Collaborative Research: P2C2--Subdecadal Pleistocene Indian Monsoon Variability: A Dual Archive Perspective

研究小组试图利用印度季风变化的更新世记录来研究在不同的平均状态和全球边界条件下，十年以下降雨动态如何变化，以完善目前对印度季风系统对气候强迫的反应的理解。 虽然更新世的档案提供了几个重要的见解印度季风动力学，推断到近十年季风变率一直缺席，由于样本分辨率不足。 以前的重建表明强烈的平均状态季风的变化，在日照和温室气体强迫的反应，但在这些期间调制的方式subdecadal变率是不清楚的。 目前的研究工作集中在温室气体，日照和冰量条件差异很大的时期，以概述季风季节性及其短期变化对全球气候变化的敏感性。研究人员将应用成像和质谱技术，从先前收集的印度次大陆陆地和海洋档案中提取亚十年水文气候信号。 具体来说，研究小组将使用先前从印度半岛收集的洞穴石笋和孟加拉湾U1446站点的沉积物，这些石笋和沉积物已经产生了古季风变化的粗尺度记录。研究的目标是帮助证实或反驳以下假设：（1）季节性和年际季风变化表现出快速的变化。（2）夏季风和冬季风动力学在不同的更新世气候状态下彼此异相变化;以及（3）季风核心区和印度半岛的季节性降雨同样受到外部强迫的调制。潜在的更广泛影响包括将最先进的地球化学技术与古气候动力学相结合，以提高对气候强迫如何调节短期印度季风变化及其极端情况的认识。该项目将支持博士后学者，并将大大扩大她的研究组合。该项目还将支持来自亚利桑那大学代表性不足背景的本科研究人员，并将通过SARSEF计划让亚利桑那州南部的高中生参与进来。这项工作将加强美国和印度科学家之间先前建立的合作关系，从而以对社会负责和互利的方式成功收集样本。该奖项反映了NSF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 research team seeks to use the Pleistocene record of Indian Monsoon variation to examine how subdecadal rainfall dynamics change under disparate mean-states and global boundary conditions to refine the current understanding of the Indian Monsoon system’s response to climate forcing. Although Pleistocene archives have provided several essential insights into Indian Monsoon dynamics, inferences into subdecadal monsoon variability have been absent due to insufficient sample resolution. Previous reconstructions indicate strong mean-state monsoon responses to variations in insolation and greenhouse gas forcing, but the manner in which subdecadal variability is modulated across these periods is unclear. The current research effort focuses on periods with vastly different greenhouse gas, insolation, and ice-volume conditions to outline the sensitivity of monsoon seasonality and its short-term variability to global climate change. The researchers will apply imaging and mass spectrometric techniques to extract subdecadal hydroclimate signals from previously collected archives from terrestrial and oceanic realms of the Indian subcontinent. Specifically, the team will use previously collected cave stalagmites from peninsular India and sediments from Site U1446 in the Bay of Bengal, for which coarser-scale records of paleomonsoon variability have already been generated.The goal of the research is to help confirm or refute the following hypothesis: (1) seasonality and interannual monsoon variability exhibit a fast (instantaneous) response to gradual insolation forcing; (2) summer and winter monsoon dynamics vary out-of-phase with each other across disparate Pleistocene climate states; and (3) seasonal rainfall in the core monsoon zone and peninsular India is modulated similarly by external forcing.The potential Broader Impacts include integrating state-of-the-art geochemical techniques alongside paleoclimate dynamics to advance knowledge on how climate forcing modulates short-term Indian Monsoon variability and its extremes. The project will support a postdoctoral scholar and will significantly expand her research portfolio. The project will also support undergraduate researchers from underrepresented backgrounds at the University of Arizona and will involve southern Arizona high school students through the SARSEF program. This work will strengthen previously established collaborations between US and Indian scientists, which has enabled successful collection of samples in a societal responsible and mutually beneficial manner.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.