Iceland-Scotland Ridge Exchange Flow Seaglider Surveys

该项目的科学目标是记录和了解冰岛-苏格兰海脊上北欧海洋大西洋流入和深溢流的季节和年际变化，该区域形成经向翻转环流深分支，重要的浅分支集中。目前，对冰岛-苏格兰海脊交换的最可靠估计是基于不同空间和时间分辨率、不同技术以及有争议的参考温度和盐度的海流和水文采样。该区域环流的详细空间结构、季节和年际变化尚待解决。在全球气候变化的背景下，经向翻转环流的减弱被广泛预测。气候模型对这些输送非常敏感，解决这些输送对于理解海洋气候的过去、现在和未来的可变性至关重要。新的观测(主要是物理观测)将被用来推断卷吸带的位置，并按水团类型量化输送，用于改进气候模型，其在全球变暖下的预测对高纬度海洋的物理很敏感。依赖于这些环流和水团的该地区强烈的生物生产力也将被光学描绘出来。将使用远程自主水下航行器(Seagliders)收集全深度水文图，并同时估计冰岛-法罗海脊和法罗-设得兰海峡北面浅流和南面密集溢流的绝对地转速度剖面。据认为，这一区域约占大西洋向极地输送的90%，约占向赤道方向深水输送的一半(其余部分通过丹麦海峡)。海滑仪将收集温度、盐度、溶解氧、荧光和光学后向散射以及深度平均水平速度的高分辨率部分。这些剖面将解决季节变化，并开始发现显著的年际变化。一艘海豹滑翔机将每周穿越法罗-设得兰海峡，而两架海豹滑翔机将勘测冰岛-法罗海脊的西南侧，每月重复约1000公里的航迹。这些车辆将在为期4个月的任务中连续部署3年，使用法罗群岛的船只进行发射和回收。该项目计划在三年内收集约30,000条全深度(500-1000米)剖面，水平分辨率为3-6公里，跨越近60,000公里的轨道，所有这些剖面都通过卫星近乎实时地传送。实时指挥Seagliders将允许绘制精细水团和锋面特征的地图。这些观测将与正在进行的项目的系泊/船舶观测相结合，并与挪威、冰岛和法罗群岛的科学家合作进行。这项研究是对美国CLIVAR(气候可变性和可预测性)计划的贡献。全球海洋颠覆环流的最基本动态平衡正在辩论中。全球变化可能会改变颠覆的循环，并随之而来的是全球气候和生态系统。高分辨率的气候观测具有全新的平台，并及时得到支持，可以指导在政策和规划更广泛的影响方面越来越依赖的数值气候模型。除了物理科学，这项工作还涉及地球上生物生产力最高的地点之一的生态系统，以及一个从大气中大量吸收碳的地区。这项工作将在生物生产力异常高的地区提供高分辨率的生物光学剖面和切片。该区域渔业和自然海洋学的相互依存性非常强，因为初级生产力与捕获浮游植物的浮力低盐度层有关。这项研究有助于我们的环境研究本科教学，把科学的方法和成果摆在青年学生面前，他们是环境的受益者和保管者。

The scientific goal of the project is to document and understand the seasonal and interannual variability of both Atlantic inflow to and deep overflow from the Nordic Seas over the Iceland-Scotland Ridge, a region where meridional overturning circulation deep branches are formed and important shallow branches concentrate. Currently, the most reliable estimates of exchange across the Iceland-Scotland Ridge are based on currents and hydrography sampled with different spatial and temporal resolution, with different techniques, and with debatable values for reference temperature and salinity. The detailed spatial structure and seasonal and interannual variability of circulation in this region has yet to be resolved. In the context of global climate change, decline of the meridional overturning circulation is widely predicted. Climate models are very sensitive to these transports and resolution of them is crucial to understanding ocean climate variability, past, present and future. New observations (primarily physical) will be used to infer entrainment sites and to quantify transports by water mass type for use in improving climate models, whose predictions under global warming are sensitive to the physics of the high-latitude ocean. The intense biological productivity of the region, which depends on these circulations and water masses, will also be profiled optically. Long-range autonomous underwater vehicles (Seagliders) will be used to collect full-depth hydrography and estimate absolute geostrophic velocity sections simultaneously of both shallow northward inflow and dense southward overflow across the Iceland-Faroe Ridge and the Faroe-Shetland Channel. This domain is thought to account for about 90% of the Atlantic transport poleward and about half of the deep water transport equatorward (the remaining portion passes through the Denmark Strait). Seagliders will collect high-resolution sections of temperature, salinity, dissolved oxygen, fluorescence and optical backscatter as well as depth-averaged horizontal velocity. The sections will resolve seasonal variations and begin to detect prominent interannual variations. One Seaglider will traverse the Faroe-Shetland Channel weekly while a pair of Seagliders will survey the southwestern flank of the Iceland-Faroe Ridge, repeating a ~1000 km track monthly. The vehicles will be deployed in 4-month missions continuously for 3 years, using vessels in the Faroe Islands for launch and recovery. The plan is to collect about 30,000 full-depth (500-1000m) profiles with 3-6 km horizontal resolution across nearly 60,000 km of track during the three year project, all delivered in near real-time via satellite. Real-time command of the Seagliders will allow mapping of finescale water masses and frontal features. The observations will be carried out in conjunction with mooring/ship observations of on-going projects, and with Norwegian, Icelandic and Faroese collaborating scientists The study is a contribution to the U.S. CLIVAR (CLImate VARiability and predictability) program..Intellectual Merit. The most basic dynamic balances of the global overturning circulation of the oceans are under debate. Global change may alter the overturning circulation and with it, global climate and ecosystems. High resolution climate observations with radically new platforms, sustained in time, can guide the numerical climate models which are increasingly relied upon in matters of policy and planning Broader Impacts. Beyond physical science, this work relates to ecosystems in one of the most biologically productive sites on Earth, and a region of strong uptake of carbon from the atmosphere. The work will provide bio-optical profiles and sections at high resolution in regions of unusually high biological productivity. The interdependence of fisheries and physical oceanography in this region is extremely strong, as primary productivity is associated with buoyant, low-salinity layers which trap phytoplankton. The research contributes to our undergraduate teaching in environmental studies, in which the methods and results of science are put before young students who are the beneficiaries and custodians of the environment.