The efficiency of baroclinic instability in the global ocean

这项工作将有助于更好地了解全球海洋中的能量路径以及与大气的交换。这些过程发生在不同的时间和空间尺度上，并调节着地球的气候。海洋通常在热带地区从太阳获得能量(热量)，然后被主要洋流沿着大洋盆地的西部边界向极地输送，如墨西哥湾流，最终损失回中纬度的大气。最近的研究表明，与强流系统相关的这些中纬度地区的海洋湍流导致了大气能量的损失，这在传统的海洋环流模型中没有考虑到。在这些时空尺度上，能量汇聚到大气中，以不可预见的方式调节海洋循环，需要进一步研究。该项目将加强我们对这些过程的了解，并将制定参数，以便将它们纳入一般海洋环流模式，从而改进对地球气候系统的预测。这项研究将把几十年来收集的海面高度、表面温度和净热通量的遥感数据与耦合和非耦合的高分辨率地球系统模型的数值模拟结合起来。这一分析将导致更好地量化能量如何从海洋转移到大气的速率和机制，以及这与海洋中尺度涡旋的关系。这项建议将支持和帮助建立早期职业PI实验室和博士生培训。公众推广讲座将被用来宣传墨西哥湾流在气候变化中的重要性。这项工作将有助于更好地了解全球海洋中的能源路径。高分辨率气候模式一直有很高的海面温度变化，但海面温度与观测值不相上下。这项提议将有助于阐明为什么会出现这种差异。使用区域耦合模式对黑潮延伸的研究表明，这一汇占可转换为涡动动能(Eke)的EPE的70%以上。然而，OME-A汇点如何在全球范围内连接到EKE的调制仍然是一个悬而未决的问题。这项研究将使用几十年的现有遥感地表观测和一套全球高分辨率模拟，在社区地球系统模型(CESM-H)的耦合和非耦合配置中，通过局部和全球分析来获取能量转换率。局部分析需要将涡热通量场分解为散度通量和旋转通量。主要研究人员将使用Helmholtz分解来全局求解泊松方程，以提取动态重要的发散通量。主要目的是1)确定在CESM-H中OME-A反馈如何调制斜压不稳定将势能转换为动能的效率；以及2)在最先进的观测和CESM-H中检查EPE源和汇的空间和时间尺度相关性。将特别关注北半球西部边界流及其与北大西洋涛动和太平洋年代际涛动等年代际气候模式的对应关系。将定义一个不依赖于绝对模型能量学的新参数，并将允许在目前和未来的高分辨率模型相互比较项目中进行模型评估，如国际高分辨率地球系统预测实验室(IHESP)。拟议的团队将与气候过程团队(CPT)的参与者在海洋运输和涡流能源方面进行合作，并最终将在粗分辨率耦合气候模式中为OME-A EPE汇的参数化开发框架做出贡献。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。

This work will provide a better understanding of the pathways of energy in the global ocean and the exchanges with the atmosphere. These processes occur on different time and space scales and regulate Earth’s climate. The ocean generally gains energy (heat) in the tropics from the sun, which is then transported poleward by major ocean currents along the western boundaries of ocean basins, such as the Gulf Stream, and eventually lost back to the atmosphere in the midlatitudes. Recent research shows that oceanic turbulence in these midlatitude regions associated with strong current systems leads to a loss of energy to the atmosphere, not accounted for in traditional ocean circulation models. This sink of energy to the atmosphere at these turbulent time and space scales modulates the ocean circulation in unforeseen ways that need further investigation. This project will enhance our understanding of these processes and will develop parameterizations for their inclusion in general ocean circulation models leading to improving projections of Earth’s climate system. The study will combine remotely sensed data of sea surface height, surface temperature, and net heat flux collected over several decades with numerical simulations of coupled and uncoupled high-resolution Earth system models. The analysis will lead to better quantifying the rates and mechanisms of how energy is transferred from the ocean to the atmosphere and how this is associated with mesoscale eddies in the ocean. This proposal will support and help build the laboratory of an early career PI and the training of a PhD student. Public outreach lectures will be used to communicate the importance of the Gulf Stream in a changing climate.This work will aid in a better understanding of the pathways of energy in the global ocean. High-resolution climate models persistently have high sea surface temperature variance, but surface EKE comparable to observations. This proposal will help shed light on why this discrepancy occurs. Work in the Kuroshio Extension using a regional coupled model shows that this sink accounts for more than 70% of the EPE that would be available for conversion to eddy kinetic energy (EKE). However, it is still an open question how the OME-A sink connects to a modulation of EKE globally. This study will use multiple decades of available remote-sensed surface observations and a suite of global high-resolution simulations in coupled and uncoupled configurations of the Community Earth System Model (CESM-H) to access energy conversion rates through a local and global analysis. A local analysis requires a decomposition of the eddy heat flux field into divergent and rotational fluxes. The principal investigator will use Helmholtz decomposition to solve the Poisson equation globally in order to extract the dynamically important divergent fluxes. The main objectives are to 1) determine how the OME-A feedback modulates the efficiency of baroclinic instability to convert potential to kinetic energy in CESM-H; and 2) examine the spatial and temporal scale dependence of the EPE sources and sinks in state-of-the-art observations and CESM-H. There will be particular focus on the northern hemisphere Western Boundary Currents and their correspondence with decadal climate modes such as the North Atlantic Oscillation and Pacific Decadal Oscillation. A new parameter will be defined that does not depend on absolute model energetics and will allow model evaluations in current and future High-Resolution Model Intercomparison Projects such as the international Laboratory for High-Resolution Earth System Prediction (iHESP). The proposed team will collaborate with participants in the climate process team (CPT) on ocean transport and eddy energy and will ultimately contribute to a framework for parameterization development of the OME-A EPE sink in coarse-resolution coupled climate models.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.