SUMMARY OF DATA AND DISCUSSION 



Oscillations 



The isotherms fluctuated vertically with time during all the observations (fig. 

 3-14). The height of the fluctuation was not consistent over any great length of 

 time. Sometimes patterns appeared, but these were soon changed or interrupted 

 by other patterns. When one isotherm in the thermocline dipped, nearly all the 

 others did too. This was especially true when major wave-type cycles were present. 

 The shapes of the internal waves varied, but they were generally symmetrical 

 about the crests; in many waves, the advancing face of the crest was steeper than 

 the receding face (fig. 3, 4, 6A, 7, 8, 9, 10, IIB, 13B, and 14). 



Slicks 



Slicks were present about 10 per cent of the time. During the periods of oper- 

 ation 105 slicks were recorded. The duration of any single slick, as it passed any 

 point, was from 0.35 to 5 minutes, averaging 1.3 minutes. 



Wave Height 



The magnitude of the vertical fluctuations was generally inversely proportional 

 to the gradients through which they protruded (fig. 9, 10, and 14B). Smaller fluc- 

 tuations were always present. 



The maximum daily vertical migration of an isotherm in the middle of the 

 thermocline, during the periods of investigation and in the upper 35 feet, was 

 22 feet on 22 July (fig. 14B). 



The frequency distribution of heights of the shallow internal waves of each 

 day is shown by the total height of the histogram columns in figure 15. Only 

 waves greater than 2 feet were considered since the smaller ones are probably 

 only random fluctuations. Although these were for different periods of time, as 

 noted, the relative distribution can be compared for the different days. During 

 June, the wave heights for the period of observation tended to be smaller than 

 those for July and August. 



Wave Heights and Slicks 



On the same figure, the histogram columns are shown in either dark or light 

 shading. The dark shading represents internal waves which were associated with 

 a sea surface slick, and the light shading internal waves without slicks. All the 

 largest waves, that is, with heights 16 feet or greater, had slicks associated with 

 them. 



In a time of 28 hours and 4 minutes, spread over 12 days, there were 169 waves 

 greater than 2 feet. A composite distribution of the internal heights of these 

 waves is shown in figure 16. Fifty per cent of the waves considered had heights 

 of 7.2 feet or greater. The shading of this figure is also indicative of waves with 

 slicks and waves without slicks. 



Wave Period 



The frequency distribution of the durations of these 169 internal waves by 

 days in 3-minute intervals is given in figure 17 (waves with periods less than 2 

 minutes were neglected). The relation of slicks to wave period is also shown in 

 this figure by the darker part of the columns. 



A summation of the 12 days' data is given in figure 18. Fifty per cent of all 

 waves longer than 2 minutes had periods greater than 7.6 minutes. 



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