Modelling wave propagation through broken ice

模拟波浪穿过碎冰的传播

• 批准号: 2765131
• 金额: --
• 依托单位: University of Bristol
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2765131
• 关键词: Modelling; wave; propagation; through; broken

The Marginal Ice Zone (MIZ) is located in polar regions between the open ocean and the shore-fast sea ice and develops when seasonally-formed sea ice begins to break up. The MIZ can extend away from its edge with the open sea for hundreds of kilometres and consists of a variety of ice structures from large solid floating ice to grease ice and pancake ice. Because sea ice is relatively thin (typically 0.5m to 2m thick) ice sheets are able to support flexural waves which allow wave energy from the ocean to propagate into regions of unbroken ice where it can assist further break up. The dynamic process of ice break up is an important component in the climate system since it enhances melting which drives ocean circulation as well as reducing the albino effect of the polar regions. In recent years considerable effort has been placed on developing a better understanding of wave propagation through the MIZ through field measurements, laboratory experiments and by employing physical models. This PhD project is aimed at developing models which describe some of the main features of wave propagation in the MIZ. Specifically, the work will focus on 1) developing new "effective medium" equations for distributions of floating broken ice and 2) developing simulations of wave scattering through random ice floe/crack configurations. The ulimate challenge, and goal of this work, is to see if our models can be used to predict the trends see in experimental data of wave attenuation (e.g. Doble et al (2016), "Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea," J. Geophys. Res. Oceans). This challenge is particularly difficult because there is no evidence for or scientific agreement on the physical processes that lead to wave attenuation. Of the many possible mechanisms, two stand out. The first is that there are losses associated with local ocean/ice interactions (these could be mechanical of viscous losses). The second is that multiple wave scattering effects in random configurations give rise to attenuation (similar to Anderson localisation). We plan to investigate both using a variety of technical mathematical methods such as effective medium modelling, but will place a larger emphasis on the second idea. In particular we plan to apply ideas in the work of Stanke and Kino (1984, "A unified theory for elastic wave propagation in polycrystalline materials", J Acoust Soc Am) to regions of broken ice. Especially promising in this regard is the variation of wave attentuation rates with frequency reported by Stanke and Kino for elastic waves propagating into a crystalline material are similar to experimental data for Doble et al. (2016) for ice. The work will involve applied mathematical, statistical and computational methods.

边缘冰区（MIZ）位于开阔海洋和海岸固定海冰之间的极地地区，当季节性形成的海冰开始破裂时就会形成。MIZ可以从其与公海的边缘延伸数百公里，由各种冰结构组成，从大型固体浮冰到油脂冰和煎饼冰。由于海冰相对较薄（通常为0.5米至2米厚），冰盖能够支撑弯曲波，使来自海洋的波能传播到未破碎的冰层区域，在那里它可以帮助进一步破碎。冰破裂的动态过程是气候系统的一个重要组成部分，因为它促进了融化，从而推动了海洋环流，并减少了极地地区的白化病效应。近年来，通过现场测量、实验室实验和采用物理模型，人们做出了相当大的努力，以更好地了解波浪通过MIZ的传播。这个博士项目的目的是开发模型，描述在MIZ波传播的一些主要特征。具体而言，工作将集中在1）开发新的“有效介质”方程的分布的浮动破碎冰和2）开发模拟波散射通过随机浮冰/裂纹配置。这项工作的终极挑战和目标是，看看我们的模型是否可以用于预测波浪衰减实验数据中的趋势（例如，Doble等人（2016年），“秋季博福特海中煎饼和冰糕对风浪的消散”，J. Geophys. Res. Oceans）。这一挑战特别困难，因为没有证据或科学协议的物理过程，导致波衰减。在许多可能的机制中，有两种机制比较突出。第一个是与当地海洋/冰的相互作用有关的损失（这些损失可能是机械的或粘性的损失）。第二个是随机结构中的多波散射效应引起衰减（类似于安德森局域化）。我们计划使用各种技术数学方法（如有效介质建模）来研究这两种方法，但将更加强调第二种想法。特别是，我们计划将Stanke和Kino（1984年，“A unified theory for elastic wave propagation in polycrystalline materials”，J Acoust Soc Am）工作中的思想应用于碎冰区域。在这方面特别有希望的是，Stanke和Kino报告的弹性波传播到晶体材料中的波衰减率随频率的变化与Doble等人的实验数据相似。（2016）冰。这项工作将涉及应用数学、统计和计算方法。