Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

What is Scanner and NonScanner?

These are two types of instruments specifically designed by a team of electronic, thermal, and mechanical experts, built and integrated with the ERBS and NOAA satellite platforms by TRW of Redondo Beach, CA.

A set of three co-planar detectors (longwave, shortwave and total energy), all of which scan from one limb of the Earth to the other, across the satellite track (in its normal operational mode).

The scanner instrument has a smaller footprint (40 km at nadir) and scanned across the orbit plane to provide maximum spatial coverage. The scanner measures directional radiance, not hemispheric flux. The directional radiance is converted to hemispheric flux using empirical statistical model (ERBE ADM). The scanner is designed for regional to large scale analysis, and due to the smaller footprint, the scanner product is able to separate clear sky data from all-sky data to provide both clear-sky and all-sky estimates.

A set of five detectors; one which measures the total energy from the Sun, two which measure the shortwave and total energy from the entire Earth disk, and two of which measure the shortwave and total energy from a medium resolution area beneath the satellite.

The Nonscanner instrument did not scan and pointed straight down to measure hemispheric flux from the Earth. The large footprint (1000 km) is designed only for large scale analysis, thus products provide only all-sky data. Because the nonscanner had less moving parts, it lasted a lot longer than the scanner instrument.