NSFGEO-NERC:Assessing the influence of sub-annual variability in the Atlantic Meridional Overturning Circulation on the Gulf Stream and the atmosphere

NSFGEO-NERC：评估大西洋经向翻转环流的亚年变率对墨西哥湾流和大气的影响

• 批准号: NE/V014897/1
• 负责人: Arnaud Czaja
• 金额: $ 30.86万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV014897%2F1
• 关键词: NSFGEO; NERC; Assessing; influence; sub

We hypothesize that the Atlantic Meridional Overturning Circulation (AMOC) is a control on weather and climate in the Northern Hemisphere. The 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. We propose here to support or refute this hypothesis by means of a combined numerical-observational study of the ocean-atmosphere system over the North Atlantic Gulf Stream.The role of the Gulf Stream (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 catastrophic weather events. Observations show significant variability in GS meandering on monthly timescales. Recent observational experiments have also confirmed a high degree of variability in the AMOC on these monthly timescales. 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 (< 1/10o). We here at Florida State University, under prior NSF funding, have generated an ensemble of eddy resolving North Atlantic simulations that, due to their construction, appear to be ideally designed to address the above issues. In fact, currently, this is the only eddy-resolving ensemble suite of North Atlantic model simulations in the United States. We propose to leverage these runs to systematically evaluate the relationship between the AMOC and GS variability with the influence of ocean eddies explicitly resolved. Our focus 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.

我们假设大西洋子午翻转循环（AMOC）是北半球天气和气候的控制。从原因（AMOC）产生的推理（天气/气候控制）由三个组成部分组成，反过来又是该提议的重点。 （1）极端大气事件通过对风暴轨迹的异常但罕见的贡献来控制平均大气场。 （2）这些极端的大气事件受热交换与海湾流（GS）的控制，并且对GS是处于弯曲状态还是非赔偿状态的敏感。 （3）GS的（非）支票状态对AMOC的可变性做出响应。我们在这里建议通过对北大西洋墨西哥湾流的海洋 - 大圈系统的组合数值观察研究来支持或反驳这一假设。墨西哥湾流（GS）在调节北半球的天气和气候中的作用已获得了相当大的最新支持。与大气相比，GS变异性的相对持久性的兴趣在于，这为增加灾难性天气事件的可预测性提供了潜力。观察结果显示在每月时标上的GS弯曲曲折的明显差异。最近的观测实验也证实了这些月度时间表的AMOC的高度差异。这通过GS提供了AMOC和中纬度天气之间的潜在连接。但是，建模研究尚未就AMOC与GS之间的关系达成共识。这些差异有很多原因，但是总体解释似乎涉及（缺乏）涡流分辨率（<1/10o）。我们在佛罗里达州立大学的NSF资助下，我们在这里产生了一系列涡流解决北大西洋模拟的合奏，由于其构建，它们似乎是理想旨在解决上述问题的理想之选。实际上，目前，这是美国北大西洋模型模拟的唯一分辨涡流合奏套件。我们建议利用这些运行来系统地评估AMOC和GS变异性之间的关系，并明确解决海洋涡流的影响。我们的重点将主要放在那些已显示出显着影响本地和全球大气的海湾流属性上。此外，其他建模工作将通过对GS变异性（大气上的烙印）的影响来评估AMOC的变化如何。这将通过在高分辨率大气模型模拟中规定GS条件来系统地评估大气变异性和表面热通量对基础海洋的依赖性。最后，将进行耦合的高分辨率跑步，以阐明大气反馈对海洋的贡献。