Recent Changes of Sea Level and Circulation around the Grand Banks: Local Dynamics and Broader Connections

海平面和大浅滩周围环流的近期变化：局部动态和更广泛的联系

• 批准号: 2241407
• 负责人: Ke Chen
• 金额: $ 79.56万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2241407&HistoricalAwards=false
• 关键词: Recent; Changes; Sea; Level; Circulation

This project will examine large anomalous sea surface height (SSH) seen in satellite altimetry between the U.S. northeast coast and the Gulf Stream, using analyses of observations, data-model results (reanalysis products), realistic and idealized model simulations, and a simplified 2-layer process model. For example, the sea-surface height seen over the Grand Banks was about 7-8 cm higher in 2008-2018 than in 1993-2007. But still unknown are its causes and potential effects on the regional water motions, including the continuity of the Labrador Current and shelf and slope currents. Sea-level changes have broad impacts on coastal habitats, coastal hazards, and wetland ecological systems. The identified sea-level anomaly is accompanied by a rapid rising of water temperature on the shelves, which is known to have adverse impacts on the fishing industry and aquaculture. The project would: 1) investigate forcing mechanisms of this large sea level anomaly in the shelf-slope region; 2) examine how sea-level change on the continental shelf is connected to that in the open ocean; and 3) investigate whether and how the sea level changes on the Newfoundland and Scotian shelves may have affected coastal circulations and sea level off the Northeast US. Project PIs will keep NOAA Northeast Fishery Sciences Center, the Commercial Fisheries Research Foundation, and the wider fishing industry communities informed of relevant results, and engage in a range of outreach and educational activities, including efforts to engage underrepresented minorities. The proposed work is aligned with US CLIVAR Science Plan Addendum "Research Challenge on Climate at the Coasts," and is expected to generate broad interest from both the scientific community and the general public. The project identifies seven hypotheses covering the three areas of interest identified above. For the first, concerning forcing mechanisms: H1A - changes in western boundary currents related to a weakening AMOC or changing wind-driven gyres in subtropical and subpolar basins contribute to the observed SSH anomaly; H1B - a change in surface wind-stress curl forces the observed SSH anomaly; H1C – an increase in the number of warm core rings contribute to both mass and steric heat fluxes associated with increased WCR activity contribute to the observed SSH changes. For the second, concerning the cross-shelf connection of SSH variability: H2A - the cross-shelf transport in the bottom Ekman layer plays an important role in the cross-shelf SSH connectivity; H2B - the surface wind-driven Ekman layer plays an important role as well; H2C - eddy PV flux increased and contributed to enhanced cross-shelf connectivity in SSH anomaly. For the third, concerning connections between Grand Banks and Cape Hatteras: H3A - the SSH anomaly on the Newfoundland and Scotian shelves have impacted the along-shelf flows considerably, likely enhancing the equatorward flow from Newfoundland to Cape Hatteras. Both modeling and data analysis will be used to address these hypotheses. The fairly wide range of data used will include: gridded SSH altimetry, global ocean and atmosphere reanalyses, observation-based heat fluxes, evaporation and wind stress, and local multi-year in-situ data from the OOI Pioneer Array and the Oleander line. Modeling will utilize a new Northwest Atlantic Regional Circulation Model, which encompasses the entire shelf and slope region of the Labrador Sea and the Middle Atlantic Bight with a submesoscale-permitting horizontal resolution of 2-km and 40 vertical layers. A two-layer model will be used in parallel with the realistic regional circulation models for process modelling, to help guide analyses and interpretations of data analyses and NWA model simulations, as to help isolate key processes and mechanisms. This model uses realistic bathymetry and forcing and resolves the barotropic and the 1st baroclinic modes. The study will lead to a better understanding of how dynamical processes interact in a rapidly changing climate system, how coastal oceans respond to climate-induced changes in the open ocean, and inform predictability of the Northeast US shelf circulation.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.

该项目将利用观测分析、数据模型结果（再分析产品）、现实和理想化模型模拟以及简化的 2例如，2008-2018 年大浅滩上空的海面高度比 1993-2007 年高出约 7-8 厘米。其原因以及对区域水运动的潜在影响尚不清楚，包括拉布拉多洋流和陆架和斜坡洋流的连续性，海平面变化对沿海栖息地、沿海灾害和湿地生态系统产生广泛影响。异常现象伴随着陆架水温的快速上升，已知这会对渔业和水产养殖产生不利影响。该项目将：1）调查陆架斜坡区域这种大规模海平面异常的强迫机制； 2）研究大陆架海平面变化与公海海平面变化的关系；3) 调查纽芬兰和斯科舍大陆架海平面变化是否以及如何影响美国东北部项目的沿海环流和海平面。 PI 将向 NOAA 东北渔业科学中心、商业渔业研究基金会和更广泛的渔业社区通报相关结果，并参与一系列外展和教育活动，包括努力让代表性不足的少数群体参与到拟议的工作中。我们CLIVAR 科学计划附录“海岸气候研究挑战”预计将引起科学界和公众的广泛兴趣。该项目确定了涵盖上述三个感兴趣领域的七个假设。强迫机制：H1A - 与亚热带和副极地盆地中 AMOC 减弱或风驱动环流变化相关的西部边界流变化导致了观测到的 SSH 异常；旋度迫使观察到的 SSH 异常；H1C – 与 WCR 活动增加相关的质量和空间热通量的增加有助于观察到的 SSH 变化。可变性：H2A - 底部 Ekman 层的跨陆架传输在跨陆架 SSH 连接中发挥重要作用； H2B - 表面风驱动的 Ekman 层也发挥重要作用； - 涡流光伏通量增加，并有助于增强 SSH 异常中的跨大陆架连通性。 第三，关于大浅滩和哈特拉斯角之间的连接：H3A - 纽芬兰和斯科舍陆架上的 SSH 异常对沿陆架流量产生了相当大的影响，可能会增强从纽芬兰到哈特拉斯角的赤道流量。将使用建模和数据分析来解决这些假设。所使用的数据范围相当广泛，包括：网格 SSH。高度测量、全球海洋和大气再分析、基于观测的热通量、蒸发和风应力以及来自 OOI Pioneer Array 和 Oleander 线的当地多年现场数据将利用新的西北大西洋区域环流模型。涵盖拉布拉多海和中大西洋湾的整个陆架和斜坡区域，亚中尺度水平分辨率为 2 公里，垂直分辨率为 40 个 A 两层。该模型将与现实的区域环流模型并行用于过程建模，以帮助指导数据分析和NWA模型模拟的分析和解释，以帮助隔离关键过程和机制。该模型使用现实的测深和强迫并解决正压问题。该研究将有助于更好地了解动态过程如何在快速变化的气候系统中相互作用，沿海海洋如何响应气候引起的公海变化，并为美国东北部陆架环流的可预测性提供信息。这授予 NSF 的法定使命，并通过评估反映使用基金会的智力优点和更广泛的影响审查标准，被认为值得支持。