Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data
This dataset comprises high spatial- and temporal-resolution maps of coastal landfast sea ice (fast ice) distribution in the vicinity of the Cape Darnley Polynya in East Antarctica, in the June-November (winter-spring) periods of 2008 and 2009. The maps were derived from cross-correlation of pairs o...
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Format: | Dataset |
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Australian Antarctic Data Centre
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Online Access: | https://researchdata.ands.org.au/regional-high-resolution-radar-sar/1440000 https://doi.org/10.26179/5dd33c1c8e55d https://data.aad.gov.au/metadata/records/AAS_4116_Fast-Ice-SAR http://nla.gov.au/nla.party-617536 |
id |
ftands:oai:ands.org.au::1440000 |
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record_format |
openpolar |
institution |
Open Polar |
collection |
Research Data Australia (Australian National Data Service - ANDS) |
op_collection_id |
ftands |
language |
unknown |
topic |
climatologyMeteorologyAtmosphere oceans POLYNYAS EARTH SCIENCE CRYOSPHERE SEA ICE ICE TYPES ICE EXTENT FAST ICE TIME SERIES MAPPING ASAR > Advanced Synthetic Aperature Radar ENVISAT > Environmental Satellite GEOGRAPHIC REGION > POLAR OCEAN > SOUTHERN OCEAN CONTINENT > ANTARCTICA > CAPE DARNLEY POLYNYA |
spellingShingle |
climatologyMeteorologyAtmosphere oceans POLYNYAS EARTH SCIENCE CRYOSPHERE SEA ICE ICE TYPES ICE EXTENT FAST ICE TIME SERIES MAPPING ASAR > Advanced Synthetic Aperature Radar ENVISAT > Environmental Satellite GEOGRAPHIC REGION > POLAR OCEAN > SOUTHERN OCEAN CONTINENT > ANTARCTICA > CAPE DARNLEY POLYNYA Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
topic_facet |
climatologyMeteorologyAtmosphere oceans POLYNYAS EARTH SCIENCE CRYOSPHERE SEA ICE ICE TYPES ICE EXTENT FAST ICE TIME SERIES MAPPING ASAR > Advanced Synthetic Aperature Radar ENVISAT > Environmental Satellite GEOGRAPHIC REGION > POLAR OCEAN > SOUTHERN OCEAN CONTINENT > ANTARCTICA > CAPE DARNLEY POLYNYA |
description |
This dataset comprises high spatial- and temporal-resolution maps of coastal landfast sea ice (fast ice) distribution in the vicinity of the Cape Darnley Polynya in East Antarctica, in the June-November (winter-spring) periods of 2008 and 2009. The maps were derived from cross-correlation of pairs of spatially-overlapping Envisat Advanced Synthetic Aperture Radar (ASAR) images, using a modified version of the IMCORR algorithm to determine vectors of sea-ice motion (as described in Giles et al., 2011). Fast ice is then distinguished from moving pack ice by the fact that it is stationary. The raw ASAR WSM data (swath width 500 km) were processed using ENVI image processing software to produce geo-referenced images with a 75m pixel size. Use of SAR data ensures coverage uninterrupted by cloud cover or polar darkness. Image pairs were chosen with a time separation between 2 and 21 days. IMCORR processing of the image pairs for mapping fast ice follows Giles et al (2011) – using a reference tile size of 32x32 pixels and a search tile size of 64 x 64 pixels. A land mask was applied to avoid contamination from matches on stationary features over the continental ice sheet. The grid spacing was set to 16 x 16 pixels, so the images were over-sampled by a factor of 2 to provide a more dense set of results. Stationary fast ice vectors were chosen from the IMCORR results using a combination of the cluster search technique and a variation of the z-axis threshold technique as detailed in Giles et al (2011). The cluster search technique was applied to the IMCORR results from each image pair to derive the initial set of valid vectors – this set could contain both stationary fast ice vectors and non-stationary pack ice vectors. Due to registration errors in the image pairs, the stationary vectors will not necessarily be centred around zero, so using a simple window around the zero offset mark to differentiate the fast ice vectors was not possible. To select the stationary vectors, a 2D histogram was constructed from the X-Y vector displacements, and a 2D Gaussian was fitted to this histogram. The fast ice vectors will dominate because of the large image pair time separation and small search tile size, so the Gaussian peak should correspond to the centre of the stationary fast ice vectors. All vectors that are within 5 standard deviations of the Gaussian peak are tagged as valid fast ice vectors. This is a minor modification to the method of Giles et al (2011), who used a simple threshold cut on the z-axis of the 2D histogram to define the fast ice vectors. Data format – one fully annotated (self-describing) netCDF file per image pair containing latitude/longitude coordinates of the stationary fast ice vectors. This technique and dataset complement a lower resolution but longer-term dataset (2000-2014) derived from satellite MODIS visible and thermal infrared data. (AAS_4116_Fraser_fastice_mawson_capedarnley). |
author2 |
HYLAND, GLENN (hasPrincipalInvestigator) HYLAND, GLENN (processor) MASSOM, ROB (hasPrincipalInvestigator) HEIL, PETRA (hasPrincipalInvestigator) Australian Antarctic Data Centre (publisher) |
format |
Dataset |
title |
Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
title_short |
Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
title_full |
Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
title_fullStr |
Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
title_full_unstemmed |
Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data |
title_sort |
regional high-resolution fast ice maps - satellite synthetic aperture radar (sar) data |
publisher |
Australian Antarctic Data Centre |
url |
https://researchdata.ands.org.au/regional-high-resolution-radar-sar/1440000 https://doi.org/10.26179/5dd33c1c8e55d https://data.aad.gov.au/metadata/records/AAS_4116_Fast-Ice-SAR http://nla.gov.au/nla.party-617536 |
op_coverage |
Spatial: northlimit=-65; southlimit=-70; westlimit=50; eastLimit=80; projection=WGS84 Temporal: From 2008-05-01 to 2008-11-30 |
long_lat |
ENVELOPE(134.033,134.033,68.667,68.667) ENVELOPE(69.567,69.567,-67.738,-67.738) ENVELOPE(69.717,69.717,-67.717,-67.717) ENVELOPE(-137.617,-137.617,-75.150,-75.150) ENVELOPE(50,80,-65,-70) |
geographic |
Asar Cape Darnley Darnley East Antarctica Giles Southern Ocean |
geographic_facet |
Asar Cape Darnley Darnley East Antarctica Giles Southern Ocean |
genre |
Antarc* Antarctica East Antarctica Ice Sheet Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctica East Antarctica Ice Sheet Sea ice Southern Ocean |
op_source |
Australian Antarctic Data Centre |
op_relation |
https://researchdata.ands.org.au/regional-high-resolution-radar-sar/1440000 dab79118-a763-4b25-a9ff-38f1e20999f0 doi:10.26179/5dd33c1c8e55d AAS_4116_Fast-Ice-SAR https://data.aad.gov.au/metadata/records/AAS_4116_Fast-Ice-SAR http://nla.gov.au/nla.party-617536 |
op_doi |
https://doi.org/10.26179/5dd33c1c8e55d |
_version_ |
1766256113385209856 |
spelling |
ftands:oai:ands.org.au::1440000 2023-05-15T13:52:00+02:00 Regional high-resolution fast ice maps - Satellite synthetic aperture radar (SAR) data HYLAND, GLENN (hasPrincipalInvestigator) HYLAND, GLENN (processor) MASSOM, ROB (hasPrincipalInvestigator) HEIL, PETRA (hasPrincipalInvestigator) Australian Antarctic Data Centre (publisher) Spatial: northlimit=-65; southlimit=-70; westlimit=50; eastLimit=80; projection=WGS84 Temporal: From 2008-05-01 to 2008-11-30 https://researchdata.ands.org.au/regional-high-resolution-radar-sar/1440000 https://doi.org/10.26179/5dd33c1c8e55d https://data.aad.gov.au/metadata/records/AAS_4116_Fast-Ice-SAR http://nla.gov.au/nla.party-617536 unknown Australian Antarctic Data Centre https://researchdata.ands.org.au/regional-high-resolution-radar-sar/1440000 dab79118-a763-4b25-a9ff-38f1e20999f0 doi:10.26179/5dd33c1c8e55d AAS_4116_Fast-Ice-SAR https://data.aad.gov.au/metadata/records/AAS_4116_Fast-Ice-SAR http://nla.gov.au/nla.party-617536 Australian Antarctic Data Centre climatologyMeteorologyAtmosphere oceans POLYNYAS EARTH SCIENCE CRYOSPHERE SEA ICE ICE TYPES ICE EXTENT FAST ICE TIME SERIES MAPPING ASAR > Advanced Synthetic Aperature Radar ENVISAT > Environmental Satellite GEOGRAPHIC REGION > POLAR OCEAN > SOUTHERN OCEAN CONTINENT > ANTARCTICA > CAPE DARNLEY POLYNYA dataset ftands https://doi.org/10.26179/5dd33c1c8e55d 2020-01-05T23:00:15Z This dataset comprises high spatial- and temporal-resolution maps of coastal landfast sea ice (fast ice) distribution in the vicinity of the Cape Darnley Polynya in East Antarctica, in the June-November (winter-spring) periods of 2008 and 2009. The maps were derived from cross-correlation of pairs of spatially-overlapping Envisat Advanced Synthetic Aperture Radar (ASAR) images, using a modified version of the IMCORR algorithm to determine vectors of sea-ice motion (as described in Giles et al., 2011). Fast ice is then distinguished from moving pack ice by the fact that it is stationary. The raw ASAR WSM data (swath width 500 km) were processed using ENVI image processing software to produce geo-referenced images with a 75m pixel size. Use of SAR data ensures coverage uninterrupted by cloud cover or polar darkness. Image pairs were chosen with a time separation between 2 and 21 days. IMCORR processing of the image pairs for mapping fast ice follows Giles et al (2011) – using a reference tile size of 32x32 pixels and a search tile size of 64 x 64 pixels. A land mask was applied to avoid contamination from matches on stationary features over the continental ice sheet. The grid spacing was set to 16 x 16 pixels, so the images were over-sampled by a factor of 2 to provide a more dense set of results. Stationary fast ice vectors were chosen from the IMCORR results using a combination of the cluster search technique and a variation of the z-axis threshold technique as detailed in Giles et al (2011). The cluster search technique was applied to the IMCORR results from each image pair to derive the initial set of valid vectors – this set could contain both stationary fast ice vectors and non-stationary pack ice vectors. Due to registration errors in the image pairs, the stationary vectors will not necessarily be centred around zero, so using a simple window around the zero offset mark to differentiate the fast ice vectors was not possible. To select the stationary vectors, a 2D histogram was constructed from the X-Y vector displacements, and a 2D Gaussian was fitted to this histogram. The fast ice vectors will dominate because of the large image pair time separation and small search tile size, so the Gaussian peak should correspond to the centre of the stationary fast ice vectors. All vectors that are within 5 standard deviations of the Gaussian peak are tagged as valid fast ice vectors. This is a minor modification to the method of Giles et al (2011), who used a simple threshold cut on the z-axis of the 2D histogram to define the fast ice vectors. Data format – one fully annotated (self-describing) netCDF file per image pair containing latitude/longitude coordinates of the stationary fast ice vectors. This technique and dataset complement a lower resolution but longer-term dataset (2000-2014) derived from satellite MODIS visible and thermal infrared data. (AAS_4116_Fraser_fastice_mawson_capedarnley). Dataset Antarc* Antarctica East Antarctica Ice Sheet Sea ice Southern Ocean Research Data Australia (Australian National Data Service - ANDS) Asar ENVELOPE(134.033,134.033,68.667,68.667) Cape Darnley ENVELOPE(69.567,69.567,-67.738,-67.738) Darnley ENVELOPE(69.717,69.717,-67.717,-67.717) East Antarctica Giles ENVELOPE(-137.617,-137.617,-75.150,-75.150) Southern Ocean ENVELOPE(50,80,-65,-70) |