Collaborative Research: Arctic Land Fast Sea Ice Formation in the Presence of Fresh Water Input

近年来，北极最显著的变化之一是海冰范围和时间的变化。近岸海冰的性质和季节周期的变化对利用近岸海冰作为自给自足的狩猎和运输平台的土著社区特别重要。观测和模型预测还表明，由于冰川和冰盖融化、永久冻土融化和陆地降水增加，流向沿海海洋的淡水径流增加。这种径流会影响秋季形成的海冰。在淡水影响下形成的海冰在盐度、孔隙度和渗透率方面存在差异，因此其光学和机械特性也不同。该项目将提供在淡水影响条件下对海冰形成和结构的独特观察。该项目将通过为研究生的培训提供支持，为STEM劳动力的发展做出贡献。它还将招收达特茅斯？S女性科学项目(WISP)的本科生。一名本科生将参加春季实地考察。该项目还将申请对PolarTREC教师的支持。将提供K-12年级的外展活动，并将利用华盛顿大学现有的项目，如参加太平洋科学中心的极地科学周末。向沿海海洋排放淡水会改变冻结水域的盐度和温度，从而影响海冰的热力学过程。这个为期三年的试点项目旨在研究沿海海冰的形成和结构，同时解决以下重要问题：1.与开阔海洋的海冰相比，在有大量淡水输入的海冰中，形成和生长的海冰的微结构和卤水袋网络有何不同？2.我们能否在远程收集数据的同时，现场监测敏感近岸地区的冻结开始、冻结速度和冰的类型？3.微结构如何影响沿冰芯长度的热传递？该项目将结合最新开发的观测和采样技术，并整合现场监测、物理和化学海冰特征方面的专业知识。在生长季节期间，将使用钢丝梯在淡水输入的位置现场监测海冰的形成、生长速度和盐度。将使用氧同位素比值和光学薄片地层学来量化淡水影响。X-射线微计算机断层成像将用于表征沿冰芯每隔1厘米的孔隙度和卤水通道拓扑，并提供受淡水影响的冰的微结构差异的定量数据。实验室测试和建模将被用来检查通过保持在原位温度梯度的海冰核心的热传递，作为微结构地层学的函数。

One of the most notable changes in the Arctic during recent years has been the variability in sea ice extent and timing. Changes in the character and seasonal cycle of nearshore sea ice is of particular importance to indigenous communities that use the nearshore sea ice as a platform for subsistence hunting and transportation. Observations and model projections also suggest increasing freshwater runoff to the coastal ocean from increased melting of glaciers and ice sheets, thawing of permafrost, and precipitation over land. This runoff impacts the sea ice that forms in the fall. Sea ice formed under freshwater influence reveals differences in salinity, porosity, and permeability, and thus its optical and mechanical properties. This project will provide unique observations of sea ice formation and structure under conditions of freshwater influence.This project will contribute to STEM workforce development through provision of support for the training of a graduate student. It will also entrain undergraduate students from Dartmouth?s Women in Science Project (WISP). One undergraduate will participate in the spring field work. The project will also apply for support for a PolarTREC teacher. K-12th grade outreach activities will be offered and will leverage existing programs at University of Washington such as participation in the Polar Science Weekend at the Pacific Science Center. The freshwater discharge to the coastal ocean affects thermodynamic processes in sea ice by changing salinity and temperature of the waters undergoing freezing. This three-year pilot project is designed to study sea ice formation and structure in the coastal ocean, while addressing the following important questions:1. How do microstructure and the brine pocket network differ in sea ice that forms and grows where there is significant fresh water input compared to sea ice in the open ocean?2. Can we monitor the onset of freezing, freezing rate and ice type in situ in sensitive nearshore areas, while collecting data remotely?3. How does microstructure affect heat transfer along the length of an ice core?The project will combine recently developed observation and sampling technologies, and integrate expertise in field monitoring, and physical and chemical sea ice characterization. Sea ice formation, growth rate, and salinity will be monitored in situ at a location of freshwater input during the course of a growth season using a wire ladder. Oxygen isotopic ratios and optical thin section stratigraphy will be used to quantify freshwater influence. X-ray micro-computed tomography will be used to characterize porosity and brine channel topology at 1 cm intervals along ice cores and provide quantitative data on microstructural differences in ice influenced by the freshwater. Laboratory tests and modeling will be used to examine heat transfer through sea ice cores held at their in situ temperature gradient, as a function of microstructural stratigraphy.