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着深远的影响，但该地区对气候变化的响应尚不清楚，热带降水和水循环的预测仍然高度不确定。本项目旨在通过数值模式模拟和热带水文气候水示踪剂的代理衍生记录，识别不同边界条件下泛热带和区域对气候驱动因子的响应，提高该地区未来气候预估的能力。调查将集中在最后一次消冰期，其特征是大气温室气体浓度、季节性日照、冰盖和海平面的大变化。因此，末次消冰的构造为研究不同边界条件下的热带水文气候变化提供了一个独特的机会。本项目的总体目标是通过(1)合成热带水同位素记录来表征末次消冰期间热带水同位素水文记录的时空变化特征，(2)验证热带降雨的外部强迫和内部反馈影响的关键假设，从而对热带水文气候的大尺度动力学和控制有新的认识。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支持的瞬态气候模型（iTRACE）。此外，研究人员将利用同位素支持的群落地球系统模型在不同边界条件下进行新的灵敏度实验，以测试陆地-海洋配置对热带地区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了解末次消冰期间热带水文气候的时空变化和区域驱动因素。该研究将评估相对于大气环流变化的降水量对降水的影响，从而有可能增强区域古气候记录的解释。该项目将支持布朗大学一位早期职业科学家的专业发展，并通过布朗大学领导联盟- nsf - reu合作伙伴关系，支持来自少数民族服务机构的本科生的教育和研究培训。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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.