When electromagnetic radiation propagates through the atmosphere from a source to a receiver (Figure 13-1), three major phenomena are observed: 1) the intensity of the radiation reaching the sensor is reduced, 2) non-scene path radiance scattered into the field of view (FOV) reduces target contrast, and 3) image fidelity is reduced by turbulence and aerosol forward small-angle scattering. In addition, path radiance and radiation scattered into the FOV affect the noise level. The nature and magnitude of these effects depend on the sensor type (eye, imaging system), sensor characteristics (spectral response, sensitivity, and spatial resolution), the atmospheric constituents, and environmental conditions. Numerous texts have been written on atmospheric physics.
|