SKCT. 2] 



LARGE-SCALE INTERACTIONS 



149 



Particularly in the winter months, this area constitutes a key energy supply 

 for the Northern Hemisphere jet streams ; its upper circulation is one of the 

 three main high-level outflow channels from the equatorial trough zone. These 

 consist of steady, highly concentrated bands of southwesterly "antitrade" 

 winds at about 40,000 ft elevation (12 km or 200 mb pressure) emanating over 

 the Canal Zone Region, West Africa and central Indian Ocean. In the Carib- 

 bean, the low-level trades are also particularly strong and steady ; the only 

 unsteady winds are found at an elevation of about 25,000 ft (400 mb) where 

 the shift in direction between easterly and westerly is confined to a shallow 

 transition layer. The three-dimensional air-flow conditions are summarized in 

 Fig. 26 ; we see that the Mdnd vector nowhere shows appreciable rotation with 

 height. 



Fig. 25. Framework of Caribbean study. (After Colon, 1960, Figs. 1 and 174.) Dashed line 

 shows outline of ellipse boundary through which, when extended vertically, air and 

 sea fluxes were calculated. Meteorological stations denoted by crosses. Arrows repre- 

 sent sea currents (after Sverdrup, 1942, fig. 174); insert gives speed code. Dashed 

 straight line is trajectory of low-level air flow. Co-ordinates in N latitude and W longi- 

 tude degrees. 



Colon's meteorological study was mainly directed toward (27) and a separate 

 kinetic energy budget. To obtain Qs and LP in (27) he introduced an additional 

 equation for the heat balance of the sea surface, namely, 



Qs + Qe = R-S-Q,o (1) 



and the equation for atmospheric water-vapor conservation which is written 



L{E-P) =Qe-LP = Q,^, (28) 



where the term Qvtv, the water-vapor flux divergence in the atmosphere, is to 

 be stated explicitly, broken down according to scale of motion, and evaluated 

 using the weather station network. Qs and Qe are found from the energy budget 

 method using (1), (2) and the radiation evaluations as outlined in Section 3 

 (pages 100-114), and compared with separate computations from the transfer 

 formulas. Then Qe is substituted into (28) to obtain LP, the remaining un- 

 measured quantity in the atmospheric balance, as residual. In these equations, 

 the components will now be integrated over the volume bounded laterally by 

 the ring of stations in Fig. 25. 



