RAPID: Fine- and Microstructure Observations in Conjunction with a GEOTRACES Section along 40 degrees S in the Atlantic

该项目与英国资助的GEOTRACES A10剖面一起，在南大西洋沿40S进行精细和微观结构数据的采集和分析。将使用垂直剖面和滑翔机平台的组合。所得数据将用于估计区域的等轴混合和等轴搅拌速率。根据潮汐、漩涡、地形形态和平均地转流的变化，预计会有显著的区域差异。准轴混合的估计将借助于辐射平衡方程，而准轴搅拌的估计将通过与已发表的标度的比较得到。关于海洋的热量、质量、动量、能量、位势涡度或被动示踪剂的收支如何平衡的细节，特别是在亚中尺度，特别是关于非线性与波辐射的作用以及内波与地转运动的作用，存在很大的不确定性。拟议的工作将通过记录沿GEOTRACES A10剖面的精细和微观结构场来解决这种不确定性，并将定量研究与更大空间和时间尺度上的变异性的关系和依赖。测量到的湍流混合率将与基于辐射平衡方程的与区域内波气候相关的湍流产生的估计进行比较。等压搅拌速率将与发表的基于弱非线性和湍流分析的标度进行比较。更广泛的影响拟议研究的结果将有助于了解和预测全球气候变化和碳循环。这些努力将直接支持GEOTRACES项目，因为生物地球化学预算是该研究的重点，它取决于异流混合和等流搅拌速率。该项目将提供这些数据的直接估计，并将协助进行解释。它还将协助发展和实施用于预测海洋气候响应的一般环流模式的湍流混合和等环流搅拌参数化。具体来说，来自微观结构观察的异径混合和等径搅拌的表征将被牛津大学的合作者纳入他们的示踪剂运输的环流模型模拟中。

This project funds the acquisition and analysis of fine- and microstructure data in conjunction with the UK funded GEOTRACES A10 section along 40S in the South Atlantic. A combination of vertical profiling and glider platforms will be used. The resulting data will be used to estimate regional diapycnal mixing and isopycnal stirring rates. It is anticipated that there will be significant regional variability in response to variations in tides, eddies, topographic morphology and mean geostrophic currents. Estimates of diapycnal mixing will be aided by radiation balance equations and estimates of isopycnal stirring will be informed by comparison to published scalings.Intellectual MeritThere is a great deal of uncertainty regarding the details of how oceanic budgets of heat, mass, momentum, energy, potential vorticity or passive tracers are balanced, particularly at the submesoscale and especially with regards to the roles of nonlinearity versus wave radiation and the role of internal waves versus geostrophic motions. The proposed work will address this uncertainty by documenting fine- and microstructure fields along the GEOTRACES A10 section and will quantitatively investigate the relationship to, and dependence upon, variability on larger spatial and temporal scales. Measured diapycnal mixing rates will be compared to radiation balance equation based estimates of turbulent production associated with the regional internal wave climate. Isopycnal stirring rates will be compared to published scalings based upon both weakly nonlinear and turbulent analyses.Broader ImpactsResults of the proposed research will contribute to the understanding and prediction of global climate change and the carbon cycle. Efforts will be in direct support of the GEOTRACES program as the biogeochemical budgets that are the focus of that study depend upon diapycnal mixing and isopycnal stirring rates. The project will provide direct estimates of these and will assist with the interpretation. It will also assist with the development and implementation of turbulent mixing and isopycnal stirring parameterizations for general circulation models used to predict the ocean climate response. Specifically, the characterization of diapycnal mixing and isopycnal stirring derived from the microstructure observations will be incorporated by collaborators at Oxford University in their general circulation model simulations of tracer transport.