Late Holocene monsoon precipitation changes in southern China and their linkage to Northern Hemisphere temperature

Here we present a reconstruction of a ~5 year-resolution summer monsoon rainfall record for the past 3200 years, based on 622 pairs of δ18O and δ13C and 29 230Th dates from a stalagmite (Wu37) from Wulu Cave in southern China. The monsoon precipitation variations indicated by our record and other cave records nearby were inversely related to changes in Northern Hemisphere temperature over the past two millennia, in particular to variations in the thermal gradient between the Northern and Southern hemispheres. In addition, we find that variations of monsoon rainfall in southern China on multi-centennial to centennial timescales are inversely correlated with observed rainfall in the core monsoon region of India and in the northern fringe of the Asian summer monsoon region in China. This spatial pattern of rainfall variability can be interpreted as a result of the migration of the intertropical convergence zone that is likely dominated by the interhemispheric thermal gradient via cross-equatorial airflows.本研究基于中国南方武卢洞编号为Wu37的石笋中的622对氧同位素(δ¹⁸O)与碳同位素(δ¹³C)数据，以及29个钍-230(²³⁰Th)测年结果，构建了一套过去3200年、分辨率约5年的夏季季风降雨重建记录。本记录与周边其他洞穴记录所揭示的季风降水变化，在过去两千年间与北半球温度变化呈负相关，尤其与南北半球间的温度梯度变化密切相关。此外，本研究发现，中国南方夏季风降雨在数百年至百年尺度上的变化，与印度核心季风区以及中国亚洲夏季风区北缘的实测降雨呈负相关关系。这种降雨变化的空间分布格局，可通过热带辐合带（intertropical convergence zone）的移动得到解释：该移动大概率受南北半球温度梯度通过跨赤道气流主导调控。