James 



D. E stlTTiated Analysis Accuracie s 



In order to obtain some measxire of analysis accuracy ex- 

 pressed as a percent score the folloving formula was applied to the 

 results of the tests described In this report: 



A = ^-g 



Where A = percent accuracy 



T = total range of temperattire In area, °F 

 E = mean absolute error, *^ 



This formula obviously can not be tised for all cases and 

 areas but does give a means of comparing analyses in complex and 

 smooth areas. It considers both the degree of variation in the area 

 to be analyzed and the mean absolute error of the analysis. A mean 

 absolute error of 2 F may be considered good in a highly complex area 

 but not so good in a smooth thermal field. 



For Area A the temgerattire range was 25°F, from 53^ to 

 78^. Thus the present 3«^ F error would be equivalent to an analysis 

 accuracy of 86 percent. If the analysis error can be reduced in time 

 to l.i^'^ the accuracy score would be 95 percent. 



For Area B the temperattire range was 6^, trcm 6l P to 67 F. 

 Present accuracies of 2.3°F show analysis accuracies of only 62 per- 

 cent. Through svd table data sources and little new data this accur- 

 acy would be improved to 97 percent. 



A question that comes to mine here is what accuracy is 

 desired? This, of course, depends upon the use to be made of the 

 analyses but generally the charts must be reliable enough to satisfy 

 the most stringent operator requirements. This would require accur- 

 acies of 95 percent. 



V. SUMMARY AMD C0NCLU5I0H5 



Qhis report described a series of tests designed to show what 

 the data requirements are for synoptic sea surface temperature anal- 

 yses. It was shown that data requirements are not unlimited but that 

 a definite quantitative value can be placed on how much data are re- 

 quired. Data requirements for smooth and canplex thermal areas were 

 shown to be significantly different and should be so treated in plan- 

 ning of synoptic nets. 



The number of observations required for reliable sea surface 

 temperature analysis depends upon the area, the type of data and 

 the reliability desired. Table III shows the data requirements 

 estimated for various ty^s of data input and analysis accuracies. 



149 



