The Nimbus-7 Coastal Zone Color Scanner 



(CZCS) 



The Coastal Zone Color Scanner (CZCS) is the first spacecraft 

 instrument devoted to the measurement of ocean color. Although 

 instruments on other satellites have sensed ocean color, their spectral 

 bands, spatial resolution, and dynamic range were optimized for 

 geographical or meteorological use. In the CZCS, every parameter is 

 optimized for use over water to the exclusion of any other type of sensing. 

 The signal-to-noise ratios in the spectral channels sensing reflected solar 

 radiance are higher than those required in the past. These ratios need to be 

 high because the ocean is such a poor reflecting surface that the majority of 

 the signal seen by the reflected energy channels at spacecraft altitudes is 

 backscattered solar radiation from the atmosphere rather than reflected 

 solar energy from the ocean. 



The CZCS is a conventional multi-channel scanning radiometer 

 utilizing a rotating plane mirror at a 45 degree angle to the optic axis of a 

 Cassegrain telescope. The rotating mirror scans 360 degrees, however, 

 only 80 degrees of data centered on the spacecraft nadir is collected for 

 ocean color measurements. During the rest of the scan, the instrument 

 acquires a view of deep space and of internal instrument sources for 

 calibration of the various channels. Spatial resolution, at spacecraft nadir, 

 is 825 X 825 meters with some degradation at the edges of the scan swath. 

 The useful swath width from a spacecraft altitude of 955 km is 1600 km. 



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