轨道尺度东亚西风-季风演化过程及动力学机理是古气候动力学领域核心问题之一。已有研究表明，岁差驱动的低纬日射及全球冰量变化是影响东亚季风演化的主要控制因子。但斜率(地轴倾角)作为另一重要轨道参数，对高纬日射及经向日射梯度影响显著，斜率是否可以通过影响西风环流及其他高纬度气候过程进而作用于东亚季风及雨带分布，目前仍不得而知。前期工作表明，斜率能够通过影响西风急流状态，对东亚夏季风对低纬日射的响应差异有重要调制，暗示了斜率对轨道西风-季风的潜在影响。本项目拟应用基于地球系统模式针对不同斜率及岁差配置的瞬变及平衡试验，结合黄土、石笋等记录，查明斜率对东亚西风-季风相互作用的影响机制及其与岁差的耦合效应，理清高纬度气候过程对斜率变化的响应和对季风降水的反馈，评估北半球大冰盖对斜率气候效应的可能调制，最终为深入理解轨道尺度东亚气候变化动力学提供理论基础。

The evolution and dynamics of westerlies-monsoon over East Asia on the orbital timescale is one of the key questions in the paleoclimate researches. Previous studies indicate that, low-latitude insolation controlled by precession and global ice volumes are primary factors for East Asian monsoon change. However, obliquity, as another important orbital parameter, exerts great influences in changes in the high-latitude insolation and meridional insolation gradient. It is still unclear now whether these influences affect the East Asian monsoon and rainfall via the modulation of westerly circulation and other high-latitude climate processes. A preliminary work of the applicant shows that obliquity significantly modulate the response of summer monsoon to low-latitude summer insolation by affecting the westerly jet, which implies the potential role of obliquity in orbital-scale westerlies-monsoon variation. Based on the transient and equilibrium experiments by earth system models under different configurations of obliquity and precession in this project, we plan to clarify the mechanisms how obliquity affects the interaction between westerlies and monsoon over East Asia in combination with loess and cave stalagmite records. The coupled effect of obliquity with precession, as well as potential feedbacks by high-latitude climate processes, will be discriminated. The possible modulation of northern hemisphere ice sheets on the effect of obliquity will be also evaluated. The work will finally provide a theoretical basis for deeply understanding the dynamics for East Asian climate change.