Vertical Circulation off Ross Ice Shelf — Thomas 
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ported toward the shelf ice under the influence 
of the wind stress. Continuity, then, requires a 
descending motion off the ice shelf. According 
to Sverdrup (1953 b) this means that close to 
an ice shelf we can expect a thick layer of water 
of low salinity. 
To determine the rate of sinking at station 
Ed-1, the procedure of Sverdrup ( 1953^) in 
his investigation of vertical transport of water 
in the vicinity of the ice shelf at Maudheim 
(Antarctica) was used: 
T = r (s 2 w sin </> ) 1 (1) 
where r rr stress of the wind, s = water density, 
w = angular velocity of the earth, <j> — latitude 
of the observer. 
r = V 2 s i .K (2) 
where V = wind velocity, cm sec -1 , s 1 = density 
of the air, K = factor of proportionality = 
2.6 X 10 -3 . 
The equation becomes: 
T = Ks‘V 2 (s 2 w sin <j >) -1 (3) 
According to Vowinckel (1957) the prevailing 
wind at Kainan Bay (Little America) during 
the month of January is easterly. The average 
velocity is 10 knots or 510 cm sec -1 . Assuming 
this value for V and 78° for <f> we obtain: 
T =z 7.0 X 10 3 cm 3 sec -1 (4) 
where T = total volume of transport across a 
1 cm-wide surface. 
If sinking takes place uniformly from the 
barrier to an arbitrary distance of 10 km (= 10 6 
cm), the average downward velocity will be 
7.0 X 10 -3 cm sec -1 . At this velocity water re- 
quires 14 X 10 6 seconds, or about 16 days, to 
sink 100 m. This is comparable with Sverdrup’s 
calculation (1953^) of 20 days for 150 m at 
Maudheim. Probable circulation is shown in 
Figure 2. 
Vertical circulation on the above scale can 
explain the presence of diatoms at subcompensa- 
tion depths and elsewhere throughout the water 
column at Ed-1. While Cape Crozier is adjacent 
to the Ross Ice Shelf, a somewhat different pat- 
tern of circulation can be expected along a land 
ED-I 
Fig. 2. Vertical section at right angles to the coast line in about 162°W, showing isopycnic lines. Probable 
vertical circulation is indicated. 
