Dataset Edition

Présentation générale
Nom du jeu de donnéesLNG_Aerosol
Créé le2018-08-16
Date de début (yyyy-mm-dd)2017-09-05Date de fin (yyyy-mm-dd)2017-09-12
Accès aux données Dataset as provided by the Principal Investigator


Description du jeu de données
RésuméThe airborne high spectral resolution (HSR) lidar LNG operated from the SAFIRE Falcon 20 during the AEROCLO-sA campaign. The aircraft was based in Walvis Bay, Namibia, and performed 10 flights for ~30 flight hours, from 5 to 12 September 2017.
Strategie d'observationLNG made observations of atmospheric reflectivity at 3 wavelengths: 355, 532 and 1064 nm. In addition, LNG measures polarized signal at 355 nm.

LNG operated mostly in nadir pointing mode while the aircraft was flying around 8 to 10 km amsl. LNG also made zenith pointing measurements when the Falcon was performing downward spirals (sometimes down to the surface) for the sake of in situ sampling and measurements by the airborne sunphotometer PLASMA located on top of the aircraft.
RéférencesThe LNG system is described in Bruneau et al. (2015): Didier Bruneau, Jacques Pelon, Frédéric Blouzon, Joseph Spatazza, Pascal Genau, et al.. 355-nm high spectral resolution airborne lidar LNG: system description and first results. Applied optics, Optical Society of America, 2015, 54 (29), pp.8776-8785.
Description de l'instrument
Type d'instrumentEarth Remote Sensing Instruments > Active Remote Sensing > Profilers/Sounders > Lidar/Laser Sounders
Observation frequency5 s
Horizontal coverageOn the order of 1000 km (depends on the aircraft flight duration)
Vertical coverage0-12 km
Information géographique
Site 1
SiteAircraft operations from Walvis Bay, Namibia
Type de plateformeAIRCRAFT > F-FALCON 20
Longitude minimale (°)8Longitude maximale (°)20
Latitude maximale (°)-16Latitude minimale (°)-24
Altitude min0Altitude max10000
Instrument environmentThe aircraft was equipped with active and passive remote sensors as well as in situ probes to document aerosol optical and radiative properties over land and over maritime stratocumulus clouds. In addition to LNG, the Falcon 20 also housed the MICROPOL‐UV and OSIRIS instruments measuring total and polarized radiance at several wavelengths between the ultra‐violet and the middle infrared. The solar photometer PLASMA was flown for the first time to measure the extinction by aerosols in cloud‐free conditions or above stratocumulus. A dropsonde releasing system, up‐ and down‐looking pyranometers and pyrgeometers, a nadir‐facing CLIMAT infrared radiometer, together with pressure, temperature, humidity and wind sensors, and optical sensors for cloud and aerosol microphysics completed the instrumental suite of the Falcon 20.
Paramètres mesurés
Paramètre mesuré 1
Nom du paramètreAtmospheric reflectivity
Mot-clé du paramètreAtmosphere > Aerosols
Méthodologie d'acquisition et qualitéThe signal backscattered to the LNG system telescope at the 3 wavelength is range-square-corrected to produce atmospheric reflectivity. This variable is provided in the LNG2* files with a vertical resolution of 6 m and a horizontal resolution of ~1 km (profiles are averaged over 5s, with an aircraft flying at 200 m/s). The LNG atmospheric reflectivity data are provided as ascii files, containing a header in which a number of information regarding the aircraft position and atitude is provided. below the header, the data is dispatched in 5 columns. The first column is altitude over a vertical range of [-2, 12] km. The second column is high spectral resolution reflectivity at 355 nm. The Third column is depolarization at 355 nm. The forth column is reflectivity at 532 nm and the fifth column is reflectivity at 1064 nm. Reflectivity at 355 nm was only available during the first for flights on 5 and 6 September. Data in the 2nd column is null in case the high spectral resolution injection did not work. Note: the data acquired in zenith pointing mode is to be used with caution.
Date de début (yyyy-mm-dd)2017-09-05Date de fin (yyyy-mm-dd)2017-09-12
Précision du capteur / Incertitude
Derived parameter 1
Nom du paramètreAerosol Backscatter
Mot-clé du paramètreAtmosphere > Aerosols > Aerosol Backscatter
Unité1/km/sr - 1/km/sr
Méthodologie d'acquisition et qualitéAttenuated backscatter coefficient profiles are derived from atmospheric reflectivity profiles by normalizing the atmospheric reflectivity above the aerosol layers to the molecular backscatter coefficient profiles, at all 3 wavelengths. This is possible since the LNG was well aligned. Hence the slope of the lidar reflectivity above 6 km amsl matched that of the molecular backscatter derived from dropsonde measurements of pressure and temperature. This variable is provided in the ABC2* files.
Date de début (yyyy-mm-dd)2017-09-05Date de fin (yyyy-mm-dd)2017-09-12
Précision du capteur / Incertitude
Derived parameter 2
Nom du paramètreAerosol Extinction
Mot-clé du paramètreAtmosphere > Aerosols > Aerosol Extinction
Unité1/km - 1/km
Méthodologie d'acquisition et qualitéThe extinction coefficient profiles are obtained from the attenuated backscatter coefficient profiles using an Klett inversion procedure, and accounting for multiple scattering in the massive biomass burning aerosol plumes observed over Namibia during the AEROCLO-sA campaign. More details on the inversion procedure are available from the PI. This variable is provided in the EXT2* files.
Date de début (yyyy-mm-dd)2017-09-05Date de fin (yyyy-mm-dd)2017-09-12
Précision du capteur / Incertitude30%
Information sur l'utilisation des données
Conditions d'utilisation des donnéesThe Principal Investigator(s) of the LNG data for the AEROCLO-sA campaign is Cyrille Flamant. If you intend to use the following data please consult with him via e-mail: Please consider authorship for the PI whenever using the LNG data. The LNG data was acquired with the support of Frédéric Blouzon and Abdel Abchiche (DT-INSU), Mathilde van Haecke (LATMOS) and with the help of the Falcon 20 operator (SAFIRE,, a joint entity between CNRS, Météo-France and CNES).
Charte d'accès aux donnéesAEROCLO data policy
Base de donnéesAEROCLO-sA on BAOBAB
Format des fichiers de donnéesNetCDF