EAGER: Ocean Circulation in the Amundsen Sea Embayment over the 20th Century

EAGER：20 世纪阿蒙森海湾的海洋环流

• 批准号: 2333370
• 负责人: LuAnne Thompson
• 金额: $ 3万
• 依托单位: University of Washington
• 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: 2023-10-01 至 2025-09-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2333370&HistoricalAwards=false
• 关键词: EAGER; Ocean; Circulation; Amundsen; Sea

The glaciers in the Amundsen Sea Embayment of West Antarctica, such as Thwaites and Pine Island Glaciers, are rapidly retreating and contributing to sea level rise. There is evidence that the current stage of retreat began in the mid-20th century before the start of the observational record, making it difficult to understand the cause of glacier change. While modeling studies suggest that anthropogenic forcing starting in the early 1900s causing a trend toward stronger westerly conditions and consequently warmer ocean conditions near glaciers, new proxy-based reconstructions of winds since the early 1900s provide robust evidence that wind trends in this region were likely easterly instead of westerly. This project will leverage ocean models to address whether a 20th century easterly wind trend could lead to warmer ocean conditions near glaciers in the Amundsen Sea, improving our understanding of projections of sea level rise due to Antarctic ice mass loss.This project will generate the first data-constrained hindcast simulation of 20th century ocean conditions in the Amundsen Sea Embayment, using proxy-based atmospheric reconstructions and a high-resolution ocean model which has been validated against past observations. The project will downscale annual mean surface temperature, sea level pressure, and surface zonal wind anomalies to produce daily resolved datasets, simulating realistic ocean states by adding sub-annual variability from reanalyses to each of the reconstructed states. These downscaled paleoclimate reconstructions will provide forcing for ensembles of ocean simulations using a regional domain of the MITgcm that includes dynamic sea ice and thermodynamic ice shelf representation. Four sets of simulations are targeted, first to verify the efficacy of using downscaled proxy-reconstructed atmospheric fields as model forcing, then to investigate the causes of the anomalous westerly wind event of the 1940s, and finally to explore the impact of 20th century atmospheric trends on ocean conditions. This project will provide key new insight into the varied pathways that link rising greenhouse gas concentrations to glacier retreat in West Antarctica.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.

南极西部阿蒙森海嵌入的冰川，例如史蒂特斯和松岛冰川，正在迅速退缩并促进海平面上升。有证据表明，当前的撤退阶段始于观测记录开始之前的20世纪中叶，因此很难理解冰川变化的原因。虽然建模研究表明，人为强迫从1900年代开始引起趋势趋于较强的西风条件，并因此在冰川附近的海洋状况更温暖，但自1900年代初以来，新的基于代理的风重建了风，提供了强有力的证据，表明该地区的风趋势很可能是西部的，而不是西风。该项目将利用海洋模型来解决20世纪的狂风趋势是否会导致阿蒙森海冰川附近的海洋状况更温暖过去的观察。该项目将降低年平均表面温度，海平面压力和表面层状风异常，以产生每日解决的数据集，从而通过增加重新构造到每个重建状态的次年变异性来模拟现实的海洋状态。这些降尺度的古气候重建将使用MITGCM的区域域为海洋模拟的集合提供强迫，该区域包括动态海冰和热力学冰架代表。针对四组模拟，首先是验证使用缩小的代理重建大气场作为模型强迫的功效，然后研究1940年代异常的西风事件的原因，最后探索20世纪大气趋势对海洋条件的影响。该项目将为各种途径提供关键的新见解，这些途径将上升的温室气体浓度与西南极洲西部的冰川静修联系起来。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响来评估的评估。