400 



200- 



'>. -200 > 



< 

 o 



I 



^ ^ JFMAMJJASOND 

 400' 



CO 

 UJ 



or 

 o 



-J 

 < 



I I I I I I I I I I I 

 L50-55N I30-I35W J 



:oo 



-200 -> 



-400 



_i_i I II 



_ 45-50N 



JFMAMJJASOND JFMAMJJASOND 



1 I I I I I I I r 



T 



I — I — I — r-r 

 I25-I30W. 



Qt =32 

 I I I I I I I 



JFMAMJ JASOND 



J FMAMJ JASOND 



MONTH 



JFMAMJJASOND 



Plate 4. — Seasonal variation of average monthly total heat exchange, Qi, in coastal regions from northern Gulf of Alaska to Washington. Qj. 



is the average annual total heat exchange. 



temperatures, a positive annual ^ 7- implies that heat is 

 extracted from the region by currents. 



EVALUATION OF THE CHARTS 



The vahdity of these charts as quantitative represen- 

 tations of heat flux across the sea surface is subject to 

 the quality and geographical coverage of the source 

 data, the accuracy of the empirically derived formulas 

 used for computation and the method of processing. 

 Seckel (1970) has made a thorough analysis of each of 

 these factors in producing a 2-yr series of monthly heat 

 exchange tabulations by 5° quadrangles for the North 

 Pacific trade wind zone. Seckel's tabulations provide 

 an excellent set of heat flux values for comparison 

 with those presented in this report. 



Both were based on marine synoptic weather obser- 



vations as the principal data source. However, for our 

 report we utilized observations radioed ashore, while 

 Seckel's data were derived from written logs archived 

 by the National Weather Records Center.- Sets of data 

 acquired by these two methods for particular areas and 

 time periods will be similar but not identical due to 

 card-punching and transmission errors and to the fact 

 that not all data entered in weather logs are transmitted 

 by radio, and not all observations reported by radio 

 reach the archives. 



Seckel's method of averaging the observations for 

 each 5° quadrangle and month gave equal weight by 1° 

 quadrangle and by day. These weighted averages of the 

 variables needed for heat exchange computations were 

 plotted on charts at the mean locations of the observa- 



■Now the National Climatic Center, National Oceanic and ,\t- 

 mospheric Administration. 



