Where She Blows! A Ten Year Dust Climatology of Western New South Wales Australia

Abstract

Dust emissions contribute significantly to atmospheric processes impacting the functioning of various earth and human systems. The question is often asked “how much dust is acceptable?” From a land management perspective, the aim is to reduce the degradation effects of wind erosion over time. To do this, we need to know the range of dust activity over a long time period and to set a target that shows a reduction in dust activity. In this study, dust activity is described by the number of dust hours per July to June period (dust storm year, DSY). We used the DustWatch network of high resolution particulate matter less than 10 µm (PM10) instruments to characterise the dust climatology for a ten year period for western New South Wales (NSW), Australia. The ten year study period covered one of the driest and wettest periods in south-eastern Australia, providing confidence that we have measurements of extremes of dust (0 to 412 h/DSY), rainfall (98 to 967 mm/DSY), and ground cover (0 to 99% of area/DSY). The dust data are then compared to remotely sensed ground cover and measured rainfall data to develop targets across a rainfall gradient. Quantile regression was used to estimate the number of dust hours for a given DSY rainfall at 21 DustWatch Nodes (DWN). The 75th percentile is used to determine the target number of dust hours for a ten year average DSY. The monitoring network clearly identified locations of high dust activity and changes in dust and ground cover that are associated with rainfall. The dust hour targets for NSW indicated that for every 100 mm increase in DSY rainfall (between 250 and 650 mm) there is a 10 h decrease in dust hours. The dust target enables us to evaluate whether wind erosion is decreasing with time for sites with different rainfall.

Keywords

• dust storms
• climatology
• PM10
• monitoring
• DustWatch