Collaborative Research: P2C2--The Changing Width of the Tropics in Past, Present and Future Climate

研究的中心假设是，极端变暖，如始新世早期和潜在的未缓解气候情景，驱动了热带的大幅扩张，同时在大气环流和大尺度水文气候的其他方面向极地移动。该跨学科研究将古代用数据与气候模拟相结合，研究了古新世晚期和始新世早期热带宽度的变化。研究的观测部分旨在提供全面的古新世-始新世水文数据综合和模型数据比较数据。模拟组件将分析已有的耦合DeepMIP古新世-始新世气候模拟，进行有针对性的大气模拟，探索结果对海面温度的敏感性，并进行数据模型比较。热带哈德利寒带的极地边缘是地球气候的一个基本特征。哈德利细胞的边缘标志着热带和温带的分界线——这是地球上最基本的两个主要气候带。观测显示，近几十年来哈德利环流向极地扩张，推动了热带的扩张，对全球气候有潜在的重大影响。这种扩张有可能改变雨带和气旋路径，扩大沙漠，加剧干旱和野火。气候模型模拟了热带扩张，尽管速度比观测到的要低。这就提出了一些重要的问题，包括这种扩大背后的原因、模式模拟这种扩大的能力，以及在未来全球变暖的情况下，这种扩大的幅度有多大。潜在的更广泛的影响包括研究生和本科生将参与该项目，通过现有项目改善多样性和包容性的计划，以及创造性的视觉科学新闻电影项目。具体来说，多元化活动包括与女性参与科学、工程和数学项目（WISEM）合作，为她们的年度外展项目提供实践活动模块，参加面向高中生的“女孩引领道路”项目，并为地雷女童子军工程日提供科学实验模块，欢迎100名初级女童子军参加STEM活动。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。

The research centers on the hypothesis that extreme warming, such as during the Early Eocene and under potential unmitigated climate scenarios, drives a substantial expansion of the tropical belt accompanied by poleward shifts in other aspects of the atmospheric circulation and large-scale hydroclimate. This interdisciplinary research integrates paleo-proxy data with climate modeling to investigate the changing width of the tropics during Late Paleocene and Early Eocene. The observational component of the research aims to provide a comprehensive Paleocene-Eocene hydrological data synthesis and data for a model-data comparison. The modelling component will analyze pre-existing coupled DeepMIP climate simulations of Paleocene-Eocene, conduct targeted atmosphere-only simulations to explore the sensitivity of the results to sea surface temperatures, and perform the data-model comparison.The poleward edge of the tropical Hadley cell is a fundamental characteristic of Earth’s climate. The edge of the Hadley cell marks the boundary between the tropics and extratropics - the Earth’s two main climate zones at the most basic level. Observations reveal a poleward expansion of the Hadley cell in recent decades, driving an expansion of the tropical belt with potentially significant implications for worldwide climate. The expansion has the potential to shift rain belts and cyclone tracks, expand deserts, and exacerbate droughts and wildfires. Climate models simulate the tropical expansion, albeit at lower rates than what is observed. This raises important questions about the causes behind the expansion and the ability of models to simulate the expansion as well as questions surrounding the magnitude of the widening under future global warming.The potential Broader Impacts include involving graduate and undergraduate students will be involved in the project, a plan for improving diversity and inclusion through existing programs, and a creative visual science journalism film project. Specifically, the diversity activities include collaboration with the Women in Science, Engineering and Mathematics Program (WISEM) by contributing hands-on activity modules for their annual outreach programs, participation in the Girls Lead the Way program for high school students, and also providing science experiment modules for Mines Girl Scout Engineering Day which welcomes 100 Junior Girl Scouts to participate in STEM activities.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.