@article {bnh-8288, title = {Interactive influence of ENSO and IOD on contiguous heatwaves in Australia}, journal = {Environmental Research Letters}, year = {2021}, month = {11/2021}, abstract = {

Australian heatwaves have a significant impact on society. Most previous studies focus on understanding them in terms of frequency, duration, intensity, and timing. However, understanding the spatial characteristics of heatwaves, particularly those occurring in contiguous regions at the same time (here referred to as contiguous heatwaves), is still largely unexplored. Here, we analyse changes in spatial characteristics of contiguous heatwaves in Australia during 1958-2020 using observational data. Our results show that extremely large contiguous heatwaves are covering significantly larger areas and getting significantly longer during the recent period (1989/90-2019/20) compared to the historical period (1958/59-1988/89). We also investigated the association of contiguous heatwaves in Australia with interactions of the El Ni{\~n}o{\textendash}Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) using a large multi-member ensemble of a physical climate model. We found that areal magnitude, total area, median duration, and maximum area of large and extremely large contiguous heatwaves in Australia are significantly higher (lower) during the strong El Ni{\~n}o (Es), strong El Ni{\~n}o co-occurring with strong IOD positive (Es-IPs), and with moderate IOD positive (Es-IPm) (co-occurring strong La Ni{\~n}a with the strong IOD negative (Ls-INs)) seasons relative to the neutral seasons (where both ENSO and IOD are in neutral phase). During the Es, Es-IPm, and Es-IPs seasons, the large-scale physical mechanisms are characterised by anticyclonic highs over the southeast and cyclonic lows over the northwest of Australia, favouring the occurrence and intensification of heatwaves in Australia. These results provide insights into the driving mechanisms of contiguous heatwaves in Australia.

}, keywords = {Climate and Earth system modelling, ENSO, heatwaves, IOD}, doi = {https://doi.org/10.1088/1748-9326/ac3e9a}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/ac3e9a}, author = {P Jyoteeshkumar reddy and Sarah Perkins-Kirkpatrick and Jason J. Sharples} } @article {bnh-7834, title = {Modulating influence of drought on the synergy between heatwaves and dead fine fuel moisture content of bushfire fuels in the Southeast Australian region}, journal = {Weather and Climate Extremes}, volume = {31}, year = {2021}, month = {03/2021}, abstract = {

During the 2019-20 summer season, Australia experienced frequent heatwave events with scorching temperatures and massive bushfires with dense smoke. These catastrophic heatwaves and bushfires resulted in huge socio-economic and ecological losses. The frequency and intensity of both heatwaves and bushfires are projected to increase in the future warming world. While considerable effort has been directed at understanding the physical mechanisms of these individual extreme events, an investigation of their interaction is lacking. We focus on the relationship between heatwaves and bushfire fuels by considering dead fine fuel moisture content, a critical factor that regulates the intensity, spread rate and the likelihood of profuse spotting of fires. We investigate the relationship by exploring the statistical correlations between various heatwave characteristics (frequency, duration, magnitude, and amplitude) and mean dead fine fuel moisture content over southeast Australia in the peak heat and fire season. This relationship varies among different heatwave characteristics as well as with regions. The prolonged duration of a heatwave is well associated with dead fine fuel dryness around the southeastern parts of the Southeast Australian region, whereas the hotter heatwave season favours the lower dead fine fuel moisture content over the Northeast parts of the Southeast Australia and central Victorian region. Results also suggest that dead fine fuel moisture content is significantly decreased on heatwave days compared to non-heatwave days. Lastly, we explored the effects of rainfall deficit on the relationship between heatwave and mean dead fine fuel moisture content by splitting the seasons based on the Standard Precipitation Index (SPI). Results show that the correlation strength is both seasonally and regionally dependent.

}, keywords = {Australia, bushfires, Drought, Extreme events, fuel moisture content, heatwaves}, doi = {https://doi.org/10.1016/j.wace.2020.100300}, url = {https://www.sciencedirect.com/science/article/pii/S2212094720303133}, author = {P Jyoteeshkumar reddy and Jason J. Sharples and Sophie Lewis and Sarah Perkins-Kirkpatrick} } @article {bnh-6737, title = {Deconstructing factors contributing to the 2018 fire weather in Queensland, Australia}, volume = {101}, year = {2020}, month = {02/2020}, pages = {S15-S21}, edition = {1}, abstract = {

Factors including the circulation pattern and antecedent conditions contributed to 2018 northeast Australian fires. High background temperatures also played a role for which model evidence suggests an anthropogenic influence.

}, keywords = {Fire, Fire weather, Queensland}, doi = {10.1175/BAMS-D-19-0144.1}, url = {https://www.ametsoc.org/ams/index.cfm/publications/bulletin-of-the-american-meteorological-society-bams/explaining-extreme-events-from-a-climate-perspective/}, author = {Sophie Lewis and Stephanie Blake and Blair Trewin and Mitchell Black and Dowdy, Andrew J and Sarah Perkins-Kirkpatrick and Andrew King and Jason J. Sharples} } @article {bnh-7944, title = {Intensifying Australian heatwave trends and their sensitivity to observational data}, journal = {Earth{\textquoteright}s Future}, year = {2020}, month = {12/2020}, abstract = {

Heatwaves are an accustomed extreme event of the Australian climate, which can cause catastrophic impacts on human health, agriculture, and urban and natural systems. 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. The Australian heatwave trends have strengthened since last observed Australian study was conducted. We also investigated the heatwave and severe heatwave trends at a local city-scale using three different observational products (AWAP and SILO gridded datasets and ACORN_SATV2 station data) over selected time periods (1911-2019, 1911-64, and 1965-2019). Results suggest that heatwave trends are noticeably different amongst the three datasets. However, the results highlight that the severe heatwave cumulative magnitude and their season duration have been increasing significantly in recent decades over Australia{\textquoteright}s southern coastal cities (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.

}, keywords = {Australia, Climate change, heatwaves, urban}, doi = {10.1002/essoar.10505178.1 }, url = {https://www.essoar.org/doi/10.1002/essoar.10505178.1}, author = {P Jyoteeshkumar reddy and Sarah Perkins-Kirkpatrick and Jason J. Sharples} } @article {bnh-5078, title = {The Excess Heat Factor as a metric for heat-related fatalities: defining heatwave risk categories}, journal = {Australian Journal of Emergency Management}, volume = {31}, year = {2016}, month = {07/2016}, abstract = {

Heatwaves represent Australia{\textquoteright}s most significant natural disaster in terms of mortality. A unanimous definition of what constitutes a heatwave does not currently exist. However, recent work from the Bureau of Meteorology (Nairn \& Fawcett 2013) has provided a metric designed to summarise their intensity. This metric, called the Excess Heat Factor, is being increasingly adopted by the research community as it is well-suited to characterise heatwave hazards. Yet the link between the Excess Heat Factor and the potential societal or economic impacts heatwaves can have is still not well understood. Using the PerilAUS archive of heat-related fatalities in Australia, this paper proposes to develop a classification of heatwave events in terms of their risk potential for human loss of life. This paper also quantifies the likely death toll from populations exposed to each of these categories. The category scheme is used to analyse the risk gradient of the three most lethal events in south-east Australia since 1900. The scheme helps communicate about heatwave fatality risk in Australia and provides some insight into the location of the populations under greatest threat. This study also catalogued 466 events in south-east Australia using the Excess Heat Factor and the newly developed heatwave categories. Using principal component analysis to identify the key modes of variability, a synthetic catastrophic heatwave scenario is generated and analysed for projected fatalities.

}, url = {https://ajem.infoservices.com.au/items/AJEM-31-04-13}, author = {Thomas Loridan and Coates, Lucinda and Daniel Arg{\"u}eso and Sarah Perkins-Kirkpatrick and John McAneney} }