multi-channel visible space-borne observations. To resolve the chloro- 

 phyll concentration to within 50 percent over a range of concentration from 

 0.1 to 10.0 micrograms chlorophyll per liter in the open ocean and outer 

 continental shelf areas requires radiance observations to 10 bit accuracy. 



The following are the eight recommended wavelengths of which six will be 

 used for routine open ocean and/or continental shelf measurements. 



The 490 and 590 nm channels are useful under special circumstances to 

 extend the observations into more turbid coastal waters. Since the 

 technique is still experimental, these are considered to be research 

 channels which need to be selectable in the place of two of the other 

 channels under infrequent circumstances, arranged well in advance. 



II. 3 SPATIAL RESOLUTION 



The chlorophyll distribution in the ocean is patchy on all scales down to 

 the sub-kilometer level. Thus, to adequately map phytoplankton variation 

 in high-concentration shelf areas, which is the major goal of the first 

 group of MAREX studies, a satellite must be able to resolve about a 

 kilometer of the ocean. This small spot size also allows measurements 

 closer to the shore to resolve local outwelling and upwelling zones, which 

 tend to be nearshore phenomena in many cases. Such a high data rate may be 

 relaxed somewhat for wide area studies of open ocean phytoplankton where 

 statistical rather than process experiments are more likely. In this case, 

 a degradation to about a 4-kilometer resolution is accepted. Therefore, a 

 satellite system is required that can operate in two modes, analogous to 

 the present N0AA AVHRR infrared system: (1) local area coverage of high 

 resolution to about one km and (2) global area coverage of lower resolution 

 to about four km. 



xiv 



