Centre dedocumentation
scientifique

Absolute calibration of Jason radar altimeters from GPS kinematic campaigns over Lake Issykul / J.F. Cretaux in Marine geodesy, vol 34 n° 3-4 (July - december 2011)  

Public [article]  inMarine geodesy > vol 34 n° 3-4 (July - december 2011) . - pp 291 - 318 Titre : Absolute calibration of Jason radar altimeters from GPS kinematic campaigns over Lake Issykul Type de document : Article/Communication Auteurs : J.F. Cretaux, Auteur ; Stéphane Calmant, Auteur ; V. Romanovski, Auteur ; Félix Perosanz, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 291 - 318 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] altimètre radar [Termes IGN] campagne GPS [Termes IGN] étalonnage d'instrument [Termes IGN] GPS en mode pseudo-cinématique [Termes IGN] Jason [Termes IGN] Kirghizistan Résumé : (Auteur) This study presents results of calibration/validation (C/V) of Jason-1 and Jason-2 satellite altimeters over Lake Issykkul located in Kyrgyzstan, which was chosen as a dedicated radar altimetry C/V site in 2004. The objectives here are to estimate absolute altimeter biases and to quantify the altimetry instrument error budgets for lakes studies, including errors associated with the atmosphere media delay corrections of the radar signal, and with the different retracking mode used over “nonocean” surface. The C/V is conducted using various equipments, for example, GPS local network, moving GPS along the satellites tracks over the Lake Issykkul, in situ level gauges and weather stations. The absolute bias obtained for Jason-1 and Jason-2 from field campaigns conducted in 2008, 2009 and 2010 are 96 + 40 mm and 162 + 42 mm, respectively. The bias calculated for Jason-1 is in close agreement with estimates done at other dedicated C/V sites in the ocean, but the Jason-2 bias still differs by 1–2 cm with ocean C/V estimates. The relative bias (Jason-2 minus Jason-1) deduced from measurements during the tandem mission is estimated at 81 + 10 mm. The accuracy of Jason-1 and Jason-2 for the determination of the lake level variations as compared to the historical in situ gauges of the Lake Issykkul is 33 and 31 mm RMS, respectively. The bias between the two modes of retracking available on Jason-2 Geophysical Data Records (GDRs) has been estimated over the two first years of Jason-2 data over the Lake Issykkul. We found an average value of 234 + 40 mm, which is in good agreement with results obtained in a previous study on the Envisat satellite (Crétaux et al. 2009). Lake level studies using Jason-2 or Envisat must therefore take this relative bias into account if both retracked altimetry heights are used. Numéro de notice : A2011-462 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2011.584834 Date de publication en ligne : 22/08/2011 En ligne : https://doi.org/10.1080/01490419.2011.584834 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31356 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
230-2011031	RAB	Revue	Centre de documentation	En réserve 3L	Disponible

An absolute calibration site for radar altimeters in the continental domain: Lake Issykkul in Central Asia / J.F. Cretaux in Journal of geodesy, vol 83 n° 8 (August 2009)  

Public [article]  inJournal of geodesy > vol 83 n° 8 (August 2009) . - pp 723 - 735 Titre : An absolute calibration site for radar altimeters in the continental domain: Lake Issykkul in Central Asia Type de document : Article/Communication Auteurs : J.F. Cretaux, Auteur ; Stéphane Calmant, Auteur ; V. Romanovski, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 723 - 735 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] altimètre radar [Termes IGN] Asie centrale [Termes IGN] erreur instrumentale [Termes IGN] erreur systématique [Termes IGN] étalonnage d'instrument Résumé : (Auteur) Altimetry missions such as Topex/Poseidon, Jason-1, GFO and ENVISAT have been widely used in the continental domain over lakes, rivers and wetland although they were mostly dedicated to oceanic studies. Knowledge of the instrumental biases is a key issue. Numerous sites have been dedicated to calibration purposes, either in the oceanic domain (Harvest offshore platform in California, Corsica, Bass Strait in Australia) or over lakes (Lake Erie in United States). A new site (Lake Issykkul in Kirghizstan) is proposed for calibration in the continental domain. This lake is covered by past (T/P) and current radar altimetry satellites (Jason-1, T/P, GFO, and ENVISAT). Several in situ water levels and local meteorological variables are available at the site. Located in a mountainous area, it offers an opportunity for calibration far away from all other existing sites and very different environment contexts. Two GPS campaigns have been conducted on the lake in 2004 and in 2005. They consisted of cruises with stations installed onboard a boat following the satellite ground tracks, and onshore settings. This enabled estimating a bias for each altimeter and each tracking algorithm available. Biases obtained for Envisat, GFO, T/P and Jason-1 using the default ocean tracker (respectively, 48.1 + 6.6, 7.5 + 4.0, 0 + 4.3 and 7.0 + 5.5 cm) agree with biases published at the other calibration sites. For Jason-1, there is a significant disagreement with results obtained in the ocean field (7 cm instead of 13 cm) but is coherent with bias obtained on the Lake Erie site. Erroneous estimates of the sea state bias correction from non-oceanic-like waveforms is discussed as a possible explanation. Errors in the ionospheric, wet and dry tropospheric corrections for the continental domain are also highlighted and quantified. Copyright Springer Numéro de notice : A2009-324 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 0.1007/s00190-008-0285-y En ligne : https://doi.org/10.1007/s00190-008-0285-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29954 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-09071	SL	Revue	Centre de documentation	Revues en salle	Disponible