Dielectric properties of sea and sodium chloride ice at UHF and microwave frequencies

Hoekstra, Pieter J.; Cappillino, Patrick

doi:10.1029/jb076i020p04922

Cited by 72 publications

(53 citation statements)

References 8 publications

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“…The impurity level in the ice crystals is known to affect the real part of the index only slightly. On the other hand, the imaginary part of the index varies by many orders of magnitude with the introduction of impurities in the 260-273 K temperature range (Hoekstra and Cappillino, 1971). While it is approximately 0.…”

Section: Computational Resultsmentioning

confidence: 99%

Microwave Emission From Snow and Glacier Ice

et al. 1976

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The microwave emission from a model snow field, consisting of randomly spaced ice spheres which scatter independently, is calculated. Mie scattering and radiative transfer theory are applied in a manner similar to that used in calculating microwave and optical properties of clouds. The extinction coefficient is computed as a function of both microwave wavelength and ice-particle radius. Volume scattering by the individual ice particles in the snow field significantly decreases the computed emission for particle radii greater than a few hundredths of the microwave wavelength. Since the mean annual temperature and the accumulation rate of dry polar firn mainly determine the grain sizes upon which the microwave emission depends, these two parameters account for the main features of the 1.55 cm emission observed from Greenland and Antarctica with the Nimbus-5 scanning radiometer. For snow particle sizes normally encountered, most of the calculated radiation emanates from a layer on the order of 10 m in thickness at a wavelength of 2.8 cm, and less at shorter wavelengths. A marked increase in emission from wet versus dry snow is predicted, a result which is consistent with observations. The model results indicate that the characteristic grain sizes in the radiating layers, dry-firn accumulation rales, areas of summer melting, and physical temperatures, can be determined from multispectral microwave observations.

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Section: Computational Resultsmentioning

confidence: 99%

Microwave Emission From Snow and Glacier Ice

et al. 1976

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“…These correlations established in that study, however, were tentative, both because of the absence of surface-based observations and because the observations appeared to be in conflict with theoretical predictions of ice emissivity as a function of age (Hoekstra andCappillino 1971, Stogryn 1971). According to that theory, the microwave emissivity of first-year ice should decrease rapidly as temperature increases to the melt point.…”

Section: Introductionmentioning

confidence: 81%

Microwave signatures of first-year and multiyear sea ice

Gloersen¹,

Nordberg²,

Schmugge³

et al. 1973

J. Geophys. Res.

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A combination of remote sensing from an aircraft and simultaneous surface measurements have confirmed the feasibility of identifying old and new sea ice according to its emission of thermal radiation at wavelengths between 0.3 and 3 cm. Emissivity of first‐year thick ice with a surface temperature of about 260°K is 0.95 or greater for wavelengths between 0.81 and 11 cm; the emissivity of multiyear ice is 0.8 at 0.81 cm and 0.95 at 11 cm, increasing monotonically in this wavelength interval. The ease with which multiyear ice can be distinguished from first‐year ice using a passive microwave radiometer is demonstrated by comparing mosaics prepared both from photographs and images of 1.55‐cm radiation.

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“…This difference is stronsly evident in the dielectric properties^of the two ice forms (Hoekstra and Cappillino 1971). The amount of brine ei.trapped in the ice depends on the rate of ice srowth.…”

Section: Dielectric Properties Of Sea Icementioning

confidence: 95%

“…because of the presence of liquid inclusion are also strongly frequency dependent. In Figure 10 the dielectric loss of sea ice is plotted as i function of frequency (Hoekstra and Cappillino 1971). Sea ice at microwave frequencies is thus a mednim loss dielectric, whereas fresh-water ice is a low loss dielectric.…”

Section: Dielectric Properties Of Sea Icementioning

confidence: 99%