OCEANOGRAPHER'S REPORT 



laeut. Edward H. Smith, United States Coast Guard 



MARCH 



The international ice patrol, for the season of 192J:, was in- 

 augurated on March 22, when the patrol ship arrived on the south- 

 west slope of the Grand Banks. Scientific observations were com- 

 menced and surface-water temperatures were solicited from all 

 steamships within the Grand Bank regions. It is well known that 

 winter cooling of the ocean surface sets up convectional currents 

 which, in short, gi^-e to the ocean surface temperatures the virtue of a 

 true thermal picture of the water mass as a whole. Thus chart F, the 

 surface temperature chart for March, marking the temperature mini- 

 mum of the 1923-24 winter, furnishes an accurate portrait of the 

 major circulatory movements of the water masses around the Grand 

 Banks of Newfoundland. It is one of the most interesting and 

 valuable temperature charts which the patrol has secured in the 

 past six years, because it reveals thermally the relative positions of 

 Arctic, local, and Atlantic water, and which moreover was made pos- 

 sible through the agency of a mild winter. 



The most prominent feature was the leg of frigid water extending 

 southward to the Tail on the eastern side of the Grand Banks and 

 stretching westward of the Tail, on the forty-third parallel, for a 

 distance of nearly 100 miles. This area from surface to bottom was 

 occupied by the coldest water south of Newfoundland for the year 

 and has been inclosed by shaded crosshatching on chart F. 



In marked contrast to the coldest water on the chart we found a 

 large area of generally circular shape on the western and central 

 j)art of the Grand Bank occupied by a water mass warmer than 

 35° in temperature extending from surface to bottom, being the 

 portion of the Grand Bank which has characteristicalh' exhibited 

 a tendency to remain free from external intrusions and disturb- 

 ances,^ and thereby furnishes us with a thermal measurement of 

 the degree to which winter chilling has proceeded. 



The water lying over the southwestern and central part of the 

 Grand Bank being free from external intrusions is chilled nor- 



1 Smith, Edward H. : International Ice Observation and Ice Patrol Service, 1923, 

 TJ. S. C. G. Bull. No. 11, pp. 147-149. 



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