FISHERY BULLETIN t VOL. 69. NO. * 



Table 1. — Vertical shear and stability in Patch 1. 



(g3p s^\i/2 

 — ^ -I ' (Phillips 1966) where s = acceleration af gravity, p = density 



of sea woter, c = velocity of sound, and : = distance below sea surface. 



2 Velocities in this column represent component velocities in the NW-SE direction and ore based on geostrophic 

 computotions between the individual stations and the adjacent station to the west. 



a The Richardson number, Ri = N''/(—Y (Phillips (1966) where f/ = Vasdiici frequency and ~- = vertical 



\ 05 ' at 



shear using the component of horizontal velocity, V. 



* The argument of the Vasoila equation was negative for this loyer ond signifies static instability. 



the difference in zonal (east-west) velocities 

 across the patch. Water motion in the vicinity 

 of the patch suggests a divergent front with 

 greater eastward water motion found on the 

 nearshore side. The lower surface temperatures 

 and salinity values, relative to offshore salinity, 

 are evidence for localized upwelling and such a 

 mechanism could provide the water needed for 

 replacement owing to horizontal divergence near 

 the surface. 



The source for the u])welled water in the two 

 patches we studied a])pears to be a poleward flow 

 associated with a high-salinity core found at 

 50 m depth (Stevenson, 1971). Some of the 

 transport from this Coastal Undercurrent is lost 

 through upwelling as the water moves down 

 the coastline. The undercurrent has been traced 

 southward to lat 15°30' S where it was still 

 present at 50 m. The salinity in the core, how- 

 ever, had decreased to about 35.12;,, and the 



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