TM No. 377 



3. Measurements of the geostrophie departure in the layer of frictlonal 

 influence (Sheppard and Omar, 1952). 



A review of the results of these studies is presented by Neuman (1956). 

 In this paper Neuman emphasizes the inherent difficulties in marking and 



interpreting 'wind stress data. He also cites the various problems en- 

 countered in modeling natural wind stress phenomena in the laboratory. 



Spectral Analysis — One of the most significant, although perhaps unin- 

 tentional; contributions made to the studies of waves ~ and, in fact, to 

 geophysics in general — was the development of the modem techniques of spec- 

 tral analysis, in which one can utilize the capabilities of the high speed 

 electronic digital computer. These analysis techniques were developed by 

 workers in the field of communications engineering and information theory, 

 and then applied to general statistical problems. 



The basic work is by Tukey (19^9), Tukey and Hamming (19^9)> and Rice 

 (1954). Spectral analysis is summarized by Blackman and Tukey (1958)* The 

 original work was developed to analyze noise in electrical circuits. Largely 

 through the efforts of Pierson at New York University (see Fierson, 1952 

 and 1955)* these statistical techniques became known to a few wave researchers 

 and hence have become relatively familiar to oceanographers and geophysieists . 



Over the past decade the application of the Tukey spectral estimates 

 has become a commonplace tool in data analysis for a greatly diversified 

 group of geophysical problems in which analysis is desired oi complex 

 interrelationships of two or more variables. Tnese methods allow meaning - 

 ful analysis of the spectra of time series observations of a particular 

 variable, and also permit the assessment of the correlation or interaction 

 of two or more variables. This latter analysis alludes to the estimate of 

 the cross spectral properties associated with the two particular variables 

 measured. Another facet of the technique is the development of criteria 

 by which one may evaluate the reliability of the auto- and cross -spectral 

 estimates through the use of coherence properties between auto- and cross- 

 spectra. These spectral analysis techniques are the mainstay of this 

 analysis of the wave observations. A general discussion of the techniques 

 is given in chapter III* 



Formulation of the Problem 



With most scientific research the results are predicated more on the 

 actual progressive pattern of work done (involving the usual numerous 

 successes and failures) than upon the original portrayal of the problem 

 to be solved. Such is the case with this investigation. 



The original proposed problem was to determine a very specific parameter 

 within the wind-driven ocean waves j i.e., the Reynolds stress. It was obvious 

 at the outset that certain problems would arise as the study progressed -- 

 problems involving instrumentation, methods of measurement, data processing, 



