Monitoring the Western Arctic Boundary Current in a Warming Climate: Atmospheric Forcing and Oceanographic Response

由于气候变化，北冰洋正在经历深刻的变化。冰盖正在融化，水正在变暖，风暴变得更加强烈和频繁，基本的环流模式正在改变。这个项目关注的是通过白令海峡进入北冰洋的太平洋水的命运。白令海峡是美国和俄罗斯之间的狭窄通道。太平洋水在北极西部生态系统中起着至关重要的作用。在冬季，冷水会提供营养物质，刺激食物链底部的浮游植物生长。在夏季，温水融化积冰，为北冰洋提供淡水。来自太平洋的水穿过白令海峡以北的楚科奇海后，其中一些形成了一股沿着邻近的波弗特海边缘向东流动的水流。作为该项目的一部分，将在这股海流的中心保持一个系泊设备，以测量其物理和生物特性。自2002年以来，该系泊设备一直在部署(有一些空白)。通过将测量延长四年，这提供了记录和了解北极系统的这一重要部分如何应对剧烈环境变化的机会--包括不断变化的大气条件和白令海峡不断演变的水源。科学界将继续广泛使用系泊设备获得的数据，以及在维护系泊设备时收集的船上测量数据，用于观测和建模研究。一名研究生将得到该项目的支持，在其中一次探险期间将进行社区外联，以吸引公众参与。怡安监测系泊设施位于152°W处，靠近波弗特海防御工事，位于巴罗峡谷下游约150公里处--巴罗峡谷是楚科奇海的主要太平洋海水流出点。它将从2022年秋季部署到2026年秋季，这将把时间序列延长到21年。系泊设备测量水柱的速度、浮冰的厚度和速度，以及整个水柱的温度、盐度和压力。在系泊的顶部测量了叶绿素荧光和硝酸盐，被动声记录器记录了海洋哺乳动物的叫声。浮游动物密度是利用ADCP后向散射数据估计的。总而言之，这些信息可以确定洋流输送了多少水、热量、营养物质、叶绿素和淡水，并评估了北冰洋内部和边界水域之间发生了多少交换。这包括一年四季发生在波弗特坡上的风力驱动的上升流和下降流，而且随着气候变暖，这种上升流和下降流似乎还在增加。在为系泊服务的两年期巡航期间，对边界水流系统进行了水文/流速调查，以获得系泊时间序列的大范围背景。船上抽样包括一些分布式生物观测站样带的职业。与过去一样，两年一度的巡航将为一系列跨学科项目提供一个平台。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Due to the changing climate, the Arctic Ocean is experiencing profound changes. Pack-ice is melting, water is warming, storms are becoming stronger and more frequent, and basic circulation patterns are being altered. This project focuses on the fate of the Pacific water that enters the Arctic Ocean through the Bering Strait, the narrow passage between the US and Russia. Pacific water plays a critical role in the western Arctic ecosystem. In wintertime the cold inflowing water provides nutrients that spur the growth of phytoplankton at the base of the food chain. In summertime, the warm water melts pack ice and provides fresh water to the Arctic Ocean. After the Pacific-origin water crosses the Chukchi Sea, north of Bering Strait, some of it forms a current that flows eastward along the edge of the adjacent Beaufort Sea. As part of the project, a mooring will be maintained in the center of this current to measure its physical and biological properties. The mooring has been deployed (with a few gaps) since 2002. By extending the measurements for another four years, this provides the chance to document and understand how this important part of the Arctic system is responding to the drastic environmental changes – including the varying atmospheric conditions and evolving source waters from Bering Strait. The data obtained by the mooring, along with the shipboard measurements collected when the mooring is serviced, will continue to be widely used by the scientific community in both observational and modeling studies. A graduate student will be supported by the project, and community outreach will be undertaken during one of the expeditions in order to engage the public. The AON monitoring mooring is situated at 152°W near the Beaufort Sea shelfbreak, roughly 150 km downstream of Barrow Canyon – the main Pacific water outflow point from the Chukchi Sea. It will be deployed from fall 2022 to fall 2026, which will extend the timeseries to 21 years. The mooring measures the velocity of the water column, the thickness and velocity of the pack ice, and the temperature, salinity, and pressure throughout the water column. Chlorophyll fluorescence and nitrate are measured at the top of the mooring, and a passive acoustic recorder documents marine mammal calls. Zooplankton concentration is estimated using the ADCP backscatter data. Collectively, this information enables determination of how much water, heat, nutrients, chlorophyll, and freshwater are transported by the current, and assessment of how much exchange occurs between the interior of the Arctic Ocean and the boundary waters. This includes wind-driven upwelling and downwelling that take place throughout the year along the Beaufort slope, and appear to be increasing as the climate warms. During the biennial cruises to service the mooring, a hydrographic/velocity survey of the boundary current system is carried out to obtain a large-scale context for the mooring timeseries. The shipboard sampling includes occupations of some of the Distributed Biological Observatory transects. As in the past, the biennial cruises will provide a platform for a broad array of interdisciplinary projects.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.