To be sure, large values of standard devi- 

 ation did occur in the upper 100 meters, 

 particularly from May to October of most 

 years studied. These surface layer values 

 were generally more noticeable in the 

 temperature parameter tlian in the salinity 

 parameter. However, the greatest values of 

 standard deviation generally occurred at 

 depths between about 400 and 800 meters, 

 with a few occasions where it was shghtly 

 above or below this level. Additionally, 

 this maximum deviation for both salinity 

 and temperature usually occurred at or 

 nearly the same depth. Where they 

 differed, the maximum salinity deviation 

 usually occurred 100 meters shallower 

 than temperature. However, where a 

 salinity peak did occur, a high standard 

 deviation value for temperature was always 

 present. The maximum deviation invari- 

 ably occurred in the region of the largest 

 gradient of the thermocUne/halocline. 

 Therefore, small variations in the depth 

 of the isopleths resulted in relatively 

 large variations in temperature and salinity 

 values. 



The vertical migration of the isotherms 

 and isohaUnes from about 200 meters to 

 below 1000 meters (and almost notice- 

 able to about 3000 meters, although the 

 data were almost too sparce to extrapolate 

 conclusions to that depth) were fairly 

 independent of the seasonal surface tem- 

 perature and sahnity variations. In partic- 

 ular, the variations of tempeature and 

 salinity depicted in figures 6 and 7 for the 

 months of July, September and November 

 1971 and January 1972 show excursions of 

 the isopleths of up to 250 meters. At first 

 glance it might appear that these variations 

 were due to transiting water masses 

 through Ocean Station ECHO. However, 

 the T-S diagrams for these four months, 

 figures 8a through 8d, are nearly identical 

 except for the expected variations in the 

 surface levels. This would tend to discount 

 intruding water masses and eddies. It 



would appear that these variations might 

 be a barotropic response. 



SUMMARY 



The seasonal effects at Ocean Station 

 ECHO were clearly visible only in the 

 upper 100 meters. On some rare occasions, 

 however, the turnover may have resulted in 

 nearly isothermal conditions as deep as 300 

 meters. 



The permanent thermocUne-halocUne 

 may have had an annual cycle but one 

 which was masked by a shorter period, 

 possibly a barotropic response. 



REFERENCES 



Defant, Albert (1961). Physical Oceano- 

 graphy, Vol. I. Pergamon Press, London, 

 729 pp. 



Morse, R. M., J. W. McGary (1964). 

 Oceanographic Observations at North 

 Atlantic Ocean Station ECHO, January- 

 February 1963. U.S. Coast Guard 

 Oceanographic Report, CG 373-2. 



Rosebrook, Alan D. (1971). Oceano- 

 graphic Observations North Atlantic 

 Ocean Station ECHO, November 1967- 

 December 1968. U.S. Coast Guard 

 Oceanographic Report, CG 373-49. 



Shuhy, J. L. (1969). Oceanographic 

 Observations at North Atlantic Ocean 

 Station ECHO, September 1966 - 

 October 1967, U.S. Coast Guard 

 Oceanographic Report, CG 373-21. 



Sverdrup, H. U., M. W. Johnson, and 

 R. H. Fleming (1942). The Oceans; 

 Their Physics, Chemistry, snd General 

 Biology - Prentice Hall, New York, 

 1089 pp. 



U.S. Coast Guard Oceanographic Unit, 

 Manual for Oceanographic Operations, 

 CG410. 



Wust, G. (1936). Schichtung and Zirkula- 

 tion des Alt. Ozenas, 'Meteor' werk, 

 6, 1 Berline. 



8 



