UFR de Physique

Propositions de stages en laboratoire -- M2

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Study of nighttime aerosol properties and variability

  • Option International « Atmospheric Environnement » du parcours Lumière-Matière
  • Laboratoire: Laboratoire d'Optique Atmosphérique (LOA )
  • Responsable du stage: GOLOUB Philippe (Philippe.Goloub@univ-lille1.fr,
  • Co-responsable(s): I. Popovici, Q.Y Hu
  • Mots clés: aerosols, variability, remote sensing, Lidar, sun/moon photometry
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Aerosol, water vapor and clouds are highly variable components of the Earth’s atmosphere and playing a key role in the climate and air quality. Several remote sensing measurement techniques are being developed to monitor the vertical distribution and temporal evolution of aerosols, water vapor and clouds. Among them, passive photometry provides a large set of columnar aerosols properties, whereas active remote sensing technique such as LiDAR (Elastic and Raman receivers) can provide a description of vertical structure of the atmosphere in term of aerosols and cloud properties as well as water vapor mixing ratio or relative humidity. The main atmospheric objects that will be addressed during the internship are aerosols and their variability, variability that is high due the diversity and characteristics of their sources. The studies of their time variability are mostly performed during daytime since passive remote sensing instruments, like sun-photometer, are relying on solar radiation (Mortier et al., 2013, 2016). For now more than 3 years (March 2013), two lunar-photometers, belonging to LOA, have been setup, one in Africa (near Dakar, IRD/LOA geophysical platform) and the second one in Villeneuve d’Ascq (LOA atmospheric platform). At present time, a network lunar-photometers is expanding in Europe. Theses new instruments provide relevant nighttime spectral Aerosol Optical Depth (AOD) that are very valuable to constrain LiDAR measurements inversion (= retrieve aerosol profile), columnar water vapor content and provide extra knowledge on aerosols Volume Size Distribution (VSD). The main objectives of the internship are to analyze nighttime aerosol properties as revealed from by LiDAR/photometer synergy and compare them to daytime properties. In a first part, a critical analysis of nighttime AOD has to be performed. Then, the analysis of nighttime aerosol extinction profiles and LiDAR ratio (useful parameter to classify aerosol type) will be made. A focus, we’ll be considered on the SHADOW-2 campaign (Africa), as well as on pollution events and aerosol transport events over Lille. Interpretation of nighttime aerosol properties and variability will additionally be supported by i) water vapor profiles provided by Raman LiDAR, ii) cloud properties such as altitude, thickness and distance to aerosol layer.