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The impact of relative and absolute GNSS positioning strategies on estimated coordinates and ZWD in the framework of meteorological applications / Alessandro Fermi in Applied geomatics, vol 11 n° 1 (March 2019)  

Public [article]  inApplied geomatics > vol 11 n° 1 (March 2019) . - pp 25 - 38 Titre : The impact of relative and absolute GNSS positioning strategies on estimated coordinates and ZWD in the framework of meteorological applications Type de document : Article/Communication Auteurs : Alessandro Fermi, Auteur ; Eugenio Realini, Auteur ; Giovanna Venuti, Auteur Année de publication : 2019 Article en page(s) : pp 25 - 38 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] coordonnées GNSS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] positionnement absolu [Termes descripteurs IGN] positionnement différentiel [Termes descripteurs IGN] retard troposphérique [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] teneur en vapeur d'eau Résumé : (Auteur) Since many years, the GNSS has been regarded by the meteorological community as one of the systems for atmospheric water vapour remote sensing. Time series of wet delays, estimated as by-products of accurate positioning, have been assimilated into numerical weather prediction models. However, a dedicated use the system for water vapour monitoring is still under investigation. Ad hoc dense networks have been designed and implemented to collect data at a high spatial resolution, baseline lengths lower than 10 km, with the aim of describing the high spatial and temporal variability of tropospheric water vapour. Within this framework, the paper reports a study on how the positioning strategy affects the estimated coordinates and tropospheric parameters. The study was conducted on the data collected by an experimental network of geodetic receivers, used as single or dual frequency ones. More specifically, investigations were made on the use of L1-only or iono-free combinations in differential positioning of receivers 100 to 10 km apart, finding that L1-only data provide more accurate results. Therefore, comparisons between local coordinates and ZWD obtained from relative and absolute positioning were performed to provide the statistics of the differences; the agreement between the results for short baselines is always better than 1 cm standard deviation. In order to assess the differences in the results that can be obtained from the two strategies when applied to the same observation set, a further comparison was carried out in terms of baseline components and ZWD increments. It results that, even for dense networks, the differential approach produces accurate results without losing information compared to the absolute one. Numéro de notice : A2019-159 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s12518-018-0234-2 date de publication en ligne : 19/07/2018 En ligne : https://doi.org/10.1007/s12518-018-0234-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92520 [article]

Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY / Dunya Alraddawi in Atmospheric measurement techniques, vol 11 n° 5 (May 2018)  

Public [article]  inAtmospheric measurement techniques > vol 11 n° 5 (May 2018) . - pp 2949 - 2965 Titre : Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY Type de document : Article/Communication Auteurs : Dunya Alraddawi, Auteur ; Alain Sarkissian, Auteur ; Philippe Keckhut, Auteur ; Olivier Bock , Auteur ; Stefan Noël, Auteur ; Slimane Bekki, Auteur ; Abdanour Irbah, Auteur ; Mustapha Meftah, Auteur ; Chantal Claud, Auteur Année de publication : 2018 Article en page(s) : pp 2949 - 2965 Note générale : bibliographie This work was developed in the framework of the VEGA project and supported by the French program LEFE/INSU. This work is a contribution to the European COST Action ES1206 GNSS4SWEC (GNSS for Severe Weather and Climate monitoring; http://www.cost.eu/COST_Actions/essem/ES1206, last access: 15 May 2018) aiming at the development of the global GNSS network for atmospheric research and climate change monitoring. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] Atmospheric Infrared Sounder [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] image Aqua-MODIS [Termes descripteurs IGN] image Terra-MODIS [Termes descripteurs IGN] nébulosité [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] teneur en vapeur d'eau Résumé : (auteur) Atmospheric water vapour plays a key role in the Arctic radiation budget, hydrological cycle and hence climate, but its measurement with high accuracy remains an important challenge. Total column water vapour (TCWV) datasets derived from ground-based GNSS measurements are used to assess the quality of different existing satellite TCWV datasets, namely from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Atmospheric Infrared Sounder (AIRS) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The comparisons between GNSS and satellite data are carried out for three reference Arctic observation sites (Sodankylä, Ny-Ålesund and Thule) where long homogeneous GNSS time series of more than a decade (2001–2014) are available. We select hourly GNSS data that are coincident with overpasses of the different satellites over the three sites and then average them into monthly means that are compared with monthly mean satellite products for different seasons. The agreement between GNSS and satellite time series is generally within 5 % at all sites for most conditions. The weakest correlations are found during summer. Among all the satellite data, AIRS shows the best agreement with GNSS time series, though AIRS TCWV is often slightly too high in drier atmospheres (i.e. high-latitude stations during autumn and winter). SCIAMACHY TCWV data are generally drier than GNSS measurements at all the stations during the summer. This study suggests that these biases are associated with cloud cover, especially at Ny-Ålesund and Thule. The dry biases of MODIS and SCIAMACHY observations are most pronounced at Sodankylä during the snow season (from October to March). Regarding SCIAMACHY, this bias is possibly linked to the fact that the SCIAMACHY TCWV retrieval does not take accurately into account the variations in surface albedo, notably in the presence of snow with a nearby canopy as in Sodankylä. The MODIS bias at Sodankylä is found to be correlated with cloud cover fraction and is also expected to be affected by other atmospheric or surface albedo changes linked for instance to the presence of forests or anthropogenic emissions. Overall, the results point out that a better estimation of seasonally dependent surface albedo and a better consideration of vertically resolved cloud cover are recommended if biases in satellite measurements are to be reduced in the polar regions. Numéro de notice : A2018-240 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-2949-2018 date de publication en ligne : 18/05/2018 En ligne : https://doi.org/10.5194/amt-11-2949-2018 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90215 [article]

Error-regulated multi-pass DInSAR analysis for landslide risk assessment / Jung Rack Kim in Photogrammetric Engineering & Remote Sensing, PERS, vol 84 n° 4 (April 2018)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 84 n° 4 (April 2018) . - pp 189 - 202 Titre : Error-regulated multi-pass DInSAR analysis for landslide risk assessment Type de document : Article/Communication Auteurs : Jung Rack Kim, Auteur ; HyeWon Yun, Auteur ; Stephan van Gasselt, Auteur ; YunSoo Choi, Auteur Année de publication : 2018 Article en page(s) : pp 189 - 202 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] Corée du sud [Termes descripteurs IGN] effondrement de terrain [Termes descripteurs IGN] interferométrie différentielle [Termes descripteurs IGN] interféromètrie par radar à antenne synthétique [Termes descripteurs IGN] modèle numérique de terrain [Termes descripteurs IGN] montagne [Termes descripteurs IGN] risque naturel [Termes descripteurs IGN] surveillance géologique [Termes descripteurs IGN] télédétection en hyperfréquence [Termes descripteurs IGN] teneur en vapeur d'eau Résumé : (Auteur) Landslide risk assessment based on Differential Interferometric SAR analyses (DInSAR) is associated with a number of error effects. We here approach the problem of assessing landslide risks over mountainous areas, where DInSAR observations are often influenced by orographic effects and inaccurate base topographies by employing a dedicated error compensation. In order to obtain accurate information on surface deformation, we apply corrections for DInSAR interferograms using high-resolution base topography and water vapor information obtained from a satellite radiometer. We observe that the corrected DInSAR output is in accordance with the environmental context as inferred by geological and geomorphological settings. It is feasible to better quantify landslide monitoring schemes whenever high- accuracy atmospheric error maps and a methodology to effectively compensate for external errors in DInSAR interferograms are available. The approach in this study can be further upgraded for future SAR-based assessments and various error correction approaches for even more precise landslide risk assessments. Numéro de notice : A2018-138 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.84.4.189 date de publication en ligne : 01/04/2018 En ligne : https://doi.org/10.14358/PERS.84.4.189 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89688 [article]

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Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe / Monica Campanelli in Atmospheric measurement techniques, vol 11 n° 1 (January 2018)    

Public [article]  inAtmospheric measurement techniques > vol 11 n° 1 (January 2018) . - pp 81 - 94 Titre : Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe Type de document : Article/Communication Auteurs : Monica Campanelli, Auteur ; Alessandra Mascitelli, Auteur ; Paolo Sano, Auteur ; Henri Diémoz, Auteur ; Victor Estellés, Auteur ; Stefano Federico, Auteur ; Anna Maria Iannarelli, Auteur ; Francesca Fratarcangeli, Auteur ; Augusto Mazzoni, Auteur ; Eugenio Realini, Auteur ; Mattia Crespi, Auteur ; Olivier Bock , Auteur ; Jose A. Martínez-Lozano, Auteur ; Stefano Dietrich, Auteur Année de publication : 2018 Projets : 1-Pas de projet / Article en page(s) : pp 81 - 94 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Aoste (val d') [Termes descripteurs IGN] constante [Termes descripteurs IGN] coordonnées GPS [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] données spatiotemporelles [Termes descripteurs IGN] ESR/Skynet [Termes descripteurs IGN] étalonnage d'instrument [Termes descripteurs IGN] photomètre [Termes descripteurs IGN] précipitation [Termes descripteurs IGN] retard troposphérique zénithal [Termes descripteurs IGN] Rome [Termes descripteurs IGN] teneur en vapeur d'eau [Termes descripteurs IGN] Valence (Espagne) [Termes descripteurs IGN] water vapour radiometer Résumé : (Auteur) The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W, from independent sources, taken over a large range of solar zenith angle and covering a wide range of W, are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NET-work (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia. Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the agreement with the GPS (considered the reference one) from a % bias of 5.76 to 0.52. Numéro de notice : A2018-053 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-11-81-2018 date de publication en ligne : 09/01/2018 En ligne : http://dx.doi.org/10.5194/amt-11-81-2018 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89371 [article]

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Enhanced MODIS atmospheric total water vapour content trends in response to Arctic amplification / Dunya Alraddawi in Atmosphere, vol 8 n° 12 (December 2017)  

Public [article]  inAtmosphere > vol 8 n° 12 (December 2017) Titre : Enhanced MODIS atmospheric total water vapour content trends in response to Arctic amplification Type de document : Article/Communication Auteurs : Dunya Alraddawi, Auteur ; Philippe Keckhut, Auteur ; Alain Sarkissian, Auteur ; Olivier Bock , Auteur ; Abdanour Irbah, Auteur ; Slimane Bekki, Auteur ; Chantal Claud, Auteur ; Mustapha Meftah, Auteur Année de publication : 2017 Projets : VEGA (LEFE/INSU) / Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Arctique [Termes descripteurs IGN] Arctique, océan [Termes descripteurs IGN] changement climatique [Termes descripteurs IGN] Groenland [Termes descripteurs IGN] image Aqua-MODIS [Termes descripteurs IGN] image Terra-MODIS [Termes descripteurs IGN] modèle de simulation [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] Svalbard [Termes descripteurs IGN] température de surface de la mer [Termes descripteurs IGN] teneur en vapeur d'eau Résumé : (auteur) In order to assess the strength of the water vapour feedback within Arctic climate change, 15 years of the total column-integrated density of water vapour (TCWV) from the moderate resolution imaging spectrometer (MODIS) are analysed. Arctic TCWV distribution, trends, and anomalies for the 2001–2015 period, broken down into seasons and months, are analysed. Enhanced local spring TCWV trends above the terrestrial Arctic regions are discussed in relation to land snow cover and vegetation changes. Upward TCWV trends above the oceanic areas are discussed in lien with sea ice extent and sea surface temperature changes. Increased winter TCWV (up to 40%) south of the Svalbard archipelago are observed; these trends are probably driven by a local warming and sea ice extent decline. Similarly, the Barents/Kara regions underwent wet trends (up to 40%), also associated with winter/fall local sea ice loss. Positive late summer TCWV trends above the western Greenland and Beaufort seas (about 20%) result from enhanced upper ocean warming and thereby a local coastal decline in ice extent. The Mackenzie and Siberia enhanced TCWV trends (about 25%) during spring are found to be associated with coincident decreased snow cover and increased vegetation, as a result of the earlier melt onset. Results show drier summers in the Eurasia and western Alaska regions, thought to be affected by changes in albedo from changing vegetation. Other TCWV anomalies are also presented and discussed in relation to the dramatic decline in sea ice extent and the exceptional rise in sea surface temperature. Numéro de notice : A2017-858 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/atmos8120241 date de publication en ligne : 02/12/2017 En ligne : https://doi.org/10.3390/atmos8120241 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89835 [article]

Spatial–temporal variations of water vapor content over Ethiopia: a study using GPS observations and the ECMWF model / Kibrom Ebuy Abraha in GPS solutions, vol 21 n° 1 (January 2017)  

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Using a regional numerical weather prediction model for GNSS positioning over Brazil / Daniele Barroca Marra Alves in GPS solutions, vol 20 n° 4 (October 2016)  

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Diagnostic study of a high‐precipitation event in the Western Mediterranean: adequacy of current operational networks / Samiro Khodayar in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)  

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A multi-instrument and multi-model assessment of atmospheric moisture variability over the Western Mediterranean during HyMeX / Patrick Chazette in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)  

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Water vapor measurements by mobile Raman lidar over the Mediterranean Sea in the framework of HyMeX: application to multi-platform validation of moisture profiles / Julien Totems in EPJ Web of Conferences, vol 119 (2016)  

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Development of an improved empirical model for slant delays in the troposphere (GPT2w) / Johannes Böhm in GPS solutions, vol 19 n° 3 (July 2015)    

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Predicting floods with GPS / Paul Grad in Position, n° 76 (April - May 2015)

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Couplage lidar Raman et GPS pour le sondage de la vapeur d'eau atmosphérique et le positionnement précis / Leslie David (2015)

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Integrated Precipitable Water from GNSS as a climate parameter / Michal Kruczyk in Geoinformation issues, vol 6 n° 1 (2014)  

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Modeling and sensing the vertical structure of the atmospheric path delay by microwave radiometry to correct SAR interferograms / Patrizia Basili in IEEE Transactions on geoscience and remote sensing, vol 52 n° 2 (February 2014)

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