Collaborative Research: P2C2--El Niño Southern Oscillation (ENSO) Variability Changes during Abrupt Climate Events

研究小组的目标是通过测量先前从西南太平洋热带瓦努阿图收集的样本上的珊瑚三角洲O-18，重建厄尔尼诺/南方涛动（ENSO）在最后一次去冰期的变异性变化。来自瓦努阿图的现代珊瑚三角洲o -18记录和伪代理实验显示了捕捉ENSO变率变化的高度技巧，从而使人们相信所得记录可用于重建过去的ENSO变率。研究人员将把这些重建结果与之前冰河时期ENSO气候模型的输出结果进行比较，当时大西洋经向翻转环流（AMOC）既活跃又缓慢。基于气候模型的输出，研究小组目前的假设是，相对于现代，ENSO在冰川时期减少了，而相对于AMOC活跃的同时期冰川时期，AMOC关闭时ENSO更活跃。该小组将在冰川边界条件下进行管道模型实验，以测试ENSO和AMOC变化对背景条件的敏感性。该研究还将通过使用在不同气候边界条件下运行的气候模型集合来调查ENSO的非平稳性如何影响瓦努阿图珊瑚的技能。该项目可能有助于揭示ENSO对外部强迫的敏感性，这是一个非常关键的问题，因为用于未来气候预测的气候模型不同意ENSO是随着地球变暖而增强还是减弱。潜在的更广泛的影响包括更深入地了解ENSO变异性，开发用于现场研究的新钻井系统，以及研究生和本科生参与研究，包括主要是本科教学机构的本科生。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 research team aims to reconstruct changes in variability of the El Nino/Southern Oscillation (ENSO) during the last deglacial period by measuring coral delta O-18 on previously collected samples from Vanuatu in the tropical southwestern Pacific Ocean. Modern coral delta O-18records from Vanuatu and pseudoproxy experiments show a high degree of skill in capturing changes in ENSO variability, providing confidence that the resulting records can be used to reconstruct past ENSO variability. The researchers will compare the reconstructions to climate model output of ENSO during previous glacial times when Atlantic Meridional Overturning Circulation (AMOC) was both vigorous and sluggish. The research team’s current hypotheses, based on climate model output, is that ENSO was reduced during glacial times, relative to modern, and that ENSO was more active when AMOC was shutdown, relative to contemporaneous glacial times when AMOC was active. The team will conduct hosing model experiments under glacial boundary conditions to test the sensitivity of ENSO and AMOC changes to background conditions. The research will also investigate how non-stationarity of ENSO may affect the skills of Vanuatu corals by using an ensemble of climate models run under different climate boundary conditions. The project may help shed light on the sensitivity of ENSO to external forcing, a highly critical issue given that climate models used for future climate projections do not agree if ENSO will strengthen or weaken as the Earth warms.The potential Broader Impacts include a deeper understanding of ENSO variability, development of a new drilling system for field research, involvement of graduate and undergraduate students in the research including undergraduates at a primarily undergraduate teaching institution.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.