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TitleIdentification of polarimetric and nonpolarimetric C-band SAR parameters for application in the monitoring of lake ice freeze-up
AuthorGeldsetzer, T; van der Sanden, J J
SourceCanadian Journal of Remote Sensing vol. 39, no. 3, 2013 p. 263-275, https://doi.org/10.5589/m13-033
Year2013
Alt SeriesEarth Sciences Sector, Contribution Series 20130004
PublisherInforma UK Limited
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceYukon
NTS117A/04; 117B/01
AreaOld Crow Flats
Lat/Long WENS-141.0000 -139.0000 68.2500 68.0000
Subjectsgeophysics; Nature and Environment; remote sensing; radar imagery; models; modelling; SAR
Illustrationsimages; plots; tables
ProgramInformation Extraction Procedures for Landmass Monitoring, Remote Sensing Science
Released2014 06 04
AbstractPolarimetric and nonpolarimetric C-band SAR parameters were assessed for their potential to discriminate open water versus lake ice. Analysis was done for incidence angles between 18° and 50°. Open water was sampled and modelled at wind speeds of 2–24 m/s, from various directions. Lake ice samples were for new ice, less than two months old. Low-quality data, caused by low-wind slicks and ice slicks, were identified using polarimetric data. Nonparametric testing was used to initially identify parameters with discrimination potential. These parameters were then evaluated throughout the incidence angle range; bounds and thresholds were statistically estimated to provide robust discrimination potential. Classified images were both qualitatively and quantitatively assessed. For single-polarized data, the VV polarization is recommended over HH. Cross-polarized data were limited by sensor noise floors, and are not recommended. Dual co-polarized data, using the co-polarized ratio, were useful discriminators at incidence angles > 31°. The co-polarized ratio was insensitive to wind speed, and it was also the best parameter for polarimetric data. Anisotropy was a robust parameter at incidence angles <28°. Accuracies ranged from 76% to 99%, if wind speed thresholds were observed. The identification of robust discriminators enhances monitoring of lake ice freeze-up, an operational concern for departments within the Government of Canada.
Polarimetric and non-polarimetric C-Band SAR parameters are assessed for their discrimination potential of open water versus lake ice. Analysis is done for incidence angles between 18°and 50°. Open water is sampled and modelled at wind speeds of 2-24 m/s, from various directions. Lake ice samples are for ice less than two months old. Uncorrelated wind- and ice-slick data are identified using polarimetric data. Non-parametric testing is used to initially identify parameters with discrimination potential. These parameters are then evaluated throughout the incidence angle range; bounds and thresholds are statistically estimated to provide robust discrimination potential. Classified images are both qualitatively and quantitatively assessed. For single-polarized data, the VV polarization is recommended over HH. Cross-polarized data are limited by sensor noise floors, and are not recommended. Dual-co-polarized data, using the co-polarized ratio, are useful discriminators at incidence angles > 31°. The co-polarized ratio is insensitive to wind speed, and it is also the recommended parameter for polarimetric data. Anisotropy is a robust parameter at incidence angles < 28°. Accuracies range from 76% to 99%, if wind speed thresholds are observed. The identification of robust discriminators enhances monitoring of lake ice freeze-up, an operational concern for departments within the Government of Canada.
Summary(Plain Language Summary, not published)
Lake ice represents an important component of Canadian landscape and influences hydrological, climatic, biological, cultural and economic systems. The timing of it's freeze-up affects all of these systems. Within the Government of Canada, monitoring of lake ice freeze-up is of operational interest to Environment Canada and Parks Canada Agency. Effective tools and techniques that use satellite imagery are required to monitor the vast and remote landscapes that include Canada's lakes. This paper proposes and evaluates methods by which the presence of lake ice can be monitored using a particular type of satellite imagery -- Synthetic Aperture Radar (SAR). Canada operates the most advanced SAR satellite in the world - RADARSAT-2. The results identify that the ratio of two SAR images collected at different polarizations offers the best potential for the monitoring of lake ice freeze-up. The paper also indicates that lake ice can be best identified if the SAR imagery is collected within a certain image mode (geometry).
GEOSCAN ID292479