Processes of Fine Particle Formation, Dust Source Regions, and Climatic Changes

Abstract

Atmospheric dust has been supplied by two main types of source region during the Quaternary. At times of maximum continental glaciation much dust was blown from outwash plains and braided river channels adjacent to continental ice sheets and valley glaciers in mid-latitudes. Dust flux from these sources was low in the Holocene and earlier inter-glacials. Arid regions have been important sources of dust during both glacial and interglacial periods. Based on observed variations in the abundance of dust in oceans cores, several authors have suggested that the flux of desert dust is directly related to the intensity or areal extent of continental aridity. However, this interpretation is based on an oversimplified view of the factors which control dust supply. It is argued in this paper that dust flux is greater from arid areas than hyperarid areas. Sudden increases in dust flux observed in ocean cores can be caused either by a change from semi-arid to arid or from hyperarid to arid conditions, or by changes in the pattern of meso- and macro-scale atmospheric processes which control dust dispersion.