Differences in Radar Backscatter due to Wavelength
Radar signals can be generated at several different wavelengths, which is useful because the energy has an ability to travel through vegetation or soil to different amounts that are controlled by the dielectric constant of the material. As this diagram shows, short wavelength radar (3 cm) will be reflected from the tops of trees. Long wavelength radar (24 cm) data will normally go right down to the ground and be reflected off of the surface. Intermediate wavelength radars (say, 6 cm) will sometimes experience multiple scattering events within the canopy.
If we had a set of different wavelength radar images over a forest, it should be possible to use this changing penetration capability to study the structure of the trees and the total amount of material ("biomass") in the forest.
Go on to Page 6 of this Remote Sensing Tutorial to see a comparison of a radar image with aerial photographs of the same area.
Author: Pete Mouginis-Mark
Copyright by P. Mouginis-Mark
Curator: Lori Glaze