geodesy, vol 82 n° 9 (September 2008)
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Titre : The gravitational effect of ocean tide loading at high latitude coastal stations in Norway Type de document : Article/Communication Auteurs : D.I. Lysaker, Auteur ; K. Breili, Auteur ; Bjørn Ragnvald Pettersen, Auteur Année de publication : 2008 Article en page(s) : pp 569 - 583 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse comparative
[Termes IGN] Arctique
[Termes IGN] champ de pesanteur local
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] correction du signal
[Termes IGN] déformation de la croute terrestre
[Termes IGN] levé gravimétrique
[Termes IGN] littoral
[Termes IGN] Norvège
[Termes IGN] série temporelle
[Termes IGN] surcharge océaniqueRésumé : (Auteur) Gravity measurements close to the ocean are strongly affected by ocean tide loading (OTL). The gravitational OTL effect consists of three parts, i.e. a change in gravity caused by direct attraction from the variable water-masses, by displacement of the observing point due to the load, and by redistribution of masses due to crustal deformation. We compare the OTL gravitational effect of several global models to observed time-series of gravity to identify the best model for four arctic observation sites. We also investigate if the global models are sufficient for correcting gravity observations. The NAO99b model fits the observations best at three stations. At two stations (Tromsø and Bodø) the global models explain the variability in the observations well. At the other two (Honningsvåg and Andøya), a significant periodic signal remains after the OTL correction has been applied. We separate two of the gravitational effects, the direct attraction and the change in gravity due to displacement, to study the local effects. Simple geometric models of the water load and independent measurements from local tide-gauges are used to calculate these effects. This leads to improved correspondence with the OTL signal, hence demonstrating the importance of careful modelling of local effects for correction of gravity observations in coastal stations. Copyright Springer Numéro de notice : A2008-351 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0207-4 En ligne : https://doi.org/10.1007/s00190-007-0207-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29344
in Journal of geodesy > vol 82 n° 9 (September 2008) . - pp 569 - 583[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08081 RAB Revue Centre de documentation En réserve L003 Disponible 266-08082 RAB Revue Centre de documentation En réserve L003 Disponible Sea ice deformation state from Synthetic Aperture Radar Imagery: part 2 Effects of spatial resolution and noise level / W. Dierking in IEEE Transactions on geoscience and remote sensing, vol 46 n° 8 (August 2008)
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Titre : Sea ice deformation state from Synthetic Aperture Radar Imagery: part 2 Effects of spatial resolution and noise level Type de document : Article/Communication Auteurs : W. Dierking, Auteur ; J. Dall, Auteur Année de publication : 2008 Article en page(s) : pp 2197 - 2207 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] bande C
[Termes IGN] bande L
[Termes IGN] filtrage du bruit
[Termes IGN] glace de mer
[Termes IGN] image aérienne
[Termes IGN] image ALOS-PALSAR
[Termes IGN] image Envisat-ASAR
[Termes IGN] image ERS-SAR
[Termes IGN] image radar
[Termes IGN] pouvoir de résolution géométrique
[Termes IGN] radargrammétrie
[Termes IGN] rapport signal sur bruitRésumé : (Auteur) C- and L-band airborne synthetic aperture radar (SAR) imagery acquired at like- and cross-polarizations over sea ice under winter conditions is examined with the objective to study the discrimination between level ice and ice deformation features. High-resolution low-noise data were analyzed in the first paper. In this second paper, the main topics are the effects of spatial resolution and signal-to-noise ratio. Airborne high-resolution SAR scenes are used to generate a sequence of images with increasingly coarser spatial resolution from 5 to 25 m, keeping the number of looks constant. The signal-to-noise ratio is varied between typical noise levels for airborne imagery and satellite data. Areal fraction of deformed ice and average deformation distance are determined for each image product. At L-band, the retrieved values of the areal fraction get larger as the image resolution is degraded. The areal fraction at C-band remains constant. The retrieved average distance between deformation features increases both at C- and L-bands as the image resolution gets coarser. The influence of noise becomes noticeable if its level is equal or larger than the average intensity backscattered from the level ice. The retrieval of deformation parameters using simulated images that resemble ERS-2 SAR, Envisat ASAR, and ALOS PALSAR data products is discussed. Basic differences between real and simulated ERS-2 SAR images are analyzed. Copyright IEEE Numéro de notice : A2008-398 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2008.917267 En ligne : https://doi.org/10.1109/TGRS.2008.917267 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29487
in IEEE Transactions on geoscience and remote sensing > vol 46 n° 8 (August 2008) . - pp 2197 - 2207[article] Voir aussiRéservation
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Code-barres Cote Support Localisation Section Disponibilité 065-08081 RAB Revue Centre de documentation En réserve L003 Disponible Disturbance, management, and landscape dynamics: harmonic regression of Vegetation Indices in the Lower Okavango Delta, Botswana / A.L. Neunschwander in Photogrammetric Engineering & Remote Sensing, PERS, vol 74 n° 6 (June 2008)
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Titre : Disturbance, management, and landscape dynamics: harmonic regression of Vegetation Indices in the Lower Okavango Delta, Botswana Type de document : Article/Communication Auteurs : A.L. Neunschwander, Auteur ; K.A. Crews, Auteur Année de publication : 2008 Article en page(s) : pp 753 - 764 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse diachronique
[Termes IGN] analyse harmonique
[Termes IGN] Botswana
[Termes IGN] delta
[Termes IGN] image Landsat-ETM+
[Termes IGN] image Landsat-TM
[Termes IGN] indice de végétation
[Termes IGN] plan d'occupation du sol
[Termes IGN] régression
[Termes IGN] série temporelle
[Termes IGN] surface cultivée
[Termes IGN] traitement du signalRésumé : (Auteur) Focused on the Okavango Delta, Botswana, this research investigates (a) whether ecosystem signals derived from remotely sensed imagery can be decomposed using a harmonic regression, (b) if the deviations from the decomposed signal are correlated with observed flooding and fire regimes, and (c) the impact of explicitly including agriculture, settlement areas, and land management systems on the derived signals. A time-series of 85 TM/ETM+ scenes spanning the period from 1989 through 2002 was used to decompose derived landscape dynamics into trends, annual and seasonal cycles, and long term oscillations. The harmonic fit largely defined by climatic periodicities (semi-annual, annual, and quasi-decadal) accounted for 63 percent to 88 percent of the variance in the trajectories. The trends were found to be robust whether or not urban settlement or landscape management regimes were explicitly included, though there was a reversal of trend in agricultural areas. Copyright ASPRS Numéro de notice : A2008-200 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.74.6.753 En ligne : https://doi.org/10.14358/PERS.74.6.753 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29195
in Photogrammetric Engineering & Remote Sensing, PERS > vol 74 n° 6 (June 2008) . - pp 753 - 764[article]Interference heads-up: receiver techniques for detecting and characterizing RFI [radio-frequency interference] / P. Ward in GPS world, vol 19 n° 6 (June 2008)
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Titre : Interference heads-up: receiver techniques for detecting and characterizing RFI [radio-frequency interference] Type de document : Article/Communication Auteurs : P. Ward, Auteur Année de publication : 2008 Article en page(s) : pp 64 - 73 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] brouillage
[Termes IGN] interférence
[Termes IGN] rapport signal sur bruit
[Termes IGN] récepteur GNSSRésumé : (Editeur) As we all know, GPS signals are weak. At a receiver's antenna, in the open air, their strength is about-160 dBW or 1 x 10~l6watts. Compare this to a cell-phone signal, which might be 60 dBW or 1 x 10~6 watts, 10 billion times stronger! While code correlation in the receiver lifts the GPS signals above the background noise floor, the signals are still relatively fragile, and building walls and other obstructions can significantly attenuate the received signal power so that they cannot be tracked by a conventional receiver. It is the ratio of the signal power to the noise power per unit band-width that determines the trackability of | the signal. Accordingly, if the receiver's noise floor should increase sufficiently, even in an outdoor environment, the signals may also become untrackable. This can happen when the receiver is subjected to intentional or unintentional radio-frequency interference (RFI) by transmitter operating on or near GPS frequencies. If the interference is strong enough, it can jam the receiver. Although intentional jamming is typically of concern only to military GPS users, unintentional jamming can occur anywhere and any- time and can affect large numbers of users within the range of the jamming transmitter. The jamming incident in San Diego harbor in January 2007, for example, affected all GPS users within a range of about 15 kilometers including a medical services paging network. Such jamming renders a GPS receiver inoperable. But how do users know that their receivers are being jammed and not suffering some other type of malfunction? Clearly it would be advantageous for users to receive a heads-up when jamming signals are present and, if possible, for the receiver to take corrective action automatically. In this month's column, we look at some simple techniques, which can be easily incorporated into the design of a GNSS receiver, to detect, characterize, and actually mitigate RFI. Such receiver enhancements will benefit civilian and military users alike. Copyright Questex Media Group Inc Numéro de notice : A2008-165 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29160
in GPS world > vol 19 n° 6 (June 2008) . - pp 64 - 73[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 067-08061 RAB Revue Centre de documentation En réserve L003 Disponible Ocean tide loading (OTL) displacements from global and local grids: comparisons to GPS estimates over the shelf of Brittany, France / Stavros A. Melachroinos in Journal of geodesy, vol 82 n° 6 (June 2008)
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Titre : Ocean tide loading (OTL) displacements from global and local grids: comparisons to GPS estimates over the shelf of Brittany, France Type de document : Article/Communication Auteurs : Stavros A. Melachroinos, Auteur ; Richard Biancale, Auteur ; Muriel Llubes, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 357 - 371 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] baie
[Termes IGN] Bretagne
[Termes IGN] Cotentin
[Termes IGN] marée océanique
[Termes IGN] modèle physique
[Termes IGN] Mont-Saint-Michel
[Termes IGN] plateau continental
[Termes IGN] positionnement par GPS
[Termes IGN] série temporelle
[Termes IGN] surcharge océanique
[Termes IGN] trajet multipleRésumé : (Auteur) In this paper we examine OTL displacements detected by GPS stations of a dedicated campaign and validate ocean tide models. Our area of study is the continental shelf of Brittany and Cotentin in France. Brittany is one of the few places in the world where tides provoke loading displacements of ?10–12 cm vertically and a few cm horizontally. Ocean tide models suffer from important discrepancies in this region. Seven global and regional ocean tide models were tested: FES2004 corrected for K2, TPXO.7.0, TPXO.6.2, GOT00.2, CSR4.0, NAO.99b and the most recent regional grids of the North East Atlantic (NEA2004). These gridded amplitudes and phases of ocean tides were convolved in order to get the predicted OTL displacements using two different algorithms. Data over a period of 3.5 months of 8 GPS campaign stations located on the north coast of Brittany are used, in order to evaluate the geographical distribution of the OTL effect. We have modified and implemented new algorithms in our GPS software, GINS 7.1. GPS OTL constituents are estimated based on 1-day batch solutions. We compare the observed GPS OTL constituents of M2, S2, N2 and K1 waves with the selected ocean tide models on global and regional grids. Large phase-lag and amplitude discrepancies over 20° and 1.5 cm in the vertical direction in the semi-diurnal band of M2 between predictions and GPS/models are detected in the Bay of Mont St-Michel. From a least squares spectral analysis of the GPS time-series, significant harmonic peaks in the integer multiples of the orbital periods of the GPS satellites are observed, indicating the existence of multipath effects in the GPS OTL constituents. The GPS OTL observations agree best with FES2004, NEA2004, GOT00.2 and CSR4.0 tide models. Copyright Springer Numéro de notice : A2008-315 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0185-6 En ligne : https://doi.org/10.1007/s00190-007-0185-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29308
in Journal of geodesy > vol 82 n° 6 (June 2008) . - pp 357 - 371[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08051 SL Revue Centre de documentation Revues en salle Disponible Assimilation of remote sensed data for improved latent and sensible heat flux prediction: a comparative synthetic study / R. Pipunic in Remote sensing of environment, vol 112 n° 4 (15/04/2008)
PermalinkRetrieving soil temperature profile by assimilating MODIS LST products with ensemble Kalman filter / C. Huang in Remote sensing of environment, vol 112 n° 4 (15/04/2008)
PermalinkUse of a Kalman filter for the retrieval of surface BRDF coefficients with a time-evolving model based on the ECOCLIMAP land cover classification / O. Samain in Remote sensing of environment, vol 112 n° 4 (15/04/2008)
PermalinkPermalinkApplications of ICA for the enhancement and classification of polarimetric SAR images / H. Wang in International Journal of Remote Sensing IJRS, vol 29 n° 6 (March 2008)
PermalinkSpecies identification of individual trees by combining high resolution LiDAR data with multi-spectral images / Johan Holmgren in International Journal of Remote Sensing IJRS, vol 29 n° 5 (March 2008)
PermalinkFast error analysis of continuous GPS observations / M. Bos in Journal of geodesy, vol 82 n° 3 (March 2008)
PermalinkPermalinkImproving long-range RTK: getting a better handle on the biases / D. Kim in GPS world, vol 19 n° 3 (March 2008)
PermalinkTexture feature fusion with neighborhood oscillating tabu search for high resolution image classification / L. Zhang in Photogrammetric Engineering & Remote Sensing, PERS, vol 74 n° 3 (March 2008)
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