SCIENTIFIC RESULTS 199 



feet of water 1° F., we have, in the case given, 80 feet of water to 

 6 of ice. or the 467 cubic miles of pack ice in the western North 

 Atlantic (shown shaded in fig. 121), will counteract the warming 

 of the SO-foot surface layer of the sea a total of 6° F. 



Let us now investigate the amount of solar warmth that is absorbed 

 by the water masses of the melting area in the western North At- 

 lantic, beginning with the first rise in temperature of the southern 

 section in early spring and continuing until the entire area at- 

 tains its maximum heat absorption in late August or early Sep- 

 tember. The mosti accurate method of determining the amount 

 of thermal absorption and the depth to which it extends is ob- 

 tained by examining several temperature curves (see fig. 120, 

 p. 19S) for the water column of stations scattered throughout 

 the mehing area. Marion stations 911, 917, 957, 963, 1058, 1062, 

 1011. 1046, 986. 1029, 1015, 1100, 1097, 1108, 1115, and 1125 have 

 been employed. (See Smith, 1931, for station table data of the 

 Marlon, expedition.) Other stations examined were the GodthaxiVs 

 Nos. 51. 60, 71, 78, 131, 111, and 100. (See Annually 1929.) Two 

 ice-patrol stations were selected, 58 (see Nightingale, 1915, p. 54) and 

 355 (see Smith, 1924, p. 100). The position of these stations at which 

 subsurface observations were made are plotted on Figure 121, p. 200. 



The shape of the temperature curves (fig. 120) show that the 

 sun during the summer months warms the uppermost 15 to 20 meters, 

 the greatest and passing from that depth downward the seasonal gain 

 in temperature decreases directly with the depth until the 150-meter 

 (approximately 480 feet) level is reached, where more or less con- 

 stant year-round conditions prevail. A comparison of the tempera- 

 ture curves, one with another, also shows that the farther northward 

 we proceed the thinner and less heated is the sun-warmed surface 

 strata. The thickness of the isolation layer has been taken as the 

 limit to Avhich the sun's heat has penetrated, or a layer having the 

 horizontal dimensions of the melting area and a uniform thickness 

 of 150 meters. The melting area as drawn on Figure 121 has been 

 divided into six subdivisions, viz, A, B, C, D, E, and F. Division 

 A being the southernmost area is most noticeably aifected by the 

 sun and the oceanographic stations in this region record a seasonal 

 increase in temperature equivalent to 5° F. throughout the 480-foot 

 layer. Division B warms up equivalent to 4° F. surface to a depth 

 of 480 feet. Division C, 3° ; division D, 2° ; division E, 1° ; and the 

 most northern one in Smith Sound only 0.5° F. Combining these 

 values of the degree of summer heat in the 480-foot layer, and spread 

 uniformlv over the melting area, we obtain a mean temperature rise 

 of 2.1° Y\ 



The annual melting of pack ice was found to counteract the warm- 

 ing of an 80-foot surface layer 6° F. The same agency will oppose 

 the warming of a 480-foot layer 1° F., or, in other words, the cMUlng 

 of the northicestern N orth Atlantic as a result of ice melting amounts 

 to approxhnateh/ one-half the solar heating this same region receives 

 during summer.^^ 



w Ricketts (19?.0. p. 109) estimates tbat the total clillling effect of 1.350 icebergs that 

 drifted south of Newfoundland in 1929 was not sufficient to nullify more than two hours 

 of the average vernal warming to these regions. The relative insignificance of icebergs 

 cooling the North Atlantic a?irecs well with the very small proportion that annual volume 

 of glacial ice bears to annual volume of sea ice. 



120860—31—14 



