Collaborative Research: Observations of Three-dimensional Transport Pathways and Biogeochemical Fluxes in the Southern Ocean using Autonomous Gliders

南大洋通常被称为深海的窗口。 南极洲周围的这片广阔海洋是充满深海的沃茨被带到表面的主要地点，在那里它们与大气和海冰相互作用。 由于在全球气候系统中的这一独特作用，南大洋发生的物理和生物过程对全球海洋的性质产生了不成比例的巨大影响，包括被困在深海数百至数千年的热量和二氧化碳。 对南大洋和南极洲的观测资料都很少？海洋的环流结构和生物特性，如营养物和生物量浓度，是理解近表层沃茨变化及其随后与深海交换的重大障碍。近年来，南大洋碳和气候观测和建模项目使用了创新的机器人技术，即自主剖面浮标，以前所未有的空间和时间覆盖范围对南大洋的生物地球化学性质进行观测。 这一进展标志着我们机械地了解南大洋的能力发生了一步变化。虽然海洋生物在全球碳循环中的作用很大，但由于取样间隔相对较粗（10天），浮标无法充分捕捉到产生观测到的海洋地球化学分布的许多物理和生物过程。 在这个项目中，两个海洋滑翔机将被用来跟踪单个浮子，以测量影响海洋表面和内部之间交换的海洋环流特征。 滑翔机每4到5个小时对海洋上层1000米进行一次采样，能够在大约一天的时间尺度上解析流体运动的变化。在这些尺度上，垂直速度的变化是相当大的，因此，在这些较短的时间和较小的空间尺度的环流显着影响海洋性质的垂直输送。 通过SOCCOM项目，将在南极绕极流的印度部分部署两个自主海洋滑翔机，同时部署一个或多个配备地球化学传感器的半拉格朗日Argo浮标。滑翔机将被引导跟踪阿尔戈浮标至少四个月的时间，解决中尺度和亚中尺度结构周围的浮动以及变化发生在周期短于浮动？s 10天采样间隔。对上层海洋水文和速度场的测量将有助于分析混合层内的流体动力学不稳定性及其对混合层底部的垂直输送和交换的影响。 滑翔机数据还将与浮标观测和遥感产品相结合，以得出垂直示踪剂通量，目的是量化下沉和平流路径之间的输出分配。 最后，该项目将提供观测的物理过程，有助于高-该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准。

The Southern Ocean is often referred to as the window to the deep ocean. This vast ocean around Antarctica is the primary location where the waters that fill the deep ocean are brought to the surface where they interact with the atmosphere and with sea ice. Because of this unique role in the global climate system, the physical and biological processes that occur in the Southern Ocean have a disproportionately large impact on the properties of the global ocean, including the amount of heat and carbon dioxide that is trapped in the deep ocean for hundreds to thousands of years. Extremely sparse observations of both the Southern Ocean?s circulation structure and biological properties, such as nutrient and biomass concentrations, have presented a significant barrier to understanding the modification of near surface waters and their subsequent exchange with the deep ocean. In recent years, the SOCCOM (Southern Ocean Carbon and Climate Observations and Modeling) project has used innovative robotic technologies, namely autonomous profiling floats, to provide observations of biogeochemical properties in the Southern Ocean with unprecedented coverage in space and time. This advance marks a step change in our ability to mechanistically understand the Southern Ocean?s role in the global carbon cycle but many of the physical and biological processes responsible for generating the observed biogeochemical distributions are not adequately captured by the floats because of their relatively coarse sampling interval (10 days). In this project, two ocean gliders will be piloted to track individual floats in order to measure the oceanic circulation features that impact exchange between the surface and interior ocean. Gliders sample the upper 1000 meters of the ocean once every 4 to 5 hours and are able to resolve variations in fluid motion on time scales of about a day. On these scales, the variability of vertical velocities are quite large and thus the circulation at these shorter temporal and smaller spatial scales significantly influences the vertical transport of ocean properties. An improved characterization of motions at these scales, and their impact on heat and carbon transport, will lead to a better understanding of the role the Southern Ocean plays in the global carbon cycle.Two autonomous ocean gliders will be deployed in the Indian sector of the Antarctic Circumpolar Current, coincident with one or more semi-Lagrangian Argo floats equipped with biogeochemical sensors through the SOCCOM project. The gliders will be piloted to track the Argo float for a period of at least four months, resolving the mesoscale and submesoscale structure surrounding the float as well as variability occurring at periods shorter than the float?s 10-day sampling interval. Measurements of the upper ocean hydrographic and velocity fields will permit an analysis of hydrodynamical instabilities within the mixed layer and their impact on vertical transport and exchange across the base of the mixed layer. The glider data will also be combined with the float observations and remote sensing products to derive vertical tracer fluxes, with the goal of quantifying the partitioning of export between sinking and advective pathways. Ultimately, this project will provide observations of the physical processes that contribute to high-frequency spatial and temporal variability in Southern Ocean tracer distributions and will provide a significant step towards describing the mechanisms that influence physical and biogeochemical distributions and transport pathways in the Southern Ocean.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.