Understanding Southern Ocean heat uptake and redistribution in a warming climate

南大洋在吸收人为大气热量方面起着主导作用。观测表明，过去几十年来，南大洋内部迅速变暖，这主要是由于温室气体增加和平流层臭氧消耗。然而，在任一强迫下的物理机制和过程可能是不同的。此外，这两种强迫对南大洋温度的影响在21世纪可能会发生变化，特别是考虑到预计的平流层臭氧恢复。该项目的目标是深入了解各种人为强迫下南大洋热量吸收和再分配的物理机制。这项工作将澄清混合良好的温室气体和平流层臭氧在气候变化中的重要性，如南大洋变暖所显示的那样，扩大对海洋环流在南大洋热量再分布中的作用的认识，并与了解区域海平面变化有关。该项目将支持一名早期职业调查员和两名博士的培训。加州大学滨江分校是美国种族最多元化的研究型大学之一，通过滨江博物馆开展的外联活动将包括公开讲座和教师发展讲习班。拟议的工作将解决以下问题：（1）过去几十年中，在温室气体增加和平流层臭氧消耗的情况下，分别是什么物理过程导致南大洋升温？(2)预计臭氧空洞在世纪恢复将如何影响南大洋的热量吸收？(3)海洋涡旋对南大洋热量吸收和再分配的影响是什么？为了回答这些问题，该提案概述了以下计划：（一）分析现有的CESM 1大型集合模拟以及伴随的固定臭氧和固定温室气体模拟;（二）利用CESM 1进行单一强迫实验，其中模型仅在温室气体或臭氧强迫下进行历史积分; ㈢根据CESM 1单一强迫模拟进行压倒性试验，以分别探讨海洋环流在温室气体和臭氧强迫下南大洋变暖中的作用;分析CMIP 6历史和SSP模拟以及相应的仅温室气体、仅臭氧、仅气溶胶和仅自然强迫模拟，特别侧重于预测的平流层臭氧恢复对未来南大洋热量吸收的影响;（v）用两个版本的CMIP 6气候模式（涡动解析和涡动参数化）对历史和共享社会经济路径（SSP）模拟进行比较，该奖项反映了NSF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 Southern Ocean plays a dominant role in uptake of anthropogenic atmospheric heat. Observations have suggested a rapid interior warming in the Southern Ocean over the past several decades, which has been attributed primarily to greenhouse gases increases and stratospheric ozone depletion. Nevertheless, the physical mechanisms and processes under either forcing could be distinct. Moreover, the impacts of both forcings on Southern Ocean temperature may change during the twenty-first century, especially when considering the projected stratospheric ozone recovery. The goal of this project is to obtain an in-depth understanding of physical mechanisms on Southern Ocean heat uptake and redistribution under various anthropogenic forcings. The work will clarify the importance of well-mixed greenhouse gases and stratospheric ozone in climate change as shown by the Southern Ocean warming, broaden the recognition of the role of ocean circulation in Southern Ocean heat redistribution, and is relevant to understanding of regional sea level change. This project will support an early career investigator and the training of two Ph.D. students and enhance modeling capabilities at UC Riverside, one of the most ethnically diverse research universities in the country. Outreach activities through Museum of Riverside will include public lectures and teacher development workshops. Proposed work will address the following questions: (1) What are the physical processes driving the Southern Ocean warming during the past few decades under GHG increases and stratospheric ozone depletion, respectively? (2) How will the projected ozone hole recovery in the twenty-first century affect the Southern Ocean heat uptake? (3) What are the effects of ocean eddies on Southern Ocean heat uptake and redistribution? To answer these questions, the proposal outlines plans to: (i) analyze available CESM1 large ensemble simulations and accompanying fixed-ozone and fixed-GHGs simulations; (ii) conduct single forcing experiments with CESM1 in which the model is only forced with historical integrations under GHGs or ozone forcing; (iii) conduct overriding experiments based on CESM1 single forcing simulations to explore the roles of ocean circulation in Southern Ocean warming under GHGs and ozone forcings, respectively; (iv) analyze CMIP6 historical and SSP simulations and accompanying GHGs-only, ozone-only, aerosol-only and natural-forcing-only simulations, with a particular focus on the effect of projected stratospheric ozone recovery on future Southern Ocean heat uptake; (v) comparison between historical and Shared Socioeconomic Pathways (SSPs) simulations with two versions of CMIP6 climate models—eddy-resolved and eddy-parameterized—to examine the effect of ocean eddies in Southern Ocean heat uptake and redistribution.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.