Collaborative Research: Adjustment of the ACC to Variability in Southern Ocean Winds: A Modal Point of View

0424703学术价值：本项目旨在研究南极绕极流对风强迫的快速和局部变化的短时间尺度调整。众所周知，ACC对风强迫的变化做出了连贯和快速的反应。这项研究将检验这样一种假设，即南大洋的这种快速反应是由正常模式控制的，就像人们认为的副热带盆地的情况一样。南大洋在许多可能影响调整过程的方面与副热带对应物不同；空间(特别是纬向)长度尺度比副热带盆地大得多，南大洋存在脊状等显著的测深特征，在德雷克海峡的纬度范围内，不存在容纳边界流的经线边界。此外，ACC还包括一个可能影响Rossby盆地模式的强东向急流系统。该项目将解决以下问题：i)南大洋的调整是否受盆地模式的支配？ii)ACC的强流在多大程度上改变了盆地模式和调整过程？iii)水深特征在塑造南大洋对风波动的反应方面起了什么作用？iv)德雷克航道在多大程度上是正压波和正常模式的屏障？v)风应力的什么扰动将导致最大的能量扰动？更广泛的影响：更好地描述南大洋的变化对包括天气预报、波高预报、航行和渔业在内的广泛领域产生影响。此外，了解是什么决定了ACC的路径和强度及其变异性，有助于解释来自漂流物、压力计和遥感的海洋观测结果，并可能最终提高它们的准确性。从另一个角度来看，该项目将推动隐式海洋模式的发展。这些是相对较新的工具，与传统模型相比，它们提供了对海洋动力学更基本的理解。该项目将进一步促进从事自我指导项目的博士后的职业发展。最后，社区可能已经被提供了一个清晰的洞察力，让他们了解ACC如何适应快速变化的风向。这可能导致更好地认识它在过去气候中的作用，并最终可能增加预测其对未来气候变化的反应的能力。

abstract for 0424703Intellectual Merit: This project aims to study the short-time scale adjustment of the Antarctic Circumpolar Current (ACC) to rapid and localized changes in wind forcing. The ACC is known to respond coherently and rapidly to changes in wind forcing. This study will test the hypothesis that this fast response of the Southern Ocean is governed by normal modes, as is thought to be the case in the subtropical basins. The Southern Ocean is unlike its subtropical counterparts in many aspects that are likely to affect the adjustment process; the spatial (especially zonal) length scale is much larger than for subtropical basins, prominent bathymetric features like ridges are present in the Southern Ocean, and in the latitude range of the Drake Passage, no meridional boundaries exist to accommodate a boundary current. Furthermore, the ACC comprises a system of strong eastward jets that may affect the Rossby basin modes. The project will address the following questions: i) Is the adjustment of the Southern Ocean governed by basin modes?ii) To what extent does the strong flow of the ACC modify the basin modes and the adjustment process?iii) What is the role of the bathymetric features in shaping the Southern Ocean response to wind fluctuations?iv) To what extent is the Drake Passage a barrier for barotropic waves and normal modes?v) What perturbations in wind stress will lead to the most energetic disturbances?Broader Impacts: A better description of the variability in the Southern Ocean has consequences for a large range of fields, including weather prediction, wave-height prediction, navigation, and fishery. In addition, understanding what governs the path and strength of the ACC and their variability facilitates theinterpretation of oceanographic observations from drifters, pressure gauges, and remote sensing, and may ultimately increase their accuracy. From another perspective, this project will advance the development of implicit ocean models. These are relatively new tools which provide a more fundamental understanding of ocean dynamics than conventional models. The project will further the career development of a post-doc working on a self-directed project. In the end, the community may have been offered a clear insight into the way the ACC adjusts to rapidly varying winds. This may lead to a better appreciation of its role in past climates, and, ultimately, it may increase the ability to anticipate on its response to future climate changes.