In the work conducted for my thesis, I studied atmospheric aerosols and their transfer from the atmosphere to the surface by precipitation. The main strategy I followed is based on the observation of wet deposition on different time scales, interannual on one hand and intra-event on the other. It also relies on their observation in environments marked in terms of aerosol load and chemical composition, but also of atmospheric dynamics and precipitation. The two axes of my work deal with distinct and complementary issues in the study of wet deposition.

The first axis focused on wet deposition in the Sahel, a semi-arid region where the scavenging of mineral dust from the atmosphere is a key process to constrain the atmospheric mass balance of these compounds. Based on long-term observations of the INDAAF network in Niger and Mali from 2007 and 2015, I have investigated the role of cold pool phenomena on wet deposition in this region.

The second axis focused on the study of the intra-event evolution of the chemical composition of the wet deposition by precipitation. This work was conducted in urban environment for various situations of rain, concentration and composition of aerosols. I participated in the development of a new collector allowing me to sample wet deposition in successive fractions during the rain. Chemical analyses of dissolved and particulate deposits allowed me to discuss both the origin of aerosols, but also the mechanisms involved in their deposition.

Salle 774 du bâtiment Lavoisier à l’Université Paris Cité – 15, rue Jean-Antoine de Baïf, 75013 Paris

Yelva ROUSTAN  – École Nationale des Ponts et Chaussées (Rapporteur)

Nikolaos MIHALOPOULOS – Université de Crète (Rapporteur)

Karine DESBOEUFS – Université Paris Cité (Examinatrice)

Marie Pierre TURPAULT – Institut national de recherche pour l’agriculture, l’alimentation et l’environnement  (Examinatrice)

Corinne GALY-LACAUX  – Université Paul Sabatier – Toulouse III (Examinatrice)

Yves BALKANSKI – Université Paris Saclay (Examinateur)

Benoit LAURENT – Université Paris Cité (Directeur de thèse)