Seasonal to decadal variations of precipitation oxygen isotopes in northern China linked to the moisture source

A precise characterization of moisture source and transport dynamics over the inland margins of monsoonal China is crucial for understanding the climatic significance of precipitation oxygen isotope (δ¹⁸O_p) variability preserved in the regional proxy archives. Here, we use a general circulation model with an embedded water-tagging module to quantify the role of moisture dynamics on the seasonal to decadal variations of δ¹⁸O_p in northern China. Our data indicate that during the non-monsoon season, the δ¹⁸O_p variability is dominated by the temperature effect. Conversely, in the summer monsoon season, the moisture contributions from the low-latitude land areas (LLA), the Pacific Ocean (PO), and the North Indian Ocean (NIO) override the temperature effect and influence the summer δ¹⁸O_p. Intensified upstream convection along the NIO moisture transport pathway results in a more negative summer δ¹⁸O_p compared to moisture transported from the PO and LLA regions. Our analysis shows a decadal shift in summer δ¹⁸O_p around the mid-1980s, marking changes in the relative contribution of oceanic moisture from PO and NIO in response to changes in the atmospheric circulation patterns influenced by the Pacific Decadal Oscillation. We suggest that such decadal-scale δ¹⁸O_p variability can be recorded in the natural archives from the region, which can provide valuable insights into understanding past climate variability.