Effects of Surface Cover
Real researchers who use radar data have to worry about many different aspects of the surface. Different vegetation types (e.g., desert, grasslands, forests or frozen tundra) will all have different backscatter properties. In addition, the basic reflectivity of the soil, called the "dielectric constant" will change depending on the amount of water that the soil contains. Dry soil has a low dielectric constant, so that little radar energy will be reflected. Saturated soil will have the opposite effect, and will be a strong reflector. Moist and partially frozen soils will have intermediate values.
Thus, if we keep the radar incidence angle constant, we can use radar to study large differences in moisture content of the soil. This is often done in deserts (looking for subsurface water) or in tropical rain forests (looking for flooded rivers beneath the tree canopies).
Go on to Page 5 of this Remote Sensing Tutorial to see the differences in radar backscatter due to wavelength.
Author: Pete Mouginis-Mark
Copyright by P. Mouginis-Mark
Curator: Lori Glaze