Atmospheric measurement techniques . vol 10 n° 7Paru le : 01/07/2017 |
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Ajouter le résultat dans votre panierStudy and mitigation of calibration factor instabilities in a water vapor Raman lidar / Leslie David in Atmospheric measurement techniques, vol 10 n° 7 (July 2017)
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Titre : Study and mitigation of calibration factor instabilities in a water vapor Raman lidar Type de document : Article/Communication Auteurs : Leslie David, Auteur ; Olivier Bock , Auteur ; Christian Thom , Auteur ; Pierre Bosser , Auteur ; Jacques Pelon, Auteur Année de publication : 2017 Projets : VEGAN / Bock, Olivier Article en page(s) : pp 2745 - 2758 Note générale : bibliographie
This work was developed in the framework of project VEGA and supported by the French national program LEFE/INSU.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Atmosphère
[Termes IGN] azote
[Termes IGN] étalonnage d'instrument
[Termes IGN] fibre optique
[Termes IGN] lidar Raman
[Termes IGN] retard troposphérique
[Termes IGN] vapeur d'eauRésumé : (auteur) We have investigated calibration variations in the Rameau water vapor Raman lidar. This lidar system was developed by the Institut National de l'Information Géographique et Forestière (IGN) together with the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). It aims at calibrating Global Navigation Satellite System (GNSS) measurements for tropospheric wet delays and sounding the water vapor variability in the lower troposphere. The Rameau system demonstrated good capacity in retrieving water vapor mixing ratio (WVMR) profiles accurately in several campaigns. However, systematic short-term and long-term variations in the lidar calibration factor pointed to persistent instabilities. A careful testing of each subsystem independently revealed that these instabilities are mainly induced by mode fluctuations in the optic fiber used to couple the telescope to the detection subsystem and by the spatial nonuniformity of the photomultiplier photocathodes. Laboratory tests that replicate and quantify these instability sources are presented. A redesign of the detection subsystem is presented, which, combined with careful alignment procedures, is shown to significantly reduce the instabilities. Outdoor measurements were performed over a period of 5 months to check the stability of the modified lidar system. The calibration changes in the detection subsystem were monitored with lidar profile measurements using a common nitrogen filter in both Raman channels. A short-term stability of 2–3 % and a long-term drift of 2–3 % per month are demonstrated. Compared to the earlier Development of Methodologies for Water Vapour Measurement (DEMEVAP) campaign, this is a 3-fold improvement in the long-term stability of the detection subsystem. The overall water vapor calibration factors were determined and monitored with capacitive humidity sensor measurements and with GPS zenith wet delay (ZWD) data. The changes in the water vapor calibration factors are shown to be fairly consistent with the changes in the nitrogen calibration factors. The nitrogen calibration results can be used to correct the overall calibration factors without the need for additional water vapor measurements to within 1 % per month. Numéro de notice : A2017-868 Affiliation des auteurs : LASTIG LOEMI+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/amt-10-2745-2017 Date de publication en ligne : 31/07/2017 En ligne : https://doi.org/10.5194/amt-10-2745-2017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89882
in Atmospheric measurement techniques > vol 10 n° 7 (July 2017) . - pp 2745 - 2758[article]