Measurements of 540–1740 MHz Brightness Temperatures of Sea Ice During the Winter of the MOSAiC Campaign

Demir, Oguz; Johnson, Joel T.; Jezek, Kenneth C.; Andrews, Mark; Ayotte, Kenneth; Spreen, Gunnar; Hendricks, Stefan; Kaleschke, Lars; Oggier, Marc; Granskog, Mats A.; Fong, Allison A.; Hoppmann, Mario; Matero, Ilkka; Scholz, Daniel

doi:10.1109/tgrs.2021.3105360

Cited by 6 publications

(6 citation statements)

References 49 publications

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“…6b. As expected from theory (Demir et al, 2022a;Johnson et al, 2021), the thicker sea ice at sites 1, 3 and 5 shows a "flatter" spectrum, having brightness temperatures in the 240-250 K range. This is due to the sensitivity of brightness temperature to ice thickness: for a salinity of 6 g kg −1 (as measured in situ) the electromagnetic (EM) signal saturates for thicknesses higher than 1.5-2 m even at 500 MHz.…”

Section: Sea Icesupporting

confidence: 72%

“…Indeed, this continental ice is generated by the accumulation of snow on the plateau over centuries and can be considered to be pure ice with very small losses, as opposed to the sea ice of the other sites that is characterized by high dielectric losses due to the inclusion of saline brine pockets. These differences significantly impact microwave penetration through the ice and therefore the ice properties sensed by UWBRAD (Demir et al, 2022a).…”

Section: Sea Icementioning

confidence: 99%

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Ice Sheet and Sea Ice Ultrawideband Microwave radiometric Airborne eXperiment (ISSIUMAX) in Antarctica: first results from Terra Nova Bay

et al. 2023

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Abstract. An airborne microwave wide-band radiometer (500–2000 MHz) was operated for the first time in Antarctica to better understand the emission properties of sea ice, outlet glaciers and the interior ice sheet from Terra Nova Bay to Dome C. The different glaciological regimes were revealed to exhibit unique spectral signatures in this portion of the microwave spectrum. Generally, the brightness temperatures over a vertically homogeneous ice sheet are warmest at the lowest frequencies, consistent with models that predict that those channels sensed the deeper, warmer parts of the ice sheet. Vertical heterogeneities in the ice property profiles can alter this basic interpretation of the signal. Spectra along the lengths of outlet glaciers were modulated by the deposition and erosion of snow, driven by strong katabatic winds. Similar to previous experiments in Greenland, the brightness temperatures across the frequency band were low in crevasse areas. Variations in brightness temperature were consistent with spatial changes in sea ice type identified in satellite imagery and in situ ground-penetrating radar data. The results contribute to a better understanding of the utility of microwave wide-band radiometry for cryospheric studies and also advance knowledge of the important physics underlying existing L-band radiometers operating in space.

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Section: Sea Icesupporting

confidence: 72%

Section: Sea Icementioning

confidence: 99%

Ice Sheet and Sea Ice Ultrawideband Microwave radiometric Airborne eXperiment (ISSIUMAX) in Antarctica: first results from Terra Nova Bay

et al. 2023

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“…Later experiments recursively added additional layers including snow and sea ice of different properties (Demir et al, 2022a). The volume of snow plays a minor role in the emission but serves to more efficiently couple the upwelling radiation into the air.…”

Section: Sea Icementioning

confidence: 99%

“…In situ observations showed that new ice growth of about 8 cm was inferred from temperature profiles recorded from December 4 to December 13. Growth trends correlated with a gradual increase in the brightness temperatures by about 10 K (Demir, 2021;Demir et al, 2022a). Because the exact thickness of the basal layer was limited by the measurement interval, bottom layer thickness values between 0-15 cm were tested to compare the simulated and observed T B over the time period of December 8-13 (at fixed 35 °pointing angle).…”

Section: Multiyear Ice Signatures During the Wintermentioning

confidence: 99%

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A review of recent developments in low-frequency ultra-wideband microwave radiometry for studies of the cryosphere

Jezek

Johnson²,

Tsang³

et al. 2022

Front. Earth Sci.

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Over the past decade, a series of airborne experiments in the Arctic and Antarctica explored microwave emission from sea ice and ice sheets at frequencies from 0.5 to 2 GHz. The experiments were motivated by the fact that lower frequencies penetrate deeper into a frozen surface, thus offering the possibility to measure physical temperatures at great depths in ice sheets and, subsequently, other unique geophysical observables including sea ice salinity. These experiments were made feasible by recent engineering advances in electronics, antenna design, and noise removal algorithms when operating outside of protected bands in the electromagnetic spectrum. These technical advances permit a new type of radiometer that not only operates at low frequency, but also obtains continuous spectral information over the band from 0.5 to 2 GHz. Spectral measurements facilitate an understanding of the physical processes controlling emission and also support the interpretation of results from single frequency instruments. This paper reviews the development of low-frequency, wide band radiometry and its application to cryosphere science over the past 10 years. The paper summarizes the engineering design of an airborne instrument and the associated algorithms to mitigate radio frequency interference. Theoretical models of emission built around the morphologic and electrical properties of cryospheric components are also described that identify the dominant physical processes contributing to emission spectra. New inversion techniques for geophysical parameter retrieval are summarized for both Arctic and Antarctic scenarios. Examples that illustrate how the measurements are used to inform on glaciological problems are presented. The paper concludes with a description of new instrument concepts that are foreseen to extend the technology into operation from space.

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Studies of Sea-Ice Thickness and Salinity Retrieval Using 0.5–2 GHz Microwave Radiometry

Demir

Johnson

Jezek

et al. 2022

IEEE Trans. Geosci. Remote Sensing

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Measurements of 540–1740 MHz Brightness Temperatures of Sea Ice During the Winter of the MOSAiC Campaign

Cited by 6 publications

References 49 publications

Ice Sheet and Sea Ice Ultrawideband Microwave radiometric Airborne eXperiment (ISSIUMAX) in Antarctica: first results from Terra Nova Bay

Ice Sheet and Sea Ice Ultrawideband Microwave radiometric Airborne eXperiment (ISSIUMAX) in Antarctica: first results from Terra Nova Bay

A review of recent developments in low-frequency ultra-wideband microwave radiometry for studies of the cryosphere

Studies of Sea-Ice Thickness and Salinity Retrieval Using 0.5–2 GHz Microwave Radiometry

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