Multi-channel and multi-polarization radar measurements around the NEEM site
Ice properties inferred from multi-polarization measurements, such as birefringence and crystal orientation fabric (COF), can provide insight into ice strain, viscosity, and ice flow. In 2008, the Center for Remote Sensing of Ice Sheets (CReSIS) used a ground-based VHF (very high frequency) radar to...
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ftcopernicus:oai:publications.copernicus.org:tc68758 2023-05-15T15:53:45+02:00 Multi-channel and multi-polarization radar measurements around the NEEM site Li, Jilu Vélez González, Jose A. Leuschen, Carl Harish, Ayyangar Gogineni, Prasad Montagnat, Maurine Weikusat, Ilka Rodriguez-Morales, Fernando Paden, John 2018-09-27 application/pdf https://doi.org/10.5194/tc-12-2689-2018 https://tc.copernicus.org/articles/12/2689/2018/ eng eng doi:10.5194/tc-12-2689-2018 https://tc.copernicus.org/articles/12/2689/2018/ eISSN: 1994-0424 Text 2018 ftcopernicus https://doi.org/10.5194/tc-12-2689-2018 2020-07-20T16:23:09Z Ice properties inferred from multi-polarization measurements, such as birefringence and crystal orientation fabric (COF), can provide insight into ice strain, viscosity, and ice flow. In 2008, the Center for Remote Sensing of Ice Sheets (CReSIS) used a ground-based VHF (very high frequency) radar to take multi-channel and multi-polarization measurements around the NEEM (North Greenland Eemian Ice Drilling) site. The system operated with 30 MHz bandwidth at a center frequency of 150 MHz. This paper describes the radar system, antenna configurations, data collection, and processing and analysis of this data set. Within the framework derived from uniaxial ice crystal model, we found that ice birefringence dominates the power variation patterns of co-polarization and cross-polarization measurements in the area of 100 km 2 around the ice core site. The phase shift between ordinary and extraordinary waves increases nonlinearly with depth. The ice optic axis lies in planes that are close to the vertical plane and perpendicular or parallel to the ice divide depending on depth. The ice optic axis has an average tilt angle of about 11.6° vertically, and its plane may rotate either clockwise or counterclockwise by about 10° across the 100 km 2 area, and at a specific location the plane may rotate slightly counterclockwise as depth increases. Comparisons between the radar observations, simulations, and ice core fabric data are in very good agreement. We calculated the effective colatitude at different depths by using azimuth and colatitude measurements of the c axis of ice crystals. We obtained an average effective c axis tilt angle of 9.6° from the vertical axis, very comparable to the average optic axis tilt angle estimated from radar polarization measurements. The comparisons give us confidence in applying this polarimetric radio echo sounding technique to infer profiles of ice fabric in locations where there are no ice core measurements. Text Center for Remote Sensing of Ice Sheets (CReSIS) Greenland ice core North Greenland Copernicus Publications: E-Journals Greenland The Cryosphere 12 8 2689 2705 |
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Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
Ice properties inferred from multi-polarization measurements, such as birefringence and crystal orientation fabric (COF), can provide insight into ice strain, viscosity, and ice flow. In 2008, the Center for Remote Sensing of Ice Sheets (CReSIS) used a ground-based VHF (very high frequency) radar to take multi-channel and multi-polarization measurements around the NEEM (North Greenland Eemian Ice Drilling) site. The system operated with 30 MHz bandwidth at a center frequency of 150 MHz. This paper describes the radar system, antenna configurations, data collection, and processing and analysis of this data set. Within the framework derived from uniaxial ice crystal model, we found that ice birefringence dominates the power variation patterns of co-polarization and cross-polarization measurements in the area of 100 km 2 around the ice core site. The phase shift between ordinary and extraordinary waves increases nonlinearly with depth. The ice optic axis lies in planes that are close to the vertical plane and perpendicular or parallel to the ice divide depending on depth. The ice optic axis has an average tilt angle of about 11.6° vertically, and its plane may rotate either clockwise or counterclockwise by about 10° across the 100 km 2 area, and at a specific location the plane may rotate slightly counterclockwise as depth increases. Comparisons between the radar observations, simulations, and ice core fabric data are in very good agreement. We calculated the effective colatitude at different depths by using azimuth and colatitude measurements of the c axis of ice crystals. We obtained an average effective c axis tilt angle of 9.6° from the vertical axis, very comparable to the average optic axis tilt angle estimated from radar polarization measurements. The comparisons give us confidence in applying this polarimetric radio echo sounding technique to infer profiles of ice fabric in locations where there are no ice core measurements. |
format |
Text |
author |
Li, Jilu Vélez González, Jose A. Leuschen, Carl Harish, Ayyangar Gogineni, Prasad Montagnat, Maurine Weikusat, Ilka Rodriguez-Morales, Fernando Paden, John |
spellingShingle |
Li, Jilu Vélez González, Jose A. Leuschen, Carl Harish, Ayyangar Gogineni, Prasad Montagnat, Maurine Weikusat, Ilka Rodriguez-Morales, Fernando Paden, John Multi-channel and multi-polarization radar measurements around the NEEM site |
author_facet |
Li, Jilu Vélez González, Jose A. Leuschen, Carl Harish, Ayyangar Gogineni, Prasad Montagnat, Maurine Weikusat, Ilka Rodriguez-Morales, Fernando Paden, John |
author_sort |
Li, Jilu |
title |
Multi-channel and multi-polarization radar measurements around the NEEM site |
title_short |
Multi-channel and multi-polarization radar measurements around the NEEM site |
title_full |
Multi-channel and multi-polarization radar measurements around the NEEM site |
title_fullStr |
Multi-channel and multi-polarization radar measurements around the NEEM site |
title_full_unstemmed |
Multi-channel and multi-polarization radar measurements around the NEEM site |
title_sort |
multi-channel and multi-polarization radar measurements around the neem site |
publishDate |
2018 |
url |
https://doi.org/10.5194/tc-12-2689-2018 https://tc.copernicus.org/articles/12/2689/2018/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Center for Remote Sensing of Ice Sheets (CReSIS) Greenland ice core North Greenland |
genre_facet |
Center for Remote Sensing of Ice Sheets (CReSIS) Greenland ice core North Greenland |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-12-2689-2018 https://tc.copernicus.org/articles/12/2689/2018/ |
op_doi |
https://doi.org/10.5194/tc-12-2689-2018 |
container_title |
The Cryosphere |
container_volume |
12 |
container_issue |
8 |
container_start_page |
2689 |
op_container_end_page |
2705 |
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1766388934693093376 |