Particle Mineralogy, Boundary Layer Mixing, and the Climate Response to Soil Dust Aerosols

Columbia University, New York NY

Investigators

Abstract

The PIs will combine recent compilations of optical properties of various atmospheric-borne minerals and their regional distribution in order that dust optical properties reflect the mineralogy of their source region. They will address the following questions: (i) How does the composition of a dust plume vary along its trajectory away from the source region, as the size distribution changes with the preferential deposition of larger particles? Is the fraction of certain minerals enriched with distance from the source? (ii) What is the horizontal distribution of atmospheric concentration and deposition for particular minerals, e.g., carbonates, clays such as illite and kaolinite, and hematite? (iii) What is the radiative forcing by dust aerosols and the climate response if the mineralogy of the source region is accounted for? (iv) What regional errors in forcing and the associated climate response result from assigning optical properties of far-traveled Saharan dust to each source region? (v) What is the radiative effect of treating particles as external mixtures? To address these questions the PIs will undertake modeling that includes the effect of subgrid scale fluctuations of surface wind upon dust emission. The work is important because it will enhance our understanding of the role of dust particle mineralogy upon climate.