Understanding the low frequency dynamics of the throughflow from the Pacific to the Arctic

了解从太平洋到北极的通流的低频动态

• 批准号: 1740756
• 负责人: Allan Clarke
• 金额: $ 50万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-01-15 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1740756&HistoricalAwards=false
• 关键词: Understanding; low; frequency; dynamics; throughflow

The Bering Strait is a narrow ocean gap between Alaska and Russia and is the only ocean pathway between the Pacific and the Arctic. In the past, ocean transport through this region may have played a key role in climate fluctuations. In the future, disappearing Arctic ice may make the Bering Strait the Pacific gateway to an Arctic ship route between the Pacific and Atlantic. Lying at the southern end of the Bering Strait is the Bering Sea, a shallow continental shelf hosting some of the most valuable fisheries in the U.S. and huge populations of marine wildlife. Although winds on average blow southward through the Strait, the average flow of ocean currents is northward, carrying nutrients, heat, and fresh water into the Arctic. Previous work suggests that a pressure head at the southern end of the Strait drives flow to the north against the southward wind, and evidence suggests that this pressure head has increased by about 70% since 2001. The origin of year-to-year and longer-term variability of this pressure head is unknown. This project will combine existing data on sea surface height, coastal sea level, theory, and modeling to understand changes in the pressure head and the basic dynamics of the Bering Sea continental shelf. A graduate student will be supported. The Bering Strait connects the Pacific and Arctic Oceans, and serves as a conduit of nutrients, heat, and fresh water. Therefore, understanding the factors influencing that connection will help predict current and future regional ocean conditions. Analysis of satellite altimetry, coastal sea level, theory, and a model will be used to: determine the origin and dynamics of the low-frequency pressure head that drives flow through the Bering Strait into the Arctic; understand the origin and basic dynamics of the interannual sea level and flow on the wide Bering Sea shelf; and determine the low-frequency variability of volume, heat, and fresh water flux of the Alaskan Coastal Current. A wealth of along-track satellite altimeter data available from TOPEX/Poseidon and Jason1,2,3 (TPJ123) will be used to address the question of what drives the Bering Sea pressure head. Preliminary analysis suggests that a major contributor to the low-frequency Bering Strait pressure head originates on the Gulf of Alaska continental shelf. This contribution is communicated along the Gulf of Alaska coastal wave guide, through Unimak Pass in the Aleutian Arc, onto the shallow Bering Sea shelf wave guide, and then through the Bering Strait. A second factor is the interannual and lower frequency signal generated on the Bering Sea shelf.

白令海峡是阿拉斯加和俄罗斯之间的一个狭窄的海洋缺口，也是太平洋和北极之间唯一的海洋通道。过去，通过该地区的海洋运输可能在气候波动中发挥了关键作用。未来，北极冰层的消失可能会使白令海峡成为太平洋和大西洋之间北极航线的太平洋门户。位于白令海峡南端的是白令海，这是一个浅大陆架，拥有美国最有价值的一些渔业和大量的海洋野生动物。虽然风一般都是向南吹过海峡，但洋流一般都是向北，把营养物质、热量和淡水带到北极。先前的研究表明，海峡南端的一个压力头驱使水流向北，对抗南风，证据表明，自2001年以来，这个压力头增加了约70%。这种压头的年度和长期变化的来源尚不清楚。该项目将结合现有的海面高度、沿海海平面、理论和模型数据来了解压力头的变化和白令海大陆架的基本动态。研究生将获得资助。白令海峡连接太平洋和北冰洋，是营养物质、热量和淡水的输送管道。因此，了解影响这种联系的因素将有助于预测当前和未来的区域海洋状况。对卫星测高、沿海海平面、理论和模型的分析将用于：确定驱动流过白令海峡进入北极的水流的低频压头的起源和动力学；了解白令海陆架年际海平面和水流的起源和基本动态；并确定阿拉斯加海岸流的体积、热量和淡水通量的低频变化。TOPEX/Poseidon和jason1,2,3 （TPJ123）提供的大量沿轨卫星高度计数据将用于解决驱动白令海压力头的问题。初步分析表明，低频白令海峡压力头的主要来源是阿拉斯加湾大陆架。这种贡献沿着阿拉斯加湾沿海波导传播，通过阿留申弧的乌尼马克山口，进入浅白令海陆架波导，然后通过白令海峡。第二个因素是在白令海陆架上产生的年际和低频信号。