The HRIR data for the region for each day were printed by computer 

 using a Mercator projection of 1:2 million scale. The mesh size of the 

 data printout at this scale formed the resolution of the study. The 

 printed temperature value for each day for each point was an average 

 of ten HRIR scan spots and represents an approximate area of hg'J sq. km. 

 {2,C'2'j rq. nm. ) within the nadir angle limitation of 50 . The temperature 

 printed was a "corrected average" determined by excluding from the 

 average all data lying outside boundary temperatures based on historical 

 extremes. 



The five-day composite, called a High Daily Average (HDA) composite, 

 was made by examining the daily temperature average at a point for 

 each of the five days, and printing the highest daily average which 

 occurred during the period. This process was repeated for the entire 

 HDA chart. The resulting printed values were designed to reflect either 

 no clouds or the smallest concentration of clouds over each point for 

 the five-day period. 



The HDA composite method can be used in a variety of ways, the 

 number of days used in the composite varying according to the magnitude 

 of oceanic change in the study area. A study in preparation by Paul 

 E. LaViolette of the Naval Oceanographic Office and L. J. Allison of 

 the Goddard Space Flight Center involves a ten-day HDA composite of 

 the North Pacific Ocean. This study has not been completed and is 

 included here only as an example of work in progress. 



Despite the short life span of the Nimbus 1 and 2 spacecraft, an 

 enormous quantity of infrared data and imagery was collected. Properly 

 used, these data can do much to increase our knowledge of the oceans. 

 They have already proven to be a fertile testing ground for the develop- 

 ment of techniques for future satellite applications. 



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