Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products
The NASA MEaSUREs Inter-mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) project seeks to accelerate understanding of critical glaciers and ice sheet processes by providing researchers with global, low-latency, comprehensive and state of the art records of surface velocities and ele...
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ftcopernicus:oai:publications.copernicus.org:essd98867 2023-05-15T16:41:26+02:00 Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products Lei, Yang Gardner, Alex S. Agram, Piyush 2022-11-22 application/pdf https://doi.org/10.5194/essd-14-5111-2022 https://essd.copernicus.org/articles/14/5111/2022/ eng eng doi:10.5194/essd-14-5111-2022 https://essd.copernicus.org/articles/14/5111/2022/ eISSN: 1866-3516 Text 2022 ftcopernicus https://doi.org/10.5194/essd-14-5111-2022 2022-11-28T17:22:43Z The NASA MEaSUREs Inter-mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) project seeks to accelerate understanding of critical glaciers and ice sheet processes by providing researchers with global, low-latency, comprehensive and state of the art records of surface velocities and elevations as observed from space. Here we describe the image-pair ice velocity product and processing methodology for ESA Sentinel-1 radar data. We demonstrate improvements to the core processing algorithm for dense offset tracking, “ autoRIFT ”, that provide finer resolution (120 m instead of the previous 240 m used for version 1) and higher accuracy (20 % to 50 % improvement) data products with significantly enhanced computational efficiency ( > 2 orders of magnitude) when compared to earlier versions and the state of the art “dense ampcor” routine in the JPL ISCE software. In particular, the disparity filter is upgraded for handling finer grid resolution with overlapping search chip sizes, and the oversampling ratio in the subpixel cross-correlation estimation is adaptively determined for Sentinel-1 data by matching the precision of the measured displacement based on the search chip size used. A novel calibration is applied to the data to correct for Sentinel-1A/B subswath and full-swath dependent geolocation biases caused by systematic issues with the instruments. Sentinel-1 C-band images are affected by variations in the total electron content of the ionosphere that results in large velocity errors in the azimuth (along-track) direction. To reduce these effects, slant range (line of sight or LOS) velocities are used and accompanied by LOS parameters that support map coordinate ( x / y ) velocity inversion from ascending and descending slant range offset measurements, as derived from two image pairs. After the proposed correction of ionosphere errors, the uncertainties in velocities are reduced by 9 %–61 %. We further validate the ITS_LIVE Version 2 Sentinel-1 image-pair products, with 6-year time series composed ... Text Ice Sheet Copernicus Publications: E-Journals Earth System Science Data 14 11 5111 5137 |
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English |
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The NASA MEaSUREs Inter-mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) project seeks to accelerate understanding of critical glaciers and ice sheet processes by providing researchers with global, low-latency, comprehensive and state of the art records of surface velocities and elevations as observed from space. Here we describe the image-pair ice velocity product and processing methodology for ESA Sentinel-1 radar data. We demonstrate improvements to the core processing algorithm for dense offset tracking, “ autoRIFT ”, that provide finer resolution (120 m instead of the previous 240 m used for version 1) and higher accuracy (20 % to 50 % improvement) data products with significantly enhanced computational efficiency ( > 2 orders of magnitude) when compared to earlier versions and the state of the art “dense ampcor” routine in the JPL ISCE software. In particular, the disparity filter is upgraded for handling finer grid resolution with overlapping search chip sizes, and the oversampling ratio in the subpixel cross-correlation estimation is adaptively determined for Sentinel-1 data by matching the precision of the measured displacement based on the search chip size used. A novel calibration is applied to the data to correct for Sentinel-1A/B subswath and full-swath dependent geolocation biases caused by systematic issues with the instruments. Sentinel-1 C-band images are affected by variations in the total electron content of the ionosphere that results in large velocity errors in the azimuth (along-track) direction. To reduce these effects, slant range (line of sight or LOS) velocities are used and accompanied by LOS parameters that support map coordinate ( x / y ) velocity inversion from ascending and descending slant range offset measurements, as derived from two image pairs. After the proposed correction of ionosphere errors, the uncertainties in velocities are reduced by 9 %–61 %. We further validate the ITS_LIVE Version 2 Sentinel-1 image-pair products, with 6-year time series composed ... |
format |
Text |
author |
Lei, Yang Gardner, Alex S. Agram, Piyush |
spellingShingle |
Lei, Yang Gardner, Alex S. Agram, Piyush Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
author_facet |
Lei, Yang Gardner, Alex S. Agram, Piyush |
author_sort |
Lei, Yang |
title |
Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
title_short |
Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
title_full |
Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
title_fullStr |
Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
title_full_unstemmed |
Processing methodology for the ITS_LIVE Sentinel-1 ice velocity products |
title_sort |
processing methodology for the its_live sentinel-1 ice velocity products |
publishDate |
2022 |
url |
https://doi.org/10.5194/essd-14-5111-2022 https://essd.copernicus.org/articles/14/5111/2022/ |
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Ice Sheet |
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Ice Sheet |
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eISSN: 1866-3516 |
op_relation |
doi:10.5194/essd-14-5111-2022 https://essd.copernicus.org/articles/14/5111/2022/ |
op_doi |
https://doi.org/10.5194/essd-14-5111-2022 |
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Earth System Science Data |
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5111 |
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