SAR RESPONSE TO TERRAIN
Two sets of factors exert primary control over radar
backscattering from terrain as detailed in Figure 1: (1)
geometrical factors related to structural attributes of
the surface and any overlying vegetation-cover relative
to the sensor parameters of wavelength and viewing
geometry and (2) electrical factors determined by the
relative dielectric constants of soil and vegetation at a
given wavelength. Both the geometrical and electrical
factors may be time-variant in response to atmospheric
forcing (i.e., precipitation, temperature, and wind), phenological
development of vegetation and disturbances
(i.e., harvest, tillage, and fire). The challenge in extracting
useful information from SAR data resides in
how to deconvolve the geometrical and electrical effects
on radar backscatter.
The relative dielectric constant e of a medium determines
transmission, absorption, and scattering.