108 



of water vapor and temperature will approach some constant value and the 

 magnitude of the energy transports in the trades will be governed by this. 

 Within the trade wind -equatorial trough system synoptic scale disturbances 

 will produce internal convergences of water vapor and sensible heat and a 

 vertical flux of energy. But synoptic scale systems, as was shown by the 

 CRAWFORD cruise of 1957 (Garstang, 1958), significantly increase the trans- 

 port of both latent and sensible heat from the ocean to the atmosphere . 

 Gradients, particularly of temperature, in the air immediately above the 

 sea surface steepen markedly and wind speeds increase during synoptic 

 disturbances. The total flux of water vapor and sensible heat at the surface 

 over the area of a synoptic disturbance is, therefore, likely to be signifi- 

 cantly greater than during undisturbed conditions. Thus the mean picture is 

 constrained by overall planetary budget requirements and departures from it 

 are primarily due to the travelling synoptic systems which form a vital link 

 between the ocean and the atmosphere . An attempt will be made here to 

 evaluate the role that organized synoptic scale disturbances play in determin- 

 ing the distribution of latent and sensible heat transfer over the tropical 

 oceans . 



II. ANALYTICAL TOOLS AND AVAILABLE DATA 



In restricting our attention to the tropical oceans we encounter the 

 fortunate situation that the lower decameters of the tropical atmosphere are 

 by and large barotropic and close to neutral stratification. Under these 

 circumstances, the most practical equations for the computation of the flux 

 of latent and sensible heat are the bulk aerodynamic equations expressed 

 below: 



LE = Q^ = p L C^ (q^ - q^) u^ ^^^ 



^s = ^ S % (V ^) -a ' (2) 



where Q and Q are, respectively, the eddy vertical transport of latent 

 and sensible heat and are directly proportional to the differences between 

 the mean specific humidity and mean potential temperature measured at the 

 surface and at some point above the surface multiplied by the mean wind 

 speed measured at the same point above the surface . If the atmosphere above 

 the sea surface is close to neutral stratification, then the most restrictive 

 assumptions that must be made in order to arrive at the equations are most 

 nearly satisfied. 



Forty-six days of observations were made on two separate cruises, each 

 of 23 days duration, on a fixed station. Both cruises took place during the 

 months of August and September. The first in 1957 when the ship (R. V. 

 CRAWFORD , Woods Hole Oceanographic Institution, Garstang (1958)) was 

 stationed near 11*^ 52*^?; the second in 1963 when the same ship was stationed 

 near 13°N 55°W (La Seur and Garstang {l96h)) . 



