X-, C-, and L-band SAR signatures of newly formed sea ice in Arctic leads during winter and spring Article Swipe
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· 2017
· Open Access
·
· DOI: https://doi.org/10.1016/j.rse.2017.10.032
· OA: W2765271612
We examine an extensive synthetic aperture radar (SAR) data set from the Arctic Ocean spanning a time period\nfrom January to June 2015, with the aim of identifying multi-polarization parameters that can be used to\naccurately separate newly formed sea ice from the surroundings. Newly formed sea ice areas both provide\nfavourable routing for ship traffic, and are key to Arctic climate science because they enable heat exchange\nbetween the ocean and the atmosphere. Our data set encompasses three different frequencies, X-, C- and L-band,\nat a range of incidence angles, and were acquired under different environmental conditions. Our results suggest\nthat by combining the scattering entropy and the co-polarization ratio we can successfully separate the newly\nformed sea ice from open water and thicker sea ice within all three frequencies throughout the winter and spring\nseason. We observe a high correlation between scattering entropy values calculated using quad-polarization Cand\nL-band data and scattering entropy values calculated using the same scenes reduced to the co-polarization\nchannels (HH and VV). We therefore conclude that dual-polarization (HH and VV) X-band scenes can be directly\nused to complement quad-polarimetric C- and L-band scenes for studies of newly formed sea ice. To confine the\nquad-polarimetric data sets to their co-polarization channels one can ensure a higher signal-to-noise ratio.\nIncidence angles below 35° are needed to keep the signal-to-noise ratios sufficiently high for the scattering\nentropy and co-polarization ratio. Due to its lack of incidence angle dependency, the polarization difference can\nprovide additional support in newly formed sea ice studies. The regular coverage of the Arctic Ocean with Cband\nSAR means that such scenes should to be included in any automatic monitoring, however, X- and L-band\nSAR can, based on their difference in penetration depth, provide additional information about newly formed sea\nice types and surface structure.
