Laboratory measurements of sea ice: connections to microwave remote sensing

Kwok, R.; Nghiem, S. V.; Martin, Seelye; Winebrenner, D. P.; Gow, Anthony J.; Perovich, Donald K.; Swift, C.T.; Barber, David G.; Golden, Kenneth M.; Knapp, Eric J.

doi:10.1109/36.718640

Cited by 14 publications

(4 citation statements)

References 35 publications

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“…A similar depolarization was also observed over snow deposition, and this depolarization was explained by increases in volume scattering or increases in absorption by wet snow [Garrity, 1992;Wensnahan, 1995;Grenfell et al, 1998;Hwang et al, 2007]. Kwok et al [1998] also found that active microwave signatures were affected by seawater flooding the surface. Besides the direct contribution of ice temperature on T B , the ice temperature controls the brine volume in thin ice and thus also indirectly affects microwave emissivity.…”

Section: Introductionmentioning

confidence: 63%

Impact of ice temperature on microwave emissivity of thin newly formed sea ice

2008

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[1] This study examines the impact of ice temperature on microwave emissivity over thin, newly formed sea ice at 6, 19, and 37 GHz during October 2003 in the southern Beaufort Sea, where the physical properties of newly formed sea ice were coincidently measured with microwave emissions. Six ice stations with distinct properties were selected and divided according to ice surface temperature into warm (above -3°C) or cold (below -3°C) stations. The warm stations had a lower emissivity at the vertical polarization by 0.1 than the cold stations and a corresponding difference in brine volume and dielectric properties. Significant correlations were observed between brine volume and ice emissivity (R 2 = 0.8, p value < 0.05). A sensitivity study showed that decreasing ice temperatures from À2.1°to À5.0°C explained the observed difference of 0.1 in ice emissivity between warm and cold stations. The results suggest that the temperature of thin bare ice could be the critical factor in determining ice emissivity near the melting point (about À2°C). Furthermore, a slight decrease in ice temperature (i.e., from À2°to À5°C) significantly reduces the brine volume, thus resulting in high ice emissivity. Finally, we demonstrate the potential of newly formed ice to cause errors in estimating sea ice concentrations using Advanced Microwave Scanning Radiometer-E data.

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Section: Introductionmentioning

confidence: 63%

Impact of ice temperature on microwave emissivity of thin newly formed sea ice

2008

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“…This variation in difference is likely due to the difference in polarization: RADARSAT has an HH polarization, and ERS-2 has a VV polarization. Laboratory measurements of radar backscatter from sea ice, the difference in HH and VV polarization, were greatest for bare ice and less for ice covered with frost (Kwok and others, 1998).…”

Section: Resultsmentioning

confidence: 99%

“…Air temperatures during the fieldwork and image acquisition averaged –3˚ to –4°C with a good wind. High sublimation rates are common in the valley, cooling and drying the surface significantly (Lewis and others, 1995). If the ice surface was wetter than the snow, the image should exhibit a broad transition zone between the ice and snow because the patchy snow and ice would present a mixture for the SAR pixels, changing in tone with the changing snow cover.…”

Section: Discussionmentioning

confidence: 99%

Synthetic aperture radar detection of the snowline on Commonwealth and Howard Glaciers, Taylor Valley, Antarctica

Bardel

Fountain

Hall³

et al. 2002

Ann. Glaciol.

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ABSTRACT. Synthetic aperture radar (SAR) images of Taylor Valley, Antarctica, were acquired inJanuary 1999 in coordination with ground-based measurements to assess SAR detection of the snowline on dry polar glaciers. We expected significant penetration of the radar wave resulting in an offset of the SAR-detected snowline relative to the true snowline. Results indicated no detectable displacement of the SAR snowline. Snow depths of 15 cm over ice can be detected on the imagery. We hypothesize that the optical depth of thin snowpacks is enhanced by reflection and refraction of the radar beam by internal snow layers. The enhanced optical depth increases the volume scattering, and thereby enhances backscatter sufficiently to be detected by the SAR. Consequently, SAR imagery may be used directly to image the position of transient snowlines in dry polar regions.

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“…In fact, backscatter from dry snow-covered ice was a slightly stronger scatter than flooded ice. An even larger damping of backscatter (4-8 dB decrease) was observed during the ARI [15] when a new ice surface was flooded with saline water. Wide-band radar data acquired during the ARI support these observations and suggest the crossover in dominant scattering mechanisms occurs between 9 and 10 GHz for new snow on new ice [3], [4].…”

Section: B Field Componentmentioning

confidence: 97%

A broad spectral, interdisciplinary investigation of the electromagnetic properties of sea ice

Jezek

Perovich

Golden

et al. 1998

IEEE Trans. Geosci. Remote Sensing

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Abstract-This paper highlights the interrelationship of research completed by a team of investigators and presented in the several individual papers comprising this Special Section on the Office of Naval Research (ONR), Arlington, VA, Sponsored Sea Ice Electromagnetics Accelerated Research Initiative (ARI). The objectives of the initiative were the following: 1) understand the mechanisms and processes that link the morphological and physical properties of sea ice to its electromagnetic (EM) characteristics; 2) develop and verify predictive models for the interaction of visible, infrared, and microwave radiation with sea ice; 3) develop and verify inverse scattering techniques applicable to problems involving the interaction of EM radiation with sea ice. Guiding principles for the program were that all EM data be taken with concurrent physical property data (salinity, density, roughness, etc.) and that broad spectral data be acquired in as nearly a simultaneous fashion as possible. Over 30 investigators participated in laboratory, field, and modeling studies that spanned the EM spectrum from radio to ultraviolet wavelengths. An interdisciplinary approach that brought together sea ice physicists, remote-sensing experts (in EM measurements), and forward and inverse modelers (primarily mathematicians and EM theorists) was a hallmark of the program. Along with describing results from experiments and modeling efforts, possible paradigms for using broad spectral data in developing algorithms for analyzing remote-sensing data in terms of ice concentration, age, type, and possibly thickness are briefly discussed.

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Laboratory measurements of sea ice: connections to microwave remote sensing

Cited by 14 publications

References 35 publications

Impact of ice temperature on microwave emissivity of thin newly formed sea ice

Impact of ice temperature on microwave emissivity of thin newly formed sea ice

Synthetic aperture radar detection of the snowline on Commonwealth and Howard Glaciers, Taylor Valley, Antarctica

A broad spectral, interdisciplinary investigation of the electromagnetic properties of sea ice

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