Assessment of a revised dust prediction model for Mildura, Australia

Abstract

Dust storms are regarded as global natural hazards, adversely impacting the climate, economy, and human health. As a dry continent, Australia is extensively impacted by dust storm activity, particularly in dry seasons. Located in the Mallee region and 600 km downwind of the Lake Eyre Basin, Mildura is one of the most vulnerable regional cities to dust storms. Rapid development of agriculture in the Mildura region removed natural vegetation and increased the frequency of dust storms in the 20th century. To better understand the factors and processes that affect dust storm activity in Mildura, a seasonal predictive model for dust event days was developed in the early 1990s. This was based on an empirical relationship between seasonal rainfall in preceding autumn and summer dust event days (the most active dust season in Mildura). In this study, this model was applied for a further 24‐year period (from 1990 to 2013) to test model validity for forecasting dust activity. Results show that the r2 was 0.13 and the root mean square error was 5.33 days in the ‘forecast’ mode, which indicates poorer model performance than that for the original calibration period (1960–1989). All large ‘forecast’ errors occurred in the 1990s. Winter rainfall was identified as the main climate factor for overprediction. The effect of the preceding winter rainfall on summer dust event occurrence was found to increase with the ratio of winter rainfall over autumn rainfall for the whole period of 1960–2013. An updated dust prediction model for 1960–2013 was constructed based on preceding autumn and winter rainfall. Autumn rainfall was used as the predictor when the ratio of winter and autumn rainfall was no more than 3.1; otherwise, winter rainfall was used. This was a marked improvement in model performance with an r2 value of 0.37 to that of 0.26 for the original model performance for the period as a whole (1960–2013).