  In Australia, hailstorms present considerable public safety and economic
risks, where they are considered the most damaging natural hazard in terms of
annual insured losses. Despite these impacts, the current climatological
distribution of hailfall across the continent is still comparatively poorly
understood. This study aims to supplement previous national hail climatologies,
such as those based on environmental proxies or satellite radiometer data, with
more direct radar-based hail observations. The heterogeneous and incomplete
nature of the Australian radar network complicates this task and prompts the
introduction of some novel methodological elements. We introduce an empirical
correction technique to account for hail reflectivity biases at C-band, derived
by comparing overlapping C- and S-band observations. Furthermore, we
demonstrate how object-based hail swath analysis may be used to produce
resolution-invariant hail frequencies, and describe an interpolation method
used to create a spatially continuous hail climatology. The Maximum Estimated
Size of Hail (MESH) parameter is then applied to a mixture of over fifty
operational radars in the Australian radar archive, resulting in the first
nationwide, radar-based hail climatology. The spatiotemporal distribution of
hailstorms is examined, including their physical characteristics, seasonal and
diurnal frequency, and regional variations of such properties across the
continent.
