136 



ty the charts of wind constancy (e.g., MacDonald, 1938)- For the months of 

 July through October a belt 15 degrees wide with wind constancies of 

 8o percent or less exist about the equatorial trough zone. A constancy of 

 So percent signifies that during 80 percent of the time steadiness is better 

 than 90 percent. Therefore, the 8o percent constancy boiuxdary roughly corres- 

 ponds to the division between disturbed and undisturbed conditions used above. 

 Outside this belt other synoptic systems would affect the distribution of 

 energy flux, but within the stronger and more persistent trade wind belts 

 such fluctuations would have less effect upon the net transport than is the 

 case in the vicinity of the equatorial trough. 



The month of August was chosen as representative of the wet season 

 and the month of February as representative of the dry season. Computations 

 for the tropical Atlantic have, in each case, been based upon the mean wind 

 speed values depicted in Figures 15 and l6. On the August map the 15-degree 

 wide region under the influence of disturbances has been centered on the 

 position of the mean asymptote. Latitudinal means were obtained for Qe and 

 Qg at l-degree intervals from the values computed for the composite storms. 

 These values were applied to 2k of the days of August, the remaining 7 days 

 represent undisturbed conditions. The region between ±7.5 degrees of the 

 asymptote and about 30°N and 20°S was then subdivided on the basis of mean 

 sea surface temperatures (MacDonald, 1938). Based upon these values, the i 

 air-sea temperature difference was scaled according to observed values from I 

 the 1957 and I963 data. The difference between the saturated specific humidity 

 and the humidity at 6.0 m was assumed constant at 5-0 g kg"l. Computations 

 (as before) of Qe and Qs were then made for 5-degree squares. This procedure 

 of computing Qe and Qs outside the equatorial trough region in August was 

 applied to the whole area in February. Transport during the transition 

 months between wet and dry seasons will depend upon the occurrence and 

 frequency of synoptic disturbances. Thus, an annual mean map of Qe and Qs 

 has been constructed from an average of the August and February maps . These 

 six maps are presented in Figures 17 through 22. The mean value of Qe for 

 the month of August shown in Figure 17 shows similarities with the mean annual 

 map of Budyko (1956) only near 30°N. On Figure 17 a well defined maximum now 

 appears to the north of the asymptote as a result of synoptic sqale systems. 

 A secondary maximum appears in the southwestern tropical Atlantic in associa- 

 tion with the maximum in the winter trade of that hemisphere . The overall 

 results indicate a pronounced increase in latent heat transport within the 

 equatorial and southern tropical Atlantic. 



The mean sensible heat transport for August shown in Figure 18 

 indicates, in general, lower values than reported by Budyko (1956) but higher 

 values than Jacobs (1951)- Within the equatorial trough regions values are 

 close to those shown by Budyko. This is due to the added transixDrt associated 

 with synoptic systems. Outside this region the values reported in Figure I8 

 are lower than those of Budyko. This is in large part due to the exclusion 

 of diurnal effects, a factor not considered by Budyko. 



During February the mean transport of latent heat shown in Figure 19 

 corresponds in the southern hemisphere to that obtained by Budyko (1956) on 



