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

DIMES 精细结构剖面浮标：东南太平洋、德雷克海峡和斯科舍海剪切测量的增强和分析

• 批准号: 1129564
• 负责人: James Girton
• 金额: $ 74.33万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129564&HistoricalAwards=false
• 关键词: DIMES; Finestructure; Profiling; Floats; Enhancement

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.

知识成果：南大洋混合有可能在经向翻转环流中发挥重要作用，但造成最大混合的位置和过程仍然存在相当大的不确定性。DIMES（南大洋纵贯和等密度混合实验）示踪剂释放，加上10个EM-APEX剖面浮标和船舶微观结构调查，量化了东南太平洋（德雷克海峡以西）的混合，揭示了由于风产生的近惯性波，混合略有升高，但尚未完全扩展到德雷克海峡和斯科舍海的高能环境。EM-APEX（一种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部波场（波长在10米至1 000米之间的速度和密度剖面中所见的“精细结构”）特征的宝贵工具。考虑到密度特征相对较弱的近惯性波占主导地位（即，例如，高剪切/应变比）。EM-APEX结合了2000米以上的高质量剪切和密度剖面以及持续时间，使其成为将这些类型的测量扩展到采样较少的地区和一年中的时间的经济选择。在该项目中，研究人员和他的学生将充分利用现有的DIMES数据集，（a）对中尺度和精细尺度进行深入分析，来自初始EM-APEX的尺度切变和分层数据，沿着来自卫星测高的表面场，以了解内波场与中尺度海流、风和海底地形之间的联系，以及（B）部署8个额外的EM-APEX以扩大德雷克海峡和斯科舍海内的观测阵列的覆盖范围，填补季节循环中的空白，更广泛的影响：该项目对模型参数化的发展具有重要意义，例如由气候过程内波和混合小组开发的。将内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，那么不直接模拟内波的大尺度模型中的混合就几乎没有希望是正确的。该项目的大部分工作将由研究生拜伦基尔本负责，并将成为他攻读博士学位的基础。论文 这是一个宝贵的教育机会，考虑到测量的新颖性和需要全职专注于了解这个复杂的区域。它还提供了培训海洋科学工作队伍中有才能的新成员的好处。将通过西雅图水族馆和太平洋科学中心开展教育推广活动，重点是将关于南大洋物理海洋学的基本信息介绍给公共论坛。