compared with values computed witli the 1952 expression of 0.83, 

 0.07, and 2.65. 



The quantity H involves the sea level at Charleston and the de- 

 parture from average sea level at Bermuda. Average sea level at 

 Charleston enters the constant 5.07. Part of the difficulty in obtaining 

 a good correlation in the postwar years is believed to be the changes in 

 relative sea level which have taken place at both stations. The aver- 

 age sea level at Charleston for the 8-year period 1947-54 is 0.27 foot 

 higher than during the prewar 8-year period 1933-40, and the postwar 

 average sea level at Bermuda is 0.10 foot higher than that for the 

 prewar period. Another possible difficulty is the exceptionally large 

 variation in difference in sea level at these stations during the postwar 

 period. Figure 23 shows the fluctuations in annual average values 

 of the difference in sea level Bermuda minus Charleston. If this is 

 taken as a measure of the activity of the North Atlantic eddy and if 

 the total difference in sea level is inferred from density distribution, 

 the range of 0.8 foot shown in figure 23 represents a fluctuation of 

 about 30 percent. It is possible that the simple expressions given 

 above may represent the relationship between the sea-level difference, 

 the strength of the Labrador Current and the position of the cold wall 

 in the Grand Baidvs region adequately for small changes, but become 

 inadequate when major changes in the driving forces require the 

 establishment of large compensating circulation patterns. 



Figure 24 shows the dynamic topography of the sea surface relative 

 to the 1,500-dicibar surface from the observations made during the 

 1954 postseason cruise along the section acrosss the Labrador Sea and 

 the Greenland triangle. The temperature and salinity distribution 

 along these four sections are shown in figures 25 to 32. In figure 25 

 it will be noted that the temperature minimum in the Labrador 

 Current over the shelf has only a small cross section colder than 

 — 1.5°. The temperature maximum reaching bottom at intermediate 

 depths along the continental shelf is defined bv the 3.5° isotherms 

 and contains observed temperatures up to 3.79°. The temperature 

 minimum at intermediate depths in the central part of the section is 

 indicated by the area enclosed in the 3.2° isotherm. Although the 

 area thus enclosed is small, the temperature of the minimum is close 

 to that of the colder years 1934-39 and 1950 when the minimum was 

 about 3.17°. During the other 7 years for which data are available 

 (1940-41, 1948-49, and 1951-53), the minimum was about 0.10° to 

 0.15° warmer. The temperature maximum below this minimum 

 was for the most part less than 3.3°. At the Greenland end of the 

 section the warm water of the West Greenland Current had about the 

 same cross-sectional area with water warmer than 4° as was found in 

 1953, but the areas enclosed by the 5° and 6° isotherms was greater 

 in 1954. 



98 



