Forward and inverse modeling of Black spruce tree ring series: applications to paleohydrology and paleoclimatology

黑云杉年轮系列的正向和逆向建模：在古水文学和古气候学中的应用

• 批准号: RGPIN-2016-05244
• 负责人: Boucher, Étienne
• 金额: $ 1.75万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=679739
• 关键词: Forward; inverse; modeling; Black; spruce

The long-term objective of this NSERC DG is to produce hydro-climatic, tree-ring-based reconstructions in regions, such as the temperate and the boreal zones, where knowledge on past hydro-fluctuations is critically lacking. These reconstructions will provide a more accurate baseline to which recent changes can be compared and will cast a new light on the origin of long-term hydro-climatic variability in these understudied regions. To achieve this, we will propose a novel proxy-model fusion approach, specifically designed to overcome the difficulties encountered by dendrochronologists in regions where trees grow far from environmentally stressful conditions.*********In the past few decades, dendrochronology has greatly contributed to the understanding of long-term hydro-climatic changes. However, it led to equivocal results in regions where both temperature and precipitation control growth rates. The basic approach to climate reconstruction dictates a trade off between spatial resolution and climate-sensitivity, and favours the inclusion of either temperature-sensitive (restricted to latitudinal / altitudinal tree lines) or precipitation-sensitive (restricted to semi-arid regions) forest stands as proxies for past climates. However, refining our understanding of past instabilities will force tree ring scientists to extract robust hydro-climatic signals from regions that have contributed less to our understanding of global changes. Indeed, such regions are typically characterized by complex, multivariate and time-varying (divergent) proxy-climate relationships that represent major obstacles to the production of tree-ring-based reconstructions.******The novel reconstruction approach will be implemented in North-Eastern North-America (NENA)'s boreal forest which represents an archetypal example of a region where ambiguous tree-ring-to-climate relationships prevail. The approach will be based on two complementary aspects. First, climatic signal extraction will rely on multiple proxies (tree ring widths, carbon and oxygen stable isotopes) in order to strengthen the analysis of both temperature and precipitation signals. Second, relationships between proxies and climate will be assessed using process-based modeling anchored to a vast network of multi-proxy measurements that integrate all temporal scales relevant to infer past climates from tree rings: infra-annual, inter-annual, decadal, millennial. This research program will generate crucial information on long-term hydro-climate variability and persistence in NENA, which will help refine our capacity to predict (and adapt to) future changes. The program will rely on a strong and active network of collaborations at the national and international levels and will represent an excellent opportunity for trainees to be involved in a research initiative that represents the cutting edge of paleoclimatology.**

NSERC DG的长期目标是在温带和寒带等地区进行水文气候和基于树木年轮的重建，这些地区严重缺乏对过去水文波动的了解。这些重建将提供一个更准确的基线，最近的变化可以进行比较，并将在这些研究不足的地区长期水文气候变化的起源投下新的光。为了实现这一目标，我们将提出一种新的代理模型融合方法，专门用于克服树木生长远离环境压力条件的地区树木年代学家遇到的困难。在过去的几十年里，树木年代学极大地促进了对长期水文气候变化的理解。然而，在温度和降水控制生长率的地区，它导致了模棱两可的结果。气候重建的基本方法要求在空间分辨率和气候敏感性之间进行权衡，并赞成将对温度敏感（限于纬度/海拔树木线）或对降水敏感（限于半干旱地区）的森林林分作为过去气候的替代物。然而，完善我们对过去不稳定性的理解将迫使树木年轮科学家从那些对我们对全球变化的理解贡献较小的地区提取强大的水文气候信号。事实上，这些地区的典型特征是复杂、多元和时变（发散）的代理气候关系，这是基于树木年轮重建的主要障碍。*新的重建方法将在北美东北部（NENA）的北方森林，这是一个典型的例子，一个地区的模糊树轮气候关系占上风。这一办法将基于两个相辅相成的方面。首先，气候信号的提取将依赖于多种代用指标（树木年轮宽度、碳和氧稳定同位素），以加强对温度和降水信号的分析。其次，代理和气候之间的关系将使用基于过程的建模进行评估，该建模锚定在一个庞大的多代理测量网络上，该网络集成了与从树木年轮推断过去气候相关的所有时间尺度：年内，年际，十年，千年。这项研究计划将产生关于NENA长期水文气候变化和持续性的关键信息，这将有助于提高我们预测（和适应）未来变化的能力。该计划将依赖于在国家和国际层面上强大而活跃的合作网络，并将为学员提供参与代表古气候学前沿的研究计划的绝佳机会。