The amplitude is the amount of the signal sent out by the sensor that returns to be measured, and is often referred to as radar backscatter. This part of the NISAR data is best represented in the GCOV products. The individual covariance layers in the GCOV product can be used like Radiometric Terrain Corrected (RTC) products. The pixel values represent the intensity of radar backscatter, with a different layer for each polarization.
The values in the GCOV covariance layers represent the conditions of the scatterers on the earth’s surface in that area, and can indicate the degree of surface roughness, structural complexity, and relative moisture content. These values are impacted by changes to the physical structure of the earth’s surface, including processes that alter vegetation or built structures.
Because of NISAR’s regular acquisition schedule and insensitivity to cloud cover, data is available at regular intervals all over the world. This makes it very valuable for time-series analysis, which can be used to track short- or long-term changes to natural and anthropogenic features.
The L-band sensor can penetrate through moderately complex vegetation and more deeply into the soil than C-band SAR sensors such as Sentinel-1. This provides insight into the conditions under the canopy, and at deeper levels in the soil column, and having observations using both wavelengths (and, in some areas, S-band data in addition) increases the ability to understand processes driving change on the landscape.