i 4 DISCOVERY REPORTS 



the water whose density is increased by the freezing processes is made heavy enough to 

 sink below the warm deep layer to give rise to the Antarctic bottom current, but 

 generally it finds its way northwards in the lower stratum of the surface layer. In 

 summer the southward movement at the surface is likely to be hindered by the liberation 

 of fresh water from melting ice and snow which will restrict the southward movement 

 of the drift current by the formation of an opposing solenoid field. Assuming the winds 

 to be the same in both seasons, the effect of the low winter temperatures will be to bind 

 the Antarctic pack-ice closely round the continent, whilst the warmer climate in summer 

 will facilitate its dispersion towards the north. 



THE EAST WIND DRIFT 



Since there is very little doubt that the drift towards the west along the coast of the 

 Antarctic Continent is primarily the result of the prevailing east wind it is probably best 

 referred to as the East Wind Drift. Like the West Wind Drift farther north it is 

 practically a circumpolar current. 



It is only interrupted in the south-west corner of the Atlantic Ocean where its path is 

 obstructed by Graham Land, Trinity Peninsula, and by the adjoining South Shetland 

 Group. There is, however, a small current towards the west round the northern ex- 

 tremity of Trinity Peninsula, where a stream of cold water which has its origin in the 

 Weddell Sea flows westwards into the Bransfield Strait (Clowes, 1934, p. 62). A sum- 

 mary of the wind observations north-east of Trinity Peninsula made by Mossman 

 (Antarctic Pilot, pp. 73-4) shows that winds from the south and east are more frequent 

 than those from the north and west. The movement of Weddell Sea water westwards into 

 the Bransfield Strait is evidently partly due to the greater prevalence of south-east 

 winds, but it may also be caused by an accumulation of water from the circumpolar 

 westward movement, in the north-west corner of the Weddell Sea, or it may be a counter- 

 current to the great eastward movement through the Drake Passage. It appears to be 

 only a weak current, flowing a short distance down the southern side of the Bransfield 

 Strait and forming an eddy with water flowing in the opposite direction. 



Farther south, in the neighbourhood of the Palmer Archipelago, there appears to be 

 a break in the westward movement. In the De Gerlache Strait between Brabant and 

 Anvers Islands and the mainland the current flows towards the north-east (Antarctic 

 Pilot, 1930, p. 84). The high salinity of the surface water at Sts. 1002 and 1003 (section 

 19, Plate XLIII) on the continental shelf north-west of the islands is evidence that a 

 current towards the north-east is causing the water to upwell there. 



The information from the west coast of Graham Land south of the Palmer Archi- 

 pelago indicates that the westerly current is soon regenerated. A winter's observations 

 at Petermann Island showed that winds from the north-north-east and north-east pre- 

 dominated and were always strong, whilst winds from the south-south-west and south- 

 west were much less frequent and blew less strongly (Rouch, 191 1, p. 182). The pre- 

 vailing wind should therefore give rise to a movement to the south-west along the coast 

 and also to an onshore current. 



