Intensifying Australian heatwave trends and their sensitivity to
observational data
Abstract
Heatwaves are an accustomed extreme event of the Australian climate and
cause catastrophic impacts on human health, agriculture, and urban and
natural systems. Heatwaves are measured by various metrics developed for
the employment of different impact-based studies. We have analysed the
trends in Australia-wide heatwave metrics (frequency, duration,
intensity, number, cumulative magnitude, timing, and season duration)
across 69 extended summer seasons (i.e., from Nov-1951 to Mar-2020). Our
findings not only emphasise that heatwaves are becoming hotter, longer,
and more frequent, but also signify that they are occurring with excess
heat, commencing much earlier, and expanding their season over many
parts of Australia in recent decades. We also investigated the heatwave
and severe heatwave trends at a local city-scale using two different
observational products (AWAP gridded dataset and ACORN_SATV2 station
data) over selected time periods (1911 to 2019, 1911-64, and 1964-2019).
Results suggest that heatwave trends are different amongst the two
datasets. However, the results highlight that the severe heatwave
cumulative magnitude and their season duration has been increasing
significantly in recent decades over the southern coastal cities of
Australia (like Melbourne and Adelaide). The climatological mean of the
most heatwave and severe heatwave metrics is substantially higher in
recent decades compared to earlier periods across all the cities
considered. The findings of our study have significant implications for
the development of advanced heatwave planning and adaptation strategies.