Collaborative Research: Understanding the Links between Tropical Cyclones and Tropical Circulation under Climate Change through Idealized Coupled Climate Modeling

合作研究：通过理想化耦合气候模型了解气候变化下热带气旋与热带环流之间的联系

• 批准号: 2327958
• 负责人: Kevin Reed
• 金额: $ 67.78万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-11-15 至 2026-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2327958&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Links; between; Collaborative; Research; Understanding; Links; between

Tropical cyclones (TCs), including the hurricanes of the Atlantic and Caribbean, derive their destructive power from the heat of the ocean beneath them. The fueling of TCs by warm sea surface temperatures (SSTs) thus suggests that the warming of the oceans by greenhouse gas emissions should bring more frequent and more damaging TCs. One part of this expectation holds true: the strongest TCs have become even stronger in recent decades, in agreement with model simulations and theoretical arguments. But there is no satisfactory theory for how TC frequency will change in a warming world and model-based studies have shown mixed results. The recent study of Chand et al. (2022) shows a decline in TC numbers which the authors attribute to a reduction in the strength of the the north-south oriented Hadley cell and the east-west oriented Walker cell. The former features rising air over the warm SSTs of the deep tropics and subsidence over the cooler subtropics, while the latter features convection over the "warm pool" of the tropical western Pacific and subsidence over eastern Pacific "cold tongue". But other studies suggests that reductions in overturning strength should result in an increase in the number of TCs rather than a decrease.Research under this award considers the role of the overturning cells in setting TC frequency and other aggregate properties and the consequences for TC behavior of changes in overturning due to greenhouse warming. The work is conducted using two idealized configurations of the Community Earth System Model (CESM) which are designed to isolate the mechanisms of interest and study them in their simplest form. The first configuration is an "aquaplanet", with an atmosphere coupled to a dynamic ocean model but no land surface. In this configuration there is no equivalent of the Pacific warm pool and cold tongue and hence no analog for the Walker cell, although the SST contrast between lower and higher latitudes still produces a Hadley cell. The second is a "ridge" configuration, in which a narrow oceanic ridge stands in for the American landmass that separates the tropical Atlantic and Pacific Oceans. The ocean dynamics created by the imposition of a north-south ridge creates a contrast between cooler surface water to the west of the ridge and warmer SST to the east, which in turn induces a Walker circulation. These configurations are augmented by simulations at higher resolution (0.25 degree grid spacing) which are better able to capture TC behavior. For reasons of computational cost the high-resolution simulations use a motionless "slab" ocean in which the SST contrasts generated by the aquaplanet and ridge configurations are imposed indirectly so as not to compromise heat transfer from the ocean to the TCs.The work is of societal as well as scientific interest given the tremendous destructive power of TCs and the need to assess changes in TC risk due to greenhouse warming. The work also has scientific broader impacts through the addition of new configurations to the CESM model hierarchy. The model versions developed in this project will be made available to the research community through the Simpler Models web portal (www.cesm.ucar.edu/models/simple) and will be supported with documentation and reference simulations. In addition, the project provides support and training to two graduate students, thereby providing for the future scientific 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.

热带气旋（TCS），包括大西洋和加勒比海的飓风，从它们下面的海洋中获得了破坏性的力量。 因此，温暖的海面温度（SST）加油TC表明，温室气体排放对海洋的变暖应带来更频繁，更具破坏性的TC。 这一期望的一部分是正确的：与模型模拟和理论论点一致，近几十年来，最强大的TC变得更加强大。但是，对于温暖世界中的TC频率将如何变化，基于模型的研究表现出不同的结果，没有令人满意的理论。 Chand等人的最新研究。 （2022）显示了TC数量的下降，作者将其归因于降低了面向南北的Hadley细胞和以东西方为导向的Walker Cell的强度。 前者的空气在深层热带地区的温暖SST上升起，在冷却器亚热带上的沉降，而后者则在热带西太平洋的“温暖游泳池”上以及东太平洋“冷舌”上的“温暖游泳池”。但是其他研究表明，倾覆强度的降低应导致TC的数量增加，而不是减少。搜索该奖项考虑了倾覆细胞在设置TC频率和其他骨料特性中的作用，以及由于温室变暖而导致的倾覆变化的TC行为。这项工作是使用社区地球系统模型（CESM）的两种理想配置进行的，旨在隔离感兴趣的机制并以最简单的形式研究它们。 第一种配置是一种“ aquaplanet”，其气氛与动态海洋模型相结合，但没有陆地表面。 在这种配置中，尽管较低纬度和较高纬度之间的SST对比仍会产生Hadley细胞，但没有相当于太平洋温暖的池和冷舌，因此没有类似物。 第二个是“山脊”配置，其中狭窄的海洋山脊占据了分隔热带大西洋和太平洋的美国地产。 通过强加南北山脊创造的海洋动力学在山脊西部的凉爽地表水和东部温暖的SST之间形成了对比，这又引起了助行器的循环。 这些配置是通过更高分辨率（0.25度网格间距）的模拟来增强的，该模拟能够更好地捕获TC行为。出于计算成本的原因，高分辨率模拟使用了一动不动的“平板”海洋，在这种海洋中，a木板和山脊配置所产生的SST是间接强加的，以免从海洋到TC的热量转移到TC。这项工作是妥协的，因为它是社会兴趣，并且具有巨大的危险，因此可以将其造成TC的更改，并构成了TC的巨大危险，并且可以将其造成TC的变化。 这项工作还通过在CESM模型层次结构中添加新的配置会产生更广泛的影响。该项目中开发的模型版本将通过更简单的模型Web门户（www.cesm.ucar.edu/models/simple）提供给研究社区，并将得到文档和参考模拟的支持。 此外，该项目为两名研究生提供了支持和培训，从而为该研究领域提供了未来的科学劳动力。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估来通过评估来支持的。