Influence of ENSO on multi-annual temperature variations at Hongyuan, NE Qinghai-Tibet plateau: evidence from δ13C of spruce tree rings

摘要

Influence of ENSO on global temperature variations has aroused wide attention. However, little is known about this effect at regions where different monsoons prevail. In this study, we measured 13C of spruce trees (picea likiangensis var. rubescens) and reconstructed temperature variations during the past 270 years at Hongyuan, the Zoige plateau where Indian summer monsoon (ISM) dominates. Temperature variation inferred from 13Ctree ring at the Zoige plateau shows anti-teleconnection on multi-annual timescales to the sea-surface temperature (SST) anomaly in the Nino3 region (SSTANino3 for short) which has been widely used as an indicator of the “El Nino–South Oscillation” (ENSO). We speculate that the ENSO may modulate the regional surface temperature by influencing the intensity of the ISM, which affects the influx of warm/moist air mass to the study region and subsequently changes the latent heating. On multi-annual scales, when the SSTANino3 is high (low), the ISM is weak (strong), monsoon precipitation decreases (increase), the latent heating is weakened (strengthened) and surface air temperature is lower (higher).