Australian rainfall variability—Why is the eastern seaboard of Australia different to the rest of Australia and also internally inhomogeneous

Abstract

The Eastern Seaboard of Australia (ESA) has been identified as being different to the rest of Australia in terms of rainfall patterns. However, rainfall patterns within the ESA itself are not well understood. This study identifies Australian rainfall districts that exhibit similar (and different) temporal variation, with the primary aim being to determine if the ESA can be considered a homogenous region with respect to rainfall. The results (a) confirm that the ESA is different to the rest of Australia and (b) show that the ESA is not homogenous and that East Coast Lows (ECLs) are linked to this inhomogeneity. For winter (JJA) three separate divisions within the ESA are identified and at least two clear divisions are identified in other seasons. ECL sub‐types contribute to this inhomogeneity because each ECL sub‐type is associated with different spatio‐temporal rainfall patterns across the ESA. This is an important insight for natural resources management and emergency services within the heavily populated ESA because it demonstrates that existing climate related risks are different across the ESA. Further, the way climate risks change in the future is also likely to be inconsistent across the ESA. Future climate related risks will depend on how ECL behaviour (e.g., intensity, frequency, location, duration, path and geographical extent) changes. This reinforces the need for locally relevant and practically useful climate science information and adaptation strategies—as opposed to the State‐ or country‐wide information and adaptation approaches that are commonly used.