19/04/2021
The Human Resources Strategy for Researchers

CDD 12m H/F Polarimetry and spectroscopy to reveal the intrinsic depolarization of dust aerosol in laboratory

This job offer has expired


  • ORGANISATION/COMPANY
    CNRS
  • RESEARCH FIELD
    Physics
  • RESEARCHER PROFILE
    First Stage Researcher (R1)
  • APPLICATION DEADLINE
    10/05/2021 23:59 - Europe/Brussels
  • LOCATION
    France › VILLEURBANNE
  • TYPE OF CONTRACT
    Temporary
  • JOB STATUS
    Full-time
  • HOURS PER WEEK
    35
  • OFFER STARTING DATE
    17/05/2021

OFFER DESCRIPTION

Building on the existing Pi-polarimeter lab (Miffre et al., 2016), the candidate will:
- Contribute to the development of a Pi polarimeter in the IR spectral range.
- Minimize polarization and wavelength interference in the resulting multispectral polarimeter.
- Evaluate the variation of the PDR (particle depolarization ratio, see assignments above for details) of the dust aerosol as a function of dust particle size and mineralogy to reveal the intrinsic PDR of the mineral dust taking into account its complexity.

Scientific background and motivation
As noted in the latest IPCC report (IPCC, 2013), atmospheric aerosols are complex physical objects that can somewhat counteract the warming effect of most greenhouse gases. However, to draw such a conclusion, one must first quantify the interaction of light with such complex systems. The mineral aerosol is indeed a complex physical object, exhibiting a wide range of sizes, a very irregular shape, sometimes with sharp edges and surface roughness, which prevents analytical solutions to Maxwell's equations (Mishchenko et al., 2002), thus limiting our ability to quantify the interaction of these complex systems with the electromagnetic field. Numerical simulations of light scattering do exist, but they rely on assumptions that must be carefully tested. For example, while light backscatter is of paramount importance for future satellite lidar missions (MESCAL, Earth Care, or ACCP) as highlighted by CNES in France, it is only recently that light backscatter has been observed in the laboratory for particles in ambient air (Miffre et al., 2016) where a unique polarimeter (UV, VIS) operating at a specific lidar backscatter angle Pi has been designed. This Pi polarimeter quantifies the deviation of particles from isotropy through precise measurements of the particle depolarization ratio (PDR). It is not only polarimetry that is involved, spectroscopy is also involved, as PDR measurements are currently made at multiple wavelengths, spanning the UV and VIS spectral ranges (Miffre et al., 2016).

Work plan
The purpose of this call is to extend this unique laboratory Pi polarimeter to the IR spectral range in order to quantify the PDR spectral dependence, which is critical for aerosol identification (Burton et al., 2016). Specifically, fundamental and intensive laboratory work is needed to study the PDR of desert-origin mineral aerosol at the exact backscatter angle for each property of that aerosol (size, origin). These unique laboratory measurements of the intrinsic PDR of this aerosol will then be made available to a large scientific community, in France and abroad, through publications and conferences.

References
Burton, S. et al, Atmos. Chem. Phys. 15, 13453-13473, (2016).
IPCC, Intergovernmental Panel on Climate Change: the physical science basis. (2013).
Mishchenko, M. I. et al: Scattering, Absorption, and Emission of Light by Small Particles, Cambridge, (2002).
Miffre, A., T. Mehri, M. Francis, and P. Rairoux, UV-VIS depolarization from Arizona Test Dust particles at exact backscattering angle, J. Quant. Spec. Rad. Transf. 169, 45-59, (2016).

The ILM is a joint research unit between the University of Lyon (UCBL) and the Centre National de la Recherche Scientifique (CNRS). It comprises about 300 people, including researchers, teacher-researchers, research support staff, PhD students and post-doctoral fellows. The ILM is composed of 17 research teams organized along six thematic axes, addressing various topics ranging from solid state physics and nanosciences to ultrafast optics and matter-light interaction. The iLM is located on the Lyon Tech La Doua campus in Villeurbanne.

The research activity will be carried out under the supervision of A. Miffre of the ATMOS research group (group leaders Prof. Rairoux and Dr. Ross). This 12-month position funded by CNES will be located at the Institut Lumière Matière (iLM) under the supervision of Dr. A. Miffre of the ATMOS research group (team leaders Prof. Rairoux and Dr. Ross).

More Information

Eligibility criteria

Candidate profile
To carry out this research project, candidates must hold a PhD in optics (polarimetry, spectroscopy, laser physics) and/or atmospheric physics (atmospheric aerosols, satellite remote sensing). Precision is primarily needed to reveal the intrinsic ability of this complex aerosol to depolarize laser light.

Additional comments

For more information, please contact
Alain Miffre
HDR lecturer at the iLM
Atmos research group of the ILM
alain.miffre@univ-lyon1.fr

Web site for additional job details

Required Research Experiences

  • RESEARCH FIELD
    Physics
  • YEARS OF RESEARCH EXPERIENCE
    None

Offer Requirements

  • REQUIRED EDUCATION LEVEL
    Physics: PhD or equivalent
  • REQUIRED LANGUAGES
    FRENCH: Basic
Work location(s)
1 position(s) available at
Institut Lumière Matière
France
VILLEURBANNE

EURAXESS offer ID: 630870
Posting organisation offer ID: 20986

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