Revisiting the Holocene orbital-scale summer temperature–precipitation relationship in Northern Hemisphere land monsoon regions

The summer precipitation–temperature relationship on the orbital scale in Northern Hemisphere land monsoon regions (NHLMR) during the Holocene remains debated, which has implications for our understanding of local temperature uncertainties and monsoon dynamics. We explore their relationship based on a transient simulation forced by Earth’s orbital parameters. The simulation reveals a remarkable shift of their overall relationship from significant positive correlation during 10–5 ka to significant negative correlation thereafter. Over the midlatitude NHLMR, summer temperature and precipitation vary in-phase during the Holocene, decreasing synchronously in response to local insolation. The low-latitude NHLMR exhibit a complex and temporally evolving precipitation–temperature relationship, shifting from weak correlation to significant negative correlation. This shift can be attributed to the increasing dominance of cloud–radiation feedbacks, whereby insolation-induced monsoon enhancement increases cloud cover, inducing surface cooling that decouples temperature from direct insolation forcing. Additionally, tropical atmosphere–ocean interactions modulated by spring insolation contribute to the early‒mid-Holocene temperature trend. Hence, our simulation indicates considerable spatiotemporal variations in the summer precipitation–temperature relationship over NHLMR during the Holocene. 全新世期间北半球陆地季风区轨道尺度上的夏季降水–温度关系仍存在争议, 这一问题对于理解区域温度不确定性和季风动力学具有重要意义. 本文基于地球轨道参数驱动的瞬变模拟, 探究了二者之间的关联. 模拟结果显示, 二者的整体相关关系发生显著转变: 在10–5 ka期间呈现显著正相关, 此后转为显著负相关. 在中纬度北半球陆地季风区, 全新世夏季温度与降水呈同位相变化, 二者在区域太阳辐射的驱动下同步降低. 低纬度北半球陆地季风区的降水–温度关系复杂且随时间演变, 从弱相关逐渐转变为显著负相关. 这一转变可归因于云–辐射反馈作用的主导性不断增强, 即太阳辐射驱动的季风增强会使云量增加, 进而引发地表冷却, 使温度变化脱离太阳辐射的直接驱动. 此外, 受春季太阳辐射调控的热带海气相互作用, 对全新世早中期的温度变化趋势亦有贡献. 因此, 本模拟结果表明, 全新世北半球陆地季风区的夏季降水–温度关系存在显著的时空差异.