The role of oceans in climate asymmetries

海洋是地球气候中一系列具有科学意义和社会意义的不对称现象的原因。此外，海洋的长时间尺度和不同的区域环流对温室气体强迫下表层和次表层变暖的模式产生了强烈的制约。反过来，海洋通过以下方式调节全球变暖的速度和程度：(1)在深部储存异常热量；(2)表面变暖模式与大气辐射反馈之间的耦合，这支配着全球气候敏感性的演变。对海洋在气候中的作用的洞察来自理想化的耦合全球气候模式(GCM)实验，其中不同的海洋环流和气候是通过规定不同的大陆几何形状来诱导的。该项目旨在研究大规模海洋环流在地球气候系统中的作用，采用简化的几何图形和云反馈。将考虑不同的理想化大陆配置。这项工作改进了以前的工作，这些工作使用了仅限于海洋的模式或不包括云反馈的耦合模式。这项工作将支持一名女研究生，一名助理教授为研究提供建议，以及一名兼职软件工程师在计算和建模的技术方面提供帮助。该研究生将在气候科学的教学和交流方面获得宝贵的经验。该项目成果的理想化性质将使其成为本科生和研究生课程的宝贵补充。为设计耦合模式中的理想化大陆(或测深)几何图形而开发的工具将通过GitHub和最终在NCAR的社区地球系统模型(CESM)理想化海洋模型层次中广泛提供给社区。该项目在先前理想化的耦合模式框架的基础上进行了三个关键方面的改进：(I)通过使用最先进的模型组件，这些组件重要地代表了以前被忽视的真实的云反馈；(Ii)通过使用新的大陆几何结构和变化的行星自转速度进行模拟；以及(Iii)通过对由这些不同的大陆几何形状引起的一系列背景海洋环流进行二氧化碳强迫模拟。这些模型实验旨在回答有关海洋在气候和气候变化中的作用的关键悬而未决的问题。这项工作将有助于更好地了解大规模海洋环流产生的条件，并进而支配：(1)气候的大规模不对称；(2)气候变化的地理模式；(3)全球变暖的速度和程度。特别是，它将提供关于海洋和大气影响极地至赤道温度梯度的具体动态的更深入的知识；经向热输送及其在海洋和大气之间的分配；淡水输送；热带降雨模式；深水形成和经向翻转的局部化。这项工作还可以为为什么GCM预测在温室气体强迫下气候敏感性增加提供一个物理理论，从而提高我们对气候预测中的主要不确定性之一的理解。评估云和云反馈在促进这些功能方面的关键作用将是贯穿始终的重点。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 oceans are responsible for a range of scientifically interesting and societally relevant asymmetries in Earth's climate. Moreover, the ocean's long timescales and diverse regional circulations impose strong constraints on the patterns of surface and subsurface warming under greenhouse-gas forcing. In turn, oceans mediate the rate and magnitude of global warming through (i) storage of anomalous heat at depth and (ii) the coupling between surface warming patterns and atmospheric radiative feedbacks, which governs the evolution of global climate sensitivity. Insights into the role of oceans in climate have come from idealized coupled global climate model (GCM) experiments wherein different ocean circulations and climates are induced by prescribing distinct continental geometries. This project is to examine the role of large scale oceanic circulation in the earth's climate system in simplified geometries and with cloud feedbacks. Different idealized continental configurations will be considered. This work improves upon previous efforts that have used ocean-only models or coupled models that did not include cloud-feedbacks. This work would support a female graduate student, an assistant professor to advise the research, and a part-time software engineer to assist in technical aspects of computing and modeling. The graduate student would gain valuable experience in teaching and communicating climate science. The idealized nature of results from this project would make them valuable additions to undergraduate and graduate courses. Tools developed for the purposes of designing idealized continental (or bathymetric) geometries in the coupled model will be made widely available to the community through both GitHub and, eventually, within NCAR's Community Earth System Model (CESM) idealized ocean model hierarchy.This project improves on previously idealized, coupled modeling framework in three key ways: (i) By employing state-of-the-art model components that, importantly, represent realistic cloud feedbacks which were previously neglected; (ii) By performing simulations with novel continental geometries and with varying planetary rotation rates; and (iii) By performing carbon dioxide forcing simulations with a range of background ocean circulation regimes induced by those distinct continental geometries. These model experiments are designed to answer key outstanding questions about the role of oceans in climate and climate change. The work will lead to improved understanding of the conditions by which large-scale ocean circulations arise and in turn govern: (i) large-scale asymmetries in climate; (ii) geographic patterns of climate change; and (iii) the rate and magnitude of global warming. In particular, it will provide deeper knowledge of the specific dynamics by which the oceans and atmosphere affect pole-to-equator temperature gradients; meridional heat transport and its partitioning between oceans and atmosphere; freshwater transport; tropical rainfall patterns; and localization of deep-water formation and meridional overturning. The work could also provide a physical theory for why GCMs predict increasing climate sensitivity under greenhouse-gas forcing, thus improving our understanding of one of the major uncertainties in climate projection. Evaluating the key role of clouds and cloud feedbacks in contributing to these features will be a focus throughout.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.