chief factors which gives oceanography its 

 present tone. 



1-3 OCEANOGRAPHIC FACILITIES — 



The hydrographic and oceanographic organi- 

 zations of many nations have made important 

 contributions to the knowledge of the sea. 

 There are a number of international oragniza- 

 tions, notably the International Council for 

 the Exploration of the Sea, which have 

 both encouraged and initiated oceanographic 

 investigations. 



The oceanographic institutions and marine 

 biological laboratories are organizations pri- 

 marily devoted to the study of the oceans and 

 its organisms. The Museum of Oceanography 

 at Monaco, the Marine Biological Station at 

 Naples, the Bergen Geophysical Institute, 

 and the Institute of Oceanography in England 

 are European examples of the many institu- 

 tions and laboratories throughout the world. 



In the United States such institutions are 

 comparatively new. The Woods Hole Ocea- 

 nographic Institution at Woods Hole, Mass., 

 and Scripps Institution of Oceanography at 

 La Jolla, Calif., are the principal organizations. 

 In 1946, the Division of Oceanography was 

 organized at the U. S. Navy Hydrographic 

 Office, at Suitland, Md. 



1-4 THE TYPES OF INFORMATION 

 SOUGHT. — In the sense that oceanography 

 encompasses a portion of all the physical 

 sciences, types of information sought on 

 oceanographic surveys and expeditions include 

 data concerning these fields. Although man 

 has exploited the oceans for thousands of years, 

 there is still much to be learned from them. 



Because of the high costs of maintaining the 

 laboratory, i. e., the ship needed to obtain 

 oceanographic information, it is important that 

 the most profitable use be made of the time at 

 sea. Although a particular project may con- 

 cern itself primarily with a certain oceanog- 

 raphic feature such a study usually cannot be 

 prosecuted effectively without supporting data 

 from many other variables. For example, 

 investigations of the growth of plankton be- 

 comes immediately involved with water temper- 

 ature and salinities, nutrient concentrations, 

 transparencies, and mass transport of water. 

 Information pertaining to these variables re- 

 quires, in turn, related observations of air 

 temperatures and other meteorological data. 



Variables in the sea may change with respect 

 to both space and time. It is often important 

 to know the periodicity and extent of these 

 changes. In the case of the time variable, this 

 may require repeated surveys of the same area, 

 while in the case of the space variable, it is 



valuable to have simultaneous observations 

 taken over a distance, thus necessitating the 

 use of two or more ships or recording units. 



Oceanography usually is divided into its 

 five basic sciences: physics, chemistry, me- 

 teorology, biology, and geology. A few com- 

 ments concerning the general types of informa- 

 tion sought in each of the fields are given below. 



1-5 Physical Oceanography. — The study 

 of physical oceanography is probably the 

 largest and most complicated of the five basic 

 divisions. It involves information from all the 

 other fields, especially that of chemical ocea- 

 nography. It includes the studies of tides, 

 currents, sea and swell, temperatures, densities, 

 origin and circulation, sound propagation, 

 transparency, sea ice, and other physical 

 problems of sea water. 



Of major importance is knowledge concerning 

 surface and subsurface currents — whence they 

 originate, their speed and direction, and their 

 influence on other oceanic factors. 



Determinations of subsurface currents maybe 

 made by direct measurements with current 

 meters, described in chapter 9, or by math- 

 ematical computations utilizing the densities 

 of the masses in question. Density is a func- 

 tion of the temperature and salinity of the 

 water under a given pressure. It is therefore 

 desirable to gain knowledge of the vertical 

 distribution of temperatures and salinities at 

 accurately determined depths. These two vari- 

 ables also provide basic information required 

 to determine sound propagation and patterns, 

 both vertically and horizontally, in sea water. 



The studies of internal waves have concerned 

 investigators in the field of underwater sound 

 transmission. These waves are similar to the 

 commonly observed surface waves, but occur 

 at the interface of layers of water of different 

 densities rather than at the sea-air bbundary. 

 The study of wind waves (sea) and swell is in 

 its infancy. Until - only the past few years 

 observations of deep-water waves were limited 

 to visual data. Recent developments of elec- 

 trical wave staffs and pressure-operated wave 

 indicators provide recorded data for analyses. 

 The success of long- and short-range wave 

 forecasting is dependent upon the number of 

 observers reporting and the accuracy of the 

 observations. Such forecasts are of utmost 

 value for many marine operations, both military 

 and commercial. 



Observations of transparency, light penetra- 

 tion, scattering, and color are aided by the use 

 of photoelectric cells which are lowered to 

 various depths. Such studies assist in the 



H. O. 607 



