Abstract: Understanding the differences in how coral geochemical proxies respond to various intensities and types of El Niño-Southern Oscillation (ENSO) events is crucial for reconstructing historical ENSO activities. This study analyzes sea surface temperature (SST) data from the southern South China Sea (SCS) since 1950, along with published coral skeletal δ¹⁸O and Sr/Ca time series from four locations: Hòn Tre Island, Yongshu Island, Anemone’s Garden, and Palawan Island. We employed methods such as frequency domain analysis and lag correlation analysis to investigate the response of SSTs and coral geochemical proxies to different types and intensities of ENSO events. The results indicate that the accuracy of coral geochemical proxies in distinguishing between EP-El Niño and CP-El Niño events increases from east to west, whereas the accuracy in identifying SBW-El Niño events decreases in the same direction. Similarly, for CP-La Niña events, the accuracy of geochemical proxy responses improves westward, whereas for EP-La Niña, the trend is reversed. Overall, coral geochemical proxies in the southern SCS are less effective at distinguishing between EP-El Niño and CP-La Niña events compared to SBW-El Niño and EP-La Niña.

Key words: southern South China Sea, ENSO, Coral, Sr/Ca, δ¹⁸O, graded response