Measurement of the microwave properties of sea ice at 90 GHz and lower frequencies

Troy, B. E.; Hollinger, J. P.; Lerner, Robert M.; Wisler, M.

doi:10.1029/jc086ic05p04283

Cited by 43 publications

(22 citation statements)

References 9 publications

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“…At present, except for determining the position of the ice edge, there are no plans for using the 85.5 GHz radiances to retrieve sea ice parameters. Current studies and recent field experiments, however, suggest that use of higher frequency radiances may improve discrimination of ice concentration and ice type (Troy et al, 1981;Grenfell, 1984).…”

Section: Afultifrequency Methodsmentioning

confidence: 99%

Passive microwave remote sensing for sea ice research

Swift

Cavalieri

1985

EoS Transactions

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This report summarizes how data gathered by. remote sensors on satellites can be utilized for sea ice research, and describes how the brightness temperatures measured by a passive microwave imager can be converted to maps of total sea ice concentration, and to the areal fractions covered by first year and multiyear ice. Several ancillary observations, especially by means of automatic data buoys and submarines equipped with upwardlooking sonars, are needed to improve the validation and interpretation of satellite data. The design and performance characteristics of the Navy's Special Sensor Microwave Imager, expected to be in orbit in late 1985, are described. It is recommended that data from that instrument be processed to a form suitable for research applications and archived in a readily accessible form. The report concludes with a description of the sea ice data products required for research purposes and recommendations for their archival and distribution to the scientific community.-vi-

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Section: Afultifrequency Methodsmentioning

confidence: 99%

Passive microwave remote sensing for sea ice research

Swift

Cavalieri

1985

EoS Transactions

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“…During the past few years, several studies have investigated the microwave signature and dielectric properties of sea ice [Ramseier et al, 1975;Vant el al., 1978;Ketchum and Lohanick, 1980;Troy et al, 1981;Gray et al, 1982]. The studies included in-situ, laboratory, and aircraft measurements with some coordinated ground support.…”

Section: Paper Number 3c0668mentioning

confidence: 99%

“…The use of the dual-polarization scanning multichannel microwave radiometer (SMMR) offers an even greater potential because of its ability to distinguish different ice types and to give a more accurate estimate of the amount of open water within the ice pack [Gloersen and Barath, 1977]. However, the emissivities of sea ice, which are known to vary with age, thickness, salinity, density, composition, and surface characteristics [Gloersen et al, 1973;Vant et al, 1974;Gloersen and Larabee, 1981;Troy et al, 1981;Carsey, 1982], have not been adequately established, especially for multiyear ice. Improved average values and a knowledge of spatial and temporal variability of ice emissivities are important if one wants to be able to use microwave sensors at their full capabilities.…”

Section: Introductionmentioning

confidence: 99%

Sea ice effective microwave emissivities from satellite passive microwave and infrared observations

Comiso¹

1983

J. Geophys. Res.

122

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Microwave sea ice emissivities are investigated on a global scale by using near‐simultaneous images from the temperature‐humidity infrared radiometer (THIR) and the dual‐polarization scanning multichannel microwave radiometer (SMMR), both onboard the Nimbus 7 satellite. The emissivities in several study areas in the Arctic region are observed to be approximately constant during a 9‐month period within the fall, winter, and spring months for both first‐year and multiyear ice, with a standard deviation of about 3%. During the onset of summer, when the snow cover starts to melt, emissivity increases of about 30% are observed at 37 GHz for multiyear ice, with the effect decreasing to less than 5% at the 6.6‐GHz channels. Multichannel cluster analysis over very large study areas during winter shows considerable variability in emissivities of well‐defined clusters of consolidated ice at 37 GHz and about one third as much at 18 GHz. Some nonlinearities in the functional relationship of the emissivities in the consolidated ice regions between first‐year and multiyear ice are also evident, especially when data from one frequency is plotted against that of another. However, the cluster analysis technique separates the various emissivity data points into distinct clusters corresponding to radiometrically different ice types. If the variability within each cluster is quantified and taken into account by using multispectral analysis, in addition to improving the capability of classifying ice by age, information about ice thickness and surface characteristics might also be obtainable.

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“…Comparison of thickness‐emissivity relationships (a, b) from our observations and (c, d) from previous studies [ Troy et al , 1981; Tucker et al ., 1991; Eppler et al , 1992]. For Figures 5c and 5d, mean values are used for different sea ice types according to the WMO nomenclature.…”

Section: Resultsmentioning

confidence: 54%

Thin sea ice thickness as inferred from passive microwave and in situ observations

et al. 2008

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[1] Microwave radiometric signals from sea ice strongly reflect physical conditions of a layer near the ice surface. This study examines the extent to which the relationships of thickness with brightness temperature and with emissivity hold for thin sea ice, approximately <0.2-0.3 m, and how those relationships may arise from changes in brine characteristics through modification of dielectric properties near the ice surface. In order to address these questions we made concurrent measurements of sea ice thickness in the Sea of Okhotsk from a ship and passive microwave radiometry from an over-flying aircraft. The results show that the brightness temperature and emissivity increase with thickness approximately within the thin ice for a frequency range of 10-37 GHz. The relationship is more pronounced at lower frequencies and at the horizontal polarization. We also established an empirical relationship between ice thickness and salinity in the layer near the ice surface from a field experiment, which qualitatively supports the idea that changes in the near-surface brine characteristics contribute to the observed thickness-brightness temperature/emissivity relationship. On the basis of our results, we conclude that for thin ice, passive microwave radiometric signals likely contain indirect information on ice thickness through the dependence of dielectric properties on brine, which provides a plausible and common explanation for previously proposed passive microwave thickness algorithms.

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Measurement of the microwave properties of sea ice at 90 GHz and lower frequencies

Cited by 43 publications

References 9 publications

Passive microwave remote sensing for sea ice research

Passive microwave remote sensing for sea ice research

Sea ice effective microwave emissivities from satellite passive microwave and infrared observations

Thin sea ice thickness as inferred from passive microwave and in situ observations

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