Microphysical and optical characterization of aerosols in urban areas by in situ and balloon flight measurements: application to the study of air quality in Burkina Faso, West Africa.

The work presented is a report on a research stay as part of LE STUDIUM for visiting researchers from September 1 to November 30, 2025, at the Laboratory of Physics and Chemistry of the Environment and Space (LPC2E) of the CNRS in Orléans. This is a research stay whose objective is to apply an in-depth methodology for the microphysical, optical, and radiative characterization of aerosols at the surface and at altitude. This technique is based on in situ measurements taken by the LOAC instrument during flights using weather balloons, climate model simulations, and data from airborne and satellite sensors. This enabled us to understand the measurement methodology using the LOAC instrument, which has already been tested by the CNRS's LPC2E, and aerosol modeling using ECSM2 model simulations. Based on the measurement campaigns carried out, we analyzed the aerosol profile as well as that of PM1, PM2.5, and PM10, and the volume size distribution of the particles. Also, based on aerosol extinction evaluated using the Mie code, we were able to determine the aerosol optical depth (AOD), which is an integration of the extinction coefficient across the atmospheric layer. In addition, this trip was an opportunity to participate in a validation study of the ATLID lidar aboard the EarthCare satellite, which has been in orbit since May 2024. This has enabled us to learn a new approach to the optical and microphysical characterization of aerosols that can be applied in Burkina Faso and West Africa in general.