Arctic Sea-ice Attenuation of Sea Swell, Microseism and the Prospect for using Seismology as a way to Observe Sea-ice Conditions

北极海冰对海涌的衰减、微震以及利用地震学观测海冰状况的前景

• 批准号: 2336786
• 负责人: Douglas MacAyeal
• 金额: $ 20.43万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2336786&HistoricalAwards=false
• 关键词: Arctic; Sea; ice; Attenuation; Swell

Climate models predict acceleration in Arctic Ocean sea-ice loss, particularly during summer. Uncertainty in this prediction arises, however, from difficulty observing the thickness and mechanical strength of sea ice over large parts of the Arctic Ocean using just satellite and aircraft technology. One approach to addressing this difficulty is through seismology - the study of ground vibrations - along the coastline of the Arctic Ocean. The main scientific activity of this project will be to observe special ground vibrations that are generated by or otherwise influenced by sea ice. One such signal is called “microseism”, and is a constant “thrumming” of the ground caused by waves in the ocean both near and far from the coastline. The project will use existing, virtually continuous seismic data from various stations along the northern coasts of Alaska, Canada and Greenland to detect how this microseism changes with season and from year to year. The scientific outcome to be achieved is the creation of a continuous time history of how sea-ice thickness and strength have evolved over the past several decades. In addition to the scientific goals of the research project, broader impact activity will be focused in two areas. First, the project will interface with artists in the Chicago area to develop ways in which musical expressions can be developed to convey how climate change is affecting Arctic sea-ice conditions. This science and art interaction will build on previous musical compositions that involved interpretation of seismic data coming from icebergs in Antarctica. Second, the project will seek to advance the new Climate Systems Engineering initiative of the University of Chicago by advocating for and facilitating community dialogue about the pros and cons of glacial geoengineering as a way to mitigate the effects of climate change.We propose to investigate whether microseism spectral power density observations can be used to constrain sea-ice properties such as concentration, thickness, and “strength” (the ability to attenuate flexural gravity waves generated by sea swell) in the North American sector of the Arctic Ocean (also known as the “last ice area” where the transpolar drift impinges on the North American continent and Greenland). Data to be used are from coastal seismometer stations located in Alaska, the Canadian Arctic Archipelago, and Greenland. Sea-ice data will be obtained from the U.S. National Snow and Ice Data Center. The microseism power in the 0.1-3 s period band (as in Tsai and McNamara, 2011), and possibly other frequency bands, will be related to a proxy for sea-ice strength (involving sea-ice concentration and the tendency for sea ice to absorb wind stress as indicated by sea-ice drift and surface wind data) and compare with remote sensing observations. The goal of this study is to obtain the highest possible resolution of sea-ice data empirical orthogonal functions (EOFs) from the simplest possible EOFs of the microseism data. This involves seeking data-inversion algorithms that can optimize “resolving power” by minimizing “spread” in the linear operator that connects the EOFs of microseism with sea ice. The algorithms will then be categorized by their ability to resolve aspects of sea-ice data that go beyond the simple sea-ice concentration data that is otherwise routine and easy to be constrained with satellite data. Depending on the outcome of this assessment, seismic microseism observation can potentially provide complementary information to improve sea-ice data and thus facilitate better climate-model predictions. With regard to broader impact activity, the project will provide a local artist consortium in Chicago with short segments of seismic data portraying tremor and other signals generated by sea ice. These data will be sped up to allow their frequencies to be audible, and will serve to inspire musical compositions either directly or indirectly (e.g., where musical instruments are used to mimic the seismic data). Additional broader impact activity will be undertaken to appropriately advocate for community conversations about glacial geoengineering. This advocacy will take the form of organizing Town Hall meetings for the American Geophysical Union and writing white papers to help inform the Polar Research Board of the US National Academy of Sciences.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.

气候模型预测北冰洋海冰流失加速，尤其是在夏季，但由于仅使用卫星和飞机技术难以观测北冰洋大部分地区的海冰厚度和机械强度，这一预测存在不确定性。解决这一困难的方法是通过地震学——对北冰洋海岸线的地面振动进行研究。该项目的主要科学活动将是观察由海冰产生或以其他方式影响的特殊地面振动。信号称为“微震”，是由靠近和远离海岸线的海洋波浪引起的地面持续“震动”，该项目将使用来自阿拉斯加、加拿大和加拿大北部海岸的各个站点的现有、几乎连续的地震数据。格陵兰岛探测这种微震如何随季节和逐年变化，除了科学之外，还需要创建关于过去几十年海冰厚度和强度如何演变的连续时间历史。研究项目的目标更广泛首先，该项目将与芝加哥地区的艺术家合作，开发音乐表达方式，以传达气候变化如何影响北极海冰状况。其次，该项目将通过倡导和促进有关冰川利弊的社区对话来推动芝加哥大学的新气候系统工程倡议。地球工程作为减轻气候变化影响的一种方法。我们建议研究微震谱功率密度观测是否可用于限制海冰特性，例如浓度、厚度和“强度”（减弱海洋产生的弯曲重力波的能力）膨胀）在北冰洋的北美部分（也称为跨极漂移撞击北美大陆和格陵兰岛的“最后的冰区”）所使用的数据来自位于阿拉斯加的沿海地震仪站，加拿大北极群岛和格陵兰岛的海冰数据将从美国国家冰雪数据中心获得 0.1-3 秒周期范围内的微震功率（如 Tsai 和 McNamara，2011 年），以及可能的其他频率。频带，将与海冰强度的代理相关（涉及海冰浓度和海冰吸收风应力的趋势，如海冰漂移和表面风数据所示），并与这项研究的目标是从尽可能简单的微震数据经验正交函数（EOF）中获得尽可能高的分辨率，这涉及寻找可以优化“分辨率”的数据反演算法。通过最小化连接微震 EOF 和海冰的线性算子中的“传播”，然后算法将根据其解析海冰数据方面的能力进行分类，这些数据超出了简单的海冰浓度数据。这是常规的，很容易受到卫星数据的限制，根据评估的结果，地震微震观测可以提供补充信息，以改进海冰数据，从而促进更好的气候模型预测更广泛的影响活动。 ，该项目将为芝加哥当地的艺术家联盟提供描述地震和海冰产生的其他信号的短段地震数据，这些数据将被加速以允许其频率被听到，并将直接激发音乐创作的灵感。或者间接地（例如，使用乐器来模拟地震数据）将采取其他更广泛的影响活动来适当倡导有关冰川地球工程的社区对话。这种倡导将采取为美国地球物理联盟和组织市政厅会议的形式。撰写白皮书以帮助向美国国家科学院极地研究委员会提供信息。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。