Past Global Warming Influence on Intense Typhoons Reaching Southern China During El Niño and La Niña Using a Variable Resolution Global Model

ABSTRACT

Four equilibrium climate simulations using the Community Earth System Model version 2.2 forced by prescribed Sea Surface Temperature (SST). The model mesh was regionally refined to 0.25° horizontally over the Asia‐Pacific, in order to generate intense typhoons (maximum sustained winds above 41.5 m s ⁻¹ ). Two baseline simulations were forced by SSTs of 1997 (El Niño), 2000 (La Niña). The global SST was detrended by removing Mode 1 from Empirical Orthogonal Function decomposition. Two more “non‐warming” simulations of 1997 and 2000 were performed. Intense typhoon tracks were grouped with agglomerative hierarchical clustering and categorized into westward and curved tracks. Mode 1 decreased the number of westward tracks for 2000, while there were no statistically significant changes in curved tracks for 2000 and both types for 1997. Mode 1 also increased track density over the Luzon Strait toward Guangdong in 1997 (not significant), and over the Yangtze River mouth in 2000 (significant). It is therefore possible that the perceived increased typhoon damage in recent years may be due to intense typhoon tracks shifting to more populated and economically important regions. However, since only 2 years were analyzed, the track changes may be due to residual SST anomalies that were event‐specific. Furthermore, there remained uncertainty in the individual effects of global warming and climate variability signals contained inside Mode 1.