The brightness composites (Figure 17 ) may be used to remove 

 transitory clouds over ice fields and thus define the areal coverage of 

 the ice during the period of days making up the composite. The method 

 is similar to the HDA method of compositing discussed in the section 

 devoted to infrared sensors. Within the time period of the composite, 

 each day's meso-scale array is examined resolution point by resolution 

 point and the darkest tone for each resolution point printed. If the 

 proper number of days is chosen (minimum number so as not to hide ice 

 movement and maximum number to discard transitory clouds) the only 

 portion of the print that remains white is the ice field and any 

 permanent cloud cover. 



This method can not be used during the polar darkness portion of 

 the year. However, it may be possible to tie infrared composites with 

 brightness composites for year round observations. This has not yet been 

 done. 



ATS pictures are extraordinary because they cover nearly half of 

 the globe in one picture. ATS 1, situated over 151° W., is able to 

 make a picture of the entire Pacific Ocean approximately every half hour. 

 When ATS 3 was positioned over the Amazon River, it complemented the ATS 

 1 Pacific Ocean coverage and gave a similar half hourly picture of the 

 Atlantic Ocean, (As of 31 December I968, ATS 3 was being moved to a 

 new position of 73° W.). 



Four "television" camera systems were used on the ATS satellites. 

 ATS 1 used a Spin Scan Cloud Camera (SSCC), ATS 2 used a two-camera 

 Advanced Vidicon Camera System (AVCS ) and ATS 3 used a Multicolor Spin 

 Scan Cloud Camera (MSSCC) and an Image Dissector Camera System (IDCS). 



31 



