400 



200 



'^ -200 



^ '^^^JFMAMJJASOND 

 400 



en 



UJ 



tr. 

 o 



< 



I I I I I I I I — TT 

 L30-35N II5-I20WJ 



200 



-200 



-400 



Ot =124 



I I I I I I I I I I I 



I I I I I I 

 I20-I25W. 



JFMAMJJASOND JFMAMJJASOND 



I I I I I I 



I 1 I T 

 25-30N 



I5-I20W. 



Qt =137 



I l—J L 



_ 20-25 N 



II5-I20W_ 



Qt =62 



I I I I I I I I 



JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND 



MONTH 



Plate 5. — Seasonal variation of average monthly total heat exchange, Q, , in coastal regions from Oregon to Baja California. Q^. is the average 



annual total heat exchange. 



tions. The charts were then contoured and used to 

 obtain values of each variable at the centers of the 5° 

 quadrangles by interpolation. 



In the method of Johnson et al. (1965), which was 

 used in the preparation of this report, unweighted aver- 

 ages of the meteorological variables for each 5° quad- 

 rangle and month were used to compute the heat 

 exchange components. The refinements employed in 

 SeckeFs method improve the accuracy of his results 

 because of the fact that obervations are concentrated 

 along shipping routes and generally are not distributed 

 evenly in either time or space. 



The empirical equations used by Seckel to compute 

 the components of heat exchange differ in some re- 

 spects from those used to obtain the results presented 

 in this report. The greatest difference occurs in the 

 equations for heat loss through evaporation. Seckel 

 used a variable drag coefficient which is formulated as 



a function of wind speed. His equation would give 

 approximately the same values of evaporation as that 

 of Johnson et al. (1965) at a wind speed of about 7 

 m/sec. 



The equation for incoming radiation employing 

 Berliand's table, used by Johnson et al. (1965). gives 

 higher values of heat fiux than the corresponding equa- 

 tion used by Seckel for equivalent conditions. Com- 

 puted values of sensible heat conduction, on the other 

 hand, would be 25% greater in magnitude using 

 Seckei's equation due to a difference in constants. The 

 equations used for effective back radiation are the 

 same. 



In consequence, discrepancies between values of 

 total heat exchange given in this report and those pub- 

 lished by Seckel may arise from differences in the em- 

 pirical equations, from differences in processing tech- 

 niques and from differences in the observational data 



