Synthetic aperture radar (SAR) backscatter response from methane ebullition bubbles trapped by thermokarst lake ice

2013 ◽  
Vol 38 (6) ◽  
pp. 667-682 ◽  
Author(s):  
Melanie Engram ◽  
Katey Walter Anthony ◽  
Franz J. Meyer ◽  
Guido Grosse
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Lake Ice ◽  
Thermokarst Lake ◽  
Methane Ebullition ◽  
Aperture Radar

The Potential Use of Synthetic Aperture Radar for Estimating Methane Ebullition From Arctic Lakes1

2008 ◽  
Vol 44 (2) ◽  
pp. 305-315 ◽  
Author(s):  
Katey M. Walter ◽  
Melanie Engram ◽  
Claude R. Duguay ◽  
Martin O. Jeffries ◽  
F.S. Chapin
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Methane Ebullition ◽  
Potential Use ◽  
Aperture Radar

scholarly journals Mapping potential signs of gas emissions in ice of Lake Neyto, Yamal, Russia, using synthetic aperture radar and multispectral remote sensing data

2021 ◽  
Vol 15 (4) ◽  
pp. 1907-1929
Author(s):  
Georg Pointner ◽  
Annett Bartsch ◽  
Yury A. Dvornikov ◽  
Alexei V. Kouraev
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
The Arctic ◽  
Lake Ice ◽  
Gas Emissions ◽  
L Band ◽  
Optical Imagery ◽  
Sar Data ◽  
Sar Imagery ◽  
Aperture Radar

Abstract. Regions of anomalously low backscatter in C-band synthetic aperture radar (SAR) imagery of lake ice of Lake Neyto in northwestern Siberia have been suggested to be caused by emissions of gas (methane from hydrocarbon reservoirs) through the lake’s sediments. However, to assess this connection, only analyses of data from boreholes in the vicinity of Lake Neyto and visual comparisons to medium-resolution optical imagery have been provided due to a lack of in situ observations of the lake ice itself. These observations are impeded due to accessibility and safety issues. Geospatial analyses and innovative combinations of satellite data sources are therefore proposed to advance our understanding of this phenomenon. In this study, we assess the nature of the backscatter anomalies in Sentinel-1 C-band SAR images in combination with very high resolution (VHR) WorldView-2 optical imagery. We present methods to automatically map backscatter anomaly regions from the C-band SAR data (40 m pixel spacing) and holes in lake ice from the VHR data (0.5 m pixel spacing) and examine their spatial relationships. The reliability of the SAR method is evaluated through comparison between different acquisition modes. The results show that the majority of mapped holes (71 %) in the VHR data are clearly related to anomalies in SAR imagery acquired a few days earlier, and similarities to SAR imagery acquired more than a month before are evident, supporting the hypothesis that anomalies may be related to gas emissions. Further, a significant expansion of backscatter anomaly regions in spring is documented and quantified in all analysed years 2015 to 2019. Our study suggests that the backscatter anomalies might be caused by lake ice subsidence and consequent flooding through the holes over the ice top leading to wetting and/or slushing of the snow around the holes, which might also explain outcomes of polarimetric analyses of auxiliary L-band Advanced Land Observing Satellite (ALOS) Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) data. C-band SAR data are considered to be valuable for the identification of lakes showing similar phenomena across larger areas in the Arctic in future studies.

scholarly journals Characterization of L-band synthetic aperture radar (SAR) backscatter from floating and grounded thermokarst lake ice in Arctic Alaska

2013 ◽  
Vol 7 (6) ◽  
pp. 1741-1752 ◽  
Author(s):  
M. Engram ◽  
K. W. Anthony ◽  
F. J. Meyer ◽  
G. Grosse
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
The Arctic ◽  
Great Promise ◽  
Late Winter ◽  
Lake Ice ◽  
Arctic Alaska ◽  
L Band ◽  
Phase Water ◽  
Aperture Radar

Abstract. Radar remote sensing is a well-established method to discriminate lakes retaining liquid-phase water beneath winter ice cover from those that do not. L-band (23.6 cm wavelength) airborne radar showed great promise in the 1970s, but spaceborne synthetic aperture radar (SAR) studies have focused on C-band (5.6 cm) SAR to classify lake ice with no further attention to L-band SAR for this purpose. Here, we examined calibrated L-band single- and quadrature-polarized SAR returns from floating and grounded lake ice in two regions of Alaska: the northern Seward Peninsula (NSP) where methane ebullition is common in lakes and the Arctic Coastal Plain (ACP) where ebullition is relatively rare. We found average backscatter intensities of −13 dB and −16 dB for late winter floating ice on the NSP and ACP, respectively, and −19 dB for grounded ice in both regions. Polarimetric analysis revealed that the mechanism of L-band SAR backscatter from floating ice is primarily roughness at the ice–water interface. L-band SAR showed less contrast between floating and grounded lake ice than C-band; however, since L-band is sensitive to ebullition bubbles trapped by lake ice (bubbles increase backscatter), this study helps elucidate potential confounding factors of grounded ice in methane studies using SAR.

scholarly journals Characterization of L-band synthetic aperture radar (SAR) backscatter from floating and grounded lake ice in arctic Alaska

2013 ◽  
Vol 7 (3) ◽  
pp. 2061-2088 ◽  
Author(s):  
M. Engram ◽  
K. W. Anthony ◽  
F. J. Meyer ◽  
G. Grosse
Keyword(s):  
Synthetic Aperture Radar ◽  
Fish Habitat ◽  
Synthetic Aperture ◽  
Lake Ice ◽  
Local Climate ◽  
Backscatter Intensity ◽  
Arctic Alaska ◽  
L Band ◽  
Aperture Radar

Abstract. Synthetic aperture radar (SAR) backscatter from floating lake ice is high, in contrast to low backscatter values from lake ice that is frozen completely to the lake bed (grounded ice). Knowledge of floating vs. grounded lake ice is useful for determining winter water supply, fish habitat, heat transfer to permafrost, and to observe changes in perennial lake ice status that could correlate with variations in local climate. Here, we compare calibrated L-band (23.6 cm wavelength) single- and L-band quadrature-polarized SAR return to the backscatter intensity of C-band (5.6 cm wavelength) SAR from floating and grounded lake ice over two regions in Alaska. Our primary goal was to determine if C or L-band is more useful to distinguish floating from grounded lake ice. C-band SAR showed far greater contrast between floating and grounded lake ice, making it the preferred wavelength for identifying lake ice regimes. L-band SAR backscatter was much lower from floating ice than C-band and it was different for our two study regions. Furthermore, since L-band is sensitive to ebullition bubbles trapped by lake ice (bubbles increase backscatter), this study helps to elucidate potential confounding factors of bubbles in efforts to detect floating vs. grounded ice using L-band SAR.

scholarly journals Mapping potential signs of gas emissions in ice of lake Neyto, Yamal, Russia using synthetic aperture radar and multispectral remote sensing data

2020 ◽  
Author(s):  
Georg Pointner ◽  
Annett Bartsch ◽  
Yury A. Dvornikov ◽  
Alexei V. Kouraev
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
The Arctic ◽  
Alos Palsar ◽  
Lake Ice ◽  
Gas Emissions ◽  
Optical Imagery ◽  
Sar Data ◽  
Sar Imagery ◽  
Aperture Radar

Abstract. Regions of anomalously low backscatter in C-band Synthetic Aperture Radar (SAR) imagery of lake ice of lake Neyto in northwestern Siberia have been suggested to be caused by emissions of gas (methane from hydrocarbon reservoirs) through the lake's sediments before. However, to assess this connection, only analyses of data from boreholes in the vicinity of lake Neyto and visual comparisons to medium-resolution optical imagery have been provided so far due to lack of in situ observations of the lake ice itself. These observations are impeded due to accessibility and safety issues. Geospatial analyses and innovative combinations of satellite data sources are therefore proposed to advance our understanding of this phenomenon. In this study, we assess the nature of the backscatter anomalies in Sentinel-1 C-band SAR images in combination with Very High Resolution (VHR) WorldView-2 optical imagery. We present methods to automatically map backscatter anomaly regions from the C-band SAR data (40 m pixel-spacing) and holes in lake ice from the VHR data (0.5 m pixel-spacing), and examine their spatial relationships. The reliability of the SAR method is evaluated through comparison between different acquisition modes. The results show that the majority of mapped holes in the VHR data are clearly related to anomalies in SAR imagery acquired a few days earlier and also more than a month before, supporting the hypothesis of gas emissions as the cause of the backscatter anomalies. Further, a significant expansion of backscatter anomaly regions in spring is documented and quantified in all analysed years 2015 to 2019. Our study suggests that the backscatter anomalies might be caused by expanding cavities in the lake ice, formed by strong emissions of gas, which could also explain outcomes of polarimetric analyses of auxiliary L-band ALOS PALSAR-2 data. C-band SAR data is considered to be valuable for the identification of lakes showing similar phenomena across larger areas in the Arctic in future studies.

Analysis of lake ice dynamics and morphology on Lake El'gygytgyn, NE Siberia, using synthetic aperture radar (SAR) and Landsat

2002 ◽  
Vol 108 (D2) ◽  
Author(s):  
Matt Nolan ◽  
Glen Liston ◽  
Peter Prokein ◽  
Julie Brigham-Grette ◽  
Virgil L. Sharpton ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Lake Ice ◽  
Ice Dynamics ◽  
Lake El’Gygytgyn ◽  
Aperture Radar
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