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

这项研究的中心假设是，极端变暖，例如在始新世早期和潜在的未缓解的气候情景下，推动热带地带的大幅扩张，同时伴随着大气环流和大规模水文气候的其他方面的极地转移。这项跨学科的研究将古替代数据与气候模拟相结合，以调查古新世晚期和始新世早期热带宽度的变化。这项研究的观测部分旨在提供全面的古新世-始新世水文数据合成和数据，以供模型数据比较。模拟部分将分析已有的DeepMIP古新世-始新世耦合气候模拟，进行仅针对大气的模拟，以探索结果对海洋表面温度的敏感性，并进行数据模型比较。热带哈德利环流的极地边缘是地球气候的基本特征。哈德利环带的边缘标志着热带和温带之间的分界线--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，对全球气候产生了潜在的重大影响。这种扩张有可能改变雨带和龙卷风路径，扩大沙漠，并加剧干旱和野火。气候模型模拟了热带扩张，尽管速度比观测到的要低。这引发了关于扩张背后的原因和模型模拟扩张的能力的重要问题，以及围绕未来全球变暖下扩张的规模的问题。潜在的更广泛影响包括参与该项目的研究生和本科生，通过现有项目提高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，多元化活动包括与妇女参与科学、工程和数学计划(WISEM)合作，为她们的年度外展计划提供动手活动模块，参与高中学生的女孩带头计划，以及为矿山女童子军工程日提供科学实验模块，欢迎100名少女童子军参加STEM活动。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。

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.