This research highlight was originally published in NCI's 2021-2022 Annual Report.

In recent years, Australians are all too familiar with the significant impacts and damage that extreme rainfall can cause. Some regions have experienced devastating floods on more than one occasion, with the human and economic cost of these events challenging the resilience of affected communities, and forcing difficult discussions around how best to manage ongoing risks.

Better understanding the processes underlying these types of events is one of the priorities of the ARC Centre for Excellence for Climate Extremes. The Centre comprises many of Australia’s leading climate scientists across 5 universities, including researchers from The University of Melbourne’s School of Geography, Earth and Atmospheric Sciences. These researchers are drawing on NCI’s computing power and data infrastructure to analyse how the various drivers of rainfall interact, from local factors to global climate and weather processes.

“Rainfall is complex, and understanding it is a multiscale problem,” says Dr Claire Vincent, Senior Lecturer at The University of Melbourne and a Chief Investigator at the Centre. “It can be a very local event, so it is necessary to drill down to those small scales. At the same time though, rainfall is strongly influenced by very large scale variability, such as La Niña and El Niño, that is controlled by sea surface temperature in the Pacific Ocean. It is in the space of these interactions that extremes sometimes occur.”

Blurry Melbourne streetscape, including a tram, seen through a rain-soaked window.

This presents a challenge for researchers, with high-resolution models needed over large areas and timeframes, linking up very different scales of variability to see how they control the rainfall climate in various locations. One project, led by Dr Vincent, focused on the occurrence of thunderstorms in the tropics. While these are known to be driven by heating of the earth’s surface, which in turn initiates clouds and storms, the project investigated how to better take into account how cloud formation is also affected by planetary-scale waves propagating around the equator.

This is computationally intensive work and reliant on access to large datasets made available at NCI. This infrastructure, together with support offered by the Centre’s computational modelling support team, greatly benefits researchers. “It allows you to get on with your research. The computing environment is set up in an optimal way, you do not have to stress about making a compiler work or finding a computer that can manage to run your model. Rather, you can focus on the science, on trying to better understand processes to more meaningfully interpret the data available.”

NCI is supporting the foundational science that is improving Australia’s ability to predict climate extremes and helping us better prepare for the future.