Collaborative Research: Testing the Indian Ocean El Nino Hypothesis

合作研究：检验印度洋厄尔尼诺假说

基本信息

批准号：
2043447
负责人：
Pedro Di Nezio
金额：
$ 38.61万
依托单位：
University of Colorado at Boulder
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2043447&HistoricalAwards=false
关键词：
Collaborative Research Testing Indian Ocean

项目摘要

This research will explore whether the Indian Ocean could sustain climate variability resembling El Nino under continued greenhouse warming. Testing this hypothesis is important because the activation of such a mode could drive large changes in year-to-year variability and hydrological extremes over the densely populated Indian Ocean rim. This mode of climate variability has not been observed in historical data, and therefore paleoclimate reconstructions are required to study conditions that favor its emergence, its spatial characteristics, and the ability of climate models to simulate it realistically. According to climate simulations, the activation of this mode depends on the state of the Indian Ocean, which currently does not exhibit upwelling nor has a shallow thermocline (the zone of the ocean water-column where temperatures rapidly decrease with depth) -- features needed to support strong, large-scale interactions between the ocean and atmosphere. Paleoclimate records indicate that these features could have existed in the geological past, particularly during the Last Glacial Maximum, roughly 19,000-21,000 years before present, albeit with cooler average conditions. Accordingly, simulations indicate greater cooling in the eastern Indian Ocean concurrent with strong upwelling and a shallow thermocline, which is reflected in the paleo-data as an altered basin-wide (east-west) temperature gradient. Preliminary data also reveal greatly increased seasonal and year-to-year temperature variations in this region, consistent with a state favoring stronger air-sea interactions. Climate simulations of this interval show that this increase in variability could have been caused by the activa- tion of the hypothesized "Indian Ocean El Nino". Throughout this project, the researchers will further test this hypothesis by generating new datasets of seasonal and year-to-year climate variability as well as investigating new model simulations that will help determine whether, and when, this mode will emerge in the future.This project builds on preliminary model-data investigations that indicate dramatically intensified seasonal and interannual climate variability in the eastern Indian Ocean during the Last Glacial Maximum. These data suggest that changes in oceanic conditions similar to those predicted for the future could cause the emergence of a presently unobserved mode of climate variability in the Indian Ocean that resembles modern El Nino in the Pacific. In order to test this hypothesis, the researchers will develop new paleoclimate datasets and model analyses to explore climate variability in the Indian Ocean under altered conditions. The proposed new paleodata will isolate seasonality and thermocline depth signatures and thus more rigorously test the "Indian Ocean El Nino" hypothesis. Advanced model-proxy comparison techniques using existing and new model simulations from the Paleoclimate Modelling Intercomparison Project (PMIP) will be developed to perform additional tests. Historical observations and model simulations will be analyzed to determine whether this mode is distinct from present-day climate variability, and address questions related to its precursors and background conditions under which it can become active. These questions will also be explored using existing and new climate model simulations from the Coupled Model Intercomparison Project (CMIP). These simulations will be used to assess uncertainties regarding the potential activation of the "Indian Ocean El Nino" in the near future. Constraints from the model-proxy comparison will be used to determine whether these uncertainties could be reduced. Further broader impacts include student and postdoc training, and support for a new faculty member at the University of Arizona.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.

这项研究将探讨印度洋是否可以在持续的温室变暖下维持类似于El Nino的气候变化。检验该假设很重要，因为这种模式的激活可能会导致人口稠密的印度洋边缘的年度变化和水文极端变化。在历史数据中尚未观察到这种气候变化模式，因此需要古气候重建来研究有利于其出现的条件，其空间特征以及气候模型现实模拟它的能力。根据气候模拟，这种模式的激活取决于印度洋的状态，印度洋目前尚未表现出上升的趋势，也没有浅层热线（海洋水下区域，温度随着深度迅速降低） - 支持海洋和气氛之间强大的大规模相互作用所需的特征。古气候记录表明，这些特征可能存在于地质的过去，尤其是在最后的冰川最大值，大约19,000-21，000年之前，尽管有较凉爽的平均条件。因此，模拟表明，东印度洋和较浅的热跃层同时进行了更大的冷却，这在古data中反射为盆地范围内（东西方）温度梯度的变化。初步数据还显示，该地区的季节性和年度温度变化大大增加，这与一个有利于强烈的空气相互作用的州一致。此间隔的气候模拟表明，可变性的增加可能是由于假设的“印度洋El Nino”的激活引起的。在整个项目中，研究人员将通过生成新的季节性和年度气候变异性数据集进一步检验这一假设，并研究新的模型模拟，这些模型将有助于确定未来以及何时何时出现这种模式。该项目基于初步的模型数据基于季节性强度强度的季节性和间歇性气候变化，在较高的印度范围内，在较高的范围内，在较高的印度范围内。这些数据表明，与未来预测的海洋条件类似的变化可能会导致印度洋目前未观察到的气候变化模式，类似于太平洋的现代埃尔尼诺（El Nino）。为了检验这一假设，研究人员将开发新的古气候数据集和模型分析，以探索在改变条件下印度洋的气候变异性。拟议的新古代植物将分离季节性和热层深度签名，从而更严格地检验“印度洋El Nino”假设。使用古气候建模项目（PMIP）的现有和新模型模拟的高级模型比较技术将开发以执行其他测试。将分析历史观察和模型模拟，以确定这种模式是否与当今的气候变异性不同，并解决了与其前体和背景条件相关的问题。这些问题还将使用耦合模型对比项目（CMIP）的现有和新的气候模型模拟进行探讨。这些模拟将用于评估有关在不久的将来“印度洋El Nino”潜在激活的不确定性。模型比较的约束将用于确定是否可以减少这些不确定性。进一步的更广泛的影响包括学生和博士后培训，以及亚利桑那大学的新教师的支持。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的审查标准来评估的。