SCIENTIFIC EESULTS 203 



to about one-third of the cold discharge between Cape Eace and 

 Flemish Cap, then the cooling e-ffect of ice mdthuj amounts to only 

 10 per cent of the total cooling that the Atlantic receives from the cold 

 water masses of the Labrador current. ^^ The fact that the relative 

 proportions of ice and water are roughly similar at the other prin- 

 cipal jwint of discharge — the east Greenland current — makes this 

 figure applicable to the entire North Atlantic. Obviously, the low 

 temperature character of the Labrador and east Greenland currents 

 is not due to the melting ice with which these streams are charged 

 in spring and summer. These ocean cun^ents are cold because of the 

 small amaimt of absorption of solar radiation at the earth's surface 

 in the polar regions. 



The foregoing corroborates Campbell-Hepworth (1912, p. 4). that 

 the ice in the western North Atlantic is not the agency chilling the 

 surrounding ocean masses but it is largely the Labrador current. 

 Helland-Hansen-Xansen (1920, p. 266) conclude that the variations 

 in temperature noted in the unperiodic coolings of the North Atlantic 

 Ocean are due to the changes in the distribution of air pressure, i. e., 

 the northerly winds. Schott (1904, p. 279), in the course of remarks 

 on the intensification of the Labrador current in 1903, adds that 

 the cooling effect of Arctic ice in the Atlantic is negligible. While 

 our own researches do not find that the ice-melting effect is negligible, 

 they do prove it is of secondary magnitude. 



It is interesting to note in the quantitative treatment of these 

 northern seas phenomena that the cooling factors, viz, chilling by 

 the winter atmosphere, ice melting, snowfall, and evaporation, when 

 totaled, outweigh the solar warming of summer. We have found 

 that the ice-melting effect counteracts about one-half that of seasonal 

 solar warming, and mounts to approximately one-tenth the cooling 

 effect of the annual discharge of the cold currents. The great major 

 warming effect therefore tending to maintain more or less of a con- 

 stant counterbalance over a long period is the warm currents from 

 the Tropics. We conclude that the major controls of the thermal 

 equilibrium of the North Atlantic Ocean are the ocean currents., 

 while the direct action of veomal warming in the ice areas themselves., 

 and the opposite effect of chilling by Arctic ice., are secondary. 



The fact that the latent heat of melting ice as a chilling agent 

 amounts to only about one-tenth that of the cooling effect of the 

 ocean currents from the north also j^roves conclusively that melting 

 ice is far from being an important factor assisting to maintain the 

 present scheme of oceanic circulation. According to Pettersson 

 (190-1. 1907), the melting northern ice, which we have shown takes 

 place almost entirely in relatively shallow^ waters, sets up a certain 

 system of oceanic circulation. The waters of the Grand Bank, how- 

 ever, even when no ice is present, have been found to exhibit a similar 



■'' llnntsnian (1930), in discussing the Arctic ice which is brousht into the Gulf of 

 St. I>:i\vrciice via the Strait of Belle Isle, states that in his opinion its melting is the 

 chief cooling agent in the Gulf. He points out that if the branch of the Labrador current 

 that enters the Gulf has a velocity of 1 knot per hour for the three winter months, enough 

 ice might be carried in to cover half the Gulf of St. Lawrence. He also adds that were 

 this ice to melt it would chill by 8° C. a 30-foot layer of water equal in area to the entire 

 Gulf. As a matter of fact, however, the inflow through Belle Isle is not believed to main- 

 tain such a high rate as assumed in the above example. It is estimated moreover, that the 

 Gulf of St. Lawrence normally cools 8° each year throughout a mean depth of about .300 

 feet, and if this be a fact, the chilling effect of the ice importation amounts to less than 

 one-tenth that of the other agents. Here, apparently, as in the Atlantic, the cold-water 

 masses arc the deciding factors. 



