SECT. 2] I.AROE-SCALE INTERA(!TIONS 123 



Kuroshio and much enhanced effects of the cold currents in the eastern Pacific. 

 Nevertheless, the averaged flux divergences have the same sign at each latitude 

 belt, the same general magnitude and mostly differ by less than 50%. All 

 Northern Hemisphere evidence thus converges to support oceanic flux diver- 

 gence south of 30°, convergence north of that, of a magnitude comparable to 

 one-third Qe and thus not negligible in the planet's heat budget. In other words, 

 the oceans are taking on heat equatorward of the subtropical ridges, and 

 emitting it at higher latitudes, thus introducing an important factor in effecting 

 a milder climate of temperate regions during the cold season. 



We may now make the additional consistency check of the isopleth patterns 

 of Fig. 11 with the known distribution of ocean currents. In examining the 

 longitudinal anomalies, we see that, in general, there is good agreement between 

 areas of high positive values (positive ocean -flux divergence, or ocean currents 

 taking on heat in an annual balanced situation) and regions of cold sea currents. 

 Conversely, there is good association between high negative Qvo values (flux 

 convergence, currents giving up heat) and the warm currents. This agreement 

 is particularly observed in the case of warm currents — the Gulf Stream, 

 Kuroshio, Agulhas, Southwest Pacific Currents — and in the case of cold currents 

 — Canary, Benguela, California Currents and the northern portion of the 

 Peruvian Current. 



At the same time, in some regions of the ocean, the distribution of isolines in 

 'Fig. 11 does not coincide with the main locations of warm and cold streams. 

 This is explained partly by the fact that the map shows oceanic heat-transport 

 divergence and not directly the heat transport, which can be obtained by 

 spatial integration oiQvo- For this reason, the greatest absolute values oiQvo in 

 the Gulf Stream region of moderate and high latitudes are located more to the 

 west, away from the main core of the stream. It is quite probable that the 

 greatest loss of heat by the stream takes place in its western portions which are 

 closest to the cold region of the northwestern shores of the Atlantic coast. 



Regardless of details, which should not be pursued too far, the degree of 

 quahtative agreement encourages belief that the residual quantity Qvo has some 

 real physical meaning and exists outside the uncertainties of the calculation. 

 This point is of the utmost concern to both meteorologists and oceanographers, 

 as we shall continue to see throughout the chapter. To oceanographers, the 

 implications of Fig. 1 1 and Tables VI and VII are crucial since the Qvo distribu- 

 tion provides to date the only known way of arriving at a global picture of 

 heat transports by ocean currents. 



In order to compute the current fluxes from their divergence, Qvo may be 

 integrated by multiplying it by the ocean area between the given latitude belts 

 and accumulating from some boundary latitude where the flux can be specified. 

 This may be done separately for individual oceans or for the world as a whole. 

 Before describing the transports obtained in this manner, a word of caution is 

 in order. A sample calculation shows that with identical boundary conditions 

 a uniform 20% alteration in the magnitude oiQvo leads easily to factors of two 

 discrepancies in the deduced heat transports. With this in mind, we have 



