Collaborative Research: Interaction of eddies with mixed layers

将在气候模式中推导和检验中尺度涡旋与上层海洋湍流混合相互作用的参数化。在海洋环流模式中使用的中尺度参数化，通常只代表可用的位能的绝热释放涡，建议由Gent和McWilliams。在上层海洋，涡通量发展的非绝热成分，因为密度保持垂直均匀的强混合，而地转运动被限制在边界附近的水平。此外，中尺度应变相互作用，并修改湍流混合在小尺度。这些非绝热表面涡动通量的动态及其与小尺度湍流的相互作用尚未完全了解，目前也没有在海洋模型的表面混合层参数化。取而代之的是，锥形方案被用来转动的绝热涡通量计划在表面。耦合气候模式对这种逐渐减少方案的选择非常敏感。本文提出了一种新的基于变换欧拉平均的涡参数化方法。新方法为处理绝热内部和非绝热表面边界层中的涡旋通量提供了一个统一的框架。该项目包括：1）分析具有上层海洋涡旋输送关键信息的观测数据集，2）明确解决混合层中全部运动范围的高分辨率过程模式，以及3）基于数值效率和从观测和模拟中获得的理论信息之间的折衷来推导新的参数化方案。该小组的主要重点是在GFDL、NCAR和GSFC的模拟中心目前使用的耦合气候模式中实施和测试新的参数化方案。这项研究的目的是改进最先进的大气和海洋模型，以研究地球气候及其未来可能如何变化。因此，它具有很大的社会影响。该项目还将有助于一些博士后和研究生的教育，在观察，理论和建模之间架起桥梁。

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.