OCEANOGRAPHIC SUMMARY. 



Lieut. (Junior Grade) Edward H. Smith, detailed as oceanographic 



observer. 



From the preceding detailed discussion of the section profiles, 

 certain facts have been established which now may be summed up 

 in a comiective way, thereby giving us a clearer conception of the 

 sequence of developments during the ice season of 1922. 



Oceanic circulation* is subject to seasonal variations. These 

 variations are exhibited in volume, position, and strength of the 

 currents and are caused by any one or all of the following in com- 

 bination: (a) Meteorological conditions, (6) dynamic principles of 

 circulation, and possibly (c) variations in solar energy. Local con- 

 ditions, such as prevailing winds, may set up a temporary surface 

 drift in a limited area, but such a factor is of so slight and temporary 

 a nature that it does not alter the underlying oceanic movement. 

 It is necessary to search farther afield for the fundamental factors 

 which cause the major water movements over large areas, although 

 these may produce local currents apparently inconsistent with the 

 winds at the particular time and place. 



This should be borne in mind when discussing the subject of 

 physical phenomena in the vicinity of the Grand Banks of New- 

 foundland, where for the larger part of the year we have the Labrador 

 Current pressing into the Gulf Stream with continual variations on 

 the part of both in position, volume, and velocity. An example of 

 this occurs every summer in the well-known augmentation of the 

 polar currents caused by the great increase of water from melted 

 ice. Since southerly winds J5i*^evail over the Grand Bank area 

 at this time, an observer who confined his observations solely 

 to this region might well be puzzled at finding the southerly Arctic 

 current swelling in opposition to the prevailing wind. But this 

 apparent inconsistency vanishes if one searches for the underlying 

 causes. 



The following lines contain a summary of certain facts established 

 by the profiles. Attention will be called to variations in circulation, 

 but no attempt will be made to determine or explain the cause, if 

 not of a local, temporary nature. It is considered sufficient to record 

 these phenomena over a period of years in the vicinity of the Grand 

 Banks of Ne^^^oundland ; after the compilation of these data the 

 relationship existing between local currents in the bank area and 

 more general oceanic phenomena may be developed. 



The following discussion is based on the observations of 1922. 

 Judging from past ice-patrol records this was, in general, a nonnal 

 year for amounts of ice, position, and strength of currents, hence it 

 may fairly be used as the basis for describing typical conditions, 



' Sandstrom, J. W., "Canadian fisheries expedition, 1914-1915," pp. 221-231. Pettersson, O., "Con- 

 nection between hyrtrographical and meteorological phenomena," Qiiart. Jour. Roy. Met. Soe., July, 

 1912, pp. 123-191. Bjerknes, V. E. K., "Dynamic meteorology and hydrography," Carnegie Inst., Wash- 

 ington, 1910-1911, Pub. No. 8.1. Dickson, H. N., "The circulation of the surface waters of the North 

 Atlantic," Phil. Trans., Roy. So?., London, 1906, vol. 196A. 



