ENSO flavors during the Last Glacial Maximum: Assessing spatial variability under varying climate background conditions

最后一次冰盛期的ENSO特征：评估不同气候背景条件下的空间变异性地球上年际气候变异性的最大来源是厄尔尼诺南方涛动(ENSO)，其特点是热带太平洋海面温度的独特空间模式。这些模式(或“味道”)通过强大的耦合海洋-大气相互作用与气候变化联系在一起，这种相互作用在全球范围内产生反响，并可能对人类社会产生不利影响。最近的观察表明，这些模式可能正在改变，限制了社会预测和减轻ENSO影响的能力。然而，目前还不清楚ENSO的空间表达和气候效应的变化是否与全球平均温度或热带海洋表面和次表层温度等背景气候条件有关。该项目将使用大约2万年前沉积的海洋沉积物来研究ENSO的“味道”--温度的空间模式--在较冷的背景气候状态下是如何变化的。这一结果将促进我们对ENSO系统的理论理解，并使我们能够更好地预测未来气候条件下全球ENSO的影响。该项目将为本科生和研究生提供气候研究机会，并将促进创建在线内容，以突出与ENSO有关的气候变异性在区域和国家一级的重要性。背景气候条件与以厄尔尼诺南方涛动(ENSO)为特征的海洋温度异常模式或“味道”之间的关系的性质尚不清楚。该项目将检验背景气候状态，如平均温度和热带太平洋表层和次表层海洋状况，影响ENSO变率的空间格局，以及温跃层在调制ENSO中起关键作用的假设。热带太平洋在不同气候背景条件下的空间变异性将通过发展热带太平洋中部和东部关键地点最后一次冰川高峰期(20000年前)的变异性记录来评估。将对浮游有孔虫贝壳的地球化学进行分析，以重建这些地点的海洋条件。个别贝壳的痕量元素和稳定同位素比率的总体分布将提供对表层和次表层海洋变异性的估计。这些数据将重建最后一次冰盛期ENSO的空间表达，并测试背景气候和/或温跃层条件是否影响ENSO的“味道”。这项研究将促进我们对气候系统过程、机制以及不同气候状态下的海洋-大气动力相互作用的了解，并对预测未来的ENSO行为具有重要意义。该项目结合了本科生和研究生的研究，并将为公共教育制作在线内容。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。

ENSO flavors during the Last Glacial Maximum: Assessing spatial variability under varying climate background conditionsThe largest source of interannual climate variability on Earth is the El Niño Southern Oscillation (ENSO), characterized by distinct spatial patterns of tropical Pacific sea surface temperatures. These patterns (or ‘flavors’) are linked to climatic changes through powerful coupled ocean-atmosphere interactions that reverberate globally and can adversely affect human societies. Recent observations suggest these patterns may be changing, limiting societies’ ability to forecast and mitigate ENSO impacts. However, it remains unclear whether changes to ENSO’s spatial expression and climatic effects are related to background climate conditions such as mean global temperature or tropical ocean surface and subsurface temperatures. This project will use ocean sediments deposited approximately 20,000 years ago to study how ENSO ‘flavors’ – the spatial pattern of temperatures – change during a colder background climate state. The results will advance our theoretical understanding of the ENSO system and enable better predictions of global ENSO impacts under future climate conditions. This project will offer climate research opportunities for undergraduate and graduate students and will facilitate creation of online content to highlight the importance of ENSO-related climate variability at the regional and national level. The nature of the relationship between background climate conditions and the patterns of ocean temperature anomalies, or ‘flavors’ that characterize the El Niño Southern Oscillation (ENSO) remains unclear. This project will test hypotheses that background climate state, such as mean temperature and tropical Pacific surface and subsurface ocean conditions, influence the spatial pattern of ENSO variability, and that the thermocline plays a key role in modulating ENSO. The spatial variability of the tropical Pacific under differing climate background conditions will be assessed by developing records of variability spanning the last glacial maximum (20,000 years ago) from key locations in the central and eastern tropical Pacific. The geochemistry of planktic foraminifera shells will be analyzed to reconstruct oceanic conditions at these sites. Population distributions of trace elemental and stable isotopic ratios from individual shells will provide estimates of surface and subsurface ocean variability. These data will reconstruct ENSO’s spatial expression during the last glacial maximum and test whether background climate and/or thermocline conditions influence ENSO ‘flavors’. This research will advance our knowledge of climate system processes, mechanisms, and dynamical ocean-atmosphere interactions during different climate states with implications for predicting future ENSO behavior. This project incorporates undergraduate and graduate student research and will produce online content for public education.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.