A research group led by Associate Professor Yohei Sawada of the Graduate School of Engineering, The University of Tokyo, and Associate Professor Kazumune Hashimoto of the Graduate School of Engineering, Osaka University, has developed a new simulation-based method for finding small artificial interventions that are effective in altering severe weather phenomena such as typhoons.
In this study, the research group conducted computer simulation to explore the controllability of typhoons using a new mathematical approach known as ensemble Kalman control. This method is entirely novel compared with previous studies. By applying a mathematical method from control engineering, it can automatically design an optimal intervention once a control objective is specified. The simulation finds interventions involving the removal of water vapor from the lowest layer of the atmosphere at a location about 250 km from the center of the typhoon (Figure 1). The amount of water vapor to be removed was estimated to be less than 1% of the original water vapor amount. According to the simulations, this intervention could increase the central pressure of the typhoon by approximately 3 hPa and reduce the maximum surface wind speed by around 5 m/s. The required intervention was found to be smaller in both strength and scale than those proposed in previous studies, demonstrating the usefulness of the new method for efficiently identifying promising intervention strategies. However, the intervention found in this study remains large in scale and would still be difficult to implement in practice. Therefore, these results do not directly demonstrate that typhoons can be artificially modified in the real world. Despite this limitation, the newly developed method may lead to the discovery of effective intervention strategies for altering extreme weather events such as typhoons in the future and is expected to contribute to disaster prevention and mitigation.
Figure 1. Typhoon control simulation by Ensemble Kalman Control
(left) Four panels show examples of interventions. Water vapor is reduced at the lowest atmospheric layer in blue shaded areas. The typhoon eye is located in the center of the square, and black dots show strongly convective area. (right) Timeseries of typhoon intensity (central pressure). Black and blue lines are uncontrolled and controlled typhoons, respectively. By intervention, intensity is mitigated.
Papers
Journal: Geophysical Research Letters
Title: Data-driven exploration of tropical cyclone’s controllability
Authors: Yohei Sawada, Masashi Minamide, Yuyue Yan, Kazumune Hashimoto, Le Duc
DOI: 10.1029/2025GL120393
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