that the model is correct in order to obtain the distribution of contact con- 

 ditions. This would require a much smaller volume of observations. To 

 this end the Air Frame Design Division of the Bureau of Naval Weapons 

 undertook a study to evolve such a model and to perforna computer simula- 

 tions and analyses on this model. This problem breaks down into the follow- 

 ing phases: 



1. Determination of the distribution of wave conditions. 



2. Determination of the transfer function characteristics of a class 

 of aircraft carriers, 



3. Deriving a mathematical model of the landing control system, 

 i. e. the AN/SPN-10. 



Under ordinary circunnstances the first item would be carried out by 

 analyzing the wave climatology of the relevant operating areas. However, 

 such data are not available especially so since a rather detailed description 

 of the surface in terms of its spectral characteristics is required. The 

 only environmental data on an ocean-wide scale which were available were 

 the atmospheric pressure patterns. In order to obtain any wave data, it 

 would be necessary to be able to compute rather than observe. To this goal, 

 a contract was let to New York University School of Engineering and Science 

 by way of the U. S. Naval Oceanographic Office to derive a computer-based 

 procedure for calculating the spectral distributions of the waves on the 

 surface of the North Atlantic from surface pressure and wind data, and to 

 calculate, using this procedure, a wave climate of the North Atlantic for 

 the year 1959. From these data, distributions of carrier motions would be 

 determined by the David Taylor Model Basin and finally the distribution of 

 landing conditions for certain set of conditions would be computed by the 

 Bell Aerosystems Company. This paper reports the results of the New 

 York University effort. It should also be stated here that the California 

 Division of the Lockheed Aircraft Corporation also participated. 



THE WAVE HINDCASTING PROBLEM 



The basic problem was to develop a computer oriented numerical pro- 

 cedure for computing the directional wave spectra using the wind velocity 

 field as the driving mechanism. Originally it was thought that the atmo- 

 spheric pressure field could be used to determine the wind field. 



Preliminary descriptions of the procedures used have been given by 

 Pier son and Tick (1964). Reports on the details of the computer based 

 numerical procedure are in the first draft stage of preparation, and should 

 appear first as Technical Reports at New York University and later as 

 papers in the Journal of Geophysical Research. ^ 



"^ (See Trans. Amer. Geophys. Un. , vol. 46, no. 1, March 1956, p. 109 

 papers 059 and 060. ) 



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