Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway)
Due to recent climate change conditions, i.e. increasing temperatures and changing precipitation patterns, arctic snow cover dynamics exhibit strong changes in terms of extent and duration. Arctic amplification processes and impacts are well documented expected to strengthen in coming decades. In th...
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2021
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Online Access: | https://epic.awi.de/id/eprint/54995/ https://doi.org/10.5194/egusphere-egu21-149 https://hdl.handle.net/10013/epic.90248998-33d8-4c7e-8590-d57c965544db |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
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Due to recent climate change conditions, i.e. increasing temperatures and changing precipitation patterns, arctic snow cover dynamics exhibit strong changes in terms of extent and duration. Arctic amplification processes and impacts are well documented expected to strengthen in coming decades. In this context, innovative observation methods are helpful for a better comprehension of the spatial variability of snow properties relevant for climate research and hydrological applications. Microwave remote sensing provides exceptional spatial and temporal performance in terms of all-weather application and target penetration. Time-series of Synthetic Active Radar images (SAR) are becoming more accessible at different frequencies and polarimetry has demonstrated a significant advantage for detecting changes in different media. Concerning arctic snow monitoring, SAR sensors can offer continuous time-series during the polar night and with cloud cover, providing a consequent advantage in regard of optical sensors. The aim of this study is dedicated to the spatial/temporal variability of snow in the Ny-Ålesund area on the Br∅gger peninsula, Svalbard (N 78°55’ / E 11° 55’). The TerraSAR-X satellite (DLR, Germany) operated at X-band (3.1 cm, 9.6 GHz) with dual co-pol mode (HH/VV) at 5-m spatial resolution, and with high incidence angles (36° to 39°) poviding a better snow penetration and reducing topographic constraints. A dataset of 92 images (ascending and descending) is available since 2017, together with a high resolution DEM (NPI 5-m) and consistent in-situ measurements of meteorological data and snow profiles including glaciers sites. Polarimetric processing is based on the Kennaugh matrix decomposition, copolar phase coherence (CCOH) and copolar phase difference (CPD). The Kennaugh matrix elements K0, K3, K4, and K7 are, respectively, the total intensity, phase ratio, intensity ratio, and shift between HH and VV phase center. Their interpretation allows analysing the structure of the snowpack linked to the near real time of in-situ measurements (snow profiles). The X-band signal is strongly influenced by the snow stratigraphy: internal ice layers reduce or block the penetration of the signal into the snow pack. The best R2 correlation performances between estimated and measured snow heights are ranging from 0.50 to 0.70 for dry snow conditions. Therefore, the use of the X-band for regular snow height estimations remains limited under these conditions. Conversely, this study shows the benefit of TerraSAR-X thanks to the Kennaugh matrix elements analysis. A focus is set on the Copolar Phase Difference (CPD, Leinss 2016) between VV and HH polarization: Φ CPD = Φ VV - Φ HH. Our results indicate that the CPD values are related to the snow metamorphism: positive values correspond to dry snow (horizontal structures), negative values indicate recrystallization processes (vertical structures). Backscattering evolution in time offer a good proxy for meteorological events detection, impacting on snow metamorphism. Fresh snowfalls or melting processes can then be retrieved at the regional scale and linked to air temperature or precipitation measurements at local scale. Polarimetric SAR time series is therefore of interest to complement satellite-based precipitation measurements in the Arctic. |
format |
Conference Object |
author |
Dedieu, Jean-Pierre Wendleder, Anna Cerino, Bastien Boike, Julia Bernard, Eric Gallet, Jean-Charles Jacobi, Hans-Werner |
spellingShingle |
Dedieu, Jean-Pierre Wendleder, Anna Cerino, Bastien Boike, Julia Bernard, Eric Gallet, Jean-Charles Jacobi, Hans-Werner Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
author_facet |
Dedieu, Jean-Pierre Wendleder, Anna Cerino, Bastien Boike, Julia Bernard, Eric Gallet, Jean-Charles Jacobi, Hans-Werner |
author_sort |
Dedieu, Jean-Pierre |
title |
Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
title_short |
Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
title_full |
Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
title_fullStr |
Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
title_full_unstemmed |
Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
title_sort |
snow change detection from polarimetric sar time-series at x-band (svalbard, norway) |
publishDate |
2021 |
url |
https://epic.awi.de/id/eprint/54995/ https://doi.org/10.5194/egusphere-egu21-149 https://hdl.handle.net/10013/epic.90248998-33d8-4c7e-8590-d57c965544db |
geographic |
Arctic Norway Ny-Ålesund Svalbard |
geographic_facet |
Arctic Norway Ny-Ålesund Svalbard |
genre |
Arctic Climate change Ny Ålesund Ny-Ålesund polar night Svalbard |
genre_facet |
Arctic Climate change Ny Ålesund Ny-Ålesund polar night Svalbard |
op_source |
EPIC3EGU General Assembly 2021, online, 2021-04-19-2021-04-30Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) |
op_relation |
Dedieu, J. P. , Wendleder, A. , Cerino, B. , Boike, J. orcid:0000-0002-5875-2112 , Bernard, E. , Gallet, J. C. and Jacobi, H. W. (2021) Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) , EGU General Assembly 2021, online, 19 April 2021 - 30 April 2021 . doi:10.5194/egusphere-egu21-149 <https://doi.org/10.5194/egusphere-egu21-149> , hdl:10013/epic.90248998-33d8-4c7e-8590-d57c965544db |
op_doi |
https://doi.org/10.5194/egusphere-egu21-149 |
_version_ |
1766330937810878464 |
spelling |
ftawi:oai:epic.awi.de:54995 2023-05-15T14:58:49+02:00 Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) Dedieu, Jean-Pierre Wendleder, Anna Cerino, Bastien Boike, Julia Bernard, Eric Gallet, Jean-Charles Jacobi, Hans-Werner 2021-04-29 https://epic.awi.de/id/eprint/54995/ https://doi.org/10.5194/egusphere-egu21-149 https://hdl.handle.net/10013/epic.90248998-33d8-4c7e-8590-d57c965544db unknown Dedieu, J. P. , Wendleder, A. , Cerino, B. , Boike, J. orcid:0000-0002-5875-2112 , Bernard, E. , Gallet, J. C. and Jacobi, H. W. (2021) Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) , EGU General Assembly 2021, online, 19 April 2021 - 30 April 2021 . doi:10.5194/egusphere-egu21-149 <https://doi.org/10.5194/egusphere-egu21-149> , hdl:10013/epic.90248998-33d8-4c7e-8590-d57c965544db EPIC3EGU General Assembly 2021, online, 2021-04-19-2021-04-30Snow change detection from polarimetric SAR time-series at X-band (Svalbard, Norway) Conference notRev 2021 ftawi https://doi.org/10.5194/egusphere-egu21-149 2021-12-24T15:46:38Z Due to recent climate change conditions, i.e. increasing temperatures and changing precipitation patterns, arctic snow cover dynamics exhibit strong changes in terms of extent and duration. Arctic amplification processes and impacts are well documented expected to strengthen in coming decades. In this context, innovative observation methods are helpful for a better comprehension of the spatial variability of snow properties relevant for climate research and hydrological applications. Microwave remote sensing provides exceptional spatial and temporal performance in terms of all-weather application and target penetration. Time-series of Synthetic Active Radar images (SAR) are becoming more accessible at different frequencies and polarimetry has demonstrated a significant advantage for detecting changes in different media. Concerning arctic snow monitoring, SAR sensors can offer continuous time-series during the polar night and with cloud cover, providing a consequent advantage in regard of optical sensors. The aim of this study is dedicated to the spatial/temporal variability of snow in the Ny-Ålesund area on the Br∅gger peninsula, Svalbard (N 78°55’ / E 11° 55’). The TerraSAR-X satellite (DLR, Germany) operated at X-band (3.1 cm, 9.6 GHz) with dual co-pol mode (HH/VV) at 5-m spatial resolution, and with high incidence angles (36° to 39°) poviding a better snow penetration and reducing topographic constraints. A dataset of 92 images (ascending and descending) is available since 2017, together with a high resolution DEM (NPI 5-m) and consistent in-situ measurements of meteorological data and snow profiles including glaciers sites. Polarimetric processing is based on the Kennaugh matrix decomposition, copolar phase coherence (CCOH) and copolar phase difference (CPD). The Kennaugh matrix elements K0, K3, K4, and K7 are, respectively, the total intensity, phase ratio, intensity ratio, and shift between HH and VV phase center. Their interpretation allows analysing the structure of the snowpack linked to the near real time of in-situ measurements (snow profiles). The X-band signal is strongly influenced by the snow stratigraphy: internal ice layers reduce or block the penetration of the signal into the snow pack. The best R2 correlation performances between estimated and measured snow heights are ranging from 0.50 to 0.70 for dry snow conditions. Therefore, the use of the X-band for regular snow height estimations remains limited under these conditions. Conversely, this study shows the benefit of TerraSAR-X thanks to the Kennaugh matrix elements analysis. A focus is set on the Copolar Phase Difference (CPD, Leinss 2016) between VV and HH polarization: Φ CPD = Φ VV - Φ HH. Our results indicate that the CPD values are related to the snow metamorphism: positive values correspond to dry snow (horizontal structures), negative values indicate recrystallization processes (vertical structures). Backscattering evolution in time offer a good proxy for meteorological events detection, impacting on snow metamorphism. Fresh snowfalls or melting processes can then be retrieved at the regional scale and linked to air temperature or precipitation measurements at local scale. Polarimetric SAR time series is therefore of interest to complement satellite-based precipitation measurements in the Arctic. Conference Object Arctic Climate change Ny Ålesund Ny-Ålesund polar night Svalbard Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Arctic Norway Ny-Ålesund Svalbard |