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

该研究小组的目标是通过测量先前从热带西南太平洋瓦努阿图采集的样本来测量珊瑚三角洲O-18，重建上一次去冰期期间厄尔尼诺/南方涛动(ENSO)的变异性变化。来自瓦努阿图和伪替代实验的现代珊瑚三角洲O-18记录表明，在捕捉ENSO变率变化方面具有很高的技能，从而使人们相信所产生的记录可以用来重建过去的ENSO变率。研究人员将把重建的结果与之前冰川时期ENSO的气候模型输出进行比较，当时大西洋子午线翻转环流(AMOC)既活跃又缓慢。研究小组目前的假设是，基于气候模型的输出，ENSO在冰川时代相对于现代减少，而在AMOC关闭时ENSO更活跃，相对于同期冰川时代AMOC活跃。该团队将在冰川边界条件下进行冲洗模型实验，以测试ENSO和AMOC变化对背景条件的敏感性。这项研究还将利用在不同气候边界条件下运行的一组气候模型，调查ENSO的非平稳性如何影响瓦努阿图珊瑚的技能。该项目可能有助于阐明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并不同意ENSO会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的可变性，为实地研究开发新的钻探系统，让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。这一奖项反映了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 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.