Speaker: Dr. Adeyemi Adebiyi of UCLA

Title: "How much solar radiation does atmospheric mineral dust absorb?"

Abstract: Mineral dust particles are critical to the Earth’s climate system because they account for
approximately ~25 % of the shortwave radiation scattered and absorbed by all aerosols in the
atmosphere. But despite the importance of these radiative effects, the amount of shortwave
radiation absorbed by atmospheric dust remains largely unclear. This is because knowledge of
dust absorption properties, characterized by the dust aerosol absorption optical depth, primarily
depends on the dust size distribution and the complex refractive index, which are difficult to
observe from remote-sensing platforms. As a result, climate model simulations and retrieval
algorithms rely on certain assumptions about dust properties that have led to significant
uncertainties in their estimation of the global dust absorption optical depth. In this talk, I will
describe a framework that leverages dozens of in-situ measurements of the dust size distribution
and single-scattering albedo to obtain a more accurate constraint on the global dust absorption
optical depth. I will show that atmospheric dust is much coarser with significant spatial
variability in the imaginary refractive index than represented in climate models. Consequently, I
will show that amount of solar radiation absorbs by dust differs substantially from what climate
models simulate, which has important implications for the Earth’s energy balance