Study shows cloud clustering causes more extreme rain

Understanding cloud patterns in our changing climate is essential to making accurate predictions about their impacts on society and nature. Institute of Science and Technology Austria (ISTA) and Max-Planck-Institute for Meteorological Scientists published A study in the journal Advances in science which uses a high-resolution global climate model to understand how cloud and storm clusters affect rainfall extremes in the tropics. They show that with increasing temperatures, the intensity of extreme precipitation events increases.

Extreme rainfall is one of the most damaging natural disasters causing loss of human lives and billions in damages. Their frequency has been increasing over the years. Warming climate.

For decades, scientists have been using computer models of Earth’s climate to better understand the mechanisms behind these events and to predict future trends.

In the new Advances in science In the study, a team of researchers from the Institute of Science and Technology Austria (ISTA) and the Max-Planck-Institute for Meteorology (MPI-M) led by ISTA postdoc Xiaoyi Bao State-of-the-art climate models To study how clouds and storm clusters influence extreme precipitation events—especially in the tropics—in greater detail than before.

“This new type of model, with much better resolution, showed that with a warmer climate, the intensity of extreme rainfall events in the tropics increases much more than that due to more cloud clustering. The theory of causality was expected,” explains Bao, who originally initiated the project in his previous postdoc position at MPI-M.

“We can see that when clouds accumulate more, it rains longer, so the total amount of rain increases. We also found that more rain in high-rainfall areas comes at the expense of expanding drier areas. happens. Shifting to extreme weather patterns. That’s because of how clouds and storms cluster together, which we can now simulate with this new climate model.”

This new model, first proposed in 2019, simulates climate with much higher resolution than the previous model. Previous models could not reproduce clouds and storms in such detail, so they are missing most of the complex dynamics of air movement that create clouds and assemble them to form more intense storms.

While the model simulates the entire globe at once, the scientists focused their analysis on the tropical region around the equator. They did this because cloud and storm formation there works differently than at other latitudes.

Caroline Müller, assistant professor at ISTA, adds, “Previous models indicated the influence of cloud clusters on precipitation extremes but did not provide the necessary data. Our colleagues Bjorn from the Max Planck Institute for Meteorology Together with Stevens and Lukas Kluft, our findings add to the growing body of evidence showing that small-scale cloud formation has a significant impact on climate change outcomes.”

Collaborative models

Researchers around the world are collaborating to create more detailed and realistic models of the world’s climate to understand the effects of climate change.

Climate models divide the Earth’s atmosphere into three-dimensional compartments, each with its own data on temperature, pressure, humidity, and many other physical properties. They then use physical equations to simulate how these pieces interact and change over time to represent the real world. Because computing power and storage are not unlimited, these models have to introduce simplifications and scientists constantly work to make them more accurate.

Older generations of climate models used slices of about 100 km in horizontal length, still resulting in tens to thousands of slices over the entire globe. Advances in algorithms and supercomputers enabled scientists to greatly increase the resolution of models.

“We used a climate model developed at MPI-M and analyzed data hosted at the German Climate Computing Center in Hamburg with a resolution of only five kilometers, which was computationally expensive,” Bau added. ” “All climate research is a huge collaborative effort by hundreds of people who want to contribute to our understanding of the world and our impact on it.”

Bao, who first became interested Climate research During his PhD at the University of New South Wales, Australia, and who now works at ISTA as an IST-BRIDGE Postdoctoral Fellow, he used additive models to find more evidence for causes and effects. wants to continue its work on extreme rainfall events for

Caroline Muller, who first studied mathematics and then found her passion for research questions with real-world implications, and her research group use climate models to study. Movement of air and the formation of clouds and storms at different scales – from tropical cyclones – to better understand their causes and the effects of climate change on society and nature.