PhD in Physics and Chemistry, Sciences de la Matière, du Rayonnement et de l’Environnement (SMRE)
Thesis defended on 22th November 2016
Laboratoire d'Optique ATmosphérique (LOA) and
PhysicoChimie des Processus de Combustion et de l'Atmosphère (PC2A)
Title and thesis summary
Mineral particle extinction spectra and retrieval of complex refractive indices in the infrared and UV-visible spectral region
Due to their ability to absorb and scatter radiations, aerosols play an important role in the Earth’s radiative budget. However, quantitative estimations of their effects on climate are quite uncertain due to their large spatial and temporal variability in terms of concentration and physical properties. Measurements from remote sensing instruments are efficient tools to observe and investigate aerosol distributions from regional to global scales. Nevertheless, to fully exploit instrument capabilities, precise optical properties – dependent on chemical or mineralogical properties – are needed. These properties are linked by the Complex Refractive Index (CRI), which represents one of the main sources of uncertainty for studying aerosols from remote sensing instruments.
The objective of this study is to propose and exploit a new methodology, aiming to determine precise CRI of particles. For this purpose, a new robust and versatile approach has been developed and implemented. Moreover, to determine capabilities of this approach, validation of each step in the procedure for CRI determination has been realized. The complete approach has been also applied for suspended particles of amorphous and crystalline SiO2, which are the major fraction of volcanic and mineral dust aerosols.
Lastly, first results from collected samples from measurement campaigns are also presented. These results highlight the potential of the proposed approach to determine CRI, in order to improve the aerosol measurement exploitations by remote sensing instruments.
PETITPREZ, Denis and HERBIN, Hervé
FORMENTI, Paola and SELLEGRI Karine
CLARISSE, Lieven and TANRE, Didier
Financing: 50% Labex CaPPA; 50 % Région Nord Pas de Calais
Laboratories: PC2A and LOA