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Improved algorithms for the measurement of total precipitable water and cloud liquid water from SARAL microwave radiometer observations / Rajput Neha Mangalsinh in Marine geodesy, vol 42 n° 4 (July 2019)  

Public [article]  inMarine geodesy > vol 42 n° 4 (July 2019) . - pp 367 - 381 Titre : Improved algorithms for the measurement of total precipitable water and cloud liquid water from SARAL microwave radiometer observations Type de document : Article/Communication Auteurs : Rajput Neha Mangalsinh, Auteur ; Atul Kumar Varma, Auteur Année de publication : 2019 Article en page(s) : pp 367 - 381 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes descripteurs IGN] cryosphère [Termes descripteurs IGN] données altimétriques [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] image GPM [Termes descripteurs IGN] image SSMIS [Termes descripteurs IGN] image TRMM-MI [Termes descripteurs IGN] nuage [Termes descripteurs IGN] précipitation [Termes descripteurs IGN] radiomètre à hyperfréquence [Termes descripteurs IGN] température de luminance [Termes descripteurs IGN] vapeur d'eau Résumé : (auteur) SARAL carried onboard a radar altimeter that provides very precise measurements of the sea surface height (SSH). Like other altimetric missions, SARAL carries a passive microwave radiometer (PMR) for wet tropospheric correction to SSH. In the present study, new algorithms are developed for the retrieval of cloud liquid water (CLW) and total precipitable water vapor (TPW) over the global oceans from PMR measurements of the brightness temperatures. A radiative transfer and genetic algorithm based retrieval scheme is proposed for the estimation of CLW and TPW from SARAL PMR. The comparisons of CLW from PMR with independent measurements from GPM-GMI and SSMIS within and outside ±40° latitudes show correlation (R) of 0.86 and 0.83, bias of 0.7 and −3.61 mg/cm2, and root mean square error (RMSE) of 8.42 and 8.07 mg/cm2, respectively. Similarly, TPW from PMR with GPM-GMI and SSMIS show R of 0.99 and 0.98, bias of −0.04 and −0.03 g/cm2 and RMSE of 0.17 and 0.17 g/cm2, respectively. The retrieval accuracy of CLW and TPW from the new algorithms is compared with these parameters provided in the SARAL geophysical data records as finished products, which showed substantial improvement in the quality of the parameters from the new algorithm. Numéro de notice : A2019-282 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2019.1624662 date de publication en ligne : 12/06/2019 En ligne : https://doi.org/10.1080/01490419.2019.1624662 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93116 [article]

On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state / Alexey Androsov in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 141 - 157 Titre : On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state Type de document : Article/Communication Auteurs : Alexey Androsov, Auteur ; Lars Nerger, Auteur ; Reiner Schnur, Auteur ; Alberta Albertella, Auteur ; Reiner Rummel, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 141 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] assimilation des données [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] données altimétriques [Termes descripteurs IGN] données CHAMP [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] geoïde marin [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] modèle de simulation [Termes descripteurs IGN] modèle océanographique [Termes descripteurs IGN] océanographie dynamique [Termes descripteurs IGN] salinité [Termes descripteurs IGN] température de surface de la mer Résumé : (auteur) General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation. Numéro de notice : A2019-076 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1151-1 date de publication en ligne : 12/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1151-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92190 [article]

Retrieval of significant wave height and mean sea surface level using the GNSS-R interference pattern technique : results from a three-month field campaign / Alberto Alonso-Arroyo in IEEE Transactions on geoscience and remote sensing, vol 53 n° 6 (June 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 6 (June 2015) . - pp 3198 - 3209 Titre : Retrieval of significant wave height and mean sea surface level using the GNSS-R interference pattern technique : results from a three-month field campaign Type de document : Article/Communication Auteurs : Alberto Alonso-Arroyo, Auteur ; Adriano Camps, Auteur ; Hyuk Park, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 3198 - 3209 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] Espagne [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] interférence [Termes descripteurs IGN] niveau moyen des mers [Termes descripteurs IGN] océanographie spatiale [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] réflectométrie par GNSS [Termes descripteurs IGN] vague Résumé : (Auteur) Since 1993, when the European Space Agency (ESA) proposed the use of Global Navigation Satellite Systems reflected signals for sea mesoscale altimetry, a wide range of applications have appeared. This paper focuses on the retrieval of significant wave height (SWH) and the mean sea surface level (MSSL) from a ground-based experiment using the interference pattern technique (IPT). Two different observables on the IPT are analyzed: the oscillation frequency and the angle where coherency is lost. The point where coherency in the reflection process is lost can be related to the Rayleigh criterion for smooth surfaces and helps to determine the SWH. Spectral analysis on the interference pattern helps to determine the MSSL. A three-month field campaign was performed on the “Pont del Petroli” pier, Badalona, Spain, to see how the reflected GNSS signals were affected by coastal sea state and check previous assumptions. Results from this field experiment are shown, confirming that the SWH can be retrieved with accuracy of 6 cm and the MSSL with 4 cm. Estimations of both parameters are obtained every 30 min approximately. Numéro de notice : A2015-284 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2374218 date de publication en ligne : 18/12/2014 En ligne : https://doi.org/10.1109/TGRS.2014.2374218 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76401 [article]

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Tsunami-wave parameter estimation using GNSS-based sea surface height measurement / Keguen Yu in IEEE Transactions on geoscience and remote sensing, vol 53 n° 5 (mai 2015)

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 5 (mai 2015) . - pp 2603 - 2611 Titre : Tsunami-wave parameter estimation using GNSS-based sea surface height measurement Type de document : Article/Communication Auteurs : Keguen Yu, Auteur Année de publication : 2015 Article en page(s) : pp 2603 - 2611 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] estimation des paramètres [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] longueur d'onde [Termes descripteurs IGN] réflectométrie par GNSS [Termes descripteurs IGN] simulation [Termes descripteurs IGN] traitement de données GNSS [Termes descripteurs IGN] tsunami [Termes descripteurs IGN] vague Résumé : (auteur) This paper focuses on the estimation of tsunami-wave parameters (propagation direction, propagation speed, and wavelength) using the Global Navigation Satellite System (GNSS) reflectometry (GNSS-R)-based sea surface height (SSH) measurements. By exploiting multiple surface specular reflection tracks of GNSS signals as well as the geometry of wave propagation direction and the multiple tracks, concise mathematical expressions are derived to determine the propagation direction and speed and wavelength of a tsunami wave. Real tsunami-wave data measured by buoy sensors are employed to model GNSS-R-based SSH measurements by adding Gaussian measurement noise. The simulation results demonstrate that the proposed method can achieve a propagation direction estimation accuracy of about 4.4° and 5.9° when the SSH error standard deviations are 10 and 20 cm, respectively. The propagation speed estimation accuracies are about 12.7 and 17.7 m/s, respectively, under the same conditions when the speed ground truth is 200 m/s. The results also show that the wavelength estimation error can be as large as 100 km when the wavelength ground truth is about 400 km. Better filtering methods are needed to improve the wavelength estimation accuracy by mitigating the effect of the SSH estimation error particularly on the wave trailing edge of small negative magnitudes. Numéro de notice : A2015-632 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78120 [article]

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Oceanwide precise determination of sea surface height from in-situ measurements on cargo ships / Ole Roggenbuck in Marine geodesy, vol 37 n° 1 (March - May 2014)  

Public [article]  inMarine geodesy > vol 37 n° 1 (March - May 2014) . - pp 77 - 96 Titre : Oceanwide precise determination of sea surface height from in-situ measurements on cargo ships Type de document : Article/Communication Auteurs : Ole Roggenbuck, Auteur ; Jörg Reinking, Auteur ; Alexander Härting, Auteur Année de publication : 2014 Article en page(s) : pp 77 - 96 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] données Jason [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] Pacifique (océan) [Termes descripteurs IGN] précision centimétrique Résumé : (Auteur) Thanks to the latest developments in GNSS data processing the antenna heights aboard a ship can be determined with accuracies of up to 5 cm, also in the open ocean. These heights are a good basis to derive precise in-situ data of sea surface heights independently from satellite altimetry. However, for a reliable determination of sea surface heights, some essential hydrostatic and hydrodynamic corrections must be considered, as explained in this paper. Furthermore, an ocean wide determination of sea surface height from measurements on a container ship in the Pacific Ocean is presented. The results are compared with those from the Jason-2 altimeter. Numéro de notice : A2015-164 Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2013.868385 date de publication en ligne : 14/01/2019 En ligne : https://doi.org/10.1080/01490419.2013.868385 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75851 [article]

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Comparison of grid averaged altimeter and buoy significant wave heights in the Northern Indian Ocean / L. Sabique in Marine geodesy, vol 36 n° 1 (January - March 2013)  

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Nontidal ocean loading: amplitudes and potential effects in GPS height time series / Tonie M. van Dam in Journal of geodesy, vol 86 n° 11 (November 2012)    

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Singular spectrum analysis of global mean sea level variations / S. Khelifa in Bulletin des sciences géographiques, n° 26 (octobre 2011)

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The 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)  

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Geoid and high resolution sea surface topography modelling in the mediterranean from gravimetry, altimetry and GOCE data: evaluation by simulation / R. Barzaghi in Journal of geodesy, vol 83 n° 8 (August 2009)

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Large-scale errors in ERS altimeter data / J.Y. Cherniawsky in Marine geodesy, vol 31 n° 1 (March - May 2008)

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Improved recovery of gravity anomalies from dense altimeter data / J.H. Kim (1996)

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Determination of gridded mean sea surface from Topex, ERS-1 and Geosat altimeter data / Y. Yi (1995)

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Estimation of sea dynamic topography, ocean tides, and secular changes from Topex altimeter data / Y.M. Wang (1994)

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