The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
Figure 6: Data Processing Flow Diagram 
4. ICE APPLICATIONS 
Comparing to RADARSAT-1 single polarization SAR data, 
RADARSAT-2 is capable of acquiring dual-polarization and 
fully polarimetric SAR data. The RADARSAT-2 dual 
polarization options include HH-HV or VV-VH modes. The 
additional information provided by the cross-polarization 
channel could be very useful, as the cross polarization channel 
responds to different scattering mechanisms than the co 
polarization channel (Scheuchl et al. 2004). These dual 
polarization data are available in all beam configurations, 
giving a wide choice in resolution, coverage, and incidence 
angle. Most importantly, dual polarization is available in 
ScanSAR modes, which are mostly used for ice and oil 
monitoring at CIS from RADARSAT-1 data. Operational 
experience by CIS analysts results in a preference of HH over 
VV for co-polarization channels. 
The cross-polarization HV and VH backscatter response from 
water are generally low and are relatively independent of wind- 
induced surface roughness conditions, whereas their backscatter 
from sea ice are affected by surface roughness, volume 
scattering, and multi-bounce scattering. Thus, the ice-ocean 
contrast of cross-polarization can be expected to be greater than 
that for either of the co-polarization channels, especially at high 
wind conditions as shown in Figure 7. The cross-polarization 
data can enhance the structural information of sea ice and have 
demonstrated some utility for improving discrimination 
between smooth and deformed ice as well. The combined use of 
co-polarization and cross-polarization channel will give better 
results across a wider range of incidence angles. 
Co-Polarization Channel: VV Cross-Polarization Channel: VH 
Figure 7: Co-Polarization vs Cross-Polarization at High Wind 
Condition 
5. OIL SPILL APPLICATIONS 
CIS is an important partner to Canada’s NASP (National Aerial 
Surveillance Program) by using earth observation technology 
(RADARSAT imagery) to look for oil-like signatures 
(anomalies) on the ocean’s surface that could be indicative of 
an oil spill. The CIS operational ISTOP (Integrated Satellite 
Tracking of Pollution) program currently uses RADARSAT-1 
ScanSAR HH polarization data to identify potential oil spills, to 
track ship targets (Gauthier et al. 2007), and to direct pollution 
surveillance flights to the locations of potential pollution 
incidents. 
The SAR signal is sensitive to the roughness of the sea surface, 
which is modulated by wind speed and direction; imagery 
acquired at VV polarization is the most sensitive to wind speed 
variability (as shown in Figure 7). The suppression of the 
capillary waves by oil from either anthropogenic sources, such 
as an oil spill, or from natural biological slicks, reduces the 
surface roughness resulting in less radar backscatter and darker 
image tones. The detection of oil slicks has been found to be 
best in moderate wind conditions in the range of 3 to 10 m/s. 
Although imagery in both VV and HH polarizations from 
RADARSAT-2 can be used for slick detection, the VV imagery 
might be preferred as, in general, it offers a better signal to 
clutter ratio than other polarization choices (i.e., HH, VH, or 
HV). Although VV is more sensitive than HH for slick 
detection, there may not be any advantage to using the co 
polarized or cross-polarized signatures as oil-free and oil- 
covered surfaces tend to have similar contrast and polarization 
ratios. Slick thickness and the inability to differentiate oil slicks 
from "look-alikes" such as areas of low-wind, grease ice, or 
biological surfactants remain problematic. 
One of CIS research priority is to assess the utility of 
RADARSAT-2 VV/VH dual channel ScanSAR data for the 
ISTOP program. It is known that VV polarization provides 
superior CNR for oil detection over HH polarization. On the 
other hand, VV is less appropriate for ship detection. However, 
VH polarization has shown promise in detecting ships (figure 
3)[2], ISTOP will be working with others to investigate more 
fully whether the VH channel of RADARSAT-2 can perform