BERING STRAIT 2022-2026: Quantifying status and change in Pacific-to-Arctic physical/biogeochemical oceanic fluxes, a central part of the Arctic Observing Network

约50米深，85公里宽的白令海峡是连接太平洋和北冰洋的唯一通道。通过该海峡的向北流动是海洋热量、淡水和北极营养物质的主要来源，影响着大约一半北冰洋的200米以上水域。这既提供了分层的上层海洋层，保护海冰免受更深和更温暖的大西洋原水的影响，也提供了为北极生态系统提供燃料的主要营养来源。通过海峡向北携带的海洋热量是北极西部海冰融化的触发因素，也是楚科奇海海冰消退日期的最佳预测指标，楚科奇海是海峡以北的一个高产浅海。洋流的新鲜程度可以影响远至大西洋的海洋环流。为了了解和量化北冰洋和阿拉斯加北冰洋的气候和生态系统是如何变化的，以及这些变化与全球其他地区的关系，需要通过观测来量化白令海峡水流的变化特性。从1990年开始对海峡进行全年海洋测量（从系泊处，即系泊在海底的仪器），结果显示水流的强度和温度都在增加，在冬季急剧变新鲜。这些变化被认为对北极及其他地区有重大影响。此外，卫星研究表明，北极食物链底部的营养物质大量增加，这表明从太平洋经过该海峡的营养物质通量增加。然而，到目前为止，还没有对白令海峡营养物质流动的全年或年际测量来验证这一观点。由于系泊仍然是测量白令海峡季节性和年际变化的唯一可行方法，该项目支持：四年的系泊，测量物理特性，如流量，温度，盐度，海冰；生物地球化学性质，包括营养成分和生物活性测量；以及相应的分析和推广工作。后者包括向科学界、公众和工业界提供数据产品和结果，以及将白令海峡和北极科学带给普通公众、大学生和学校，包括白令海峡社区以及华盛顿州西雅图市以西班牙裔/拉丁裔为主的公立学校。从2022年9月到2026年9月，白令海峡地区的美国水域将部署三个全年系泊，并提供年度船舶服务，并在白令海峡和楚科奇海南部进行水文调查。每小时的系泊测量将用于计算水的性质，以及进入北极的热量、淡水和硝酸盐的通量。这些现场测量数据将与卫星数据、数值天气预报模式数据和经过验证的北极模式结果相结合，研究通流变化的原因，并了解和量化楚科奇海的变化，从而更好地估计白令海峡通流直接对北冰洋的强迫。该项目旨在获得白令海峡第一次全年硝酸盐的测量数据，硝酸盐是该地区关键的限制性营养物质，并通过扩展北冰洋最长的原位物理仪器记录，对这个关键的北极门户进行几十年的变化测量。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The ~50m deep, 85km wide Bering Strait is the only connection between the Pacific and Arctic Oceans. The generally northward flow through the strait is a key source of oceanic heat, freshwater, and nutrients for the Arctic, influencing the upper ~200m of roughly half of the Arctic Ocean. This provides both a stratified upper ocean layer, which protects sea-ice from deeper and warmer Atlantic origin waters, and a major source of nutrients which fuel Arctic ecosystems. Oceanic heat carried northward through the strait acts as a trigger for western Arctic sea-ice melt and is the best predictor of sea-ice retreat date in the Chukchi Sea, the highly productive, shallow sea immediately north of the strait. The freshness of the flow may influence ocean circulation as far away as the Atlantic Ocean. To understand and quantify how the climate and ecosystems of the Arctic Ocean and the Alaskan Arctic seas are changing, and how those changes relate to the rest of the globe, observations are needed to quantify the changing properties of the flow through the Bering Strait. Year-round oceanographic measurements in the strait (from moorings, i.e., instruments moored to the sea-floor) started in 1990 and show the flow is increasing in strength and temperature, and freshening dramatically in winter. These changes are believed to have significant effects on the Arctic and beyond. Additionally, satellite studies, which are indicating large increases at the base of the Arctic food chain, suggest an increased nutrient flux from the Pacific Ocean through the strait. However, to date, no year-round or interannual measurements of nutrient flow through the Bering Strait exist to test this idea. Since moorings are still the only viable way of measuring seasonal and interannual change in the Bering Strait, this project supports: four years of moorings, measuring physical properties such as flow, temperature, salinity, sea-ice; biogeochemical properties including nutrient content and measures of biological activity; and accompanying analysis and outreach efforts. The latter include making data products and results available to science, public, and industry communities as well as bringing Bering Strait and Arctic science to the general public, university students, and schools, including Bering Strait communities and public and Hispanic/Latino-dominated schools in Seattle WA.From September 2022 to September 2026, three year-round moorings will be deployed in the US waters of the Bering Strait region, supported by annual ship-based servicing, and accompanying hydrographic surveys in the Bering Strait and southern Chukchi Sea. Hourly mooring measurements will be used to compute water properties, and fluxes of heat, freshwater, and nitrate into the Arctic. These in situ measurements will be combined with satellite data, numerical weather prediction model data, and verified Arctic model results to investigate causes of change in the throughflow, and to understand and quantify transformations in the Chukchi Sea, thus giving a better estimation of the forcings of the Bering Strait throughflow directly on the Arctic Ocean. The project aims to obtain the Bering Strait’s first year-round measurements of nitrate, the key limiting nutrient of the region, and, by extending the longest in situ physical instrument record from the Arctic Ocean, give a multidecadal measure of change in this key Arctic gateway.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.