Microscopic observations of core-shell particle structure and implications for atmospheric aerosol remote sensing
Résumé
Tropospheric aerosols play an important role in atmospheric chemistry, Earth’s radiative budget, and climate.
After their generation, aerosols can suffer ageing processes and alter their physicochemical properties. An
accurate accounting for these processes requires observations of the aerosol properties on different temporal
and spatial scales. The current work is dedicated to: (i) study of physicochemical properties and mixing state of
individual particles by means of analytical scanning and transmission electron microscopy for aerosols
collected during episodes of elevated aerosol loading; (ii) analysis of the effect of microphysical properties on
optical characteristics as measured and retrieved by remote sensing; and (iii) investigation of possible
parameterization of aerosol composition and core-shell structure in remote sensing algorithms. The work
presents observations conducted in northern France and western Africa (Senegal) as part of Labex CaPPA
project and SHADOW field campaigns. It includes simultaneous analyses of collected individual particles’
composition and structure, remote sensing and in situ observations of urban/industrial, Saharan dust and
biomass burning particles near the surface and at different altitudes. A series of numerical simulations devoted
to an analysis of the sensitivity of remote sensing observations to aerosol mixing state is conducted. Insights on
a possible parameterization of aerosol core-shell structure in retrieval algorithms are finally presented.