RAPID: Evaluating Fine-Structure Estimates of Diapycnal Mixing from the DIMES 2010 Research Cruise

知识价值：纵向（主要是垂直）混合在决定全球海洋的总体热量收支和水质量分布方面起着关键作用。横向扩散系数最好使用专门的微结构传感器来测量，这些传感器可以收集高垂直分辨率的测量结果。近年来，各种精细结构方法作为廉价的微结构测量方法出现。精细结构方法利用了电导率-温度-深度仪（ctd）、低声学多普勒电流分析器（LADCPs）和/或消耗型ctd （xctd）的数据，所有这些数据都是在全球范围内、在所有季节常规收集的。因此，精细结构方法似乎提供了在全球范围内绘制扩散率时空变化的低成本可能性。然而，与精细结构方法相关的误差预算仍然缺乏特征。这个拟议的RAPID项目旨在通过促进微观结构和精细结构测量的详细相互比较，减少精细结构混合估计的不确定性。36台xctd将在2010年1月至2月的南大洋深涡旋和等涡旋混合实验（DIMES）研究巡航期间部署。该项目还将支持使用Thorpe尺度和应变精细结构方法对XCTD测量结果进行分析，并与微观结构估计值进行比较，并与计划用于LADCP和CTD数据的类似剪切应变精细结构分析进行比较。更广泛的影响：这项工作的结果将有助于科学界越来越多地评估与精细结构方法有关的不确定性，这些方法用于评估海洋中的底激流混合。这些发现将在确定精细结构方法是否可以合理地用于绘制混合的全球变化方面发挥关键作用。结果应该允许对最有效的精细结构方法的类型进行评估。由于该项目的目的是在基于精细结构的全球扩散度图上设置可用的误差界限，因此该项目的研究结果可能对全球预测气候建模工作产生深远的影响。此外，该项目将有助于培养一名研究生。

Intellectual Merit: Diapycnal (mostly vertical) mixing plays a critical role in determining the overall heat budget and water mass distribution of the global ocean. Diapycnal diffusivities are best measured using specialized microstructure sensors, which collect measurements with high vertical resolution. In recent years a variety of fine-structure methods have emerged as inexpensive alternatives to microstructure measurements. Fine-structure methods take advantage of data from conductivity-temperature-depth instruments (CTDs), lowered acoustic Doppler current profilers (LADCPs), and/or eXpendable CTDs (XCTDs), all of which are routinely collected globally and through all seasons. Finestructure methods thus appear to offer the possibility of inexpensively mapping spatial and temporal variations in diffusivity on a global scale. However, the error budgets associated with finestructure methods remain poorly characterized. This proposed RAPID project is aimed at reducing the uncertainties in fine-structure mixing estimates, by facilitating a detailed inter-comparison of microstructure and fine-structure measurements. Thirty-six XCTDs will be deployed during the January-February 2010 research cruise of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). The project will also support analysis of the XCTD measurements using Thorpe scale and strain fine-structure methods and comparison with microstructure estimates and with similar shear-strain based fine-structure analyses planned for the LADCP and CTD data.Broader Impacts: Results of this work will contribute to a growing community effort to assess the uncertainties associated with fine-structure methods for evaluating diapycnal mixing in the ocean. These findings will play a critical role in determining whether fine-structure methods can plausibly be used to map global variations in mixing. Results should allow an assessment of the types of fine-structure methods that are most effective. Since the project aims to place usable error bounds on fine-structure based maps of global diffusivity, the findings from this project will potentially have a profound impact on global predictive climate modeling efforts. In addition, the project will contribute to the training of one graduate student.