Analysis of polarimetric signatures of Arctic lead ice using data from AIRSAR and RADARSAT

• Main Author: Bäck, Daniel
• Other Authors: Chalmers tekniska högskola / Institutionen för radio- och rymdvetenskap, Chalmers University of Technology / Department of Radio and Space Science
• Format: Other/Unknown Material
• Language: English
• Published: 2019
• Subjects: Rymd- och flygteknik; Aerospace Engineering; Arctic; Beaufort Sea; Sea ice
• Online Access: https://hdl.handle.net/20.500.12380/96321

In December 2004 the JPL airborne synthetic aperture radar (AIRSAR) flown on the NASA DC-8 acquired fully polarimetric data in the Beaufort Sea at C, L and P-band. This work presents the backscatter coefficients (σHH, σVV, σHV), copolarized ratios (σHH/σVV) and copolarized phase differences (ϕHH-VV) at the three frequencies from various sea ice types and in particular different young sea-ice types formed in recently frozen leads. Two weeks of RADARSAT imagery from the same region as the AIRSAR data was used in order to identify when and where leads were formed and the age of the newly formed ice contained within the leads. By using a known empirical relationship based on freezing degree days, the thickness of a sea-ice layer could be estimated from its age. Several stages of new and young ice were identified and examined by using RADARSAT imagery to track back in time to find sea-ice openings: lead ice 1-2 days old, lead ice 2-3 days old, lead ice 9-14 days old, lead ice/first year ice older than 15 days and multi-year ice. Furthermore, narrow cracks with unique signatures, hypothesized to be a few hours old, found in several 1-2 days old leads have been included in the analysis. In addition to report the polarimetric signatures of these ice types, this study seeks to find which combination of polarimetric parameters that best differentiates the primary ice types as well as the stages of new and young ice within the leads. Ice that is thought to be less than one day old has the lowest backscatter coefficients for C- and L-band. This ice type also has significantly larger copolar phases for C- band than the other ice types and is the only ice type that shows negative phase differences for L-band, in correspondence with previous reported results for very young ice. Furthermore, it has the lowest observed C-band copolar ratios. Ice 1- 2 days old is characteristic for the large variability of the significantly negative P-band phases. Ice up to three days old has the lowest C-band copolar ratios. Using copolar ratios ...