image: Associate Professor Koji Iwano and his research team at Okayama University of Science received the 2025 MEXT Award for Science and Technology (Research Category). The award recognizes their pioneering work in measuring air-sea momentum, heat, and CO₂ transfers under typhoon conditions—contributing to improved accuracy in typhoon intensity forecasting and climate change prediction.
Credit: Okayama University of Science
On April 15, 2025, Associate Professor Koji Iwano from the Department of Mechanical Systems Engineering, Faculty of Engineering at Okayama University of Science, along with his research collaborators, received the 2025 MEXT Award for Science and Technology (Research Category), presented by Japan’s Ministry of Education, Culture, Sports, Science and Technology.
Their research enabled high-precision measurements of momentum (friction), heat, and CO₂ transfer across the air-see interface, which are closely linked to typhoon intensity and global warming. Notably, it marks the first successful modeling of how these transport phenomena correlate with wind speed and wave morphology under extreme wind conditions.
The study, titled "Investigation of Momentum, Heat, and CO₂ Transport Mechanisms at the Air-Sea Interface Under Typhoon Conditions," was conducted in collaboration with Professor Naohisa Takagaki of the Graduate School of Engineering at the University of Hyogo and Professor Emeritus Satoru Komori of Kyoto University.
According to Associate Professor Iwano, accurately predicting typhoon tracks and maximum wind speeds using global coupled atmosphere-ocean models is essential for developing effective disaster mitigation strategies. However, existing models have lacked clarity in representing air-sea momentum and heat exchange under extreme wind conditions. To bridge this gap, the research team designed and built Japan’s only large-scale indoor typhoon simulation tank, capable of simulating intense, wave-breaking ocean surfaces by generating airflow across the water surface at speeds equivalent to 70 m/s—comparable to a severe typhoon.
Using this facility, the team achieved unprecedented precision in measuring the transfer of momentum, heat, and CO₂ across the air-sea interface, effectively capturing interactions between the airflow and water flow under extreme conditions. Their findings revealed a regime shift at a threshold wind speed of 30 m/s: momentum transfer coefficients, which increase steadily at lower wind speeds and plateau at higher speeds; conversely, heat transfer coefficients, relatively stable at lower wind speeds, increase sharply under higher wind conditions.
These discoveries are expected to contribute to improving accuracy in typhoon intensity forecasts and the development of innovative typhoon control strategies, including potential methods involving artificial intervention to ocean surface conditions.
Commenting on the award, Associate Professor Iwano stated:
“It is a tremendous honor to receive this prestigious recognition. This award acknowledges the outcomes of our indoor experimental research using a large-scale simulation tank. All of us on the research team are sincerely grateful that the significance and value of this work have been recognized—especially at a time when large-scale experimental research is no longer mainstream. I also wish to express my heartfelt thanks to everyone who supported this project. Moving forward, we will continue to advance this research and use these experiments as a platform to foster the next generation of scientists.”