High-Resolution Measurements of Mineral Dust Light Absorption
TOMMASO ISOLABELLA, Clarissa Baldo, Marco Brunoldi, Mathieu Cazaunau, Claudia Di Biago, Paola Formenti, Federico Mazzei, Edouard Pangui, Franco Parodi, Paolo Prati, Bénédicte Picquet-Varrault, Virginia Vernocchi, Dario Massabò, University of Genoa
Abstract Number: 317
Working Group: Aerosol Physics
Abstract
Desert dust aerosols play a critical role in Earth's climate system by modulating the radiative balance through absorption and scattering of radiation. Accurately characterizing the optical properties of these aerosols is essential for improving climate models and remote sensing applications.
We present new high-resolution absorption measurements of desert dust obtained using the Broadband Light Analyzer of Complex Aerosol (BLAnCA), a novel instrument designed to provide continuous, broadband spectral absorption data with unprecedented resolution.
BLAnCA employs an innovative optical design that combines a broadband light source with a high-sensitivity spectrometer, enabling spectral absorption measurements from the ultraviolet across the visible to near-infrared (UV-NIR) range.
In this study, we analyzed samples of mineral dust collected from multiple arid regions and conducted controlled laboratory experiments to measure their spectrally-resolved absorption coefficients.
The desert dust samples were generated in the laboratory starting from dust specimens collected in several deserts around the world. The samples were then analyzed with BLAnCA to measure optical absorption, as well as with X-ray diffraction for the mineralogical composition.
We observed distinct absorption characteristics among dust samples from different geographical sources, suggesting that local mineralogical differences play a crucial role in their optical behavior. In particular, while all mineral dust aerosol samples share the same generic optical features, their fine structure is markedly different. The slope and the location of the inflection points in the absorption coefficient plots are different across the samples, and can be determined with BLAnCA’s high resolution and linked to the aerosol mineralogical composition and size distribution.
This work highlights BLAnCA’s capabilities as a powerful tool to distinguish fine structures in the optical absorption of aerosol, which can then be linked to its composition in order to perform source identification and apportionment based solely on optical data.