A new hydrogen-isotope approach to understand North African monsoon changes in the Holocene (HYDRACENE)

该项目的目的是更好地了解西北非洲季风系统在全新世，特别是在气候突变期间的水文演变，并解决原因，如由于海洋表面温度梯度和大气-植被反馈引起的季风雨带的变化。作为一种新的科学方法，我们基于西北非洲关键地点海洋沉积物中植物类脂的特定化合物氢同位素组成，以高时间分辨率分析水文信号。这些同位素分析还得到了详细的气候模拟的补充，其中包括对水循环和叶水中的同位素分馏进行显式模拟。第一个项目的结果显示，同位素数据和模型结果之间有很好的一致性，无论是关于今天西北非洲海岸的空间同位素梯度，还是关于上个世纪与萨赫勒干旱有关的时间同位素变化。对于即将到来的项目期，我们建议继续这项成功的科学工作，并扩大我们对全新世气候变化的分析。将对选定的时间片进行模拟实验，并进行敏感性测试，以揭示重要的强迫因素。该项目的成果将有助于更深入地了解非洲西北部发生的大规模大陆水文变化及其成因过程。

This project aimes at a better understanding of the hydrologic evolution of the North-West African monsoon system over the Holocene, in particular during abrupt climate changes, and resolving causal factors, such as shifts in the monsoonal rain belt due to sea surface temperature gradients and atmosphere-vegetation feedbacks. As a new scientific approach, we analyze the hydrological signal based on compound-specific hydrogen isotope compositions of plant lipids in marine sediments from North-West African key sites in high temporal resolution. These isotope analyses are complemented by detailed climate simulations, which include an explicit modeling of isotopic fractionations within the hydrological cycle and in leaf water. First project results reveal a very good agreement between isotope data and model results, both for a present-day spatial isotope gradient along the North-West African coast as well as for temporal isotope variations related to the Sahel drought during the last century. For the forthcoming project period we propose continuing this successful scientific work and extending our analyses towards Holocene climate variations. Modeling experiments will be performed for selected time-slices and sensitivity test will be conducted to unravel significant forcing factors. The outcome of this project will lead to improved insights into the occurrence of large-scale continental hydrologic changes in North-West Africa and their causal processes.