Modeling and Observational Study of Decadal El Nino-Southern Oscillation (ENSO) Modulation and Tropical Pacific Decadal Variability

十年厄尔尼诺-南方涛动（ENSO）调制和热带太平洋年代际变化的模拟和观测研究

• 批准号: 1302346
• 负责人: Yuko Okumura
• 金额: $ 48.24万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-05-01 至 2017-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1302346&HistoricalAwards=false
• 关键词: Modeling; Observational; Study; Decadal; El

The El Nino-Southern Oscillation (ENSO) phenomenon provides an important source of climate predictability on interannual time scales. The research aims for mechanistic understanding of the processes important to the decadal modulation of ENSO and tropical Pacific decadal variability through model experiments and observational analysis. It is hypothesized that the low frequency components of stochastic atmospheric variability in the North and South Pacific, namely, the North Pacific Oscillation (NPO) and Pacific-South American (PSA) variability, independently drive tropical Pacific decadal variability. Furthermore the tropical Pacific decadal variability driven by NPO interacts with ENSO and modulates its amplitude through meridional displacement of the mean intertropical convergence zone (ITCZ). The PSA variability, on the other hand, appears to drive ENSO-like decadal variability associated with the Pacific Decadal Oscillation (PDO), affecting precipitation in the South Pacific convergence zone (SPCZ). These hypotheses will be tested through detailed analysis of climate and atmospheric model experiments. The model results will also be validated with observational analysis of various instrumental data and paleoclimate proxy records for the past 100-200 years. The observational analysis will show if the ITCZ and SPCZ vary independently on decadal-interdecadal time scales and how their decadal variability is associated with the decadal ENSO modulation. The results obtained from the project will not only shed light on the nature of tropical Pacific climate variability but also provide guidance in understanding the uncertainty of future ENSO behavior and in interpreting paleoclimate proxy records of ENSO.

厄尔尼诺-南方涛动（ENSO）现象是年际时间尺度上气候可预测性的一个重要来源。本研究旨在通过模式试验和观测分析，从机制上理解ENSO和热带太平洋年代际变率的年代际调制过程。据推测，在北太平洋和南太平洋的随机大气变率的低频分量，即北太平洋涛动（NPO）和太平洋-南美（PSA）的变化，独立驱动热带太平洋年代际变化。此外，NPO驱动的热带太平洋年代际变率与ENSO相互作用，并通过热带辐合带的纬向位移调制ENSO的振幅。另一方面，PSA变率似乎驱动与太平洋年代际振荡（PDO）相关的ENSO样年代际变率，影响南太平洋辐合区（SPCZ）的降水。这些假设将通过气候和大气模型实验的详细分析来检验。模型结果还将通过对过去100-200年各种仪器数据和古气候代用记录的观测分析进行验证。观测分析将显示ITCZ和SPCZ是否在十年-年代际时间尺度上独立变化，以及它们的十年变率如何与十年ENSO调制相关联。从该项目获得的结果不仅将揭示热带太平洋气候变率的性质，而且还将为理解未来ENSO行为的不确定性和解释ENSO的古气候代用记录提供指导。