Polarimetric coherences have been used to characterize surface
roughness (Mattia et al., 1997) and map urban areas (Moriyama et
al., 2005), and can be a useful polarimetric discriminator between
damaged and undamaged conditions. The polarimetric orientation
angle is the angle about which the antenna has to be rotated in
order to align its horizontal polarization axis to the tangential plane
of the surface (Schuler et al., 1996), and changes in θPO may provide