Asynchronous 500-year summer monsoon rainfall cycles between Northeast and Central China during the Holocene

摘要

Although the summer monsoon is the dominant source of precipitation in the East Asian monsoon region (EAMR), there is long-standing uncertainty about the spatial and temporal variability of precipitation on the centennial time scale. In this study we analyzed two well-dated, high-resolution, published paleoclimatic records in order to determine the variability of precipitation in the EAMR during the Holocene. One record is a decadal-resolution pollen record from an annually-laminated Maar lake in Northeast (NE) China, and the other is a UeTh dated, multi-decadal-resolution speleothem record from Central China. Advanced time-series analysis of the two records provides unambiguous evidence for asynchronous summer monsoon rainfall variability on centennial to millennial time scales in the EAMR. The pollen and speleothem records indicate long-term and similar to 500-yr quasi periodic changes in humid/dry climatic shifts against the background of an insolation-forced climatic trend throughout the past 8580 years. Phases of wetter climate (during similar to 7000-5500 cal yr BP) and drier climate (during similar to 1400-300 cal yr BP) in NE China are closely related to different climatic phases in Central China. However, the similar to 500-yr cyclic rainfall changes in Central China lag those in NE China by several decades to almost two centuries. During the similar to 500-yr periodic changes in the monsoon, a climatic pattern encapsulated as "Northern drought, southern flooding" prevailed during an El Nino-like phase, whereas the opposite pattern "Southern drought, northern flooding" occurred during a La Nina-like phase. The asynchronous pattern of similar to 500yr climatic cyclicity between the northern and southern EAMR may have been caused by the El Nino-Southern Oscillation, linked to low-latitude oceanic and atmospheric interactions.