Satellite detection of air pollutants

NASA's ERTS-1 satellite, with its high resolution and multispectral capabilities, has been found useful in the detection and analysis of smoke from large point sources (power plants, steel mills, etc.), and widespread atmospheric turbidity associated with atmospheric stagnations. Smoke plumes from the Chicago-Northern Indiana industrial complex have been tracked over Lake Michigan for over 100 km. Experience has shown that smoke plumes are relatively easy to detect over water (in the 0.6-0.7 micrometer band) but much more difficult over land surfaces. Pattern recognition techniques (cluster analysis) were applied to the digital ERTS data, and it was found that the smoke plumes indeed had a unique spectral signature. Studies are currently underway to use measured plume geometries to obtain quantitative estimates of diffusion over water surfaces.