A similar presentation for the deeper isotherm is given (fig. 

 20) (absolute-value 50th percentile, open points; absolute -value 

 70th percentile, closed points). The average curve has two modes. 

 The higher values, implying steeper isotherms, occur when the 

 towing is to the north or south. Also indicated is an east -west 

 orientation in the wave crests on the deeper part of the thermo- 

 cline. The 50th percentile slopes of all shallow and deep iso- 

 therms were combined and averaged by 45-degree increments of 



70 



60 



50 



40 



30 - 



20 - 





1 



1 



*R 



1 



l 



i 



f 



•e 









• Q 

















• 1 













•u 















— 70TH 1 



\ 





• B 



• M / 



/ * A 



V«»C 



w 





\* Z 



p# .o 







•x 









• F 











• AA #T 





• Y 





OR 









• H 







•G 



• D ' 

 • K 



OQ 



ON 



ov 



'oC 



-Los 



OZ 





OE ~~ 



OU 





oy r 



Ol * N 

 OB OM / 



/ OA 

 OF 



ow 







OX 





 OH 



OT 

 OAA 





oG 





50TH PEF : 















1 



OD 

 OK 



1 



1 



1 



l 



1 







45 90 135 180 225 270 



AVERAGE DIRECTION OF TOW (DEGREES) 



315 



360 



Figure 20. Direction of tow vs average median vertical isotherm angle derived from 

 differences in depth between the half-minute or 304- foot- spaced depth readings. Curve 

 represents isotherm slopes averaged by 45-degree groupings. 



(A) Upper: 70th percentile of absolute value of isotherm slope fae/oi 

 dine. Sample values in solid points. 



(B) Lower: 50th percentile of absolute value of isotherm slope belo 

 dine. Sample values in open points. 



the main thermo- 

 the main thermo- 



43 



