Saltation bombardment versus direct aerodynamic entrainment: A case study for Australia
1, Yaping Shao2, Harry Butler3, John Leys4
1USDA-ARS Jornada Experimental Range, Las Cruces, NM, USA, 2Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany, 3School of Agriculture, Computational and Environmental Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia, 4Scientific Services Division, Office of Environment and Heritage, Gunnedah, New South Wales, Australia, 5Griffith School of Environment, Griffith University, Nathan, Queensland, Australia
Three dust emission mechanisms are commonly referred to in aeolian research: saltation bombardment, aggregate disintegration and aerodynamic entrainment. Saltation bombardment and aggregate disintegration are very efficient in lifting dust and are the dominant mechanisms in strong dust events. Aerodynamic entrainment is usually regarded negligible in comparison and is most relevant in the absence of saltation. The relative importance of saltation induced and aerodynamically lifted dust is determined by the occurrence frequency of each mechanism and the amount of sediment readily available for lifting. Here, we make use of state-of-the-art dust emission schemes to estimate the relative importance of the dust emission mechanisms based on their occurrence frequency for Australia. The schemes are coupled to WRF-Chem V3.7.1 and simulations are conducted for one year (July 2007 - June 2008). Results are compared to measurements conducted within the DustWatch Australia Network. The model results suggest that despite the low magnitude of aerodynamic dust emission, its high frequency can make it an important mechanism especially during times without strong dust events.