The Contribution of Dust Semi-Direct Effects to Uncertainties in Dust-Radiation Interactions over the North Atlantic Ocean.

Mineral dust, an important component in the atmosphere, is one of the three main absorbing aerosols with significant impacts on the Earth’s radiative budget. Despite its importance, there are substantial uncertainties in dust radiative effect, which have partly been linked to uncertainties in dust absorption properties often facilitated by uncertainties in dust size distribution and mineralogical composition. In addition, most estimates of dust’s effective radiative effect do not fully account for uncertainties from all pathways of dust-radiation interactions, including dust semi-direct effect (SDE) – which is the adjustment in dust radiative effects due to the cloud responses to dust absorption of radiation. In this presentation, we examine the role of dust SDE in its effective radiative effect by understanding how dust's physical characteristics and its absorption properties contribute to uncertainties in dust SDE and, consequently, the dust-radiation interactions over the North Atlantic Ocean. Our result will underscore the importance of accounting for dust longwave absorption, its geometric thickness, and vertical location in dust-radiation interactions and estimates of dust’s effective radiative effects.