5 \ears, and 6 are based on 7 years. Furthermore, as pointed out above, 

 conditions during approximately the second half of the 8-year period 

 were much different (probably abnormal) from the first half of the 

 period. Thus the mean values appearing in table 1 and the mean curves 

 shown in figures 5 and 7, while representing the mean conditions fairly 

 accurately for the period 1934-41, cannot be considered as normals, but 

 are used here in lieu of normals because they represent all the observa- 

 tions that are available. 



Because the volume of flow and the mean temperature are integrated 

 characteristics of the current, they are more representative and less 

 subject to the effects of the chance location of stations with respect to 

 the axis of the current than is the minimum observed temperature. 

 However, the minimum temperature, occurring in the core of the current, 

 in combination with the mean temperature, may be revealing as to 

 the causes of fluctuations in the current and thus may help us to under- 

 stand the sequence of events bearing on the quantity and distribution 

 of ice. In 1941 the minimum observed temperature at each occupation 

 of each section was w^armer than the 8-year mean, and for the season 

 as a whole it was about 0.65° warmer. 



To examine the degree to which the minimum observed temperature 

 indicated by reversing thermometers may depart from the minimum 

 actual temperature through chance spacing of oceanographic stations, 

 some vertical sections were run in which bathythermograph^ observa- 

 tions were made at intervals of about 1 mile, concurrently with the 

 routine occupation of stations. Two such detailed temperature profiles 

 are shown in figures 8 and 9. Here the locations of the different bathy- 

 thermograph casts are indicated by the short vertical lines near the 

 surface, the observations extending to about 135 or 140 meters when 

 the depth of water permitted. The locations of the reversing ther- 

 mometer observations are indicated by black dots at the various 

 oceanographic stations. In each of the sections the minimum tempera- 

 ture given by the reversing thermometers was within a tenth of a 

 degree of the minimum given by the bathythermograph. As this is 

 about the limit of accuracy of the bathythermograph used, it is con- 

 sidered that the usual spacing of oceanographic stations used in current 

 surveys of the Grand Banks will ordinarily give the actual minimum 

 temperature within a few tenths of a degree. Probably this is because 

 the core of minimum temperature of the Labrador Current bears a 

 characteristic relation to the continental slope, with regard to which 

 also the station positions are selected. 



In the light of the foregoing, with due regard for the limitations of 

 the method of determining the minimum temperature, and again 

 calling attention to the probability that the 8-year mean, 1934-41, 

 departs from the normal, figure 10 is presented to show the variation in 



* A. F. Spilhaus, a Detailed study of the surface layers of the ocean in the neighborhood of the Gulf 

 Stream with the aid of rapid measuring hydrographic instruments. Jl. Mar. Res., vol. Ill, No. 1, pp. 

 51-7.^>, (May 1, 1940), New Haven. 



11 



