scholarly journals Consistent ice and open water classification combining historical synthetic aperture radar satellite images from ERS-1/2, Envisat ASAR, RADARSAT-2 and Sentinel-1A/B

2020 ◽  
Vol 61 (82) ◽  
pp. 40-50 ◽  
Author(s):  
A. Malin Johansson ◽  
Eirik Malnes ◽  
Sebastian Gerland ◽  
Anca Cristea ◽  
Anthony P. Doulgeris ◽  
...  
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Satellite Images ◽  
Satellite Image ◽  
Open Water ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Synthetic Aperture ◽  
Envisat Asar ◽  
Aperture Radar

AbstractSynthetic Aperture Radar (SAR) satellite images are used to monitor Arctic sea ice, with systematic data records dating back to 1991. We propose a semi-supervised classification method that separates open water from sea ice and can utilise ERS-1/2, Envisat ASAR, RADARSAT-2 and Sentinel-1 SAR images. The classification combines automatic segmentation with a manual segment selection stage. The segmentation algorithm requires only the backscatter intensities and incidence angle values as input, therefore can be used to establish a consistent decadal sea ice record. In this study we investigate the sea ice conditions in two Svalbard fjords, Kongsfjorden and Rijpfjorden. Both fjords have a seasonal ice cover, though Rijpfjorden has a longer sea ice season. The satellite image dataset has weekly to daily records from 2002 until now, and less frequent records between 1991 and 2002. Time overlap between different sensors is investigated to ensure consistency in the reported sea ice cover. The classification results have been compared to high-resolution SAR data as well as in-situ measurements and sea ice maps from Ny-Ålesund. For both fjords the length of the sea ice season has shortened since 2002 and for Kongsfjorden the maximum sea ice coverage is significantly lower after 2006.

Satellite Radar Imagery for Detection and Monitoring of Geohazards

2020 ◽  
Vol 2674 (3) ◽  
pp. 283-292
Author(s):  
Sumanth V. Byrraju ◽  
Dimitris C. Rizos ◽  
Yu Qian
Keyword(s):  
Moisture Content ◽  
Synthetic Aperture Radar ◽  
Satellite Images ◽  
Satellite Image ◽  
Synthetic Aperture ◽  
Small Scale ◽  
Interferometric Synthetic Aperture Radar ◽  
Right Of Way ◽  
The Right ◽  
Aperture Radar

This paper presents three case studies that were part of a 1-year study that explores the feasibility of using commercially available satellite and other aerial imagery to monitor the right of way of railroads for effects and conditions that could potentially trigger landslides and other geohazards. Two satellite image processing techniques in the Interferometric Synthetic Aperture Radar (InSAR) family have been studied and employed, that is, the Differential Interferometric Synthetic Aperture Radar (DInSAR) and the Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR). All satellite images used in this work are in the public domain and the software is open source. Showcase studies have demonstrated that the current satellite technology makes it feasible to monitor the railway right of way for large- and small-scale deformations and changes in the ground moisture content in adequate resolution. The frequency of acquisition of satellite images is adequate for the long-term monitoring of the infrastructure. The satellite analysis results can be superimposed to visual imagery for ease of visual inspection and evaluation. Future work for the development of a monitoring system of the railway right of way needs to focus on verifying the accuracy of the techniques with in situ measurements through conventional means and quantifying the changes of the moisture content.

scholarly journals A Digital Technique to Estimate Polynya Characteristics from Synthetic Aperture Radar Sea-Ice Data

1987 ◽  
Vol 33 (114) ◽  
pp. 243-245
Author(s):  
James D. Lyden ◽  
Robert A. Shuchman
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Autocorrelation Function ◽  
Open Water ◽  
Binary Image ◽  
Synthetic Aperture ◽  
Digital Technique ◽  
Preliminary Results ◽  
A New Technique ◽  
Aperture Radar

AbstractA new technique has been developed to estimate digitally the concentration and structure of open-water leads (polynyas) in synthetic aperture radar (SAR) sea-ice data. This procedure consists of smoothing the original SAR sea-ice data to reduce speckle effects, level slicing this smoothed image to produce a binary image consisting of ice and open water, generating the autocorrelation function of this image, and interpreting the autocorrelation function for lead information. Preliminary results indicate that this technique yields useful estimates of lead characteristics, but that additional research is required to evaluate fully its performance.

scholarly journals Waveform classification of airborne synthetic aperture radar altimeter over Arctic sea ice

2013 ◽  
Vol 7 (4) ◽  
pp. 1315-1324 ◽  
Author(s):  
M. Zygmuntowska ◽  
K. Khvorostovsky ◽  
V. Helm ◽  
S. Sandven
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Arctic Sea Ice ◽  
Synthetic Aperture ◽  
The Arctic ◽  
Ice Thickness ◽  
Radar Altimeter ◽  
Sea Ice Thickness ◽  
Ku Band ◽  
Aperture Radar

Abstract. Sea ice thickness is one of the most sensitive variables in the Arctic climate system. In order to quantify changes in sea ice thickness, CryoSat-2 was launched in 2010 carrying a Ku-band radar altimeter (SIRAL) designed to measure sea ice freeboard with a few centimeters accuracy. The instrument uses the synthetic aperture radar technique providing signals with a resolution of about 300 m along track. In this study, airborne Ku-band radar altimeter data over different sea ice types have been analyzed. A set of parameters has been defined to characterize the differences in strength and width of the returned power waveforms. With a Bayesian-based method, it is possible to classify about 80% of the waveforms from three parameters: maximum of the returned power waveform, the trailing edge width and pulse peakiness. Furthermore, the maximum of the power waveform can be used to reduce the number of false detections of leads, compared to the widely used pulse peakiness parameter. For the pulse peakiness the false classification rate is 12.6% while for the power maximum it is reduced to 6.5%. The ability to distinguish between different ice types and leads allows us to improve the freeboard retrieval and the conversion from freeboard into sea ice thickness, where surface type dependent values for the sea ice density and snow load can be used.

scholarly journals BEPERS pilot study: an experiment with X-band synthetic aperture radar over Baltic Sea ice

1992 ◽  
Vol 38 (128) ◽  
pp. 23-35 ◽  
Author(s):  
Matti Leppäranta ◽  
Rlsto Kuittinen ◽  
Jan Askne
Keyword(s):  
Pilot Study ◽  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Baltic Sea ◽  
Open Water ◽  
Synthetic Aperture ◽  
Speckle Reduction ◽  
X Band ◽  
Sar Imagery ◽  
Aperture Radar

Abstract Remote-sensing methods are the primary ones used for ice mapping in the Baltic Sea. A major methodological improvement is now being introduced by satellite radars due to their weather independency and high resolution. To learn how to use ERS-1 synthetic aperture radar (SAR) data, an extensive field programme BEPERS (Bothnian Experiment in Preparation for ERS-1) with airborne SARs has been arranged. The BEPERS pilot study was undertaken in 1987 using the French VARAN-S X-band SAR. The SAR was flown on 1 day over four study areas of size approximately 10 km x 50 km, and intensive validation observations were made. The data were most useful for the education they provided on how to work with SAR in sea-ice mapping. They have been used for developing SAR image-analysis methods, back-scatter modelling investigations and geophysical validation of SAR imagery. Cleaning-up of images consisted of speckle reduction and segmentation. Back-scatter characteristics of undeformed ice and ridges were examined. Ice-type classification was based on the box-classification method. Eight ice types were defined but basically only two types, undeformed ice/open water and deformed ice, could be discriminated. Two basic problems of high practical importance remained: how to discriminate between (1) open water and undeformed ice, and (2) ridged ice and brash ice. The data further showed illustrative examples of SAR imagery over sea ice.

Observation of melt onset on multiyear Arctic sea ice using the ERS 1 synthetic aperture radar

1994 ◽  
Vol 99 (C11) ◽  
pp. 22425 ◽  
Author(s):  
D. P. Winebrenner ◽  
E. D. Nelson ◽  
R. Colony ◽  
R. D. West
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Arctic Sea Ice ◽  
Synthetic Aperture ◽  
Arctic Sea ◽  
Aperture Radar

scholarly journals A practical algorithm for the retrieval of floe size distribution of Arctic sea ice from high-resolution satellite Synthetic Aperture Radar imagery

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Byongjun Hwang ◽  
Jinchang Ren ◽  
Samuel McCormack ◽  
Craig Berry ◽  
Ismail Ben Ayed ◽  
...  
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Size Distribution ◽  
Ground Truth ◽  
Arctic Sea Ice ◽  
Synthetic Aperture ◽  
Distribution Data ◽  
Synthetic Aperture Radar Data ◽  
Arctic Sea ◽  
Aperture Radar

In this study, we present an algorithm for summer sea ice conditions that semi-automatically produces the floe size distribution of Arctic sea ice from high-resolution satellite Synthetic Aperture Radar data. Currently, floe size distribution data from satellite images are very rare in the literature, mainly due to the lack of a reliable algorithm to produce such data. Here, we developed the algorithm by combining various image analysis methods, including Kernel Graph Cuts, distance transformation and watershed transformation, and a rule-based boundary revalidation. The developed algorithm has been validated against the ground truth that was extracted manually with the aid of 1-m resolution visible satellite data. Comprehensive validation analysis has shown both perspectives and limitations. The algorithm tends to fail to detect small floes (mostly less than 100 m in mean caliper diameter) compared to ground truth, which is mainly due to limitations in water-ice segmentation. Some variability in the power law exponent of floe size distribution is observed due to the effects of control parameters in the process of de-noising, Kernel Graph Cuts segmentation, thresholds for boundary revalidation and image resolution. Nonetheless, the algorithm, for floes larger than 100 m, has shown a reasonable agreement with ground truth under various selections of these control parameters. Considering that the coverage and spatial resolution of satellite Synthetic Aperture Radar data have increased significantly in recent years, the developed algorithm opens a new possibility to produce large volumes of floe size distribution data, which is essential for improving our understanding and prediction of the Arctic sea ice cover.

scholarly journals A Digital Technique to Estimate Polynya Characteristics from Synthetic Aperture Radar Sea-Ice Data

1987 ◽  
Vol 33 (114) ◽  
pp. 243-245
Author(s):  
James D. Lyden ◽  
Robert A. Shuchman
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Autocorrelation Function ◽  
Open Water ◽  
Binary Image ◽  
Synthetic Aperture ◽  
Digital Technique ◽  
Preliminary Results ◽  
A New Technique ◽  
Aperture Radar

Abstract A new technique has been developed to estimate digitally the concentration and structure of open-water leads (polynyas) in synthetic aperture radar (SAR) sea-ice data. This procedure consists of smoothing the original SAR sea-ice data to reduce speckle effects, level slicing this smoothed image to produce a binary image consisting of ice and open water, generating the autocorrelation function of this image, and interpreting the autocorrelation function for lead information. Preliminary results indicate that this technique yields useful estimates of lead characteristics, but that additional research is required to evaluate fully its performance.

scholarly journals BEPERS pilot study: an experiment with X-band synthetic aperture radar over Baltic Sea ice

1992 ◽  
Vol 38 (128) ◽  
pp. 23-35
Author(s):  
Matti Leppäranta ◽  
Rlsto Kuittinen ◽  
Jan Askne
Keyword(s):  
Pilot Study ◽  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Baltic Sea ◽  
Open Water ◽  
Synthetic Aperture ◽  
Speckle Reduction ◽  
X Band ◽  
Sar Imagery ◽  
Aperture Radar

AbstractRemote-sensing methods are the primary ones used for ice mapping in the Baltic Sea. A major methodological improvement is now being introduced by satellite radars due to their weather independency and high resolution. To learn how to use ERS-1 synthetic aperture radar (SAR) data, an extensive field programme BEPERS (Bothnian Experiment in Preparation for ERS-1) with airborne SARs has been arranged. The BEPERS pilot study was undertaken in 1987 using the French VARAN-S X-band SAR. The SAR was flown on 1 day over four study areas of size approximately 10 km x 50 km, and intensive validation observations were made. The data were most useful for the education they provided on how to work with SAR in sea-ice mapping. They have been used for developing SAR image-analysis methods, back-scatter modelling investigations and geophysical validation of SAR imagery. Cleaning-up of images consisted of speckle reduction and segmentation. Back-scatter characteristics of undeformed ice and ridges were examined. Ice-type classification was based on the box-classification method. Eight ice types were defined but basically only two types, undeformed ice/open water and deformed ice, could be discriminated. Two basic problems of high practical importance remained: how to discriminate between (1) open water and undeformed ice, and (2) ridged ice and brash ice. The data further showed illustrative examples of SAR imagery over sea ice.

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