A 120-year seasonally resolved speleothem record of precipitation seasonality from southeastern China

Speleothem oxygen isotope (delta O-18(s)) record as a climatic proxy in southeastern China is still in debate due to multifaceted influencing factors, a modern delta O-18(s) record, which can be calibrated or compared with observational data, is critical to explore the interpretation of delta O-18(s) proxy. Here we present a seasonally resolved delta O-18(s) record spanning the interval of 1898-2018 CE from Niubi Cave, Guangdong Province, southeastern China. A comparison between the Niubi delta O-18(s) and instrumental data reveals that the Niubi delta O-18(s) variability is primarily controlled by changes in precipitation seasonality modulated by El Nino-Southern Oscillation on interannual to interdecadal timescales. Higher (lower) delta O-18(s) values correspond to lower (higher) ratios of the East Asian summer monsoon/non-summer monsoon precipitation during the El Nino (La Nina) events associated with concomitant changes in the outgoing longwave radiation, wind field and Western Pacific Subtropical High. While similar to 73% historical drought events correlate to positive anomalies in Niubi delta O-18(s) values over the last 120 years, the rest of drought events associate with the negative delta O-18(s) anomalies. This observation suggests two different mechanisms for the drought events with more and less diminution of rainfall amount in the East Asian summer monsoon relative to the non-summer monsoon precipitation, respectively. Additionally, our Niubi delta O-18(s) record from southeastern China, together with other high-resolution speleothem and tree ring records, demonstrate a "tripole pattern" of summer precipitation during the last similar to 100 years in eastern China. (C) 2021 Elsevier Ltd. All rights reserved