3:30 PM - 3:45 PM
[AAS10-01] Application of Building-Resolving Large-Eddy Simulation for the Quantification of Wind Hazards in Urban Districts under Climate Change
Keywords:strong wind, large-eddy simulation, urban meteorology, climate change, typhoon
Airflows in urban districts are highly variable and sometimes become a threat to human lives and social infrastructures. Such wind fluctuations can be disastrous especially under disturbed meteorological conditions such as tropical cyclone landfalls. With the urbanization and the reform of urban districts, strong wind hazards should be more quantitatively assessed. This study investigates the turbulent nature of airflows in urban districts with a large-eddy simulation (LES) model that explicitly resolves individual buildings and structures in order to quantitatively assess the strong wind hazards. By combining the LES analysis with meteorological simulations with a regional meteorological model, the Weather Research and Forecasting (WRF) model, wind hazards are quantified on a district scale in realistic meteorological situations and under climate change. Building-resolving LESs are conducted for airflows in an urban district of Osaka City and are used to derive statistical relationships of wind gustiness with urban geometrical features derived from a high-resolution digital surface model dataset. Meteorological simulations for the case of Typhoon Jebi (2018) are conducted to obtain a baseline wind condition. The pseudo-global warming experiments with the use of the WRF model indicate how the external forcing of intense typhoons changed in a future climate. A combination of the meteorological, LES, and urban geometrical feature analyses demonstrated a 10% strengthening of the wind hazards under +4K global warming. Since not only climate change but also urban geometry affects wind fluctuations and hazards in urban districts, quantitative estimation using a building-resolving LES analysis should be used.