UFR de Physique

Propositions de stages en laboratoire -- M2

Les offres sont actualisées en mai. Par exemple, les offres de stages pour l'année universitaire 2015-2016 seront mises en place en mai 2015, les offres de stages pour l'année universitaire 2016-2017 seront mises en place pour en mai 2016, etc.

Global scale characterization of the relation between cloud heterogeneity and retrieved satellite cloud parameters

  • Option International « Atmospheric Environnement » du parcours Lumière-Matière
  • Laboratoire: Laboratoire d'Optique Atmosphérique (LOA )
  • Responsable du stage: CORNET Céline (celine.cornet@univ-lille1.fr,
  • Mots clés: Clouds, Satellite Remote Sensing, Cloud heterogeneity
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Clouds cover 60-70% of the Earth. They are key parameters of the radiative and hydrological budget of the Earth (IPCC, 2013). The global and continuous monitoring of their properties and evolutions are thus of major importance. Among many satellite radiometers, POLDER/PARASOL, which gave measurements between 2005 and 2013 and 3MI/MET-SG, which will be launched at the horizon 2021 are multi-angular radiometers. In order to obtain cloud properties from satellite measurements, we need to define a cloud model, which so far is, for computation time and simplicity reasons, a flat, homogeneous cloud with horizontal infinite extensions. In reality, clouds present lot of heterogeneities, which, as numerous studies showed, lead to errors related to the sub-pixel variabilities, the so-called plan-parallel bias, and related to the geometrical configuration of the measurements. The POLDER and 3MI are multi-angular and consequently bring the possibility to characterize, in many situations the geometrical effects. The quasi-simultaneity of their measurements with higher spatial resolution radiometers such as MODIS and Met-Image, should also allow characterizing the plan-parallel bias. The purpose of this training consists to study the relation between heterogeneity indicators as the radiances or optical thickness sub-pixel (or angular) variability and the bias/errors due to the homogeneous cloud assumption computed as the difference between the optical thickness retrieved at the two different scales of POLDER and MODIS. The student will have to learn about the measurements and cloud products of the passive instruments, POLDER and MODIS and to study the relation described previously for different types of clouds, different latitudes and seasons.