oa Reappraisal of the Amount Effect in the Southern Part of the East Asian Monsoon Region During the Last Deglaciation

The East Asian summer monsoon (EASM) system influences 10% of the world’s population. Yet debates exist in the past spatio-temporal patterns of rainfall amount/isotopic composition in different EASM regions and the underlying forcing mechanisms. The southern part of the EASM region has the highest annual rainfall but is limited in paleo-records of rainfall amount/isotopic composition. In this study we use the stable hydrogen isotope of leaf wax lipids from a marine sediment core in the northern South China Sea to reconstruct the changes in rainfall isotopes in Taiwan through the last deglaciation. We also simulate deglacial changes in rainfall amount and isotopes based on isotope-enabled Transient Climate Evolution (iTRACE) experiments. The deglacial variability of our dD record is against the previously proposed coherent continental-scale pattern shown by speleothem records. Instead, our dD is negatively correlated with both simulated and proxy-derived annual rainfall amount in Taiwan our record on the millennial timescale, suggesting a distinct amount effect in the southern part of the EASM region.