Abstract
Using two generations of regional climate simulations (NARCliM1.0 and NARCliM1.5) downscaled from CMIP3 and CMIP5 global climate models, three drought indices: the SPI (Standardised Precipitation Index), aSPI (agricultural SPI), and SPEI (Standardised Precipitation‐Evapotranspiration Index) are assessed for Australia. Biases in simulated drought frequency vary among models, while consistency is observed in duration and intensity biases. Compared to NARCliM1.0, biases in NARCliM1.5 are consistently smaller for frequency, duration, and intensity of drought. Projections for 2060–2079 indicate an overall increase in drought frequency in Australia, though differences between NARCliM1.0 and NARCliM1.5 introduce uncertainties. NARCliM1.5 consistently projects greater increases in drought duration and intensity across most regions compared to NARCliM1.0, which can be at least partly explained by differences in the driving global climate models between these ensembles. However, projections for the Australian wheatbelt are consistent in trends between the ensembles, enhancing confidence, although NARCliM1.5 projected much higher drought intensity and duration during the far future. Correlation analysis highlights precipitation strongly influences drought duration across most of Australia, with some regions also showing a high correlation with drought intensity. Potential evapotranspiration (PET) plays a notable role in influencing drought intensity in coastal areas.