Improved Constraints on Hematite Refractive Index for Estimating Climatic Effects of Dust Aerosols (Invited)

Uncertainty in desert dust composition poses a big challenge to understanding Earth’s climate across
different epochs. Of particular concern is hematite, an iron-oxide mineral dominating the solar
absorption by dust particles, for which current estimates of absorption capacity vary by over two
orders of magnitude. Here, we show that laboratory measurements of dust composition, absorption,
and scattering provide valuable constraints on the absorption potential of hematite, substantially
narrowing its range of plausible values. The success of this constraint is supported by results from an
atmospheric transport model compared with station-based measurements. Additionally, we identify
substantial bias in simulating hematite abundance in dust aerosols with current soil mineralogy
descriptions, underscoring the necessity for improved data sources. Encouragingly, the next-
generation imaging spectroscopy remote sensing data hold promise for capturing the spatial
variability of hematite. These insights have implications for enhancing dust modeling, thus
contributing to efforts in climate change mitigation and adaptation.