In situ field measurements of the temporal evolution of low-frequency sea-ice dielectric properties in relation to temperature, salinity, and microstructure
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...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | The Cryosphere |
| Online Access: | http://www.the-cryosphere.net/10/2923/2016/tc-10-2923-2016.pdf |
| Summary: | 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 to 95 kHz in landfast ice off the coast of Barrow (Utqiaġvik),
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. |
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| ISSN: | 1994-0416 1994-0424 |