The seventh set of observations would also Indicate that BT 12330 is 

 slightly more accurate than BT 12220 from the surface through ko feet 

 and from 360 through 680 feet and is less accurate from I60 through 320 

 feet. 



The third through seventh sets of paired observations (table 3) 

 were taken at OWS ECHO during March 1959 using four different instruments. 

 Little temperature change with depth occurred at this time. Thus, the 

 instriunents were not subjected to a severe test. Correlation coefficients 

 and standard deviations were expected to be low. Negative correlations 

 observed in the fourth and seventh sets indicated possible instrument bias 

 in BT 12330. In spite of the low correlations, paired standard deviations 

 were relatively low and nearly equal, indicating acceptable instrument 

 performance and low ocean variability. 



Correlations and standard deviations for all depths in the fifth 

 set were the highest of all sets taken during ECHO II. Although the third 

 set shows that BT 12257 was slightly biased and the seventh set shows that 

 BT 12220 performed within acceptable limits, both instruments apparently 

 suffered damage during collection of the fifth set, re stilting in large 

 standard deviations. The data indicated that sets 3 and 7 were recorded 

 before set 5* 



Results of the sixth set of observations are unusual in that the 

 correlation and standard deviations for the surface temperature are of a 

 completely different order of magnitude than those for all other depths. 

 The correlation is very low and standard deviations are two to six times 

 larger than those at the other depths. BT prints indicate that this dis- 

 crepancy results from inaccurately read sea surface temperature owing to 

 blurred traces. 



The eighth and ninth sets of observations were taken at a^TS DELTA 

 during June and September 19^2, respectively. During June, the thermal 

 structure was quite variable; however, the seasonal thermocline was not 

 completely established. During September, the seasonal thermocline was 

 fully developed. 



The eighth set of observations exhibits a relatively low correlation. 

 BT 13823 appears to have considerable instrument bias, because its mean 

 standard deviation for most depths is .3°F greater than that of BT I3819. 



The ninth set of observations exhibits extremely high correlation at 

 all depths and the largest standard deviations of any set. Because of 

 their magnitude, the paired standard deviations appear to be approximately 

 equal. Thus, for this pair of instruments, the standard error of estimate 

 corresponds to random instrument errors. The mean standard error for 

 BT 1261)-6 is .36°F. The mean error of BT 1217^^ is .32°F. 



For many years prior to I963* the processing procedure for all 

 bathythermograms included an average sea surface temperature correction 



