Collaborative Research: Revisiting the Low-Frequency Variability of the Extratropical Circulation Using Non-Empirical Orthogonal Function (EOF) Modes and Linear Response Functions

合作研究：使用非经验正交函数 (EOF) 模式和线性响应函数重新审视温带环流的低频变化

基本信息

批准号：
1921413
负责人：
Pedram Hassanzadeh
金额：
$ 38.6万
依托单位：
William Marsh Rice University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-15 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921413&HistoricalAwards=false
关键词：
Collaborative Research Revisiting Low Frequency

项目摘要

One dominant pattern of the atmospheric circulation variability in the extratropical troposphere of both hemispheres is the oscillation between stronger and weaker westerly jet streams with a time scale longer than 10 days. Such low-frequency variability of extratropical westerly jet streams is called the annular mode. The annual mode influences the day-to-day weather and extreme events in the middle and high latitude regions and is therefore of great interest to understand. The annular mode in winter hemisphere also influences, and is influenced by, the stratospheric polar vortex. This project seeks a deeper understanding of the factors that control the annular mode. The outcome of this work will potentially transform the understanding of jet stream variability and weather in the middle and high latitudes. The outcome could also lead to advances in predictability past the current weather prediction barrier of about 10 days, and lead to improvements in capabilities of climate models. Furthermore, the new quantitative framework will aid the interpretation of the range of outcomes predicted by comprehensive climate models. These outcomes have the potential to advance the national and global efforts aimed at preparing for climate change and weather-related extremes, resulting in significant socio-economic benefits. This project will support the education and training of two PhD students and a postdoctoral researcher, thus preparing the next generation of atmospheric dynamists and climate scientists. Some of the tools developed during this work will be used by the PIs in their undergraduate and graduate-level teaching to help the students with visualizing and quantifying some aspects of the jet stream variability. Also, the project will engage K-12 students in climate and computer modeling-related research through several STEM outreach programs at Rice and Stanford.In this project, novel analysis methods will be developed, and will be employed along with computer models and observational data to gain a deeper understanding of this variability of the jet streams. Furthermore, a new framework will be developed to quantitively link this variability in the present day to variability in the future. This framework will integrate the response of the jet stream variability and polar vortex to various climate forcings, such as greenhouse gas increase or ozone depletion. The specific tasks of this project are 1) examining the coupling between the barotropic and baroclinic annular modes in observations and in climate models; 2) developing an eddy feedback model for propagating annular modes; 3) understanding stratospheric influence on the tropospheric annular mode in both hemispheres using numerical experiments; 4) studying low-frequency variability modes and fluctuation-dissipation relationship in climate model simulations to better evaluate the fidelity of the climate change projections in these simulations.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.

两半球温带对流层大气环流变化的主要模式是强弱西风急流之间的振荡，时间尺度超过10天。温带西风急流的这种低频变化称为环形模式。年模影响着中高纬度地区的日常天气和极端事件，因此非常值得了解。冬半球的环模也影响平流层极地涡旋，也受到平流层极地涡旋的影响。该项目寻求更深入地了解控制环形模式的因素。这项工作的成果将有可能改变对中高纬度急流变化和天气的理解。这一结果还可能导致预测能力的进步，突破目前大约 10 天的天气预报障碍，并导致气候模型能力的提高。此外，新的定量框架将有助于解释综合气候模型预测的一系列结果。这些成果有可能推动国家和全球应对气候变化和与天气相关的极端事件的努力，从而产生显着的社会经济效益。该项目将支持两名博士生和一名博士后研究员的教育和培训，从而培养下一代大气动力学家和气候科学家。这项工作中开发的一些工具将由 PI 在本科和研究生教学中使用，以帮助学生可视化和量化急流变化的某些方面。此外，该项目还将通过莱斯大学和斯坦福大学的多个 STEM 推广项目，让 K-12 学生参与气候和计算机建模相关的研究。在该项目中，将开发新颖的分析方法，并将与计算机模型和观测数据一起使用为了更深入地了解喷射流的这种变化。此外，将开发一个新的框架来定量地将当前的这种变化与未来的变化联系起来。该框架将整合急流变化和极涡对各种气候强迫的响应，例如温室气体增加或臭氧消耗。该项目的具体任务是1）研究观测和气候模型中正压和斜压环模之间的耦合； 2）开发传播环形模式的涡反馈模型； 3）通过数值实验了解平流层对两个半球对流层环模的影响； 4) 研究气候模型模拟中的低频变率模式和波动耗散关系，以更好地评估这些模拟中气候变化预测的保真度。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力评估进行评估，认为值得支持优点和更广泛的影响审查标准。