Intense Tropical Cyclones in the Western North Pacific under Global Warming: A Dynamical Downscaling Approach

Abstract

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.

A Global Increase in Nearshore Tropical Cyclone Intensification

“…Under global warming, a heightened nearshore intensification rate implies a potential strengthening of landfalling TCs' destructive capacity, primarily determined by their maximum intensity and inner‐core precipitation (Hsu et al., 2021). Changes in these factors are closely associated with the intensification rate of TCs within coastal regions (Chih et al., 2023; Hsu et al., 2021; R. C. Li et al., 2017; Park et al., 2014). The stronger winds and heavier precipitation produced by landfalling TCs can exacerbate the impacts of storm surge and increase the risk of coastal flooding (Timmermans et al., 2017, 2018; Woodruff et al., 2013).…”

Intense Tropical Cyclones in the Western North Pacific Under Global Warming: A Dynamical Downscaling Approach

“…The data and functions are available in the Zenodo repository https://zenodo.org/record/8381723 (Chih et al, 2023). The High-Resolution Atmospheric Model are publicly available online (https://www.gfdl.noaa.gov/ hiram/ GFDL, 2023).…”