How is the El Niño–Southern Oscillation signal recorded by tree‐ring oxygen isotopes in southeastern China?

Abstract

AbstractPrevious studies universally found that tree‐ring oxygen isotope (δ18OTR) in southeastern China (SEC) significantly recorded the El Niño–Southern Oscillation (ENSO) signal. However, the correlation between the climate in SEC and ENSO is insignificant, so the local climatic response of SEC δ18OTR fails to explain the significant positive correlations between these δ18OTR records and ENSO. In this study, based on four δ18OTR series from SEC, meteorological data, simulated precipitation oxygen isotope (δ18OP) data, and a moisture uptake atlas deduced from Lagrangian backward trajectory experiments, a conceptual model was established to explain how the ENSO signal is recorded by SEC δ18OTR. During the El Niño decaying years, the Northwest Pacific (NWP) convective activity weakens; the convective weakening areas coincide with the main moisture sources for SEC, which enriches 18O in moisture that is transported to SEC, resulting in positive anomalies of δ18OP in SEC; finally, the ENSO‐modulated δ18OP signal is inherited by SEC δ18OTR. The opposite situations occur in the La Niña events. It was also indicated that the change in the moisture contribution percentage from different sources may not be a primary factor that connects SEC δ18OTR with ENSO. These findings contribute to understanding climatic signals represented by δ18OTR and δ18OP in the East Asian monsoon region.