Collaborative Research: Ideas Lab: BLUES: Boundary Layer Under-ice Environmental Sensing

全球气候变化正在促使各种形式的冰从地球表面融化，导致全球海平面上升。虽然全世界都有冰融化的证据，例如海冰面积减少、极地地区冰架消失以及湖冰年覆盖面积减少，但由于实地数据有限和对冰厚度的测量相对粗糙，冰融化率的量化工作很差。通过在冰中传播声学信号进行的冰厚测量的分辨率随着衰减特性和总冰厚的变化而降低。新的声学超材料将用于这个想法实验室：推进水下科学的工程技术（ETAUS）项目，以开发一种变革性的技术工具，可以提供对冰厚度的长距离，高分辨率测量，并提供一种新的机制来成像冰的内部结构。这些高分辨率观测将用于通过观察随时间的变化来完善对冰融化的全球估计。在对声学信号衰减特性可变的天然湖冰进行验证之前，将在实验室环境中进行初步测试和开发。在每个阶段，开发和实验演示将由数值模拟指导。这一开发的仪器将在科学上了解从北极到南极的冰冻圈内所有形式的冰方面具有变革性意义。虽然极地地区处于气候变化的前沿，但它们也是地球上最难进入的地区，公众很难参与其中。为此，将在塔霍环境研究中心教育和外联小组的帮助下编写新的教育材料，用于帮助扩大公众对湖泊科学和工程的参与。在冰下科学界的所有学科中，一个关键的科学需求是准确地测量冰的积冰和融化速率。水界面，然后使用这些信息来生成更好的冰下水循环和混合模型。然而，现有技术受到其成像能力、测量分辨率和庞大尺寸的限制，这阻碍了它们在科学发现中的应用。为了解决这些局限性，本项目将开发一种新的超材料增强声相控阵（MEAPA）系统，并探索该系统的应用，以高分辨率估计冰融化。将研究梯度折射率声学超材料，以提供改进的聚焦、波束转向和准直特性，从而在较薄的冰中实现高分辨率成像（亚波长分辨率），并进一步增强MEAPA系统在较厚冰中的探测范围。开发的MEAPA系统将在实验室和现场环境中进行表征和验证。然后，它将被用来更好地参数化底部粗糙度，数据将耦合到三维水动力学模型中的湖冰边界层动力学观测。将该仪器的工程开发与极地冰界的科学需求相结合，将为极地地区的次网格环流模型（GCM）提供信息。最终，该系统将使我们能够更好地预测冰的增长和融化与准确的模型，并更好地量化质量的增益和损失从湖冰到冰架在Antarctica.This award reflects NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准.

Global climate change is driving all forms of ice to melt from the Earth’s surface and contribute to global sea-level rise. While evidence of ice melt is worldwide, such as decreasing sea-ice extent, loss of ice shelves in polar regions and a reduction in annual lake-ice coverage, ice melt rates are poorly quantified, resulting from limited field data and relatively coarse measurements of ice thickness. Ice thickness measurements, made by propagating acoustic signals through the ice, decrease in resolution as a function of the attenuation properties and overall ice thickness. Novel acoustic metamaterials will be used in this Ideas Lab: Engineering Technologies to Advance Underwater Sciences (ETAUS) project to develop a transformative technology tool that can provide long-range, high-resolution measurements of ice thickness and provide a new mechanism to image the internal structure of the ice. These high-resolution observations will be used to refine global estimates of ice melt by looking at changes through time. Initial testing and development will be conducted in a laboratory setting before validation on natural lake ice that is variable in its acoustic signal attenuation properties. In every phase, the development and experimental demonstration will be guided by numerical modeling. This developed instrument will be transformative in terms of scientific understanding of all forms of ice within the cryosphere from the Arctic to the Antarctic. While polar regions are at the forefront of climate change, they are also some of the least accessible areas of the planet and make it difficult for the public to engage. To this end, new educational materials will be developed with the help of the education and outreach team at the Tahoe Environmental Research Center, which will be used to help broaden public participation in lake science and engineering.To effectively monitor and predict climate-related changes, a key scientific need in all disciplines of the under-ice scientific community is to accurately measure ice accretion and melt rates at the ice/water interface, then use that information to generate better models of under-ice water circulation and mixing. However, existing technologies are limited by their imaging capabilities, measurement resolutions, and bulky sizes, which hinder their applications for scientific discovery. To address these limitations, this project will develop a new metamaterial-enhanced acoustic phased array (MEAPA) system and to explore the application of this system for high-resolution estimations of ice melt. Graded index acoustic metamaterials will be investigated to provide improved focusing, beam steering, and collimation properties to achieve high-resolution imaging (subwavelength resolution) in thinner ice and to further enhance the detection range of the MEAPA system in thicker ice. The developed MEAPA system will be characterized and validated in laboratory and field settings. Then, it will be used to better parameterize bottom roughness, and the data will be coupled to boundary layer dynamics observations of lake ice in three-dimensional hydrodynamic models. Coupling the engineering development of this instrument with the scientific need of the polar ice community will inform subgrid processes of General Circulation Models (GCM) for polar regions. Ultimately, this system will enable us to better predict ice growth and melt with accurate models and to better quantify mass gain and loss from lake ice to ice shelves in 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.