Satellite Radar Earth Remote Sensing: Icebergs and Winds
Microwave remote sensing extracts environmental information from what is often considered the undesired components of signals encountered in surveillance radar: noise and clutter. Radiometers exploit noise, while remote sensing radars employ clutter to study the Earth. Satellite-based radar sensors, coupled with computer processing offer unique perspectives and measurements of important geophysical processes beyond just imaging. In this talk, I consider applications of satellite radar measurements of the microwave scattering properties of the Earth’s surface. Synthetic Aperture Radar (SAR) make highly detailed backscatter images regardless of the weather or solar illumination conditions. These have both military and civilian applications. However, other types of satellite radar such as altimeters, scatterometers, and weather radars provide unique measurements and perspective. For example, over the ocean radar backscatter is related wind-generated roughness and can be used to measure wind speed and direction. Radar backscatter is particularly sensitive to melt/freeze conditions and can thus be used to map and monitor sea ice and soil conditions. The contrast between ocean and ice scattering enables tracking of major icebergs in Antarctic. Using precise range measurements satellite altimeters measure ocean topography from which ocean currents can be inferred. Satellite weather radars measure rain rates and cloud density. With existing and planned systems, we are in the golden age of satellite radar remote sensing.