Decadal Modulation of El Niño Southern Oscillation and Its Interactions with Tropical Pacific Climate

厄尔尼诺南方涛动的年代际调制及其与热带太平洋气候的相互作用

• 批准号: 0925396
• 负责人: Jin-Yi Yu
• 金额: $ 37.08万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0925396&HistoricalAwards=false
• 关键词: Decadal; Modulation; El; Ni; Southern

Properties of the El Niño-Southern Oscillation (ENSO) undergo decadal variations, but the causes of these variations are not yet understood. This study explores a self-modulation mechanism that suggests extreme ENSO events should occur on decadal timescales. The mechanism depends on a two-way interaction between ENSO activity and the mean state of the tropical Pacific, in which the spatial asymmetry between El Niño and La Niña is responsible for transitions between weak and strong ENSO states. Analyses of observational data and numerical experiments using coupled general circulation models (CGCM), an intermediate coupled model, and an ocean only model, will be carried out to examine this mechanism and to understand decadal ENSO variability and its interaction with the tropical Pacific climate.Investigations will focus on the following issues: (1) How do ENSO and Pacific climate interact under various types of ENSO dynamics?(2) What is the cause of the spatial asymmetry between El Niño and La Niña and why does it reverse between a strong ENSO state and a weak ENSO state? (3) What roles do the Indian Ocean and monsoons play in the decadal ENSO variability? Does the hypothesized ENSO-Pacific climate interaction mechanism need to be modified to include the effects of the Indian Ocean and monsoons? (4) Are there any linkages between decadal ENSO variability, the proposed mechanism, and the 1976/77 rapid climate shift? This study will make use of the unprecedented collection of high-quality CGCM integrations that were produced for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The variety of ENSO behaviors simulated by these models implies that they have different ENSO dynamics and so comprise a test bed for examining ENSO-Pacific climate interaction under different ENSO dynamics and different greenhouse gas forcings. Numerical experiments that limit ocean-atmosphere coupling to individual ocean basins or constrain the Pacific basic state will be performed with the two CGCMs and an intermediate coupled model. Model results will be verified using observational data and simulations with an ocean model.Broader impacts of this study include the potential to improve long-term predictions of extreme ENSO events and to improve the simulation of ENSO in CGCMs. Ph.D. students will be trained, and undergraduate Earth System Science majors will be involved in the research.

厄尔尼诺-南方涛动（ENSO）的性质经历了十年变化，但这些变化的原因还不清楚。本研究探讨了一种自我调节机制，表明极端ENSO事件应该发生在十年的时间尺度上。该机制取决于厄尔尼诺/南方涛动活动与热带太平洋平均状态之间的双向相互作用，其中厄尔尼诺和拉尼娜之间的空间不对称性是造成弱和强厄尔尼诺/南方涛动状态之间转变的原因。本研究将利用耦合大气环流模式（CGCM）、中间耦合模式和海洋模式的观测资料和数值试验，探讨ENSO的年代际变率及其与热带太平洋气候的相互作用，主要研究以下问题：（1）在不同的ENSO动力条件下，ENSO与太平洋气候如何相互作用？(2)厄尔尼诺和拉尼娜之间的空间不对称性的原因是什么？为什么它在强ENSO状态和弱ENSO状态之间发生逆转？(3)印度洋和季风在ENSO十年变率中起什么作用？假设的ENSO-太平洋气候相互作用机制是否需要修改以包括印度洋和季风的影响？(4)十年ENSO变率、拟议的机制和1976/77年快速气候转变之间是否有任何联系？这项研究将利用为政府间气候变化专门委员会第四次评估报告编制的前所未有的高质量CGCM整合。这些模式模拟的ENSO行为的多样性意味着它们具有不同的ENSO动力学，因此构成了一个测试床，以研究不同ENSO动力学和不同温室气体强迫下的ENSO-太平洋气候相互作用。将用两个大气环流模式和一个中间耦合模式进行限制海洋-大气耦合到单个海洋盆地或限制太平洋基本状态的数值试验。将利用观测数据和海洋模式的模拟来核实模式结果，这项研究的更广泛影响包括有可能改进对厄尔尼诺/南方涛动极端事件的长期预测，并改进大气环流模式对厄尔尼诺/南方涛动的模拟。博士学生将接受培训，本科地球系统科学专业将参与研究。