PHYSICAL OCEANOGRAPHY OP THE GULF OF MAINE 
919 
of the Gulf of Maine eddies. This same distribution of temperature, however, 
reappearing in April, is reminiscent of a past state of circulation, not of a present 
one, because the corresponding charts of salinity show the dominant set to have 
assumed a southwesterly course, more nearly parallel to the coast line, from the one 
month to the next (p. 743). Neither of these early spring charts of temperature 
suggest any drift of warmer water into the eastern side of the gulf from offshore; 
but some drift of this sort is indicated on the 40-meter chart for March (p. 525) by a 
band warmer than 3° entering via the Eastern Channel. This indraft appears 
more clearly at deeper levels (p. 526). 
With the advance of spring the regional inequalities of temperature become 
increasingly significant, from the standpoint of circulation, as they outline the lines of 
dispersal followed in the gulf by the cold water of the Nova Scotian current. In 
general, temperature corroborates salinity to the effect that the current did not begin 
to flood westward past Cape Sable until after the middle of April in the year 1920, 
though it had exerted its chilling effect in this direction as far as the eastern side of 
the basin of the gulf by the last of March the year before (p. 553). The isotherms 
for May (fig. 27), however, suggest more of a tendency for this Nova Scotian water 
to spread northward toward Maine and the Bay of Fundy, as well as westward in 
the gulf, when at its head, than do the isohalines (p. 745). 
Rising temperature, like rising salinity, reflected a slackening in the current in 
1915 from May to the last half of June, when an abrupt transition in the temperature 
of the coldest stratum, from the Eastern Channel (about 8.1°) to the vicinity of 
Cape Sable (about 0.7°), located its southwestern boundary at Browns Bank. This 
is also indicated by the abrupt transition from colder to warmer water along the 
western slope of the bank at 40 meters; but the low temperatures recorded over the 
southwest slope of Georges Bank on the July profile for 1914 (fig. 58, p. 616) 85 is 
readiest explained as reminiscent of a cool current skirting the bank from northeast 
to south some time previous. It seems that in the cold year 1916 such a drift of 
cool water was either in much greater volume or persisted until later in the season, 
for it is difficult to account otherwise for the band of low temperature which the 
Grampus encountered over the southwestern slope of the bank that July (p. 629). 
“The facts that the cold band of 1916 lay almost exactly in the prolongation 
of that of 1914; that a similar streak of comparatively low temperature (6.4°) was 
encountered at the same relative position on the shelf some 60 miles farther west in 
1913 (station 10062) ; and that the axis of the coldest water noted on the shelf south 
of Nantucket in 1889 (Libbey, 1891) merely prolongs this general zone, practically 
amount to proof that a northeast to southwest flow of cold water takes place there 
annually in late spring or summer, dovetailing in between the warmer and fresher 
bank water on the north and the Gulf Stream on the south.” (Bigelow, 1922, p. 166.) 
Its source is discussed elsewhere (p. 848). The July isotherms for 1914 locate its 
extreme western boundary between longitude 68° and 69°, where the 40-meter chart 
84 This also appears on the corresponding chart for the 40-meter level, but is complicated there by active vertical mixing that 
maintains a higher temperature over the shoal parts of the bank at this depth (lower at the surface) than on its southern side; 
the alternation of a warm with a cold belt along the bank, outlined in the 40-meter chart (fig. 53), is therefore partly of local 
origin. 
