Impact of Pacific Walker Circulation driven by Interdecadal Pacific Oscillation on precipitation variability in the North China Monsoon Marginal Region over the past five centuries

The Asian Summer Monsoon system has exerted significant impact on the ecological environment and socio-economic development of North China. Understanding the variability of monsoon precipitation and its underlying drivers in the context of anthropogenic warming necessitates the development of high-resolution precipitation reconstructions extending beyond the instrumental record. This study presents a novel tree ring network comprising 869 cores from 12 site chronologies in the North China Monsoon Marginal Region (NCMMR). A Nested Principal Component Regression model is used to reconstruct August-to-July precipitation variability from 1512 to 2021. The results indicate that, compared to the preceding five centuries, the probability of extreme high and low precipitation events increased by ~9 % and ~ 2 %, respectively, during the Current Warming Period (CWP, 1850–2021), with a higher long-term mean precipitation of 465.39 mm. The standard deviation and coefficient of variation for precipitation during the CWP (48.24 mm and 10.36 %, respectively) exceed those of the Historical Period (1512–1849) (36.89 mm and 8.07 %, respectively), highlighting an increase in precipitation variability over time. Analysis of global sea surface temperature patterns reveals a strong linkage between precipitation and the Interdecadal Pacific Oscillation (IPO). This is supported by a significant negative correlation between precipitation and the IPO index (P < 0.001), alongside the IPO's substantial contribution (25 % of explained variance) to precipitation variability. Additionally, precipitation exhibits a significant positive correlation with the Pacific Walker Circulation (PWC) index (P < 0.001). Climate model simulations further demonstrate that IPO-driven variations in PWC intensity regulate interdecadal precipitation variability in the NCMMR using water vapor transport anomalies.