Waiting on the winds:
new model for predicting typhoon

By : Catherine Law

But a new system intended to make predictions more accurate is under development, thanks to pioneering work by Professor Johnny Chan Chung-leung, Chair Professor of Atmospheric Science in the School of Energy and Environment (SEE).

Professor Chan’s work holds such promise that he recently received a grant from the European Commission (EC) and Research Grants Council (RGC) Collaboration Scheme.

Typhoon Hato struck South China in August 2017.This three-year project, a collaboration with Imperial College London, is titled “Development of a Regional Prediction System for Seasonal Tropical Cyclone Landfall Prediction and Future Projections under Different Climate Change Scenarios”.

“A more accurate system for seasonal typhoon prediction could help governments better prepare their financial budgets and allocate resources accordingly,” Professor Chan said. “It would also help insurance companies to make better risk assessments and set appropriate levels of premiums.”

According to Professor Chan, several methods can be deployed to predict the number of typhoons in a year.

“One of them is to first deduce a formula by analysing the data from the atmosphere and ocean before tropical cyclones are formed as well as their correlation with the formation of a typhoon,” said the former Dean of CityU’s SEE.

“We can then use statistics to predict the number of typhoons for the summer of the current year. The problem with this model is that it is based on the presumption of a constant relationship between the atmosphere, ocean and typhoons. However, this presumption may not be valid,” said Professor Chan, whose grants is worth HK$2 million.

Forecasting the intensity of each typhoon landing in a year is another challenging issue for meteorologists, made more problematic by the relatively small number of meteorologists in the region studying typhoons.

“A more accurate system for seasonal typhoon prediction could help governments better prepare their financial budgets and allocate resources accordingly.” “That’s probably because there are too many uncertainties in the field!” Professor Chan suggested.

Professor Chan and his PhD students have tried to simulate the intensity of a typhoon when it lands. But the intensity in a simulation is generally higher than in reality.

That is because when a typhoon is formed on the sea, it will affect a large surface area. As it builds in intensity, it pushes away the warm water on the surface. Subsequently, the cold water at the bottom of the sea rises and in turn reduces the intensity of the typhoon, he explained.

“Many of the current computer models have not factored in the change in the temperature of the sea water as it is difficult to collect the necessary data,” he said.

Professor Chan’s research team will collect atmospheric and oceanic data in the South China Sea via channels such as satellites. Factors such as changes in the temperature of the sea water will be fed into a computer model. By simulating different weather scenarios, the team will try to understand how interactions between the atmosphere and the ocean affect the formation and intensity of typhoons.

Professor Johnny Chan Chung-leungProfessor Chan expects the team to develop a more accurate system that can predict the number and intensity of typhoons at the end of the three-year project.

The EC/RGC Collaboration Scheme, launched in Hong Kong this year, aims to promote collaboration on scientific research between Hong Kong and countries in the European Union and help researchers to participate in projects endorsed by the EC’s Horizon 2020 Programme.

With funding worth €80 billion for 2014–2020, Horizon 2020 is the largest research and innovation programme in Europe. The aim is to boost the development of advanced technology and encourage public and private sectors to work together to promote new ideas.

With help from the scheme, Professor Chan and his team hope to see which way, and how strong, the winds blow with greater accuracy than before.