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。观察表明，在过去几十年里，南大洋内部迅速变暖，这主要归因于温室气体增加和平流层臭氧消耗。然而，在任何一种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二十一世纪可能会发生变化，特别是在考虑到预计的平流层臭氧恢复的情况下。该项目的目标是深入了解在各种人为强迫作用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，如南大洋变暖所表明的，扩大对海洋环流在南大洋热量再分配中的作用的认识，并与理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生的培训，并增强加州大学河滨分校的建模能力，该大学是美国种族最多元化的研究型大学之一。通过河滨博物馆开展的外展活动将包括公开讲座和教师发展讲习班。拟议的工作将涉及以下问题：(1)在温室气体增加和平流层臭氧消耗的情况下，过去几十年南大洋变暖的物理过程分别是什么？(2)预计在21世纪臭氧空洞的恢复将如何影响南大洋的热吸收？(3)海洋涡流对南大洋的热吸收和再分配有什么影响？为了回答这些问题，该提案概述了以下计划：(1)分析现有的CESM1大集合模拟和伴随的固定臭氧和固定温室气体模拟；(2)利用CESM1进行单一强迫试验，其中模式仅在温室气体或臭氧强迫下进行历史积分强迫；(3)在CESM1单一强迫模拟的基础上进行凌驾试验，以探索海洋环流在温室气体和臭氧强迫下南大洋变暖中的作用；(Iv)分析CMIP6历史和SSP模拟以及伴随的仅有温室气体、仅有臭氧、仅有气溶胶和仅有自然强迫的模拟，特别侧重于预计的平流层臭氧恢复对未来南大洋热量吸收的影响；(V)历史模拟和共享社会经济路径(SSP)模拟与两个版本的CMIP6气候模式--涡旋解析和涡旋参数--的比较，以考察海洋涡动在南大洋热量吸收和再分配中的影响。这项裁决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智力优势和更广泛的影响审查标准进行评估，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.