## 3 Methods and Results
### Sar
#### 3.2.2 Polarimetry  
The polarization of a radar wave is the orientation of the electric field, and signals can be transmitted and received with multiple polarizations. Four possible linear polarizations are HH, VV, HV and VH, where the first letter refers to the transmit polarization, and the second letter refers to the receive polarization (H refers to horizontal and V to vertical).  
Full polarimetric data allow analysis of different scattering mechanisms through polarimetric decompositions [51]. The Pauli polarimetric decomposition, which represents three major scattering mechanisms (surface (shown in blue), volume (green) and double bounce (red)), was applied on RADARSAT-2 (RS-2) FQ data and found to be useful for indicating glacial ice (icebergs and ice islands). Icebergs were detected in a color composite image (FQ27, 26 September 2013) as green features (representing volume scattering) and highlighted by blue circles in Figure 12. It is interesting to note that glacial ice features were more readily distinguished with full polarimetric data than with single- and dual-pol data.  
In addition to an FQ mode, RS-2 has an FQ Wide mode that covers 50 km by 25 km with the same resolution. Pauli decomposition was applied to an FQ20W image acquired on 7 March 2014. Since that time (September 2013), the ice has dispersed, but it can be seen that one ice island (highlighted by red circle) frozen into sea ice is still in the same place (Figure 12 (bottom)). This experiment confirms that an FQW image can also be used for the detection of glacier ice features.  
Another combination of dual-pol channels of the RS-2 standard mode improved the possibilities of glacial-ice identification. Color composites of standard beams S1, S4 and S8 (incidence angles are 20, 34 and 49 degrees, respectively) were analyzed. It was found that S8 was better at identifying glacial ice than imagery acquired with lower incidence angles.  
Several dual-polarized RS-2 and TSX datasets have been acquired. Various combinations of dual-polarized imagery, as well as color composites generated from both satellites, were analyzed. Color composites of dual-polarized RS-2 standard beam mode S8 imagery (acquired on 3 March 2014) are shown in Figure 13. Original radar images are HH (a) and HV (b). An RGB color composite (c) was generated from an RS-2 image as HH--red, HV--green and HH--blue. The Landsat 8 image used as verification is shown in Figure 13. It can be seen from the Landsat 8 image that an ice island and multiyear hummock fields were present. The ice island, with a waterline length of about 370 m, can be identified in the color composite image (Figure 13). The ice island is circled in Figure 13 and is shown also on (e) and (f). Large hummocks are identified in the HV channel of the SAR image and even better in the color composite image and demonstrate how these features can be detected over large areas, as RS-2 standard images have swath coverage of 100 km. Color  
Figure 11: Single-pass TDM InSAR DEM over hummock (a); WorldView-2 image (b) and stereo DEM over the same area (c). WorldView-2 images © DigitalGlobe, 2014.  
composites are useful for identifying band combinations and can be used in the future as the basis for automated algorithms.  
Figure 12: Icebergs in sea ice shown in GeoEye-1 image, acquired on 22 September 2014 (**top**) and in RS-2 RGB image of Pauli decomposition (\(|HH+VV|\) blue, \(|HH-VV|\) red and \(|HV|\) green) of FQ mode (26 September 2013) (**middle**) and FQW (7 March 2014) (**bottom**). GeoEye-1 satellite image courtesy of GeoEye-1 © DigitalGlobe (presently it is MAXAR Technologies). RADARSAT-2 Data and Products © MDA Ltd. (2013)—All Rights Reserved.