Predicting extreme weather conditions

By Professor Francis Chi-Yung Tam

Monsoon Shanghai 2

Professor Francis Chi-Yung Tam, an Associate Professor at the Chinese University of Hong Kong, received an ACU Fellowship in 2021 to collaborate with the University of Exeter.

The two universities are joining forces to study the climate risks posed by the South China summer monsoon. Here, Professor Tam reflects on their collaborative project.

The Asian summer monsoon often causes extreme floods and damages lives and properties. To minimise the damages, we first need to understand the likelihood of extreme monsoons through well-informed risk management. However, risk management in this field  only looks at the extreme monsoons that have happened in the past which limits our ability to accurately assess risks.

To enhance the accuracy of risk evaluation, the Chinese University of Hong Kong is working with Professor Adam Scaife at the University of Exeter on a project where we make use of climate models to simulate more extreme cases that haven’t happened. This approach enables us to predict and quantify the probability of extreme weather and assess the  climate risks posed to our society.

Extreme monsoon rainfall over China in the summer of 2020 (shown as deviations from the long-term average)

The ACU Fellowship helped to support our computing resources to handle significant monsoon simulations from state-of-the-art climate models. This provided much more data for analysis than from observations alone.

The ACU Fellowship concluded that over South-East China, the risk of record-breaking summer monsoon rainfall - such as that during the summer of 2020 - is up to 10% under our current climate. The atmospheric dynamics of these unprecedented events is also examined. These highlight contributions from the upper-atmosphere upstream over Eurasia, as well as downstream from the lower-atmosphere over the Western Pacific Ocean.

These contributions improve our understanding of the risks and predictability of unprecedented extremes. We will be presenting our results at an international science conference this August, and a publication is also planned. In addition, the Fellowship opens up new research avenues and provides the basis for future collaborations and grant bidding.

The Fellowship allows me to launch a project complementary to my current approaches on studying extreme events. Not only does it broaden my research scope, but it also provides a research opportunity for undergraduate students under my mentorship.

I have also benefited professionally by extending my network. Professor Scaife and his team pioneered the methodology used. Our fellowship combines their expertise with our knowledge of the South China monsoon, both of which are essential to the project. For example, Professor Scaife’s experience guided our methodology, whilst our expertise in the monsoon system helped interpret the results.