CAREER: Fluxes and Structures in Double-Diffusive Convection

在过去几年中，双扩散混合对水-质量转化和确定所有海洋中温度-盐度关系结构的重要性变得越来越清楚。双扩散对流最有趣的一个方面是它能够将光滑的垂直梯度转化为由薄分层界面分隔的混合层组成的阶梯结构。来自热带大西洋的最新野外数据表明，与具有类似分层的非阶梯区域相比，温盐阶梯内由盐指引起的垂直通量显著（按数量级）增强。（施密特等人，2005）。因此，提高我们对温盐阶梯的形成、演化和大规模后果的理解是至关重要的。在这个职业奖中，海军研究生院的一名研究人员将量化光滑梯度和温盐阶梯中的双扩散传输，从而更清楚地了解阶梯的起源，并指定其信息的条件。这项工作将涉及数值过程建模和理论分析的结合。理论和模式运行的推论将用于解释海洋精细和微观结构数据以及实验室实验的结果。本研究的结果将解决关于热盐阶梯的动力学、热盐混合率的大小及其随环境参数的变化的争议。新发展的理论，由主要研究者将调用混合层的厚度和由此产生的横向通量，将进行探讨。除了这项工作的智力价值之外，拟议的教学活动将针对海军研究生院的学生，通过开发一个专题课程，扩大远程学习计划，并为几名研究生提供建议，使他们接触到海洋微观结构的物理学。

The significance of double-diffuse mixing for water-mass transformation and determining the structure of the temperature-salinity relationship in all oceans is becoming increasingly clear over the last few years. One of the most intriguing aspects of double-diffuse convection is related to its ability to transform smooth vertical gradients into the stepped structures consisting of mixed layers separated by thin stratified interfaces. Recent field data from the tropical Atlantic has shown that vertical fluxes due to salt fingers within thermohaline staircases are significant (by order of magnitude) enhanced over non-staircase regions with similar stratifications. (Schmitt et al., 2005). Thus, it is vital to improve our understanding of the thermohaline staircase formation, evolution and the large scale consequences. In this CAREER award, a researcher at the Naval Postgraduate School will quantify the double-diffusive transport in both smooth gradients and thermohaline staircases, developing a clearer insight into the origin of staircases and specifying the conditions for their information. The work will involve a combination of numerical process modeling and theoretical analysis. Inferences from the theory and model runs will be used to interpret the oceanic fine-and microstructure data and results of the laboratory experiments. The results from this study will resolve the controversy with regard to the dynamics of the thermohaline staircases, the magnitude of the heat and salt mixing rates, and their variation with environmental parameters. The newly developed theory by the principle investigator will invoke the thickness of the mixed layers and the resulting diapycnal fluxes, will be explored. In addition to the intellectual merit of the work, the proposed teaching activities will target the Naval Postgraduate School students and expose them to the physics of the ocean microstructure by developing a special topics course, expanding the distance learning program, and advising several graduate students.