This study aims to assess the impact of global warming on intense TCs over the western North Pacific (WNP) through a dynamical downscaling approach. 379 and 179 TCs reaching Category 1 in the High-Resolution Atmospheric Model (HiRAM) are downscaled for use in the Weather Research and Forecasting model at 5-km horizontal resolution in the current climate (1979-2015) and Representative Concentration Pathways 8.5 (RCP8.5) future climate (2074-2100) scenarios, respectively. Inclusion of the downscaling simulations helps better reproduce the probability distribution of the TC lifetime maximum intensity (LMI). In the warmer climate, the top 30 and top 5 % WNP TCs in LMI are projected to be stronger. Such an increase in intensity is statistically significant, and can be primarily explained by enhanced intensification rate (IR). Meanwhile, TCs among the top 5% in LMI can reach higher intensities which cannot be attained in the current climate. After downscaling, the probability of WNP TCs reaching Category 4-5 increases by 6.5 % in the late 21th century, which is 1.7 % higher as compared to the increase projected exclusively by HiRAM. Moreover, for TCs among the top 5 % in LMI, a 233-km and 300-km westward shift of LMI locations is identified in the late 21st century, for simulations with and without applying the downscaling approach, respectively. Both results suggest that very intense TCs would pose a higher threat to the WNP lands under global warming, as they become substantially stronger, and with their LMI locations migrating toward the coast.

This study evaluated the performance of the Taiwan Earth System Model version 1 (TaiESM1) in simulating the observed climate variability in the historical simulation of the Coupled Model Intercomparison phase 6 (CMIP6). TaiESM1 was developed on the basis of the Community Earth System Model version 1.2.2, with the inclusion of several new physical schemes and improvements in the atmosphere model. The new additions include an improved triggering function in the cumulus convection scheme, a revised distribution-based formula in the cloud fraction scheme, a new aerosol scheme, and a unique scheme for three-dimensional surface absorption of shortwave radiation that accounts for the influence of complex terrains. In contrast to the majority of model evaluation processes, which focus mainly on the climatological mean, this evaluation focuses on climate variability parameters, including the diurnal rainfall cycle, precipitation extremes, synoptic eddy activity, intraseasonal fluctuation, monsoon evolution, and interannual and multidecadal atmospheric and oceanic teleconnection patterns. A series of intercomparisons between the simulations of TaiESM1 and CMIP6 models and observations indicate that TaiESM1, a participating model in CMIP6, can realistically simulate the observed climate variability at various time scales and performs better than the other CMIP6 models in terms of many key climate features.