Assessing simulations of Southern Hemisphere tropospheric jet, meridional overturning circulation of the Southern Ocean and carbon uptake

评估南半球对流层急流、南大洋经向翻转环流和碳吸收的模拟

• 批准号: NE/J005339/1
• 负责人: Emily Shuckburgh
• 金额: $ 11.64万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ005339%2F1
• 关键词: Assessing; simulations; Southern; Hemisphere; tropospheric

Of the carbon dioxide emissions human activities generate each year, only about half stay in the atmosphere. The rest are taken up by the land and the oceans, in approximately equal measure. At present the Southern Ocean that encircles Antarctica accounts for just under half of the total ocean uptake. Were it not to do so, carbon dioxide levels in the atmosphere would increase at a significantly faster rate than we currently observe. The world's oceans are connected by a vast, slow circulation system with water sinking in the North Atlantic, travelling southward, and then rising to the surface in the Southern Ocean. When it reaches the surface, this water is able to exchange carbon dioxide with the atmosphere, before the circulation dips below the surface again, locking the carbon dioxide in the ocean, and returns north. If that circulation were to change, the carbon uptake of the Southern Ocean would change. So a key question to scientists to answer is, will climate change invoke changes to the overturning circulation of the Southern Ocean? If the answer is yes, then this could change the amount of carbon dioxide in the atmosphere and act as a strong feedback on climate change. Concern has been raised recently because some observations have indicated that indeed the Southern Ocean is taking up less carbon dioxide than we would have historically expected given the current atmospheric carbon dioxide concentrations.So how might climate change be impacting the Southern Ocean overturning circulation? Strong winds blow around Antarctic over the Southern Ocean. The winds directly drive a circulation that is directed northward at the surface. They also indirectly drive a circulation in the opposite direction, i.e. southward at the surface, via their influence on the generation of ocean storms, known as "eddies". The resultant circulation, which is directed northward at the surface, is a subtle balance of these opposing circulations. The winds have been observed to increase in recent decades. Two changes to the atmosphere are thought to have instigated the change in the winds, both of which have human cause: the increase in greenhouse gases in the atmosphere and the decrease in ozone in the stratosphere. It is reasonable to ask therefore whether the carbon uptake of the Southern Ocean might be influenced in the future by changes to the atmospheric concentration of greenhouse gases and by the recovery of the ozone layer. Computer models used to project future climate can only address this question if they are able to properly represent the different physical processes in the atmosphere and ocean that link the atmospheric composition to ocean carbon uptake via the Southern Ocean winds. This project aims to evaluate the representation of these processes in the latest generation of models that will be used as a basis for the next IPCC report.

在人类活动每年产生的二氧化碳排放中，只有大约一半留在大气中。其余的被陆地和海洋所吸收，其数量大致相等。目前，环绕南极洲的南大洋仅占海洋总吸收量的一半以下。如果不这样做，大气中的二氧化碳水平将以比我们目前观察到的更快的速度增加。世界上的海洋由一个巨大而缓慢的环流系统连接在一起，水在北大西洋下沉，向南流动，然后在南大洋上升到表面。当它到达表面时，这些水能够与大气交换二氧化碳，然后环流再次下降到表面以下，将二氧化碳锁定在海洋中，并返回北方。如果这种环流发生变化，南大洋的碳吸收也会发生变化。因此，科学家们要回答的一个关键问题是，气候变化是否会引起南大洋翻转环流的变化？如果答案是肯定的，那么这可能会改变大气中的二氧化碳含量，并对气候变化产生强烈的反馈作用。最近引起了人们的关注，因为一些观察表明，考虑到目前大气中的二氧化碳浓度，南大洋确实吸收了比我们历史上预期的更少的二氧化碳。那么，气候变化如何影响南大洋翻转环流呢？强风在南大洋上吹绕南极洲。风直接驱动着一个向北的环流。它们还通过影响称为“漩涡”的海洋风暴的产生，间接地推动相反方向的环流，即在表面向南。由此产生的环流，在地面上指向北方，是这些相反的环流的微妙平衡。据观察，近几十年来风力有所增加。大气层的两种变化被认为引发了风的变化，这两种变化都有人为原因：大气中温室气体的增加和平流层中臭氧的减少。因此，有理由提出这样一个问题：大气中温室气体浓度的变化和臭氧层的恢复是否会影响南大洋的碳吸收。用于预测未来气候的计算机模型只能解决这个问题，如果它们能够正确地代表大气和海洋中的不同物理过程，这些物理过程将大气成分与通过南大洋风吸收的海洋碳联系起来。该项目旨在评估这些过程在最新一代模型中的代表性，这些模型将用作气专委下一份报告的基础。

项目成果

Assessment of Southern Ocean water mass circulation and characteristics in CMIP5 models: Historical bias and forcing response

• DOI: 10.1002/jgrc.20135
• 发表时间: 2013-04
• 期刊: Journal of Geophysical Research
• 作者: J. Sallée;E. Shuckburgh;N. Bruneau;A. Meijers;T. Bracegirdle;Zhaomin Wang;T. Roy

Assessment of Southern Ocean mixed-layer depths in CMIP5 models: Historical bias and forcing response

• DOI: 10.1002/jgrc.20157
• 发表时间: 2013-04
• 期刊: Journal of Geophysical Research
• 作者: J. Sallée;E. Shuckburgh;N. Bruneau;A. Meijers;T. Bracegirdle;Zhaomin Wang

Representation of the Antarctic Circumpolar Current in the CMIP5 climate models and future changes under warming scenarios

• DOI: 10.1029/2012jc008412
• 发表时间: 2012-12-11
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
• 影响因子: 3.6
• 作者: Meijers, A. J. S.;Shuckburgh, E.;Wang, Z.
• 通讯作者: Wang, Z.

Assessment of surface winds over the Atlantic, Indian, and Pacific Ocean sectors of the Southern Ocean in CMIP5 models: historical bias, forcing response, and state dependence

• DOI: 10.1002/jgrd.50153
• 发表时间: 2013-01-27
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
• 影响因子: 4.4
• 作者: Bracegirdle, Thomas J.;Shuckburgh, Emily;Wilcox, Laura J.
• 通讯作者: Wilcox, Laura J.