[Satellite image of four tropical cyclones across the Pacific Ocean on 1 September 2015 (c) NASA]


Hurricane Roslyn was a Category 3 that made landfall in Mexico on 23 October 2022. IRIS estimates that, at landfall, Hurricane Roslyn it was a once-in-15-year event.

Hurricane Ian was a Category 4 storm that made landfall in Florida on 28 September 2022. IRIS estimates that, at landfall, Hurricane Ian was a once-in-50-year event.


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Tropical cyclones, hurricanes or typhoons are one of the deadliest and damaging natural hazards. However, calculating the risk of tropical cyclones at a global scale is difficult because of a lack of data. Globally there are only about six very damaging tropical cylones every year, and most countries only have reliable observations for the less than 40 years. Yet there are nearly a billion people exposed to tropical cyclones. To build resilience to these storms, and reduce the damage they cause, communities need to better understand how likely they are to occur.

How likely is a very damaging storm?

The Imperial College Storm Model (IRIS) project aims to help scientists and the public understand and predict the likelihood of a damaging storm using the computing power of smartphones on DreamLab. All of the data is freely available and will be updated frequently as we receive more model user data.

IRIS will simulate many “synthetic” tropical cyclones based on new physical algorithms that generate location, track, and wind speeds in physically informed way. Once we have enough synthetic cyclones, we can apply robust statistics. An important concept for understanding risk is the return period. For example, a 100-year return period storm refers to a storm that is expected to happen on average every 100 years (see Figure 2). We will also rapidly assess the return period for all real damaging storms making landfall throughout the world. We will provide a real time estimate of the return period based on IRIS here (see Newsflash).


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Figure 1. Map shows the return period of cyclones making landfall simulated during the entire project (October 2022-now). Click the icon for selected regions of interest. The map also shows Category 5 (their lifetime maximum) synthetic cyclones tracks (paths) simulated recently (Date: December 2022).


Figure 2. Illustration of the return period to understand the pop-ups in Figure1. In this example the dashed line shows a 100-year event would correspond to a Category 5 storm.



Figure 3. Number of model landfall damaging cyclones (Category 3, 4, 5) simulated recently by IRIS this month (Date: December 2022). Our target is to generate over 100,000 storms every month.


For more discussion on the project, join the DreamLab forum on Reddit.

"It's easy to feel overwhelmed by the climate crisis, but with mass accessible projects like these, everyone has a chance to participate & help to bring scientific insights." - Paul, from Germany
Professor Ralf Toumi introduces the IRIS project

Next steps

How much more likely are more damaging storms under climate change?

The impact of climate change on tropical cyclones is highly uncertain and one the greatest challenges. We will deploy IRIS in future DreamLab projects to assess climate change impact.

For more information, please contact us at grantham-communications@imperial.ac.uk.