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

这是一个由美国国家科学基金会地球科学理事会（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。该协议允许美国/英国提交一份联合提案，并由其调查员拥有最大比例预算的机构进行同行评审。在成功地共同确定一个奖项推荐后，每个机构资助预算的比例，以支持各自国家机构的科学家。一个值得注意的事实是，在热带大西洋形成的飓风可以对远在热带之外的美国东北部和西欧构成威胁。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的破坏。鉴于这些风暴对大西洋的影响，自然成为NSF和NERC合作的主题。该奖项下的研究旨在了解在高纬度登陆的大西洋飓风，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、锋面温度对比以及中纬度的高层脊、槽和急流时可以发生相当大的变化。当飓风在爱尔兰或纽约登陆时，它很可能至少经历了从热带气旋的暖核、垂直排列结构到温带气旋的冷核、向西倾斜的结构和面积更大的温带气旋的部分转变。这些飓风的生命周期转变使理解和预测其行为以及预测其频率和强度因气候变率和变化而变化的努力复杂化。飓风结构的变化也造成了影响上的重大差异，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。它们还可以在更大范围内造成破坏，就像飓风桑迪一样。研究高纬度地区飓风（这里称为热带起源气旋）的一个关键挑战是缺乏观测，因为热带起源气旋很少发生，而且观测记录相对较短。该项目利用了几个模式模拟档案，这些档案大大增加了观测结果，包括欧洲中期天气预报中心的季节预报集合。预测集合包含了许多可能发生但没有发生的cto的例子，从而将cto的样本量从每年3个增加到每年300个。该项目还使用专门的模型来观察飓风的影响，包括一个高分辨率的沿海海洋模型来模拟风暴潮，一个水文模型来模拟洪水。该项目具有社会价值，因为它强调危险天气事件。该项目包括为决策者提供可操作指导的协调努力。从季节预报和其他模式输出中获得的综合数据可以考虑到比观测记录中出现的更广泛的cto，从而更好地代表了可能性的范围。风暴潮和洪水模式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。可能的风暴范围及其影响以故事情节的形式综合，故事情节是对事件及其影响的叙述性描述，可用于规划目的。该项目支持博士后研究人员，从而促进该研究领域的未来劳动力。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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 outputs allow 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.