Earth System Physics and Climate Dynamics

该研究项目旨在了解涉及固体地球、海洋、大气、大陆冰盖和海冰耦合演化的现象学。该计划的一个独特贡献涉及冰-地-海相互作用和相对海平面历史的引力自洽理论。拟议工作的一个重要组成部分将涉及在最近的晚第四纪冰期旋回期间对大陆冰盖负荷历史的改进。拟议的工作还将集中于解释为什么这种冰期旋回具有明显的“锯齿”形式，其中旋回的冰期比消冰期慢得多，持续时间更长，这一特征似乎是由控制消冰期的极快冰流相关的不稳定性控制的。该计划的这一方面提供了冰川历史模型，这些模型继续被国际社会普遍使用，以提供支持基于过去气候条件的全球气候模型重建所需的边界条件。除了继续研究现代和过去气候状态的高分辨率区域气候模型外，多伦多小组的一个独特贡献将继续致力于更全面地了解所谓的Dansgaard-Oeschger振荡现象，该现象在海洋同位素阶段3期间主导了气候变化。正如Peltier小组所表明的那样，这些振荡是由被称为海因里希事件的快速冰流不稳定性引发的，该事件还提出了一个新的理论，该理论将在本研究计划中得到更充分的探索。这一领域新研究的一个主要重点将是了解这种D-O现象对轨道日晒状况的依赖性以及已经产生的成功模拟的其他特征。这些D-O结果已被证明在很大程度上依赖于UofT气候模式的全球海洋分量中对小尺度海洋湍流过程的参数化方式，特别是海洋平流扩散率的表示。多伦多计划的一个主要贡献是继续发展理论和基于数值模拟的结果，这些结果导致在低分辨率海洋模式中对这种小尺度过程的表示的重大改进。下一个拨款期的一个特别重点将是研究内波破碎对海洋潜流扩散的影响程度。这项工作得到了基于mitgcm的超高分辨率模拟的支持，这些模拟的模式明显受到天文潮汐和大气派生的地表强迫的影响。在正式流体力学分析基础上对海洋湍流过程的关注是一系列相关调查的最后一项，这些调查将构成下一个资助期将要开展的工作。

This research program seeks to understand phenomenology involving the coupled evolution of the solid Earth, the oceans, the atmosphere and continental ice sheets and sea ice. A unique contribution of this program involves the gravitationally self-consistent theory of Ice-Earth-Ocean interactions and relative sea level history. An important component of the proposed work will involve refinement of the ice sheet loading history of the continents during the most recent Late Quaternary ice-age cycle. The proposed work will also focus upon the explanation of why such glacial cycles are characterized by a distinctly "sawtooth" form in which the glaciation phase of the cycle is much slower and lasts longer than the deglaciation phase, a feature which appears to be controlled by extremely fast ice stream related instabilities that control the deglaciation phase. This aspect of the program has delivered the models of glaciation history that continue to be employed ubiquitously by the international community to provide the boundary conditions needed to support global climate model-based reconstructions of past climate conditions. Aside from continuing work on high resolution regional climate modeling of both modern and past climate states, a unique contribution of the Toronto group will continue to be work to more fully understand the so-called Dansgaard-Oeschger oscillation phenomenon that dominated climate variability during Marine Isotope Stage 3. As the Peltier group has shown these oscillations are triggered by the fast ice stream instabilities called Heinrich events for which a new theory has also been proposed that will be more fully explored in this proposed program of study. A primary focus of new research in this area will be on understanding the dependence of this D-O phenomenon upon the orbital insolation regime and other characteristics of the successful simulations that have already been produced. These D-O results have been shown to rely significantly upon the manner in which small scale ocean turbulence processes are parameterized in the global ocean component of the UofT climate model, especially the representation of ocean diapycnal diffusivity. A major contribution of the Toronto program continues to involve the development of theory and numerical simulation-based results that are leading to significant improvements in the representation of such small scale processes in low resolution ocean models. A particular focus in the next grant period will be upon the extent to which internal wave breaking may be contributing to ocean diapycnal diffusivity. This work is being supported by extremely high resolution MITgcm-based simulations with models explicitly forced by the astronomical tides and atmosphere derived surface forcing. This focus upon ocean turbulence processes based upon formal fluid mechanical analyses is the last of the linked set of investigations that will comprise the work to be undertaken in the next grant period.