Table 3. — Differences in extremum values of Q(Ei), 

 Q(E2). Q(Ni), and Q(N2), lat. 25° to 29° N., long. 

 140° to 144° W. 



Table 5. --Interyear comparisons of 3-month averages 

 of Q(Nj) and QCN^), lat. 25° to 29° N., long. 140° 

 to 144° W. 



For month-to-month differences of Q(E|) and 

 Q(E2) the averages of the absolute magnitudes 

 are 96 cal. cmT^ day"' and 84 cal. cmr^day"', 

 respectively, and for Q(N|) and Q(^2) ^^ °^^- 

 cmT^day~'and 64 cal. cmT^day"', respectively. 



For interyear comparisons of similar sea- 

 sons figure 3 shows that the maximum evapo- 

 ration period was longer during the first part 

 of 1964 than during the first part of 1965 and 

 that the differences were marked in the summer 

 and autumn evaporation of 1963 and 1964. Table 

 4 shows 4-month averages of Q(E|) and QCEg) at 

 lat. 25° to 29° N., long. 140° to 144° W., for Au- 

 gust to November and January to April. 



Figure 4 shows that values of the net heat ex- 

 change across the sea surface are highest dur- 

 ing late summer and early autumn and lowest 

 during winter. For interyear comparisons, 3- 

 month averages of Q(N,) and QCNg) (lat. 25° to 

 29° N., long. 140° to 144° W.) are listed in table 

 5. 



The trend of change is the same, but inter- 

 year differences based on results computed 

 daily are larger than differences based on re- 

 sults computed from monthly mean meteoro- 

 logical properties. When the interyear differ- 

 ences are compared, it should be remembered 

 that those for Q(E) are not expected to be the 

 same as those for Q(N) since in the latter the 

 interyear differences of Q(S) and Q(B) are also 

 involved. 



Generalizing the results of these compari- 

 sons, a tendency exists to underestimate the 

 interyear differences of the heat of evapora- 

 tion and of the net heat exchange across the sea 

 surface presented in table B. The underesti- 

 mates will be largest in areas and at times of 

 greatest variability in the meteorological prop- 

 erties that affect the heat exchange processes. 



The use of table B for interyear comparisons 

 is illustrated below for three sample areas, 

 each of which lies in a different climatic zone. 

 The trade wind zone extends over the largest 

 portion of the region under consideration here. 

 This region, however, also extends into two 

 other climatic zones. The northern portion of 

 the region lies near the North Pacific pressure 

 ridge and generally has low wind speeds but, 

 during the winter, may come under the influ- 

 ence of the Northwest Pacific atmospheric cir- 

 culation. The southern portion of the region 

 lies in the equatorial zone. 



Consider first the northern zone. The abso- 

 lute magnitude of interyear differences of Q(E) 

 and Q(N) at lat. 32° N., long. 167° W. in table B 



16 



