Wind Erosion in Western Queensland Australia

Chapter 3 – Modelling Land Erodibility Review3.4.3 Other Global Dust ModelsA number of global dust emission models have been developed, and there are similarities intheir erosion and dust emission schemes. In general, three approaches have been taken tomodel wind erosion (Zender et al., 2003a). The dependence of the model emission schemeson factors controlling land erodibility varies by the nature of their formulations.The first type parameterise mobilisation in terms of the third or fourth power of the windspeed or friction velocity, then impose size distribution factors on the emitted dust (e.g.Tegen and Fung, 1995; Mahowald et al., 1999; Perlwitz et al., 2001). These models arereliant on assumptions about the general characteristics of dust source areas and do notaccount for micro-physical entrainment processes (Zender et al., 2003a).The second type use a microphysical specification of the land surface to predict size-resolvedsaltation mass flux and dust emission (e.g. Marticorena and Bergametti, 1995; Gillette andPassi, 1988; Shao, 2001). Due to the complexity of inputs required for these models, thismodel type has typically been applied in regional scale modelling where spatial datarequirements are often better met and inherent assumptions built into the model are less likelyto violate the ranges of conditions seen in global dust source areas.The third type represents those models employing micro-physical parameterisations with anumber of simplifying assumptions to account for global dust source characteristics. Ingeneral these models are not able to accommodate fine scale soil erodibility factors like thefield to regional scale models. These models include the Community Aerosol and RadiationModel for Atmospheres (CARMA), the Global Ozone Chemistry Aerosol Radiation andTransport (GOCART) and DEAD (Ginoux et al., 2001; Woodward, 2001; Luo et al., 2003;Zender et al., 2003a, 2003b; Barnum et al., 2004).Recent advances in the application of remote sensing to detect atmospheric aerosols andglobal source areas have enabled significant improvements to be made to global dustemission models. An example of this is in the DEAD model, where global characterisationsof dust source areas by a range of geomorphic, topographic and hydrological factors haveenabled more advanced dust source parameterisations to be employed. These source area91