EAPSI: Observing seasonal changes in sea ice microstructure with electric property measurements

海冰在极地地区扮演着许多角色，包括为海洋食物网底部的微生物提供栖息地；在极地社区的生活和文化中发挥不可或缺的作用；并影响到极地海洋的自然资源勘探。海冰的微观结构从秋季形成到夏季融化不断演变。然而，在观察这种季节性演变及其对海冰与周围环境相互作用的影响方面，存在着根本性的挑战。为了获取冰的性质数据而移除冰芯，会导致卤水的立即流失和微观结构的改变。野外地点的偏远也限制了观测。因此，人们正在探索对海冰微观结构进行连续和非破坏性监测的方法。该项目将研究海冰电学特性的潜力，对冰内的盐水分布高度敏感，作为微观结构的代表。这项研究将在惠灵顿维多利亚大学（VUW）与马尔科姆·英厄姆博士合作进行，他是海冰电学特性的主要研究员。这个项目旨在将一个特殊的性质，复杂介电常数，与海冰微观结构的季节性演变联系起来。整个2013年春天，在阿拉斯加巴罗海岸测量了10Hz到95kHz范围内的低频复介电常数。此外，还收集了温度和盐度测量和冰样品，以进一步表征冰的微观结构。计划在2014年进行一组类似的测量，创建一个强大的数据集，这是同类数据集中的第一个，将低频复介电常数测量与关键海冰特性和微观结构的季节性演变联系起来。在VUW期间对这些数据集的分析将有助于建立一个改进的海冰微观结构模型，并导致全年监测冰况技术的进一步发展。NSF EAPSI奖是与新西兰皇家学会合作资助的。

Sea ice plays many roles in Polar Regions including providing habitat for microorganisms at the base of marine food webs; playing an integral part in the lives and cultures of polar communities; and impacting natural resources exploration in the polar oceans. The microstructure of sea ice is constantly evolving from formation in the fall through melt in the summer. Fundamental challenges exist however, in observing this seasonal evolution and its effect on the interaction between sea ice and the surrounding environment. Any removal of ice cores to obtain data on ice properties, results in the immediate loss of brine and alterations of microstructure. The remoteness of field sites also limits observations. Methods to monitor sea ice microstructure continuously and non-destructively are therefore being explored. This project will study the potential for the electric properties of sea ice, highly sensitive to the brine distribution within to ice, to act as a proxy for microstructure. This research will be conducted at Victoria University of Wellington (VUW) in collaboration with Dr. Malcolm Ingham, a leading researcher on the electric properties of sea ice.This project aims to link one particular property, complex dielectric permittivity, to the seasonal evolution of sea ice microstructure. Throughout the Spring of 2013, measurements of low frequency complex dielectric permittivity in the range of 10Hz to 95kHz were made off the coast of Barrow, Alaska. Additionally, temperature and salinity measurements and ice samples were collected for further ice microstructure characterization. A similar set of measurements is planned for 2014 creating a robust dataset, the first of its kind, linking low frequency complex permittivity measurements to the seasonal evolution of key sea ice properties and microstructure. Analysis of this data set while at VUW will enable the creation of an improved microstructural model of sea ice and lead to further development of techniques to monitor ice conditions throughout the year. This NSF EAPSI award is funded in collaboration with the Royal Society of New Zealand.