Microwave Backscatter From Arctic Lake Ice and Polarimetric Implications

Atwood, Donald K.; Gunn, Grant E.; Roussi, Chris; Wu, Jiangfeng; Duguay, Claude R.; Sarabandi, Kamal

doi:10.1109/tgrs.2015.2429917

Cited by 55 publications

(53 citation statements)

References 36 publications

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“…This indicates that the scattering mechanisms causing high σ 0 in the co-polarized image are also sufficient to depolarise incident microwaves. Consistently high backscatter in both the VV and VH observations also indicate that even if grey ice is present at the surface in Husky Lakes, the majority of power returned would be caused by the interaction at or near the ice-water interface [46,47]. Therefore, if surface-ice types and a rough interface caused by tubular bubble development are both present, the σ 0 return from the surface will be of much lower magnitude than surface interaction returns from the ice-water interface.…”

Section: Magic Segmentation-husky Lakesmentioning

confidence: 67%

Investigating the Influence of Variable Freshwater Ice Types on Passive and Active Microwave Observations

et al. 2017

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Dual-polarized airborne passive microwave (PM) brightness temperatures (T b ) at 6.9 GHz H/V, 19 GHz H/V and 37 GHz H/V and spaceborne active microwave (AM) X-band (9.65 GHz VV, VH) backscatter (σ 0 ) are observed coincident to in situ snow and lake-ice measurements collected over two lakes near Inuvik, Canada. Lake-ice thickness is found to be positively correlated with 19 GHz V emission (R = 0.67) and negatively with 19 GHz H emission (R = −0.79), indicating surface ice conditions influence microwave interaction. Lake ice types are delineated from TerraSAR-X synthetic aperture radar (SAR) images using the iterative region growing with semantics (IRGS) segmentation algorithm implemented in the MAGIC (MAp Guided Ice Classification) system. The spatial extent of derived ice type classes correspond well to in situ observations. The overall magnitude of emission at 19 GHz H and X-band VH σ 0 increase with the scattering potential of associated ice types (grey/rafted ice). Transects of 6.9 GHz PM and 19 GHz PM exhibit positive relationships with VH σ 0 over freshwater lake ice, with the greatest R coefficients at H-pol (R = 0.64, 0.46). Conversely, 6.9 GHz T b and 19 GHz T b exhibit negative R coefficients in regions of brackish water due to tubular bubble and brine inclusions in the ice. This study identifies congruency between PM and AM scattering mechanisms over lake ice for the purpose of identifying the influence of ice types on overall microwave interaction within the lake-ice system.

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Section: Magic Segmentation-husky Lakesmentioning

confidence: 67%

Investigating the Influence of Variable Freshwater Ice Types on Passive and Active Microwave Observations

et al. 2017

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“…This large dielectric contrast causes a strong reflectance of the radar signal from the ice-water interface. Using polarimetric analysis, recent studies have demonstrated that the single bounce at this interface is the main mechanism of backscattering from the floating ice [36,37]. Thus, backscatter intensity in the case of floating ice is mostly controlled by roughness at the ice-water interface.…”

Section: Ice Groundingmentioning

confidence: 99%

Monitoring Bedfast Ice and Ice Phenology in Lakes of the Lena River Delta Using TerraSAR-X Backscatter and Coherence Time Series

et al. 2016

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Thermokarst lakes and ponds are major elements of permafrost landscapes, occupying up to 40% of the land area in some Arctic regions. Shallow lakes freeze to the bed, thus preventing permafrost thaw underneath them and limiting the length of the period with greenhouse gas production in the unfrozen lake sediments. Radar remote sensing permits to distinguish lakes with bedfast ice due to the difference in backscatter intensities from bedfast and floating ice. This study investigates the potential of a unique time series of three-year repeat-pass TerraSAR-X (TSX) imagery with high temporal (11 days) and spatial (10 m) resolution for monitoring bedfast ice as well as ice phenology of lakes in the zone of continuous permafrost in the Lena River Delta, Siberia. TSX backscatter intensity is shown to be an excellent tool for monitoring floating versus bedfast lake ice as well as ice phenology. TSX-derived timing of ice grounding and the ice growth model CLIMo are used to retrieve the ice thicknesses of the bedfast ice at points where in situ ice thickness measurements were available. Comparison shows good agreement in the year of field measurements. Additionally, for the first time, an 11-day sequential interferometric coherence time series is analyzed as a supplementary approach for the bedfast ice monitoring. The coherence time series detects most of the ice grounding as well as spring snow/ice melt onset. Overall, the results show the great value of TSX time series for monitoring Arctic lake ice and provide a basis for various applications: for instance, derivation of shallow lakes bathymetry, evaluation of winter water resources and locating fish winter habitat as well as estimation of taliks extent in permafrost.

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“…These scenes have been acquired in Cband (approximately 5.6 cm wavelength) and HH polarizations. Backscatter intensity varies strongly for floating ice in HH with respect to incidence angle (Atwood et al, 2015). This needs to be considered for large area operational classifications and has not been addressed in previous studies.…”

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confidence: 99%

“…Duguay et al (2002) find that backscatter intensity from floating ice measured at shallower incidence angles can be similar to that observed from ground-fast ice where only small amounts of bubbles are present. This may relate to a smooth ice water boundary taking into account findings of Atwood et al (2015). Atwood et al (2015) have used a coherent numerical model to test the impact of bubbles upon the lake ice backscatter.…”

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Circumpolar Mapping of Ground-Fast Lake Ice

et al. 2017

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Shallow lakes are common across the entire Arctic. They play an important role as methane sources and wildlife habitats, and they are also associated with thermokarst processes which are characteristic of permafrost environments. Many lakes freeze to the ground along their rims and often over the entire extent during winter time. Knowledge on the spatial patterns of ground-fast and floating ice is important as it relates to methane release, talik formation and hydrological processes, but no circumpolar account of this phenomenon is currently available. Previous studies have shown that ground-fast ice can easily be detected using C-band Synthetic Aperture Radar (SAR) backscatter intensity data acquired from satellites. A major challenge is that backscatter intensity varies across the satellite scenes due to incidence angle effects. Circumpolar application therefore requires the inclusion of incidence angle dependencies into the detection algorithm. An approach using ENVISAT ASAR Wide Swath data (approximately 120 m spatial resolution) has therefore been developed supported by bathymetric measurements for lakes in Siberia. This approach was then further applied across the entire Arctic for late winter 2008. Ground-fast ice fraction has been derived for (1) two million lake objects larger than 0.025 km 2 (post-processed GlobeLand30), (2) a 50 × 50 km grid and (3) within certain zones relevant for climate studies (permafrost type, last glacial maximum, Yedoma). Especially lakes smaller than approximately 0.1 km 2 may freeze completely to the ground. The proportion of ground-fast ice increases with increasing soil organic carbon content in the proximity of the lakes. This underlines the importance of such lakes for emission studies and the need to map the occurrence of ground-fast lake ice. Clusters of variable fractions of ground-fast ice occur especially in Yedoma regions of Eastern Siberia and Alaska. This reflects the nature of thaw lake dynamics. Analyses of lake depth measurements from several sites suggest that the used method yields the potential to utilize ground-fast lake ice information over larger areas with respect to landscape development, but results need to be treated with care, specifically for larger lakes and along river courses.

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Microwave Backscatter From Arctic Lake Ice and Polarimetric Implications

Cited by 55 publications

References 36 publications

Investigating the Influence of Variable Freshwater Ice Types on Passive and Active Microwave Observations

Investigating the Influence of Variable Freshwater Ice Types on Passive and Active Microwave Observations

Monitoring Bedfast Ice and Ice Phenology in Lakes of the Lena River Delta Using TerraSAR-X Backscatter and Coherence Time Series

Circumpolar Mapping of Ground-Fast Lake Ice

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