SECT. 2] LARGE-SCALE INTERACTIONS 143 



Stream are drawn upon to provide a significant part of the evaporative and 

 turbulent heat fluxes from sea to air. 



The annual march of the heat-balance components changes considerably 

 when the effect of a warm current is combined with that of a monsoon climate 

 of moderate latitudes. Such a regime is illustrated in Fig. 21, which pertains to 

 the northwestern portion of the Pacific Ocean (southwest of the Kuril Islands). 

 Here Qs is negative in the summer season, due to northward importation of 

 warm oceanic air, and positive in the winter, due to outflow of cold continental 

 air over the sea. It is therefore clear that the value of turbulent heat flux Qs 

 represents an important quantitative index of the influence exerted by mon- 

 soonal circulation on heat exchange. In the analyzed region, as in the previous 

 one (Fig. 20), during the winter months the ocean surface receives heat from 

 the deeper layers, which is here associated to a considerable extent with 

 utilization of energy from the warm Kuroshio. In summer, however, a converse 

 relationship obtains : the supply of heat from the radiation balance and turbu- 

 lent heat exchange considerably exceeds expenditures for evaporation, which 

 results in warming the upper water layers and facilitates the transmission of 

 excessive heat into other regions by means of current transport and horizontal 

 macroconductivity. 



One aim of our study of sea-air exchange was to investigate the magnitudes 

 and functional dependence of the energy sources and sinks for the motions of 

 ocean and atmosphere. Actually, quantitative presentation of the global 

 balance components — their geographic distribution and seasonal variation — 

 has emphasized the enormous back-control upon these exerted by the circula- 

 tions themselves. We saw the effects of ocean currents highlighted by the vast 

 difierence in annual march of R, Qe and Qs between eastern and western ocean 

 basins, where cold and warm currents respectively prevail (compare especially 

 Figs. 18 and 19). 



The even more primary control upon energy transactions exerted by air 

 circulations has been revealed throughout, beginning with the very form of the 

 transfer formulas. In Fig. 13, the huge energy contrast between the trade- 

 wind zones, where the atmosphere's water-vapor fuel is accumulated, and the 

 equatorial region, where it is condensed and exported, clearly requires a dynamic 

 explanation. Radiative sources and sinks are insufficient clues, since the radia- 

 tion balance of the earth's surface is maximum in the trades and the atmospheric 

 radiative sink varies little with latitude. Fig. 13 shows that, in the trades, nearly 

 all the ocean's excess warmth goes into evaporation, loading the atmosphere 

 with latent heat but providing relatively little sensible warming. 



Mechanistically, we are told that it is the "trade-wind inversion" produced 

 by subsidence in the poleward half of the meridional cell which restricts the 

 upward convective pumping and release of the water vapor in the trades, 

 giving rise to its equatorial shipment and roundabout utilization. Fig, 15 

 brings out the fact that the major atmospheric heat source in the equatorial 

 trough is precipitation, a process clearly governed by the rising motion of air. 

 But this still does not clarify whether or how the condensation of moisture 



