National Goals in Oceanocraphv 



In oceanography the major objective, of course, 

 is the greater understanding of the environment to 

 enhance our capabilities in all forms of warfare. 

 One example, and perhaps the one which most 

 directly benefits from oceanography, is Anti-Sub- 

 marine Warfare. Here, the sophistication and 

 effectiveness of major improvements which have 

 been made in weapons systems have been due not 

 only to increased knowledge of the environ- 

 ment, but largely to advances in other areas of 

 science and technology. Signal processing is a 

 good example. The effective utilization of these 

 systems, however, requires a broader and more 

 detailed understanding of the environment, its 

 properties and processes. Such understanding 

 will, in addition, lead to new concepts of opera- 

 tions as well as new systems. It is for this main 

 purpose that the Navy has undertaken a major 

 oceanographic effort. 



Let us briefly examine some of the properties 

 of the environment and manner in which they 

 influence naval planning. Sound is the only form 

 of energy which propagates to any distance in the 

 sea so that this work centers on audibility prob- 

 lems. A submarine's audibility -to underwater 

 listening gear in various operating areas during 

 the different seasons of the year depends not 

 only on sound transmission conditions, which are 

 affected by the temperature, salinity structure, 

 depth, and reflectivity characteristics of the bot- 

 tom, but also by the screening effect of noise cre- 

 ated by breaking waves at the surface, the engines 

 of other marine traffic, and the creaks, groans, 

 snappings, and whistles emitted by a variety of sea 

 creatures. 



This is as true, of course, for enemy submarines 

 as it is for our own. Everything we learn about 

 how to hide our Polaris boats from enemy detec- 

 tion contributes, therefore, to our knowledge of 

 how best to go about finding his. 



When it is realized that sound not only travels 

 five times as fast in water as it does in air but for a 

 given source intensity produces pressures which 

 are some 60 times as great, it is not surprising 

 that such ordinary sounds as the singing of rotat- 

 ing propellers and the swish of bubbles and eddies 

 in the passage of a hull through the sea, all of 

 which seem of comparatively short range to a lis- 

 tener on land, suddenly assume tremendous sig- 

 nificance when the sound source is in water and 

 the listener has "underwater ears." 



Furthermore, the ocean is layered to an extent 

 seldom realized in the atmosphere and the trans- 

 mission of sound by "channels" in a fashion 

 somewhat like the production of mirages in the 

 air is a common occurrence in the sea. Submarines 

 tens and even hundreds of miles away can some- 

 times be heard by listening equipment exploiting 

 these sound conduits. Some layers, the most per- 

 sistent, are very deep and can be utilized only by 

 hydrophone arrays lowered down the sloping 

 edges of islands or on the edges of the continental 

 shelves to catch the deep sound transmission. 

 Certain frequencies in the sound spectrum are 

 more favored than others under some conditions. 

 In general, the high frequencies are more easily 

 attenuated and it is the very low frequencies which 

 travel farthest. Since the size of the underwater 

 ear must match the size of the wavelength being 

 listened to, there is a complex design problem 

 involved in fitting equipment to specific opera- 

 tional missions. That is, there is an important dif- 

 ference in systems optimally suited to an acoustic 

 environment where treble notes with wavelengths 

 of a few inches dominate as compared to systems 

 best suited to one where the bass notes which have 

 wavelengths of many feet are most important. 



The essential point is that increasing the range 

 of detection of hostile submarines and the accuracy 

 of target classification depends critically on ocea- 

 nographic research. The Navy's Oceanographic 

 Office, the Bureau of Ships, and the Office of 

 Naval Research conduct or support research on 

 various aspects of this problem, including the pre- 

 diction of the key features of the "anti-submarine 

 warfare environment" and how to exploit it opera- 

 tionally. 



Almost every other Navy mission depends on 

 similarly complex and critical relations between 

 operations, technology, and environment. One 

 reason aircraft carriers must be so large, for 

 example, is to be sufficiently stable in a seaway that 

 high-performance aircraft need not be exposed 

 to dangerously large excursions of the flight deck 

 as they approach the stern for a landing. Even 

 high-speed destroyers and frigates have to slow 

 down if waves are too high, and faster transits to 

 distant operating areas can often be made by 

 taking "the long way around" and avoiding the 

 worst sea conditions enroute. Where timely arrival 

 on the scene is important, such routing could 

 spell the difference between failure and success. 

 Weapons technology is also pressing against 



