Dust transporting wind systems in the lower Lake Eyre Basin, Australia: A preliminary study

Abstract

Australia does not have named dust transporting winds, like most other global dust source regions. Previous studies indicate that Australian dust is transported offshore via two dust paths to the southeast and northwest and that these dust paths are fed by three wind systems associated with the west–east passage of frontal weather systems across the southern half of the continent. This preliminary study uses 2 years of meteorological observations and mean sea level synoptic analyses to quantify the main weather systems and resultant wind systems responsible for dust entrainment and transport in the lower Lake Eyre. Of the 160 dust event days recorded in 2005 and 2006, 51% were associated with fronts and pre-frontal troughs; which generate pre-frontal northerlies, frontal westerlies and post-frontal southerlies that feed dust into the two dust paths. Heat troughs accounted for 24% of dust event days; with pre-trough northerlies and post-trough southerlies and westerlies from thunderstorms feeding the two dust paths. High pressure systems accounted for 22% of dust event days; with southeasterlies entraining most of the dust and low pressure systems account for only 3% of dust event days associated with variable winds. There is a distinct seasonality of dust entrainment; during late (austral) spring to mid summer in the north and extending to summer further south, driven by heating of the southern hemisphere in summer resulting in a poleward shift of fronts, troughs and pressure systems as spring and summer progress.