Tropical hydroclimate change during the last deglaciation: a synthesis of isotope-enabled transient climate model simulations and proxy data

热带地区对全球气候系统有深远的影响，但该地区对气候变化的反应仍不明朗，对热带降水和水循环的预测仍然高度不确定。该项目旨在通过利用热带水气候水示踪的数值模式模拟和代理派生记录来确定不同边界条件下泛热带和区域对气候驱动因素的响应，从而提高该区域未来气候预测的能力。调查将集中在最后一个消冰期，其特点是大气温室气体浓度、季节性日照、冰盖和海平面发生巨大变化。因此，末次冰川消融的格局为研究不同边界条件下的热带水气候变化创造了独特的机会。该项目的总体目标是通过(1)综合热带水同位素记录来表征末次冰川消融期间热带同位素水文记录的时空变化，以及(2)检验关于外部强迫和内部反馈对热带降水影响的关键假设，以获得对热带水气候的大尺度动态和控制的新见解。为了实现这一目标，研究人员提出了一个全面的泛热带数据模型比较，通过整合基于水同位素的代理数据、代理系统模型和新的模拟与最先进的同位素启用的瞬变气候模型(ITRACE)。此外，研究人员将利用同位素启用的社区地球系统模型在不同的边界条件下进行新的敏感性实验，以测试陆地-海洋配置对热带轨道和千年尺度变化的影响。潜在的更广泛的影响包括更好地理解上次冰川消融期间热带水气候的时空变化和区域驱动因素。拟议的研究将评估与大气环流变化相关的降水量对降水的影响，从而有可能加强对区域古气候记录的解释。该项目将支持布朗大学早期职业科学家的专业发展，以及通过布朗大学领导力联盟-国家科学基金会-REU伙伴关系对少数群体服务机构的本科生进行教育和研究培训。此外，研究人员将为本科生和研究生开发一门关于气候数据分析和数据模型比较的新研讨会课程。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The tropics have profound influence on the global climate system, but the region’s response to changing climate remains unclear and the predictions of tropical precipitation and water cycling remain highly uncertain. This project aims to improve the ability of future climate projections in this region by using numerical model simulation and proxy derived records of water tracers of tropical hydroclimate to identify pan-tropical and regional responses to climate drivers under different boundary conditions. The investigation will focus on the last deglaciation period which is characterized by large shifts in atmospheric greenhouse gases concentrations, seasonal insolation, ice sheets, and sea level. Thus, the configuration of the last deglaciation creates a unique opportunity to study the tropical hydroclimate changes under different boundary condition than today.The overarching goal of this project is to gain new insight into the large-scale dynamics and controls on tropical hydroclimate through (1) syntheses of tropical water isotope records to characterize the spatiotemporal changes of tropical isotope hydrological records during the last deglaciation, and (2) testing critical hypotheses about the impact of external forcings and internal feedbacks on tropical rainfall. To accomplish this goal, the researchers propose a comprehensive pan-tropical data model comparison through integrating water-isotope based proxy-data, proxy system models, and new simulations with a state of-the-art isotope enabled transient climate model (iTRACE). Further, the researchers will perform new sensitivity experiments under different boundary conditions with isotope-enabled Community Earth System Model to test the influence of land-ocean configuration on orbital and millennial-scale variability across the tropics.The potential Broader Impacts include a better understanding of the spatiotemporal changes and regional drivers of tropical hydroclimate during the last deglaciation. The proposed research will assess the influence of precipitation amount relative to atmospheric circulation changes on precipitation thus potentially enhancing the interpretation of regional paleoclimate records. The project will support the professional development of an early career scientist at Brown University and the education and research training of undergraduate students from minority-serving-institutions through the Leadership Alliance-NSF-REU partnership at Brown University. Additionally, the researchers will develop a new seminar course on climate data analysis and data-model comparison for undergraduate and graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.