SUMMARY OF OCEANOGRAPpiC CRUISE OCTOBER 



21-26, 1923. 



Lieut. Edward II. Smith, U, S. Coast Guard. 



A general consideration of all sections emphasizes above all else 

 that oceanographical conditions around the Tail of the Grand Bank 

 in the autumn are quite different, in the main, from what they have 

 been found to be in the spring. The standards upon which compari- 

 sons are based, naturally, must be different in October from in May, 

 for in the first instance the water mass has been under the influence 

 of an entire summer's warmth, while in the second the water is 

 just beginning to acquire warmth after a full winter's chilling. Yet, 

 fundamentally, it was found that the two periods corresponded 

 in one very important respect: water of unmistakable Arctic origin 

 was bathing the east slope and southward around the Tail of the 

 Bank during the period October 21-26, 1923. 



The proof for this statement rests on the presence of a band of 

 icy cold water of temperature below zero which was found in all 

 the sections, except the mid one on the southwest slope, 45 miles 

 west of the Tail, where no water colder than zero degrees was found. 

 The temperatures of -0.4° to -0.25^, existing around the Atlantic 

 faces of the Grand Bank, could not have been produced locally, or 

 even earlier in the season, as pointed out on page 146, and therefore 

 the}- could only have been the result of cooling somewhere in the 

 regions farther north. The salinity of this band of extremely cold 

 water. 33.867oo to 33.787oo, also accords with the salinity of the 

 northern discharge; consequently this water in question must have; 

 been transported to the Grand Bank by a current from the north. 



As pointed out above, the recognition of Arctic water depends on 

 rather different criteria of salinity and temperature in autumn than 

 in spring, this frigid water being about 0.87o„ salter and about 1° 

 warmer at the same locality in October than in the spring, when the 

 icy current is flowing at its maximum. This salting from spring to 

 summer has been ])rought about through a more extended period 

 of exposure to Atlantic adulterations, from which a slow, occasionally 

 interrupted, flow from the north must suft'er. The warming is attrib- 

 utable to two factors: (1) the heat derived from thesununer's sun 

 and (2) heat transference through mixture with the much warmer 

 offshore Atlantic. 



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