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

在过去的几十年里，随着地球气候的变暖，我们的星球经历了许多变化。没有哪个地方的变化比北冰洋更明显，发生得也更快。浮冰正在融化，海水正在变暖，风暴变得更强更频繁，基本的循环模式正在改变。我们的项目关注通过白令海峡进入北冰洋的太平洋水的命运。太平洋的水在北极西部生态系统中起着至关重要的作用。在冬季，流入的冷水为食物链底部的浮游植物提供了食物。夏季，温暖的海水融化了浮冰，为北冰洋提供了淡水。当水穿过白令海峡以北的楚科奇海后，其中一些形成了一条狭窄的洋流，沿着波弗特海的边缘向东流动。作为我们项目的一部分，我们将继续在洋流中心维持一个系泊点，以测量其物理和生物特性。自2002年以来，该系泊已经部署（有一些空白），在此期间，它已经测量了需要在不断发展的北极系统背景下放置的惊人变化。此外，我们在服务系泊时，亦会对现时及邻近水域进行船载调查，以更大规模地观察太平洋水域的命运。过去的数据已被海洋学界广泛用于观测和模拟研究，并被列入年度北极报告卡。该项目将支持一名研究生。监测系泊位于西经152度，靠近波弗特海大陆架断裂，位于AK州Pt. Barrow下游约150公里处。它将从2018年秋季部署到2022年秋季（分两期，为期两年）。这将把这个位置的时间序列延长到17年。系泊系统使用两个声学多普勒电流分析器（ADCPs）记录水柱和浮冰的速度，并使用沿电缆间隔的一系列传感器测量温度、盐度和压力。叶绿素荧光和硝酸盐将在35米（系泊的顶部浮子）处测量，而位于系泊底部附近的被动声波记录仪将记录海洋哺乳动物的叫声。浮游动物浓度将使用ADCP反向散射数据进行估计。除其他事项外，这将使我们能够确定有多少水、热量、营养物质、叶绿素和淡水被洋流输送，重要的是，评估北冰洋内部和边界水域之间发生了多少交换。上升流在波弗特斜坡的所有季节都有发生，而且随着气候变暖，上升流似乎在增加。系泊非常适合量化上升流，以及任何发生的下升流。船上取样将包括一些分布式生物观测站样带的职业，这将有助于长期研究。

As Earth's climate has warmed over the past few decades, our planet has experienced many changes. Nowhere have the changes been more pronounced, nor happened as quickly, as in the Arctic Ocean. Pack-ice is melting, water is warming, storms are becoming stronger and more frequent, and basic circulation patterns are being altered. Our project focuses on the fate of the Pacific water that enters the Arctic Ocean through the Bering Strait. Pacific water plays a critical role in the western Arctic ecosystem. In wintertime, the cold inflowing water provides food for phytoplankton at the base of the food chain. In summertime, the warm water melts pack ice and provides freshwater to the Arctic Ocean. After the water crosses the Chukchi Sea, north of Bering Strait, some of it forms a narrow current that flows eastward along the edge of the Beaufort Sea. As part of our project we will continue to maintain a mooring positioned in the center of the current to measure its physical and biological properties. The mooring has been deployed (with a few gaps) since 2002, and during this time it has measured striking changes that need to be placed in the context of the evolving Arctic system. In addition, we will carry out shipboard surveys of the current and adjacent waters when we service the mooring, to provide a larger-scale view of the fate of the Pacific water. Past data have been widely used by the oceanographic community - in both observational and modeling studies -and are included in the annual Arctic Report Card. One graduate student will be supported on the project. The monitoring mooring is situated at 152 degrees W near the Beaufort Sea shelfbreak, roughly 150 km downstream of Pt. Barrow, AK. It will be deployed from fall 2018 to fall 2022 (in two 2-year installments). This will extend the timeseries at this location to 17 years. The mooring records the velocity of the water column and pack ice using two acoustic Doppler current profilers (ADCPs), and measures temperature, salinity, and pressure using a series of sensors spaced along the wire. Chlorophyll fluorescence and nitrate will be measured at 35 m (at the top float of the mooring), and a passive acoustic recorder situated near the base of the mooring will record marine mammal calls. Zooplankton concentration will be estimated using the ADCP backscatter data. Among other things, this will allow us to determine how much water, heat, nutrients, chlorophyll, and freshwater are transported by the current, and, importantly, assess how much exchange occurs between the interior of the Arctic Ocean and the boundary waters. Upwelling occurs during all seasons along the Beaufort slope, and it appears to be increasing as the climate warms. The mooring is ideally suited to quantify the upwelling, as well as any downwelling that occurs. The shipboard sampling will include occupations of some of the Distributed Biological Observatory transects, which will contribute to that long-term study.