Atmospheric Chemistry and Physics

Abstract. Mineral dust is one of the major components of the world’s aerosol mix, having a number of impacts within the Earth system. However, the climate forcing impact of mineral dust is currently poorly constrained, with even its sign uncertain. As Australian deserts are more reddish than those in the Northern Hemisphere, it is important to bet-ter understand the physical, chemical and optical properties of this important aerosol. We have investigated the proper-ties of Australian desert dust at a site in SW Queensland, which is strongly influenced by both dust and biomass burn-ing aerosol. Three years of ground-based monitoring of spectral optical thickness has provided a statistical picture of gross aerosol properties. The aerosol optical depth data showed a clear though moderate seasonal cycle with an annual mean o