Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns
In this paper we develop a CryoSat-2 algorithm to retrieve the surface elevation of the air–snow interface over Antarctic sea ice. This algorithm utilizes a two-layer physical model that accounts for scattering from a snow layer atop sea ice as well as scattering from below the snow surface. The mod...
Published in: | The Cryosphere |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2019
|
Subjects: | |
Online Access: | https://doi.org/10.5194/tc-13-861-2019 https://doaj.org/article/6bcf9a2aaea244559950a2dbc6f5d192 |
id |
ftdoajarticles:oai:doaj.org/article:6bcf9a2aaea244559950a2dbc6f5d192 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:6bcf9a2aaea244559950a2dbc6f5d192 2023-05-15T13:07:37+02:00 Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns S. W. Fons N. T. Kurtz 2019-03-01T00:00:00Z https://doi.org/10.5194/tc-13-861-2019 https://doaj.org/article/6bcf9a2aaea244559950a2dbc6f5d192 EN eng Copernicus Publications https://www.the-cryosphere.net/13/861/2019/tc-13-861-2019.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-13-861-2019 1994-0416 1994-0424 https://doaj.org/article/6bcf9a2aaea244559950a2dbc6f5d192 The Cryosphere, Vol 13, Pp 861-878 (2019) Environmental sciences GE1-350 Geology QE1-996.5 article 2019 ftdoajarticles https://doi.org/10.5194/tc-13-861-2019 2022-12-31T15:08:47Z In this paper we develop a CryoSat-2 algorithm to retrieve the surface elevation of the air–snow interface over Antarctic sea ice. This algorithm utilizes a two-layer physical model that accounts for scattering from a snow layer atop sea ice as well as scattering from below the snow surface. The model produces waveforms that are fit to CryoSat-2 level 1B data through a bounded trust region least-squares fitting process. These fit waveforms are then used to track the air–snow interface and retrieve the surface elevation at each point along the CryoSat-2 ground track, from which the snow freeboard is computed. To validate this algorithm, we compare retrieved surface elevation measurements and snow surface radar return power levels with those from Operation IceBridge, which flew along a contemporaneous CryoSat-2 orbit in October 2011 and November 2012. Average elevation differences (standard deviations) along the flight lines (IceBridge Airborne Topographic Mapper, ATM – CryoSat-2) are found to be 0.016 cm (29.24 cm) in 2011 and 2.58 cm (26.65 cm) in 2012. The spatial distribution of monthly average pan-Antarctic snow freeboard found using this method is similar to what was observed from NASA's Ice, Cloud, and land Elevation Satellite (ICESat), where the difference (standard deviation) between October 2011–2017 CryoSat-2 mean snow freeboard and spring 2003–2007 mean freeboard from ICESat is 1.92 cm (9.23 cm). While our results suggest that this physical model and waveform fitting method can be used to retrieve snow freeboard from CryoSat-2, allowing for the potential to join laser and radar altimetry data records in the Antarctic, larger ( ∼30 cm) regional differences from ICESat and along-track differences from ATM do exist, suggesting the need for future improvements to the method. Snow–ice interface elevation retrieval is also explored as a potential to obtain snow depth measurements. However, it is found that this retrieval method often tracks a strong scattering layer within the snow layer instead of the ... Article in Journal/Newspaper Airborne Topographic Mapper Antarc* Antarctic Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic The Cryosphere 13 3 861 878 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 S. W. Fons N. T. Kurtz Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
In this paper we develop a CryoSat-2 algorithm to retrieve the surface elevation of the air–snow interface over Antarctic sea ice. This algorithm utilizes a two-layer physical model that accounts for scattering from a snow layer atop sea ice as well as scattering from below the snow surface. The model produces waveforms that are fit to CryoSat-2 level 1B data through a bounded trust region least-squares fitting process. These fit waveforms are then used to track the air–snow interface and retrieve the surface elevation at each point along the CryoSat-2 ground track, from which the snow freeboard is computed. To validate this algorithm, we compare retrieved surface elevation measurements and snow surface radar return power levels with those from Operation IceBridge, which flew along a contemporaneous CryoSat-2 orbit in October 2011 and November 2012. Average elevation differences (standard deviations) along the flight lines (IceBridge Airborne Topographic Mapper, ATM – CryoSat-2) are found to be 0.016 cm (29.24 cm) in 2011 and 2.58 cm (26.65 cm) in 2012. The spatial distribution of monthly average pan-Antarctic snow freeboard found using this method is similar to what was observed from NASA's Ice, Cloud, and land Elevation Satellite (ICESat), where the difference (standard deviation) between October 2011–2017 CryoSat-2 mean snow freeboard and spring 2003–2007 mean freeboard from ICESat is 1.92 cm (9.23 cm). While our results suggest that this physical model and waveform fitting method can be used to retrieve snow freeboard from CryoSat-2, allowing for the potential to join laser and radar altimetry data records in the Antarctic, larger ( ∼30 cm) regional differences from ICESat and along-track differences from ATM do exist, suggesting the need for future improvements to the method. Snow–ice interface elevation retrieval is also explored as a potential to obtain snow depth measurements. However, it is found that this retrieval method often tracks a strong scattering layer within the snow layer instead of the ... |
format |
Article in Journal/Newspaper |
author |
S. W. Fons N. T. Kurtz |
author_facet |
S. W. Fons N. T. Kurtz |
author_sort |
S. W. Fons |
title |
Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
title_short |
Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
title_full |
Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
title_fullStr |
Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
title_full_unstemmed |
Retrieval of snow freeboard of Antarctic sea ice using waveform fitting of CryoSat-2 returns |
title_sort |
retrieval of snow freeboard of antarctic sea ice using waveform fitting of cryosat-2 returns |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/tc-13-861-2019 https://doaj.org/article/6bcf9a2aaea244559950a2dbc6f5d192 |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Airborne Topographic Mapper Antarc* Antarctic Sea ice The Cryosphere |
genre_facet |
Airborne Topographic Mapper Antarc* Antarctic Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 13, Pp 861-878 (2019) |
op_relation |
https://www.the-cryosphere.net/13/861/2019/tc-13-861-2019.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-13-861-2019 1994-0416 1994-0424 https://doaj.org/article/6bcf9a2aaea244559950a2dbc6f5d192 |
op_doi |
https://doi.org/10.5194/tc-13-861-2019 |
container_title |
The Cryosphere |
container_volume |
13 |
container_issue |
3 |
container_start_page |
861 |
op_container_end_page |
878 |
_version_ |
1766061373850124288 |