termining the phase of the harmonics, it was also pos- 

 sible to compare relative times of maximum and 

 minimum values of each series. 



Part 2 of the chart section shows the long-term mean 

 monthly values (norrmils) of the total heat flux across 

 the air-sea interface, Q[. Negative values ofQt, imply- 

 ing heat loss from the ocean surface, occur from Sep- 

 tember through March, while positive values, imply- 

 ing heat gain by the surface layer, occur from March 

 throjjgh September. A regular yearly cycle is found in 

 the (2t series with maximum values occurring in June 

 and minimum values in December. 



Part ?i of the chart section shows the normal values of 

 net incoming solar radiation, Qj. As expected, a regular 

 yearly cycle is found in the Qi series with maximum 

 values in each quadrangle occurring in June and 

 minimum values in December due to the motion of the 



earth around the sun and the tilt of the earth's axis of 

 rotation with respect to the plane of revolution. 



Part 4 ofjhe chart section shows the effective back 

 radiiUion. (?/, . A regular yearly cycle is also found in 

 the Qh series. Maximum values occur in December 

 and January due to the relatively low values of air 

 vapor pressure and large values of sea-air temperature 

 differences during these months, while minimum val- 

 ues occur in June and July. 



Part 5 of the chart section shows the normal values 

 of evaporative heat transfer between ocean and atmo- 

 sphere, Qp. A pronounced yearly cycle is found in the 

 Q(, series with maximum values occurring in Decem- 

 ber and minimum values in June. Negative values of 

 Qe occur in all months, reflecting the fact that on the 

 average sea-air vapor pressure differences are positive 

 throughout the year. 



400 



1 — rn — n—\ — i — i — i—i — r 

 L 45-50N I75-I80W 



200 



Qt = 30 



J I I I I I I I L 



^ -400 



^ JFMAMJJASOND 



400 



en 



UJ 



T — I — I — I — I — rn — I — I — TT 

 L 30-35N I75-I80WJ 



-400 



Qt =-5 



J I I I I I I I I I L 



rn — r~r-\ — i — m — i — tt 

 40-45N I75-I80WJ 



Qt =-25 



J \ I l_l I I I L 



r-rn — i — i — i — i — i — i — rr 

 L35-40N I75-I80W 



J I I I I I I I I I L 



JFMAMJJASOND JFMAMJJASOND 



1 — I — I — I — I — rn — I — m — r- 



I I I I I I — I I I I I 

 25-30N I75-I80W. 



_I_J I L 



_l_l l_L 



_20-25N 



I75-I80W_ 



Qt = I4 



_I_J I \ I I I I I L 



JFMAMJJASOND JFMAMJJASOND JFMAMJJASOND 



MONTH 



Plate 1. — Seasonal variation of average monthly total heat exchange, Q,, by 5° quadrangles from lat. 20° to 50°N in the meridional strip long. 



175'W to the 180° meridian. Qj is the average annual total heat exchange. 



