b. Locate four spectral channels in the chlorophyll absorption bands 

 between 440 and 590 nm with characteristics similar to those of 

 the present CZCS and two atmospheric correction bands between 

 670, 765, and 865 nm. 



c. Develop a data system capable of averaginq 4-pixel by 4-line 

 groups of data points, thereby reducing the data rate by 16 and 

 enabling the on-board storage of global data. 



d. Maintain the present 820 m IFOV at the lower NOAA orbit (830 km) 

 and increase the digitizer from 8 to 10 bits to accommodate the 

 increased signal-to-noise. 



e. Provide for direct broadcast of the high resolution (1 km) data 

 stream while in sight of properly equipped ground stations. 



f. Speed up the tilt mechanism in order to minimize the loss of data 

 incurred while changing from the full aft to full forward 

 position. 



Application of the atmospheric correction alqorithm requires a hiqh degree 

 of consistency between the calibration of the sensor and the extraterres- 

 trial solar irradiance F (X) (Gordon, 1981). The sensor calibration and F 

 have independent errors, so trying to reduce this effect through very 

 careful calibration and careful measurements of F (X ) will be very 

 difficult. One way of circumventing this problem directly is the addition 

 of the capability of the sensor to view the sun in diffuse reflection as 

 suggested by Yates (Gordon, 1981). The addition of this capability on the 

 Ocean Color Imager is recommended. 



In the present atmospheric correction algorithm the assumption that 

 S(A,X ) be independent of position is required (except over Case 1 waters 

 for which C < 0.25 mg/m ). Spatial variations in aerosol 'type' 

 (APPENDIX B) will induce spatial variations in S. In the case of the 

 present CZCS there is no direct way to detect such a change in S. However, 

 if there were a band in one of the near IR windows at 765 and 865 nm, for 

 which L w = in most waters, the detection of a variable S could easily be 

 effected by looking for spatial variations in S(670,765) or S(670,865), 



A-3 



