DIMES Finestructure Profiling Floats: Enhancement and analysis of shear measurements in the Southeast Pacific, Drake Passage and Scotia Sea

知识价值：南大洋混合有可能在经向翻转环流中发挥重要作用，但对于造成最大混合的位置和过程仍存在相当大的不确定性。DIMES(南大洋Diapycna和Isopyconal混合实验)示踪剂的释放，连同10个EM-APEX剖面浮标和船舶微观结构调查，已经量化了东南太平洋(Drake Passage以西)的混合，揭示了由于风产生的近惯性波造成的适度增加的混合，但尚未完全扩展到Drake Passage和Scotia海的高能环境。EM-APEX(带有电磁速度测量的剖面浮标)的剪切测量已证明是描述南大洋内波场(波长在10米至1000米之间的速度和密度剖面中的“精细结构”)的宝贵工具。考虑到近惯性波在密度上具有相对较弱的特征(即高剪切/应变比)的优势，这种剪切的包含是特别必要的。在这个项目中，研究人员和他的学生将通过以下方式充分利用现有的DIMES数据集：(A)对来自初始EM-APEX的中尺度和细尺度切变和层结数据以及来自卫星测高的地面场进行深入分析，以了解内部波场和中尺度流、风、层结之间的联系。(B)额外部署8个EM-APEX，以扩大观测阵列在德雷克海峡和斯科舍海的覆盖范围，填补季节周期中的空白，并增加结果的稳健性。广泛的影响：该项目对模式参数化的发展具有重要影响，例如由气候过程小组开发的内波和混合。将内部波混合过程纳入大尺度环流模式，对于准确预测环流和未来对气候变化的反应至关重要。如果没有基于全面观测和对机制的坚实物理理解的参数化，在不直接模拟内波的大尺度模式中进行混合的希望微乎其微。该项目的大部分将由研究生拜伦·基尔本主持，并将构成他的博士论文的基础。这是一个宝贵的教育机会，考虑到测量的新颖性和全职关注理解这一复杂地区的必要性。它还提供了培训海洋科学劳动力队伍中有才华的新成员的好处。将通过西雅图水族馆和太平洋科学中心开展教育宣传，重点是将南大洋物理海洋学的基本信息介绍给一个公共论坛。

Intellectual Merit:Southern Ocean mixing has the potential to play an important role in the Meridional Overturning Circulation, but considerable uncertainty still exists as to the locations and processes responsible for the most mixing. The DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) tracer release, together with 10 EM-APEX profiling floats and ship microstructure surveys, has quantified the mixing in the Southeast Pacific (west of Drake Passage), revealing modestly elevated mixing due to wind-generated near-inertial waves, but has yet to extend fully into the high-energy environments of Drake Passage and the Scotia Sea. The shear measurements of the EM-APEX (a profiling float with an electromagnetic velocity measurement) have proven a valuable tool for the characterization of the Southern Ocean's internal wave field (the "finestructure" seen in velocity and density profiles with wavelengths between 10m and 1000 m). This inclusion of shear is particularly necessary, given the predominance of near-inertial waves with relatively weak signature in density (i. e., high shear/strain ratios). The combination of high-quality shear and density profiles over the upper 2000 m and sustained duration makes the EM-APEX an economical choice for extending these types of measurements into the less well-sampled regions and times of the year.In this project, the investigator and his student will take full advantage of the existing DIMES dataset by (a) conducting an in-depth analysis of both mesoscale and fine-scale shear and stratification data from the initial EM-APEX, along with surface fields from satellite altimetry, to understand the connections between the internal wave field and mesoscale currents, winds, and bottom topography and (b) deploying 8 additional EM-APEX to extend the observational array's coverage within Drake Passage and the Scotia Sea, fill gaps in the seasonal cycle, and increase the robustness of the results.Broader Impacts:The project has important implications for the development of model parameterizations, such as being developed by the Climate Process Team on Internal Waves and Mixing. The incorporation of internal wave mixing processes into large-scale circulation models is essential for accurate predictions of circulation and future response to climate change. Without parameterizations based on comprehensive observations and solid physical understanding of mechanisms, there is little hope that the mixing in large-scale models that do not directly simulate internal waves will be correct. Much of the project will be conducted by a graduate student, Byron Kilbourne, and will form the basis of his Ph.D. dissertation. This is a valuable educational opportunity, considering the novel nature of the measurements and the need for full-time focus in understanding this complex region. It also provides the benefit of training a talented new member of the ocean science workforce. Educational outreach will be conducted through the Seattle Aquarium and Pacific Science Center, with an emphasis on bringing basic information on the physical oceanography of the Southern Ocean to a public forum.