Clark and Yarnall 



The phase curve for H43 is a representation, over the full extension 

 of the test, of the "trends" illustrated in Figures 9 and 12, These 

 two sample periods of the phase data are identified respectively by 

 the symbols A and B. The half- sinusoid shape of the curve during the 

 27-28 November period can be attributed to the tidally related phenom- 

 ena to be discussed later. 



The acoustic phase data appears to contain information which 

 will be interpreted in subsequent discussion in terms of processes 

 in the medium. One point, however, needs emphasis. In our treatment 

 of the interference nulls we have pointed out that the phase records 

 are a signal plus noise situation for which no quantitative assessment 

 of the noise contribution is available. Numbers, given in the follow- 

 ing discussion, which relate magnitude of phase change over extended 

 periods to sound speed or temperature changes in the medium must be 

 taken as very approximate. For the most part, discussion will be 

 restricted to the spectral content of the phase data. 



DATA ANALYSIS 



The simple large scale perturbations of the medium that can 

 be simulated with the propagation model hardly do justice to the 

 actual processes that occur in the oceans. The ray calculations can 

 serve only to illuminate some of the more pronounced features of the 

 experimental results. 



In practice the data analytical procedures have not been 

 geared exclusively to large scale perturbations in the medium, but 

 have assumed that all time varying processes which can scatter or 

 attenuate the acoustic energy will leave spectral signatures in the 

 phase or amplitude display of the received signal. Thus, in brief, 

 the basic procedure has been a search for the spectra, in the acoustic 

 phase and amplitude data, of experimentally or theoretically estab- 

 lished geophysical phenomena which have well defined spectral char- 

 acteristics. For the most part, the search has not been difficult; 

 the signatures have been prominent in the data. It has also been 

 possible in some cases to establish correlations with environmental 

 measurements; this has contributed substantially to the analysis. 



Most of the data will be grouped under subheadings which 

 designate the geophysical phenomena to which the acoustic signatures 

 are attributed. There are elements of speculation in some of these 

 cases which will be acknowledged when the data are discussed. The 

 following groupings have been established: a) surface wave signa- 

 tures, b) short period internal wave signatures, c) tidally related 

 signatures, d) long period signatures-atmospheric phenomena. Figure 14 

 has been included to schematically summarize the time scale of the 

 signatures that have been observed in the acoustic data. 



A considerable variety of data will be presented, taken at 

 various timesln the two year span from January 1965 to January 1957. 



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