Media release

From: ARC Centre of Excellence for Climate Extremes (CLEx)

Australian researchers pioneer new weather radar technique

New technique could help prepare world for “rapid rain bursts”

Researchers at the ARC Centre of Excellence for Climate Extremes have been recognised by the Science journal for pioneering a new technique using weather radar data to identify rapid rain bursts.

Rapid rain bursts, also referred to as “sub-hourly heavy rainfall”, are destructive short bursts of rain that overwhelm roads, gutters and drainage systems in as little as 10 minutes.

Utilising weather radar data over Sydney, Australia and overlapping radars over Newcastle, Terrey Hills and Wollongong, the researchers identified a 40% increase in the intensity of rapid rain bursts over 20 years.

“Previously, it was not possible to get this kind of data about rapid rain bursts” says Dr Hooman Ayat from the University of Melbourne (Pictured).

“Previously, rain gauges, climate models and satellites have struggled to accurately identify rain bursts on such small time scales. However, our new data analysis technique was able to take historical weather radar data to get a much stronger picture of these rapid rain bursts. It was a shock to see these rapid rain bursts intensify 40% in only 2 decades over Sydney, something we would not have found out using traditional methods”

Professor Jason Evans (UNSW) says the surprise result came from the innovative work of Ayat’s PhD and collaborations with the ARC Centre of Excellence for Climate Extremes, the Climate Change Research Centre and the Bureau of Meteorology.

“This kind of stuff is what gets me coming into work every morning. This result wasn’t one we were looking for. It kind of fell out of work we were doing for another study and when we found this result, we decided to look deeper. This shows the importance of investing in new scientific talent like Hooman, who developed this as part of his PhD, and collaborating across institutions on ways to improve and expand climate science” says Evans.

Professor Steven Sherwood (UNSW) says the new technique and research has global implications.

“You’ve got to use radars to get a result like this. It’s only starting to happen now. It’s happening in other countries too - that research communities are getting ahold of this mammoth dataset and taming the beast, but it’s taken some time for this to happen. It’s important because it affects people. It’s a scientific mystery that we need more work on to understand better. We’ve identified this in Sydney, we’d like to see this technique used in other cities around the world.”

Photos and videos are available at https://cloudstor.aarnet.edu.au/plus/s/WTE42a6dahcAJGp

Editor’s note:

What is a rapid rain burst?

A rapid rain burst is a short period of extreme rain occurring over a duration of about 10 minutes.

During a rapid rain burst, a huge amount of water falls rapidly over a small region, increasing the likelihood and severity of flash flooding, especially in urban and steep mountainous regions.

Extreme rain is defined by the area experiencing it. What’s considered extreme rain in one location might not be considered so in another. Rapid rain bursts are the most extreme 5% of rainfall in a location.

Prior to 2022, it was difficult for climate scientists to identify changes in rapid rain bursts due to limitations on rain gauges, satellite data and climate models in identifying/detecting these small-scale storms.

A new technique, developed by researchers at the ARC Centre of Excellence for Climate Extremes, identified thousands of rapid rain bursts over Sydney Australia using weather radar data over two decades.

Using this technique, they found that the most severe rapid rain bursts have intensified by 40% over Sydney, Australia in the last two decades - a phenomenon not explained by regular climate processes.

Researchers also refer to rapid rain bursts as “sub-hourly heavy rainfall”.

About the ARC Centre of Excellence for Climate Extremes

The ARC Centre of Excellence for Climate Extremes reduces Australia’s economic, social and environmental vulnerability to climate extremes.

Funded by the Australian Research Council (ARC), it brings together five Australian universities and a suite of outstanding national and international Partner Organisations.

The participating universities are the University of New South Wales, Monash University, the Australian National University, the University of Melbourne, and the University of Tasmania.