Measuring the melt rate of glacier ice with underwater noise

提出了一种新的测量冰川冰融化速率的方法，该方法利用冰融化时气泡破裂产生的水下噪声。这项工作的动机在于融化在极地地区的冰-海洋相互作用中发挥的关键作用，以及随之而来的海平面上升，以及目前在直接或间接测量冰融化时遇到的巨大困难。冰川冰含有气泡，被落下的雪困住，随着时间的推移，由于覆盖冰的积累而增加的压力而被压缩。当冰川前端的冰融化时，气泡中的气体爆炸性释放，向水中辐射出强烈的声音脉冲，使冰川海湾和峡湾成为地球上最嘈杂的地方。由于气泡释放速率随着冰融化速率的增加而增加，因此应该可以使用气泡产生的噪声来量化融化速率。该项目将通过为博士后助理的培训提供支持，为STEM劳动力发展做出贡献。 它将继续与波兰和新加坡的同事进行现有的国际合作。 外联将通过在桦树水族馆举办一个创新的、计划中的展览来进行？远征地球！ 最后，一个成功的项目将是为观测冰川-海洋相互作用而开发具有潜在变革性的遥感技术的第一步，该项目将利用双管齐下的努力，着手开发观测海洋终止冰川融化速度的声学方法：用水听器阵列直接测量终点上噪声源的垂直分布，并记录大量街区的熔化噪声。物理性质已被测量的冰。 现场测量的分析和反演技术的初步发展的方法是基于早期的工作建模噪声辐射的气泡在破碎波。 数据将收集在一小群冰川终止成一个单一的峡湾，以解决以下问题，目前限制了声学数据的有用性：1。在随机选择的冰川冰样本中，气泡的密度、平均内压和半径分布是什么？这些分布与冰密度（冰深度的代理）有什么关系？2.气泡源谱如何随静水压力、气泡半径、内部气压和水温变化？3.什么是冰川之间的气泡属性的分布的变化，什么是冰的属性测量所需的最小集合，从一个到多个冰川推广的方法？也就是说，必须在逐个冰川的基础上测量哪些变量，才能使这项技术在许多冰川上发挥作用？

The development of a novel measurement of glacier ice melt rate is proposed using the underwater noise generated by bubbles bursting from the ice as it melts. The motivation for this work lies in the critical role melting plays in ice-ocean interactions in polar regions, and consequent sea level rise, combined with the great difficulty currently encountered when making direct or indirect measurements of ice melting. Glacier ice contains bubbles of air, trapped by falling snow and compressed over time by increasing pressure due to the accumulation of overlying ice. The explosive release of gas trapped within the bubbles as ice melts at the front of the glacier radiates an intense pulse of sound into the water, making glacial bays and fjords some of the noisiest places on the planet. Because bubble release rate increases with increasing ice melt rate, it should be possible to use bubble-generated noise to quantify melt rate. This project will contribute to STEM workforce development by providing support for the training of a post-doctoral associate. It will continue existing international collaborations with colleagues in Poland and Singapore. Outreach will occur through contributions to an innovative, planned exhibit at the Birch Aquarium ? Expedition Earth! Finally, a successful project will be an initial step in the development of a potentially transformative remote sensing technique for observing glacier-ocean interaction.This project will utilize a two-pronged effort to initiate development of an acoustic methodology for observing the melt rate of marine-terminating glaciers: direct measurement of the vertical distribution of noise sources on a terminus with a hydrophone array and recording the melting noise from large numbers of blocks of ice whose physical properties have been measured. An approach for the analytical analysis of the field measurements and initial development of an inversion technique is based on earlier work modeling noise radiated from bubbles in breaking waves. Data will be collected in front of a small group of glaciers terminating into a single fjord to address the following questions that presently limit the usefulness of acoustic data:1. What is the density, mean internal pressure and distributions of radii of bubbles in randomly selected samples of glacier ice, and how do these distributions correlate with ice density, which is a proxy for ice depth?2. How does the bubble source spectrum vary with hydrostatic pressure, bubble radius, internal gas pressure, and water temperature?3. What is the variability in the distributions of bubble properties between glaciers, and what are the minimal set of ice property measurements required to generalize the method from one to many glaciers? That is, what variables must be measured on a glacier-by-glacier basis to make the technique work across many glaciers?