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Etude des propriétés hygroscopiques des aérosols atmosphériques

Abstract : Aerosol particles play a dominant role in the earth's climate, especially through absorption and diffusion of the solar radiation. The hygroscopicity of these particles is an important parameter which describes their capacity to increase their diameters by water condensation according to the relative humidity. The purpose of this work is to study the hygroscopicity of the atmospheric particles with a HTDMA developed at the laboratory. Our work is based on measurements carried out in source areas (Marseille, Grenoble) and in a background area (puy de Dôme, 1465m). Generally, the measured hygroscopicity is more important in the background area than in the source areas. This information, supported by our laboratory measurements, highlights the impact of the "aerosol ageing" phenomenon on its hygroscopicity by condensation of volatile compounds on their surface, or by formation of secondary compounds in aqueous-phase reactions in cloud. The specificity of this study is also the coupling of the hygroscopicity properties with the aerosols chemical composition measured by AMS. This coupling allows us to show, with the ZSR theory, that the aerosol hygroscopicity could be calculated from its chemical composition, with an average precision of about 5%, when the aerosol mixing state in taken into account. Finally, our results show that the aerosol is always present as an external mixture, which constitutes an important information to evaluate the aerosol radiative impact (direct or indirect).
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Submitted on : Tuesday, August 21, 2012 - 2:47:45 PM
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  • HAL Id : tel-00724536, version 1

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Vincent Michaud. Etude des propriétés hygroscopiques des aérosols atmosphériques. Physique Atmosphérique et Océanique [physics.ao-ph]. Université Blaise Pascal - Clermont-Ferrand II, 2009. Français. ⟨NNT : 2009CLF21997⟩. ⟨tel-00724536⟩

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