OUTCROP: New prOcess-based UndersTanding of ocean heat Uptake with an application to improved Climate pRojections for pOlicy and Planning

露头：基于新过程的海洋吸热理解，并应用于改进政策和规划的气候预测

• 批准号: NE/R010536/1
• 负责人: Remi Tailleux
• 金额: $ 43.48万
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR010536%2F1
• 关键词: OUTCROP; New; prOcess; based; UndersTanding

Future climate change projections provide essential guidance for the efforts to curb the global warming trend caused by human emissions of greenhouse gases. One of the most important factors controlling the rate of climate change is ocean heat uptake (OHU), which is responsible for limiting global warming by absorbing part of the excess radiative forcing due to greenhouse gases by the ocean. Unfortunately, the physical processes controlling OHU remain poorly constrained and understood, as they are all associated with small scale processes related to turbulent mixing of heat and salt, meso-scale ocean eddies, deep water formation, which we do not know how to represent accurately, as well as to the surface fluxes of heat and freshwater, which are difficult to observe and measure precisely. As a result, large uncertainties in climate projections remain that are directly attributable to our lack of precise knowledge about ocean heat uptake. To understand how to make progress, a firm theoretical understanding of the physics of vertical heat transfer associated with OHU appears to be essential. Unfortunately, the validity and usefulness of the standard vertical/advection diffusion model for the horizontally-averaged temperature, which has been the primary theoretical tool to think about the vertical heat transfer, has been repeatedly questioned over the years owing to its failure to account for such effects as a varying topography, isopycnal mixing and the existence of density-compensated temperature anomalies.To resolve the above difficulties, our group recently developed a new process-based vertical advection/diffusion model for the heat balance that exploits advances from the theory of ocean water masses accumulated over the past 50 years or so. The new model represents a considerable improvement over the previous one, in that it naturally explains the precise role of a varying topography, density-compensated temperature anomalies, isoneutral mixing, and differential surface heating on the vertical heat transfer, which had remained obscure in the standard model. In this proposal, our first objective will be to demonstrate the usefulness of this new process-based model to interpret and rationalise the simulated ocean heat uptake for a wide range of climate change scenarios including increasing CO2, stabilisation, radiative forcing overshoot, and a collapse of the Atlantic meridional overturning circulation. Our second objective will be to demonstrate that the major advances due to our new process-based understanding of ocean heat uptake can be translated into a major improvement in the accuracy of climate change projections using Simple Climate Models, with a particular application to the MAGICC model, and one developed by the Met Office Hadley Centre. Indeed, although the main physical basis for our current understanding of climate change relies on coupled atmosphere-ocean general circulation models (AOGCMs), these models are computationally very expensive to run. Therefore, simple climate models (SCMs) have been developed, which are able to mimic the climate response seen in the AOGCMs, but at a much reduced computational cost. SCMs represent a key tool in the study of climate change, and are being used for several purposes, e.g. simulating how the projections depend on key climate parameters, or for the interpretation of the AOGCM projections. SCMs are often used for policy advice and play a central role in the science forming the basis for Working groups 2 and 3 of the latest International Panel on Climate Change report, the main document at the origin of the recent Paris agreement aimed at limiting the overall global warming below 2C.The improved physical understanding of ocean heat uptake will significantly contribute to improved climate projections and reductions of associated uncertainties.

未来气候变化预测为遏制人类排放温室气体导致的全球变暖趋势的努力提供了重要指导。控制气候变化速度的最重要因素之一是海洋吸热（OHU），它通过吸收海洋温室气体造成的部分过量辐射强迫来限制全球变暖。不幸的是，控制 OHU 的物理过程仍然缺乏约束和理解，因为它们都与热和盐的湍流混合、中尺度海洋涡流、深水形成相关的小规模过程相关，而我们不知道如何准确地表示这些过程，以及难以精确观察和测量的热量和淡水的表面通量。因此，气候预测仍然存在很大的不确定性，这直接归因于我们缺乏对海洋吸热的精确了解。为了了解如何取得进展，对与 OHU 相关的垂直传热物理学有一个坚实的理论理解似乎至关重要。不幸的是，水平平均温度的标准垂直/平流扩散模型的有效性和实用性一直是考虑垂直传热的主要理论工具，多年来由于未能考虑到垂直传热问题而不断受到质疑。为了解决上述困难，我们的小组最近开发了一种新的基于过程的垂直平流/扩散热平衡模型，该模型利用了以下方面的进展：海洋水团理论是过去50年左右积累起来的。新模型比前一个模型有了相当大的改进，因为它自然地解释了变化的地形、密度补偿温度异常、等中性混合和差异表面加热对垂直传热的精确作用，而这些在过去的研究中仍然很模糊。标准型号。在本提案中，我们的首要目标是证明这种新的基于过程的模型的有用性，可以解释和合理化模拟海洋吸热对各种气候变化情景的影响，包括二氧化碳增加、稳定、辐射强迫超调和崩溃大西洋经向翻转环流。我们的第二个目标是证明，由于我们对海洋吸热的新的基于过程的理解而取得的重大进展可以转化为使用简单气候模型的气候变化预测准确性的重大改进，特别是在 MAGICC 模型中的应用，以及由英国气象局哈德利中心开发的一项。事实上，尽管我们目前理解气候变化的主要物理基础依赖于耦合的大气-海洋环流模型（AOGCM），但这些模型的运行计算成本非常昂贵。因此，人们开发了简单的气候模型（SCM），它能够模拟 AOGCM 中的气候响应，但计算成本大大降低。 SCM 是气候变化研究的关键工具，并被用于多种目的，例如模拟预测如何依赖于关键气候参数，或解释 AOGCM 预测。 SCM 通常用于提供政策建议，并在构成最新国际气候变化专门委员会报告第 2 和第 3 工作组基础的科学中发挥着核心作用，该报告是近期巴黎协定的主要文件，旨在限制总体气候变化。全球变暖幅度低于2摄氏度。对海洋吸热的物理认识的提高将大大有助于改善气候预测并减少相关的不确定性。

项目成果

Isoneutral control of effective diapycnal mixing in numerical ocean models with neutral rotated diffusion tensors

具有中性旋转扩散张量的数值海洋模型中有效二重混合的等中性控制

• DOI: http://dx.10.5194/os-15-21-2019
• 发表时间: 2019
• 期刊: Ocean Science
• 影响因子: 3.2
• 作者: Hochet A

Spiciness theory revisited, with new views on neutral density, orthogonality, and passiveness

重新审视辣度理论，对中性密度、正交性和被动性提出新的看法

• DOI: 10.5194/os-2020-39
• 发表时间: 2020-04-16
• 期刊: Ocean Science
• 影响因子: 3.2
• 作者: R. Tailleux

Spiciness theory revisited, with new views on neutral density, orthogonality and passiveness

重新审视辣味理论，对中性密度、正交性和被动性提出新观点

• DOI: http://dx.10.5194/os-2020-39
• 发表时间: 2020
• 作者: Tailleux R

Global heat balance and heat uptake in potential temperature coordinates

位温坐标中的全球热平衡和吸热量

• DOI: http://dx.10.1007/s00382-021-05832-7
• 发表时间: 2021
• 期刊: Climate Dynamics
• 影响因子: 4.6
• 作者: Hochet A

On the Determination of the 3D Velocity Field in Terms of Conserved Variables in a Compressible Ocean

关于可压缩海洋中守恒变量的三维速度场的确定

• DOI: http://dx.10.3390/fluids8030094
• 发表时间: 2023
• 期刊: Fluids
• 影响因子: 1.9
• 作者: Tailleux R