In situ measurement of low-frequency sea-ice dielectric properties and implications for tracking seasonal evolution of microstructure
| Autor: | Megan O'Sadnick, Malcolm Ingham, Hajo Eicken, Erin C. Pettit |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Hydrology
Permittivity geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Temperature salinity diagrams Mineralogy Dielectric 010502 geochemistry & geophysics Microstructure 01 natural sciences Proxy (climate) Sea ice growth processes Volume fraction Sea ice Geology 0105 earth and related environmental sciences |
| DOI: | 10.5194/tc-2016-92 |
| Popis: | The seasonal evolution of sea-ice microstructure controls key ice properties, including those governing ocean-atmosphere heat and gas exchange, remote-sensing signatures and the role of the ice cover as a habitat. Non-destructive in situ monitoring of sea-ice microstructure is of value for sea-ice research and operations, but remains elusive to date. We examine the potential for the electric properties of sea ice, which is highly sensitive to the brine distribution within the ice, to serve as a proxy for microstructure and, hence, other ice transport properties. Throughout spring of 2013 and 2014, we measured complex dielectric permittivity in the range of 10 Hz to 95 kHz in landfast ice off the coast of Barrow, Alaska. Temperature and salinity measurements and ice samples provide data to characterize ice microstructure in relation to these permittivity measurements. The results reveal a significant correlation between complex dielectric permittivity, brine volume fraction, and microstructural characteristics including pore volume and connectivity, derived from x-ray microtomography of core samples. The influence of temperature and salinity variations, as well as the relationships between ice properties, microstructural characteristics, and dielectric behavior emerge from multivariate analysis of the combined data set. Our findings suggest some promise for low-frequency permittivity measurements to track seasonal evolution of a combination of mean pore volume, fractional connectivity, and pore surface area-to-volume ratio, which in turn may serve as proxies for key sea-ice transport properties. |
| Databáze: | OpenAIRE |
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