Re-evaluation of the spatiotemporal patterns of Holocene precipitation in China

Investigating the spatiotemporal variability of past precipitation in China is essential for understanding the East Asian monsoon (EAM) dynamics. However, insufficient records of Holocene palaeo-precipitation with precise chronological constraints impedes the exploration of precipitation patterns in China, and obscures the holistic understanding of EAM evolution. In this study, we reconstruct Holocene precipitation variations across eastern China since the Holocene, using the precipitation index (PRI) derived from high-quality stalagmite delta O-18 records from 25 caves. Validation against other independent hydroclimatic records confirm the robustness of the PRI reconstructions. Integrating the reconstructed PRI and other proxy-based precipitation records, we systematically characterize the spatiotemporal patterns of Holocene precipitation in China. The results demonstrate a meridional and zonal time-transgressive pattern of the Holocene Optimum (HO) throughout China, initiating earliest occurrence in southwestern and northwestern China (9-8 ka BP), followed by central and northern China (7-6 ka BP), and culminating latest occurrence in southeastern and northeastern China (similar to 2 ka BP). Spatial correlation analysis reveals statistically significant relationships between the timing of HO and latitude/longitude. The TraCE-21 ka simulations exhibit congruent temporal-spatial patterns, thereby independently validating our reconstructions. We propose that the shift of the westerly jet stream modulated by Northern Hemisphere summer insolation and the movement of the Western Pacific Subtropical High constrained by the sea surface temperature across the tropical Indian Ocean-West Pacific Ocean jointly governed the spatiotemporal distribution of Holocene precipitation in China.