SECT. 2] 



LARGE-SCALE INTERACTIONS 



259 



neglecting a mean mass flow corresponding to the estimated net subsidence of 

 5 mm/sec at 500 mb would lead to a 5% underestimate of the final Qe and a 

 15% overestimate in Qs. This is because sinking motion and outflow brings 

 drier air from aloft than that exported horizontally, while, in sensible heat, it 

 imports potentially warmer air through the top of the box than is exported at 

 the sides. Thus the net oceanic sensible heat source may be overestimated by 

 as much as one-third when the additive error of neglecting isobaric curvature is 

 also included. 



03Z 20 Dec. 1954- I5Z 3 Jan. 1955 



Fig. 76. Vertical profile of mean divergence (10~6 sec"l) on right. Computed by averaging 

 actual wind vectors at surrounding observation stations throughout outburst period . On 

 the left is shown thevertical velocity profile (mm/sec) computed from the divergehcerfield 

 and the equation of continuity. Wind data were too sparse to extend the computation 

 above 700 mb. Note the convergence extending through a major portion of the cloud 

 layer. (After Manabe, 1957, Fig. 12.) 



The calculation of long-wave radiation was performed using the radiation 

 chart of Yamamoto, an improved version of the Elsasser chart. The distribu- 

 tion of mean cloudiness in Fig, 74b, the average radiosonde observation and 

 the water-surface temperature near the coast of Japan were used in the calcula- 

 tion, of which the result is shown in Fig. 77, The radiational heating of the 

 lowest air layers is chiefly due to the large sea-air temperature difference, a 

 result quite in contrast to the tropics where a similar calculation by Riehl et al. 

 (1951) showed that even the sub-cloud layer suffers a net radiational cooling of 

 about 0.5°C per day. Manabe suggests that this radiational warming at low 

 levels may have played a significant role in maintaining the vigorous convection 

 over the sea. 



The part of Fig. 77 showing the mean vertical distribution of heating due to 



