NSFGEO-NERC: Collaborative Research: Assessing the influence of sub-annual variability in the AMOC on the Gulf Stream and the atmosphere

NSFGEO-NERC：合作研究：评估 AMOC 次年变化对墨西哥湾流和大气的影响

• 批准号: 2023585
• 负责人: Rhys Parfitt
• 金额: $ 59.21万
• 依托单位: Florida State University
• 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 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023585&HistoricalAwards=false
• 关键词: NSFGEO; NERC; Collaborative; Research; Assessing

This study is built on the hypothesis that the Atlantic Meridional Overturning Circulation (AMOC) is a control on weather and climate in the Northern Hemisphere. The causal link is envisioned to be through the strong air-sea heat exchange near the Gulf Stream (GS) and influence of that on the atmospheric extreme events. The role of the GS in modulating the weather and climate of the Northern Hemisphere has received considerable recent support. Interest in part lies in the relative persistence of GS variability compared to the atmosphere, which offers the potential for increased predictability of extreme weather events. Observations show significant variability in GS meandering on monthly timescales. A high degree of variability in the AMOC has been observed experimentally on the same monthly time scales. This provides a potential connection between the AMOC and mid-latitude weather via the GS. Modelling studies, however, have yet to agree on the relationship between the AMOC and the GS. There are many causes for these discrepancies, but an overarching explanation appears to involve (the lack of) eddy-scale resolution (less than 0.1 degree). Under prior NSF funding, this team of investigators have generated an ensemble of eddy resolving North Atlantic simulations that appear to be ideally suited to address these issues. In fact, this is currently the only eddy-resolving ensemble suite of North Atlantic model simulations in the United States. These model results will be used to systematically evaluate the relationship between the AMOC and GS variability with the influence of ocean eddies explicitly resolved. This research will lead to a better understanding of the relationship between the AMOC, the GS, and the atmosphere, on sub-annual to interannual time scales. Specifically, it will provide clarification on the mechanisms by which they interact and determine whether a robust relationship exists between the AMOC and the atmosphere on monthly timescales. Comparison with previous non-eddy resolving studies will aid in evaluating how well the current generation of models reproduce these mechanisms, whilst an improved understanding of ocean influence on the atmosphere may provide a source of untapped predictability. The AMOC has a critical role in modulating the global climate and is widely projected to change significantly in the 21st century. As such, a more complete understanding of how AMOC variability influences influential currents such as the GS, and imprints onto the atmosphere will improve both near-term forecasts and long-term projections of climate variability under warming scenarios. Comparison of results with previous studies will contribute to regional and climate model development through identifying what is required to properly capture the relevant processes. This project supports STEM education through training of two graduate students and a postdoctoral researcher in the modelling and analysis of both the ocean and the atmosphere, as well as general climate dynamics. The PIs have a strong record of commitment to mentoring undergraduates in research, and have a record of presenting seminars and meeting with undergraduate students at smaller universities that are less research-focused, to bring a broader educational experience to those studentsThe reasoning leading from the cause (AMOC) to effect (weather/climate control) consists of three components which, in turn, are the foci of this proposal. (1) Extreme atmospheric events control mean atmospheric fields through anomalously large, but rare, contributions to the storm track. (2) These extreme atmospheric events are governed by heat exchange with the Gulf Stream (GS), and are sensitive to whether the GS is in a meandering or non-meandering state. (3) The (non)-meandering state of the GS responds to AMOC variability. The focus of the study will primarily be on those Gulf Stream attributes that have been shown to significantly influence the atmosphere locally and globally. Furthermore, additional modelling work will assess how changes in the AMOC, through its influence on GS variability, imprint on the atmosphere. This will be achieved by prescribing GS conditions in high-resolution atmosphere-only model simulations to systematically assess the dependence of atmospheric variability and surface heat fluxes on the underlying ocean. Lastly, coupled high-resolution runs will be conducted to elucidate the contribution of atmospheric feedbacks on the ocean.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.

这项研究是建立在大西洋子午线翻转环流(AMOC)是对北半球天气和气候的控制的假设之上的。这种因果联系被认为是通过墨西哥湾流(GS)附近强烈的海气热交换及其对大气极端事件的影响来实现的。全球气候系统在调节北半球天气和气候方面的作用最近得到了相当大的支持。人们的兴趣部分在于与大气相比，GS变率的相对持久性，这为提高极端天气事件的可预测性提供了可能性。观测表明，GS在每月时间尺度上的曲折变化显著。在相同的每月时间尺度上，已经在实验中观察到AMOC中的高度可变性。这提供了AMOC和中纬度天气之间通过GS的潜在联系。然而，模型研究尚未就AMOC和GS之间的关系达成一致。造成这些差异的原因有很多，但最主要的解释似乎与(缺乏)涡旋尺度分辨率(小于0.1度)有关。在NSF之前的资助下，这个研究团队已经产生了一系列涡流解析北大西洋模拟，似乎非常适合解决这些问题。事实上，这是目前美国唯一的北大西洋模式模拟涡旋分辨系综。这些模式结果将被用来系统地评估AMOC和GS变率之间的关系，并明确解决海洋涡旋的影响。这项研究将有助于更好地理解AMOC、GS和大气在分年度到年际时间尺度上的关系。具体地说，它将澄清它们相互作用的机制，并确定AMOC和大气之间在每月时间尺度上是否存在牢固的关系。与以前的非涡流解析研究相比，将有助于评估当前一代模型复制这些机制的程度，而对海洋对大气影响的更好理解可能提供一个未开发的可预测性来源。AMOC在调节全球气候方面起着关键作用，人们普遍预计它将在21世纪发生重大变化。因此，更全面地了解AMOC变率如何影响GS等有影响力的洋流，并在大气中留下印记，将改善气候变暖情景下气候变率的短期预测和长期预测。通过确定适当捕捉相关过程所需的条件，将结果与以前的研究结果进行比较，将有助于区域和气候模型的发展。该项目通过培训两名研究生和一名博士后研究员对海洋和大气以及一般气候动力学进行建模和分析来支持STEM教育。私人投资机构一直致力于在研究方面指导本科生，并有在不太注重研究的较小大学举办研讨会和与本科生会面的记录，以给这些学生带来更广泛的教育体验。从原因(AMOC)到效果(天气/气候控制)的推理由三个部分组成，这三个部分反过来又是本提案的重点。(1)极端大气事件通过异常大但罕见的对风暴路径的贡献来控制平均气压场。(2)这些极端大气事件受与墨西哥湾流(GS)的热量交换控制，对GS处于曲折状态还是非曲折状态很敏感。(3)GS的(非)曲折状态响应于AMOC的变化。这项研究的重点将主要放在那些已被证明对当地和全球大气产生重大影响的墨西哥湾流属性。此外，额外的模拟工作将评估AMOC的变化如何通过其对GS可变性的影响而影响大气。这将通过在仅限大气的高分辨率模式模拟中规定GS条件来实现，以系统地评估大气可变性和表面热通量对下层海洋的依赖。最后，将进行耦合的高分辨率运行，以阐明大气反馈对海洋的贡献。这一奖项反映了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。

项目成果

A Global Perspective of Tropical Cyclone Precipitation in Reanalyses

• DOI: 10.1175/jcli-d-20-0892.1
• 发表时间: 2021-11-01
• 期刊: JOURNAL OF CLIMATE
• 影响因子: 4.9
• 作者: Jones, Evan;Wing, Allison A.;Parfitt, Rhys
• 通讯作者: Parfitt, Rhys

The role of atmospheric fronts in austral winter precipitation changes across Australia

大气锋面在澳大利亚冬季降水变化中的作用

• DOI: 10.1002/asl.1117
• 发表时间: 2022
• 期刊: Atmospheric Science Letters
• 影响因子: 3
• 作者: Lawrence, Lindsay;Parfitt, Rhys;Ummenhofer, Caroline C.
• 通讯作者: Ummenhofer, Caroline C.

A Monthly Index for the Large‐Scale Sea Surface Temperature Gradient Across the Separated Gulf Stream

分离湾流大尺度海面温度梯度月度指数

• DOI: 10.1029/2022gl100914
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Parfitt, R.;Kwon, Y.;Andres, M.
• 通讯作者: Andres, M.

Near-Surface Wind Convergence over the Gulf Stream—The Role of SST Revisited

墨西哥湾流近地表风辐合——重新审视海温的作用

• DOI: 10.1175/jcli-d-22-0441.1
• 发表时间: 2023
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Small, R. J.;Rousseau, V.;Parfitt, R.;Laurindo, L.;O’Neill, L.;Masunaga, R.;Schneider, N.;Chang, P.
• 通讯作者: Chang, P.

Routine Reversal of the AMOC in an Ocean Model Ensemble

海洋模型系综中 AMOC 的常规反转

• DOI: 10.1029/2022gl100117
• 发表时间: 2022
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Dewar, William K.;Parfitt, Rhys;Wienders, Nicolas
• 通讯作者: Wienders, Nicolas