135°W just westward of the strong influence of the 

 continental boundary. Plates 4 and 5 show the sea- 

 sonal variation in 5° quadrangles in coastal regions 

 from the northern Gulf of Alaska to Washington and 

 from Oregon to Baja California, respectively. 



The general character of the seasonal variations can 

 be described in terms of the average annual net heat 

 exchange, the range of the variations and the months 

 in which the maximum and minimum values occur. In 

 the open ocean, lat. 20° to 50"N and long. 130°W to 

 180°, the distribution of average annual net heat ex- 

 change, Qj. is highly zonal with the largest (positive) 

 values occurring in the lat. 45° to 50°N band. To the 

 west of long. I55°W a secondary maximum appears in 

 the lat. 30° to 35°N band. The maximum seasonal 

 range, nearly 600 cal/cm^/day, occurs in the lat. 35° to 

 40°N, long. 175°W to 180° quadrangle. The lowest sea- 

 sonal ranges (205 to 230 cal/cm-/day) occur in the lat. 



20° to 25°N band between long. 125° and 145°W. The 

 maximum monthly heat exchange (greatest rate of heat 

 gain by the ocean) occurs in June in all but a few 

 quadrangles where peak gains are in May or July and 

 with the exception of the area from Baja California west 

 to long. 140°W in which August maximums dominate. 

 Minimum values (greatest rate of heat loss from the 

 ocean) generally occur in December except for a few 

 quadrangles with November or January minimums. 



In the coastal regions the ranges of the average sea- 

 sonal variation are consistently large, from about 430 

 to 525 cal/cm-/day from the Gulf of Alaska to the cen- 

 tral California coast. In the northern portion of the 

 section the annual average Qj is negative. In the ab- 

 sence of declining average annual sea temperatures, a 

 negative annual Qj implies that heat is transported 

 into the region by currents. Similarly, in the southern 

 region, in the absence of increasing average annual sea 



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400 



I I I I I I I I 1 I I 

 L 30-35N I30-I35W 



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I I I I I I I I I I I 

 40-45N I30-I35W, 



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I I I I I 



_ 35-40N 



T 



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 L25-30N I30-I35W_| 



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I I I I I I I I I 



20-25 N I30-I35W 



Qt =-46 



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 MONTH 



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Plate 3. — Seasonal variation of average monthly total heat exchange, Q,, by 5° quadrangles from lat. 20° to 50°N in the meridional strip long. 



130° to 135°W. Qj is the average annual total heat exchange. 



