CHARACTERIZATION OF BRINE NETWORK MICROSTRUCTURE IN FIRST YEAR ARCTIC SEA ICE

Dartmouth College, Hanover NH

Investigators

Abstract

Arctic sea ice mediates the exchange of heat, fluids, and gases between the ocean and the atmosphere, and in doing so plays an important role in global climate. Sea ice is highly heterogeneous, with structural, chemical and phase changes occurring on very small time and relative temperature scales. The current rapid decline of the Arctic sea ice cover is accompanied by a transition from multi-year ice to mostly first-year and thinner sea ice. Current understanding of the morphology of brine networks in sea ice, and their variability, is inadequate both for the most accurate interpretation of sea ice data and for use in regional and larger scale climate models. Using micro X-ray computed tomography and applied mathematics, the investigators propose to describe in detail the morphology and variability of brine networks in first-year sea ice. The overall goal of the proposed work is to improve our ability to determine the transport of heat, gases, chemical species, and salts through and within sea ice, and specifically to shed light on the brine drainage and desalination processes and how they change with temperature. Drawing on experience in both microstructural analysis of ice and applied mathematics, the investigators will produce quantitative physical descriptions of pore microstructure in first year sea ice, which can then be used to interpret bulk properties. They will use both laboratory grown sea ice and natural first year sea ice collected at Barrow, Alaska. As part of this project, the investigators will design and build a system for storing and transporting sea ice cores at their measured in situ temperature gradients, which they will share openly with other researchers. The intellectual merit of the proposed work lies in its development of quantitative physical descriptions of pore microstructure in first year sea ice, which can be used in interpretation of bulk physical properties, and which will contribute to the scientific community's understanding of sea ice cover and its role in tropospheric chemistry. It will also contribute to the improvement of regional and global climate models, and to the understanding of Arctic environmental processes and their role in climate change. The broader impacts of the proposed activity include the training of a postdoctoral scientist and direct integration of research and engineering with education for a number of undergraduate students who will design apparatus, take part in laboratory and field work, co-author papers, and participate in conferences. The results of the research will be published in international refereed journals, presented at conferences, presented in public lectures to the Arctic community in Barrow and to other audiences, and placed on a web page. The data will also be available through the National Snow and Ice Data Center.