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

合作研究：淡水输入存在下北极陆地快速海冰形成

• 批准号: 1603683
• 负责人: Rachel Obbard
• 金额: $ 45.51万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-11-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1603683&HistoricalAwards=false
• 关键词: Collaborative; Research; Arctic; Land; Fast

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.

近年来北极最显著的变化之一是海冰范围和时间的变化。近岸海冰的特征和季节周期的变化对利用近岸海冰作为生存狩猎和运输平台的土著社区尤为重要。观测和模式预估还表明，由于冰川和冰盖融化加剧、永久冻土融化和陆地降水，流入沿海海洋的淡水径流量将增加。这些径流影响了秋季形成的海冰。在淡水影响下形成的海冰显示出盐度、孔隙度和渗透率的差异，从而显示出其光学和力学性质的差异。该项目将提供淡水影响条件下海冰形成和结构的独特观测结果。该项目将通过为研究生的培训提供支持，促进STEM劳动力的发展。它还将招收达特茅斯学院的本科生。美国妇女参与科学项目（WISP）。一名本科生参加春季野外作业。该项目还将申请支持一名PolarTREC教师。将提供k -12年级的拓展活动，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。向沿海海洋排放的淡水通过改变结冰水域的盐度和温度来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洋的海冰形成和结构，同时解决以下重要问题：在有大量淡水输入的地方形成和生长的海冰，其微观结构和盐水袋网与开阔海域的海冰有何不同？能否在远程采集数据的同时，对敏感近岸地区的冰冻开始、冻结速率和冰型进行就地监测？微观结构如何影响沿冰芯长度的传热？该项目将结合最近开发的观测和采样技术，并整合现场监测、物理和化学海冰表征方面的专业知识。海冰的形成、生长速度和盐度将在生长季节使用钢丝梯在淡水输入地点进行现场监测。氧同位素比和光学薄片地层学将用于量化淡水的影响。x射线微计算机断层扫描将用于表征沿冰芯1厘米间隔的孔隙度和盐水通道拓扑结构，并提供受淡水影响的冰的微观结构差异的定量数据。实验室测试和建模将用于检查通过保持在原位温度梯度下的海冰核的热量传递，作为微观结构地层学的功能。