Open Access

Qi Sun, Joël Arnault, Christopher Holst, Patrick Laux, Harald Kunstmann

• Climate change has the potential to significantly alter the characteristics of tropical cyclones (TCs). Understanding how representative extreme TCs with distinct meteorological structures and hydrological impacts respond to warming is critical for improving risk assessment. Super Typhoon Usagi (2013) represents a rare case, maintaining unusually high intensity at landfall while coinciding with an astronomical high tide—a combination infrequently observed in the climatological record—which led to severe compound flooding in coastal cities. However, how such exceptional TC characteristics respond to climate change remains unclear. In this study, we apply a high-resolution (5 km) Weather Research and Forecasting (WRF) model simulation within the Pseudo-Global Warming (PGW) framework, in which reanalysis-based initial and boundary conditions are perturbed by multi-variable warming signals from CMIP6 GCMs, to assess how climate change may alter the characteristics of Super Typhoon UsagiClimate change has the potential to significantly alter the characteristics of tropical cyclones (TCs). Understanding how representative extreme TCs with distinct meteorological structures and hydrological impacts respond to warming is critical for improving risk assessment. Super Typhoon Usagi (2013) represents a rare case, maintaining unusually high intensity at landfall while coinciding with an astronomical high tide—a combination infrequently observed in the climatological record—which led to severe compound flooding in coastal cities. However, how such exceptional TC characteristics respond to climate change remains unclear. In this study, we apply a high-resolution (5 km) Weather Research and Forecasting (WRF) model simulation within the Pseudo-Global Warming (PGW) framework, in which reanalysis-based initial and boundary conditions are perturbed by multi-variable warming signals from CMIP6 GCMs, to assess how climate change may alter the characteristics of Super Typhoon Usagi (2013). Our results indicate that the accumulated precipitation increases by up to 100 mm under future warming scenarios, along with an increase in peak intensity, range from 5 hPa (LESS_WARM) to 10 hPa (MORE_WARM)). Hourly precipitation is projected to rise by 6.5 %–26.4 %, exceed the temperature-induced CC scaling (4.2 %–20.3 %). Increased latent heat flux (30–90 W m−2) under warmer (0.6–2.9 K) and wetter (1.5–4.0 g kg−1) climate conditions enhances TC intensification. Warming also affects the dynamic structure of TCs, enhancing vertical velocity (2–4 Pa s−1) and tangential wind (5–10 m s−1), expanding the inflow and outflow regions contributing to a stronger TC. The unexpected increase in precipitation is driven by both thermodynamic and dynamic factors. This case study provides insights into the potential responses of landfalling TCs—particularly those linked to compound flooding—in the Western Pacific Ocean (WNP) under future climate change.…