Progress Report

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Control Theory of Weather-Society Coupling Systems for Supporting Social Decision-Making[A-1] Construction and analysis of new meteorological data leading to “controllability” and design of control methods

A-1A-2A-3B-1B-2»

Progress until FY2025

1. Outline of the project

Background: Extreme weather events, including tropical cyclones, are complex phenomena that exhibit vast amounts of energy. In this Goal 8, our aim is to develop a theory that would enable us to safely alter extreme weather using minimal external forces.

Objective: We aim at establishing a systematic method for influencing the future trajectory of extreme weather events, such as tropical cyclones, through small-scale artificial interventions. This will give rise to a new paradigm in meteorological control theory.

Method: By integration of state-of-the-art simulations and satellite weather observations, we will construct a novel dataset of the three-dimensional structures of tropical cyclones. Then, this dataset will be analyzed via a blend of process-driven and data-driven approaches (Fig. 1).

Fig.1
Fig. 1. Overview of the R&D Item.

2. Outcome so far

① We have successfully completed building the research infrastructure and developed the necessary dataset to explore the controllability of tropical cyclones.
② [Process-driven approach] We found that the meso-scale water vapor anomalies solely drive rapid intensification of a tropical cyclone (Fig. 2). We aim to deepen our understanding of these phenomena and propose concrete and feasible control intervention strategies.

Fig.2Fig.2
Fig. 2. (upper left) Simulation of a tropical cyclone. (upper right) Same as the upper left figure, but meso-scale water vapor anomalies that induce convections are artificially eliminated in the simulation. (bottom) Timeseries of maximum wind speed of a tropical cyclone. Upper figures were depicted at the time of the blue dashed line. The black and brown lines represent the simulation shown in upper left and upper right figures, respectively. It shows that the meso-scale water vapor anomalies solely drive rapid intensification of a tropical cyclone.

③ [Data-driven approach] We newly developed a control-theoretic mathematical framework that integrates Ensemble Kalman Control (EnKC), devised in R&D Item A-2, with Model Predictive Path Integral (MPPI) control, developed in control engineering, and demonstrated its theoretical effectiveness (Fig. 3).

Fig.3
Fig. 3. Overview of the new control-theoretic mathematical framework, Ensemble Kalman Guided Model Predictive Path Integral (EKG-MPPI). First, EnKC is used to “explore” the approximate region where intervention should be applied. Then, MPPI, a more refined algorithm, is used to “identify” the location and intensity of the intervention. This algorithm integrates prediction and control, enabling control to be performed while making future predictions.

3. Future plans

We have shown that small-scale water vapor fluctuations can drive tropical cyclone intensification and revealed organized atmospheric phenomena that may provide a basis for typhoon control. In cooperation with R&D Item A-2, we also found an efficient method to automatically search for good control inputs through simulation. By combining and deepening these results, we will now focus on designing actual devices to intervene the atmosphere to mitigate tropical cyclones.

A-1A-2A-3B-1B-2»