272 



WOOSTKR AND RKID 



[OHAP. 11 



[IV] 



Canary Current 



We have been unable to find any studies of time and space variations of up- 

 welling in the Canary Current. Some indication is available from temperature 

 anomaly charts (Fig. 14), which suggest that upwelling occurs throughout the 

 year, is most intense in spring and summer, and migrates northward from 

 winter to summer. 



JANUARY 



APRIL JULY OCTOBER 



Fig. 14. Seasonal migration of upwelling along Canary and Benguela coasts, as indicated 

 by surface -temperature anomaly with respect to five-degree zonal averages in the 

 Atlantic Ocean for the months of January, April, July and October. Isopleth indicates 

 — 5°C anomaly and number is extreme value of anomaly inshore from isopleth. 

 (After Bohnecke, 1936, Beil. XX-XXIII.) 



(v) West Australia 



There seems to be no clear-cut evidence of upwelling along the western coast 

 of Australia (Fig. 11), contrary to what is suggested by the index. Surface iso- 

 therms in the region remain essentially zonal throughout the year, and tem- 

 perature anomaly charts give no indication, either in summer or winter, of any 

 cooling near the coastal boundary (Schott, 1935). Although southerly winds 

 prevail in summer, so that the index predicts strong coastal upwelling, there is 

 no thermal evidence of upwelling, and currents during this season are weak 

 and variable (Koninklijk Nederlands Meteorologisch Instituut, 1952). We have 

 no explanation for the apparent failure of the index in this little known region. 



Thus, with the exception of the Indian Ocean, behavior of the index is in 

 qualitative agreement with what is known about seasonal and geographical 

 variations of coastal upwelling. This suggests that a simple model of dependence 

 of vertical motion on the component of wind stress parallel to the coast and 

 the resulting offshore Ekman transport is applicable. With better wind data it 

 might be possible to make a more sophisticated analysis of the relationship 

 which might then have some predictive value for particular seasons and years. 



