Wind Erosion in Western Queensland Australia

Chapter 5 – Land Erodibility Model Developmentdifferences in the types of dust-events being recorded at the stations. Increases in landerodibility outside the station AOIs was manifested through an increase in observed dusthazes, rather than dust storms or locally blowing dust. This should be reflected in improvedcorrelations of model output with the dust-event groups where dust hazes and whirls havebeen removed. However, the coarse temporal resolution of the comparison led to shortperiods of high erodibility and potential dust production being “lost” in the annual averagingof model output. This further contributed to the poor synchronisation of trajectories with thefew remaining events in these years (potentially with local source areas).The strongest correlations between model output and dust-event frequencies were found atstations where events were dominated by local wind erosion and dust storm activity (Boulia,Urandangie and Windorah). The poor synchronisation/correlation at Longreach can beattributed to the fact that the dust events recorded at that station were predominantly hazes forthe entire analysis period (Table 5.1). These events most likely had non-local origins, and sodo not provide a good measure of local wind erosion activity by which model performancecan be measured. Interpreting a poor correlation of model output with dust-event frequenciesas indicating poor model performance is therefore highly subjective and dependant on thedust events representing wind erosion activity within the potential dust source AOIs. Afurther issue with the dust-event comparison is indicated by the significant differencesbetween the dust-event frequency and DSI trajectories and the differences in correlationsbetween these and model output. While all observed dust events were used to compile thefrequency data, DSI is computed using the severest (lowest visibility) dust event recorded ona particular day. A smoothing of event frequencies by the index would have contributed tothe differences in correlations. Attempting to assess model performance at shorter time scales(i.e. weeks to months) using dust-event frequencies would create further problems in theanalysis as the dependence of wind erosion activity on windiness (relative to land erodibility)increases and because wind erosion activity can be low when land erodibility is high if u *