Measuring the melt rate of glacier ice with underwater noise

提出了一种新的测量冰川融化速度的方法，该方法利用冰川融化时产生的气泡产生的水下噪声来测量冰川融化速度。开展这项工作的动机在于，融化在极地地区的冰-海洋相互作用以及由此导致的海平面上升中所起的关键作用，再加上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，由于上覆冰的积累，压力不断增加而被压缩。当冰川前面的冰融化时，困在气泡中的气体爆炸性地释放出来，向水中辐射出强烈的声音脉冲，使冰川湾和峡湾成为地球上最嘈杂的地方之一。由于气泡释放率随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，为科技和经济管理学院的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。将通过为桦树水族馆的一个创新的、计划中的展览捐款来进行宣传？探险地球！最后，一个成功的项目将是开发一种可能具有变革性的观测冰川-海洋相互作用的遥感技术的第一步。该项目将利用双管齐下的努力，开始开发一种声学方法来观测海洋冰川的融化速度：用水听器阵列直接测量终端上噪声源的垂直分布，并记录大量冰块的融化噪声，这些冰块的物理性质已经被测量。一种用于现场测量的分析分析和反演技术的初步开发的方法是基于对破碎波中的气泡辐射的噪声进行建模的早期工作。将在一小群冰川前面收集数据，以解决目前限制声学数据使用的下列问题：1.随机选择的冰川冰样中气泡的密度、平均内压和半径分布是什么，这些分布与代表冰深的冰密度如何相关？2.气泡源谱如何随静水压力、气泡半径、内部气体压力和水温变化？3.冰川之间气泡特性分布的变异性是什么，将该方法从一个冰川推广到多个冰川所需的最小冰性测量集是什么？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?