Collaborative Research:Interaction of eddies with mixed layers

合作研究：涡流与混合层的相互作用

• 批准号: 0336808
• 负责人: Samar Khatiwala
• 金额: --
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0336808&HistoricalAwards=false
• 关键词: Collaborative; Research; Interaction; eddies; mixed

Parameterizations for the interaction of mesoscale eddies with turbulent mixing in the upper ocean will be derived and tested in climate models. Mesoscale parameterizations used in ocean general circulation models typically represent only the adiabatic release of available potential energy by eddies, as suggested by Gent and McWilliams. In the upper ocean, eddy fluxes develop a diabatic component because density is maintained vertically homogeneous by strong mixing while geostrophic motions are constrained to be horizontal near the boundary. Furthermore mesoscale strain interacts and modifies turbulent mixing at small scales. The dynamics of these diabatic surface eddy fluxes and their interactions with small-scale turbulence are not fully understood, and are not currently parameterized in the surface mixed layers of ocean models. Instead, tapering schemes are used to turn of the adiabatic eddy flux schemes at the surface. Coupled climate models are very sensitive to the choice of this tapering scheme. Here a new approach to eddy parameterizations, based on the Transformed Eulerian Mean is proposed. The new approach provides a unified framework for the treatment of eddy fluxes in the adiabatic interior and in the diabatic surface boundary layer.The project involves 1) analysis of observational data sets with key information on eddy transport in the upper ocean, 2) high resolution process models that explicitly resolve the full range of motions in the mixed layer, and 3) the derivation of new parameterization schemes based on a compromise between numerical efficiency and the theoretical information learned from observations and simulations. The main focus of the Team will be to implement and test the new parameterization schemes in the coupled climate models currently used in the modeling centers at GFDL, NCAR, and GSFC. This research is aimed at improving state of the art models of the atmosphere and ocean for study of the climate of the Earth and how it might change in the future. Thus it is of great societal impact. The project will also contribute to the education of a number of post-doctoral and graduate students bridging between observations, theory, and modeling.

将在气候模型中推导和测试中尺度涡旋与上层海洋湍流混合相互作用的参数化。正如 Gent 和 McWilliams 所建议的，海洋环流模型中使用的中尺度参数化通常仅代表涡流绝热释放的可用势能。在上层海洋，涡流产生非绝热分量，因为密度通过强烈混合而保持垂直均匀，而地转运动被限制在边界附近的水平方向。此外，中尺度应变相互作用并改变小尺度的湍流混合。这些非绝热表面涡流的动力学及其与小尺度湍流的相互作用尚未完全了解，并且目前尚未在海洋模型的表面混合层中进行参数化。相反，使用锥形方案来改变表面的绝热涡流方案。耦合气候模型对这种逐渐减少方案的选择非常敏感。这里提出了一种基于变换欧拉均值的涡流参数化新方法。新方法为处理绝热内部和非绝热表面边界层的涡通量提供了统一的框架。该项目包括 1) 分析具有上层海洋涡流传输关键信息的观测数据集，2) 高分辨率明确解析混合层中全方位运动的过程模型，以及3）基于数值效率与从观察和模拟中学到的理论信息之间的折衷推导新的参数化方案。该团队的主要重点是在 GFDL、NCAR 和 GSFC 建模中心目前使用的耦合气候模型中实施和测试新的参数化方案。这项研究旨在改进最先进的大气和海洋模型，以研究地球气候及其未来如何变化。因此具有很大的社会影响。该项目还将有助于对一些博士后和研究生进行观察、理论和建模之间的桥梁教育。