Collaborative Research: The Norrona Project: An International Collaboration for Sustained Studies of the Meridional Overturning Circulation between Denmark, the Faroes and Iceland

合作研究：诺罗纳项目：丹麦、法罗群岛和冰岛之间经向翻转环流持续研究的国际合作

• 批准号: 1061185
• 负责人: H. Thomas Rossby
• 金额: $ 60.04万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1061185&HistoricalAwards=false
• 关键词: Collaborative; Research; Norrona; Project; International

The Atlantic/meridional overturning circulation (A/MOC) has been the focus of growing attention in recent years. Much of this arises from the widespread recognition that the flow of warm, salty water to high latitudes - the Nordic Seas - helps shape the mild climate experienced across central and northern Europe and no doubt influences climate across the northern hemisphere. Thus the strength and stability of the MOC is a key parameter in the climate puzzle and therefore of great societal relevance. For this reason a project was funded in 2005 to monitor the inflow of warm water into the Nordic Seas across the Iceland-Faroe- Scotland ridge, a natural choke point through which virtually all north-flowing water must pass. What made the undertaking so attractive was the existence of an ocean-going ferry, the Norröna, from which current measurements using a vessel-mounted acoustic Doppler current meter (ADCP) could be made. The Norröna operates weekly across the Faroe-Shetland Channel and along the Iceland-Faroe ridge, the two major inflows. Some unexpected, but very serious start-up problems (bubble drawdown that blocks the acoustics) delayed the project by two years. The company that owns the ferry has gone out of its way to be helpful and substantial amounts of data are now being collected. The original four-year grant received a one-year add-on last year. This award is to continue and strengthen the project for an additional 4 years. First, although the bubble problem has been ameliorated thanks to a fairing and two vortex generators that bring clear water up from below, more can and should be done. Specifically, with the help of numerical calculations in collaboration with the ship designer in September an area free of bubbles will be sought, perhaps closer to the bow. Second, using an underwater camera will be used to verify the performance and wake structure of the vortex generators. Norröna is scheduled for dry-dock this coming winter-spring at which time the final adjustments will be implemented and should lead to substantially improved performance. The unanticipated problem of bubbles under the Norröna has been an extremely valuable learning process regarding the use and placement of ADCPs on commercial vessels. Second, thanks to the recent development of a new automated XBT launcher, heat fluxes can also be measured directly by combining the ADCP and XBT data. Third, the team will begin to report new findings about tidal signals, EKE activity, and inflows. Scientifically, the biggest surprise by far has been the substantial flow (to the south) on the western side of the Faroe-Shetland Channel such that the net flow through the channel appears to be to the south.Intellectual Merit: The Iceland-Faroe-Scotland ridge separates two large and distinctly different water mass systems (the North Atlantic and the Arctic Mediterranean). The exchange between the two is driven by both winds and buoyancy forcing over a wide range of scales. By monitoring the inflows and outflows (thanks to sustained moored ADCP programs) one can examine in considerable detail the space-time response of these fluxes to time-varying atmospheric forcing including the well-known North-Atlantic Oscillation.Broader Impacts: This team has developed extensive expertise with vessel-operated ADCPs. Repeat ADCP enables one to measure currents and transports in the ocean at high horizontal resolution and great confidence. Measuring currents directly adds to dynamical methods that use hydrography or altimetry. High horizontal resolution means resolving the most energetic scales in the ocean - often defined by the radius of deformation. We hope that wider knowledge and use of this technology will, in time, lead to an improved knowledge of ocean currents over a wide range of space and time scales.

大西洋/赤道翻转环流（A/MOC）是近年来研究的热点。这在很大程度上是因为人们普遍认识到，温暖的咸水流向高纬度地区--北欧海--有助于塑造中欧和北方的温和气候，毫无疑问，这会影响整个北方半球的气候。因此，主运行中心的强度和稳定性是气候难题中的一个关键参数，因此具有重大的社会意义。因此，2005年资助了一个项目，监测穿过冰岛-法罗-苏格兰海脊流入北欧海的暖水，这是一个天然的瓶颈，几乎所有向北流动的水都必须通过。这项工作之所以如此吸引人，是因为有一艘远洋渡船Norröna号，可以使用船上的声学多普勒流速计进行流速测量。Norröna每周穿越法罗-设得兰海峡和沿着冰岛-法罗海脊运行，这是两个主要的流入。一些意想不到的，但非常严重的启动问题（气泡下降，阻碍了声学）推迟了两年的项目。拥有渡轮的公司已经尽力提供帮助，现在正在收集大量数据。最初的四年赠款去年增加了一年。这个奖项是为了继续和加强该项目的额外4年。首先，尽管由于整流罩和两个涡流发生器将清水从下面带上来，气泡问题得到了改善，但可以而且应该做更多的工作。具体来说，在9月份与船舶设计师合作进行数值计算的帮助下，将寻找一个没有气泡的区域，可能更靠近船头。其次，使用水下摄像机将被用来验证涡流发生器的性能和尾流结构。Norröna计划在今年冬季和春季进行干船坞，届时将进行最后的调整，并将大幅提高性能。Norröna下的气泡问题是一个非常有价值的学习过程，关于ADCP在商业船舶上的使用和放置。其次，由于最近开发了一种新的自动XBT发射器，热通量也可以通过结合ADCP和XBT数据直接测量。第三，研究小组将开始报告有关潮汐信号、EKE活动和流入的新发现。科学上，迄今为止最大的惊喜是法罗群岛-设得兰海峡西侧的大量水流（向南），因此通过海峡的净流量似乎是向南的。智力上的优点：冰岛-法罗群岛-苏格兰海脊将两个大的和明显不同的水体系统（北大西洋和北极地中海）分开。两者之间的交换是由风和浮力在很大范围内驱动的。通过监测的流入和流出（由于持续停泊ADCP程序），人们可以检查在相当详细的时空响应，这些通量随时间变化的大气强迫，包括著名的北大西洋Oscillation.Broader影响：这个团队已经开发了广泛的专业知识与船舶经营的ADCP。重复ADCP使人们能够以高水平分辨率和高置信度测量海洋中的海流和输运。直接测量海流增加了使用水文学或测高学的动力学方法。高水平分辨率意味着解决海洋中最具活力的尺度-通常由变形半径定义。我们希望，对这一技术的更广泛的了解和使用将最终导致在广泛的空间和时间尺度上改进对洋流的了解。