Collaborative Research: NSFGEO-NERC: Hurricane Risk Amplification and Changing North Atlantic Natural Disasters

这是一个由国家科学基金会地球科学局(NSF/GEO)和英国国家环境研究委员会(NERC)通过NSF/GEO-NERC牵头机构协议共同资助的项目。该协定允许美国和英国提交一个单一的联合提案，并由该机构进行同行审查，该机构的调查员在预算中所占比例最大。在成功联合确定奖项推荐后，每个机构将资助各自国家机构的科学家的预算比例。一个引人注目的事实是，在热带大西洋形成的飓风可以对美国东北部和西欧构成威胁，这两个地区都远离热带地区，也位于大西洋的对岸。飓风造成如此远距离破坏的能力在美国是众所周知的，最近的例子包括2012年的桑迪和2021年的艾达。在盆地的另一边，奥菲莉亚(2017)和莱斯利(2018)在爱尔兰、葡萄牙和西班牙造成了严重破坏。考虑到这类风暴的跨大西洋影响，这类风暴是NSF和NERC合作的一个自然话题。该奖项下的研究试图了解在更高纬度登陆的大西洋飓风，并考虑到它们的整个生命周期和影响。生命周期是一个重要的考虑因素，因为飓风在遇到凉爽的海洋表面、锋面温差以及中纬度的高空脊线、低谷和急流时，可能会发生很大的变化。当飓风在爱尔兰或纽约登陆时，它可能已经经历了至少部分转变，从热带气旋的暖核心、垂直排列结构转变为热带气旋的冷核、西倾结构和更大的区域范围。这些飓风的生命周期转变使了解和预测它们的行为以及预测它们的频率和强度因气候变化和变化而发生变化的努力变得复杂起来。飓风结构的变化也造成了重要的影响差异，例如，在登陆时保持热带特征的风暴通常更具破坏性，但在很大程度上转变为温带气旋的风暴则更为常见。它们还可能在更大范围内造成干扰，飓风桑迪就是一个例子。在高纬度飓风(这里称为热带起源气旋(CTO))的工作中，一个关键挑战是缺乏观测，因为CTO不经常发生，而且观测记录相对较短。该项目利用了几个模型模拟档案，这些档案大大加强了观测，包括欧洲中期天气预报中心的季节性预报集合。预测集合包含了许多本可以发生但没有发生的CTO的例子，从而将CTO的样本量从每年大约3个增加到每年300个。该项目还使用专门的模型来研究飓风的影响，包括一个模拟风暴潮的高分辨率沿海海洋模型和一个用于洪水的水文模型。由于该项目强调危险天气事件，因此具有社会价值。该项目包括共同努力，为决策者提供可行的指导。季节预报和其他模式输出提供的集合允许考虑比观测记录中出现的CTO更广泛的种类，因此更好地代表了可能性的范围。风暴潮和洪水模型对这些模拟风暴的应用为CTO可能影响的范围提供了进一步的指导。可能的风暴及其影响的范围以故事情节的形式进行综合，故事情节是对事件及其影响的叙述性描述，用于规划目的。该项目支持博士后研究人员，从而促进了该研究领域未来的劳动力。该奖项反映了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。

This is a project jointly funded by the National Science Foundation’s Directorate for Geosciences (NSF/GEO) and the National Environment Research Council (NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award recommendation, each Agency funds the proportion of the budget that supports scientists at institutions in their respective countries.It is a remarkable fact that hurricanes forming in the tropical Atlantic can pose a threat to the northeastern US and Western Europe, both well outside the tropics and on opposite sides of the Atlantic. The ability of hurricanes to inflict damage at such long range is well known in the US, with recent examples including Sandy in 2012 and Ida in 2021. On the other side of the basin Ophelia (2017) and Leslie (2018) caused severe damage in Ireland, Portugal, and Spain. Such storms are a natural topic for collaboration between NSF and NERC given their transatlantic impacts.Research under this award seeks to understand the Atlantic hurricanes that make landfall at higher latitudes, taking into account their full lifecycle and impacts. Lifecycle is an important consideration as hurricanes can transform considerably as they encounter the cool ocean surface, frontal temperature contrasts, and upper-level ridges, troughs, and jet streams of the middle latitudes. By the time a hurricane makes landfall in Ireland or New York it is likely to have undergone at least a partial transition from the warm core, vertically aligned structure of a tropical cyclone to the cold-core, westward-tilted structure and larger areal extent of an extratropical cyclone. The lifecycle transitions of these hurricanes complicate efforts to understand and predict their behavior and anticipate changes in their frequency and intensity due to climate variability and change. Changes in hurricane structure also create important differences in impacts, for instance storms which retain their tropical characteristics at landfall are typically more damaging, but storms which have largely transformed into extratropical cyclones are considerably more common. They can also create disruptions over a wider area, as was the case with Hurricane Sandy.A key challenge in work on hurricanes at higher latitudes, referred to here as cyclones of tropical origin (CTOs), is scarcity of observations, as CTOs occur infrequently and the observed record is relatively short. This project takes advantage of several archives of model simulations which substantially augment the observations, including ensembles of seasonal forecasts from the European Centre for Medium-range Weather Forecasts. The forecast ensembles contain many examples of CTOs which could have happened but did not, thus boosting the sample size for CTOs from perhaps 3 per year to 300 per year. The project also uses specialized models to look at hurricane impacts, including a high-resolution coastal ocean model to simulate storm surge and a hydrological model for flooding.The project has societal value due to its emphasis on hazardous weather events. The project includes a concerted effort to provide actionable guidance to decision makers. The ensembles available from seasonal forecasts and other model output allows consideration of a wider variety of CTOs than have occurred in the observational record, thus better representing the range of possibilities. The application of storm surge and flood models to these simulated storms provides further guidance on the range of possible CTO impacts. The range of possible storms and their impacts is synthesized in the form of storylines, which are narrative descriptions of the events and their impacts to be used for planning purposes. The project supports a postdoctoral researcher, thereby promoting the future workforce in this research area.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.