Sea ice motion and open water area at the Ronne Polynia, Antarctica: Synthetic aperture radar observations versus model results

2013 ◽  
Vol 118 (4) ◽  
pp. 1940-1954 ◽  
Author(s):  
T. Hollands ◽  
V. Haid ◽  
W. Dierking ◽  
R. Timmermann ◽  
L. Ebner
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Open Water ◽  
Water Area ◽  
Synthetic Aperture ◽  
Radar Observations ◽  
Open Water Area ◽  
Versus Model ◽  
Aperture Radar

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.

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 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.

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.

scholarly journals Comparison of Target Detectors to Identify Icebergs in Quad-Polarimetric L-Band Synthetic Aperture Radar Data

2021 ◽  
Vol 13 (9) ◽  
pp. 1753
Author(s):  
Johnson Bailey ◽  
Armando Marino ◽  
Vahid Akbari
Keyword(s):  
Sea Ice ◽  
Synthetic Aperture Radar ◽  
Roc Curves ◽  
Radar Data ◽  
Open Ocean ◽  
Synthetic Aperture ◽  
False Alarms ◽  
Synthetic Aperture Radar Data ◽  
Whitening Filter ◽  
Aperture Radar

Icebergs represent hazards to ships and maritime activities and therefore their detection is essential. Synthetic Aperture Radar (SAR) satellites are very useful for this, due to their capability to acquire data under cloud cover and during day and night passes. In this work, we compared six state-of-the-art polarimetric target detectors to test their performance and ability to detect small-sized icebergs <120 m in four locations in Greenland. We used four single-look complex (SLC) ALOS-2 quad-polarimetric images from JAXA for quad-polarimetric detection and we compared with dual-polarimetric detectors using only the channels HH and HV. We also compared these detectors with single-polarimetric intensity channels and we tested using two scenarios: open ocean and sea ice. Our results show that the multi-look polarimetric whitening filter (MPWF) and the optimal polarimetric detector (OPD) provide the most optimal performance in quad- and dual-polarimetric mode detection. The analysis shows that, overall, quad-polarimetric detectors provide the best detection performance. When the false alarm rate (PF) is fixed to 10-5, the probabilities of detection (PD) are 0.99 in open ocean and 0.90 in sea ice. Dual-polarimetric or single-polarimetric detectors show an overall reduction in performance (the ROC curves show a decrease), but this degradation is not very large (<0.1) when the value of false alarms is relatively high (i.e., we are interested in bigger icebergs with a brighter backscattering >120 m, as they are easier to detect). However, the differences between quad- and dual- or single-polarimetric detectors became much more evident when the PF value was fixed to low detection probabilities 10-6 (i.e., smaller icebergs). In the single-polarimetric mode, the HV channel showed PD values of 0.62 for open ocean and 0.26 for sea ice, compared to values of 0.81 (open ocean) and 0.77 (sea ice) obtained with quad-polarimetric detectors.

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