OCEANOGRAPHIC . Of or pertaining to oceanography, 

 or knowledge of the oceans. (17) 



OCEANOGRAPHIC DREDGES . Apparatus used aboard ships 

 to bring up quantity samples of the ocean bottom 

 deposits and sediments. See also NEL DREDGE. (35) 



OCEANOGRAPHIC SURVEY . A study or examination of 

 conditions in the ocean or any part of it, with 

 reference to animal or plant life, chemical elements 

 present, temperature gradients, etc. Also called 

 marine survey. (17) 



OCEANOGRAPHY . The application of the sciences to 

 the phenomena of the oceans. It includes a study 

 of their forms; physical, chemical, and biological 

 features; and phenomena. Thus, it embraces the 

 widely separated fields of geography, geology, 

 chemistry, physics, and biology. Many subdivi- 

 sions of these sciences, such as sedimentation, 

 ecology (biological relationship between organisms 

 and their environment), bacteriology, biochemistry, 

 hydrodynamics, acoustics, and optics, have been 

 extensively studied in the oceans. (12) 



OCEAN (SEA) . 1. The intercommunicating body of 

 salt water occupying the depressions of the earth's 

 surface. 



2. One of the major primary subdivi- 

 sions of the above, bounded by continents, the 

 equator, and other imaginary lines. (24) 



OCEAN STATION . As defined by the International 

 Civil Aviation Organization, a specifically located 

 area of ocean surface, roughly square and 200 nauti- 

 cal miles on a side. An ocean station vessel on 

 patrol is said to be "on station" when it is within 

 the perimeter of the area. (24) 



OCEAN STATION VESSEL . (OCEAN WEATHER SHIP, WEATHER 

 PATROL SHIP, WEATHER SHIP.) An ocean-going vessel 

 assigned to patrol an OCEAN STATION. 



These ships are specially equipped to take 

 comprehensive meteorological observations of con- 

 ditions both at the surface and aloft. The United 

 States vessels are provided by the U. S. Coast 

 Guard, and the meteorological personnel and equip- 

 ment are provided by the U. S. Weather Bureau. (24) 



OCEAN WATER . Water having the physical-chemical 

 characteristics of the open sea and where continen- 

 tal influences are at a minimum. (15) 



OCEAN WEATHER SHIP . See OCEAN STATION VESSEL. 



OCEAN WEATHER STATION . As defined by the World 

 Meteorological Organization, a specific maritime 

 location occupied by a ship equipped and staffed 

 to observe weather and sea conditions and report 

 the observations by international exchange. (24) 



OCELLUS . A small simple eye as on many inverte- 

 brates. (19) 



OCTAVE . A band ratio having the value t-^l t^-=l is 

 the ratio long known to musicians as the octave. 

 Physicists and acoustical engineers have now 

 adopted this term. (4) 



OECD . Organization for Economic Co-operation and 

 Development. 



OEEC . Organization for European Economic Co- 

 operation. 



OFFSHORE . 1. In beach terminology, the compara- 

 tively flat zone of variable width, extending from 

 the breaker zone to the seaward edge of the CON- 

 TINENTAL SHELF. 



2. A direction seaward from the SHORE. 

 (11) 



OFFSHORE BARRIER. See BARRIER BEACH. 



OFFSHORE CURRENT . 1. Any current in the OFFSHORE 

 zone. 



2. Any current flowing away 

 from SHORE. (11) 



OFFSHORE WIND . A wind blowing seaward from the 

 land in the coastal area. (11) 



OHM'S LAW . A fundamental law of electricity. It 

 expresses the definite relationship existing be- 

 tween the voltage E, the current I, and the resis- 

 tance R;E - IR. (36) 



OIC. Oceanographic Instrumentation Center. 



OMEGA . A long range (hyperbolic) navigation system. 



Originally Omega was developed for the use of 

 submerged submarines , giving world wide coverage 

 with 6-10 ground stations. 



The Omega and RADUX systems are identical in 

 principle and both are quite similar to DELRAC. 

 Both Omega and Radux use pulsed signals on the 10 

 kc band. These and Delrac appear to be the most 

 practical of all long range navigational systems. 

 Omega can provide navigational control of sub- 

 marines, surface ships and aircraft simultaneously. 

 (29) 



OMM . Organization Meteorologique Mondiale. 



OMNIDIRECTIONAL HYDROPHONE . An omnidirectional 

 hydrophone is a hydrophone whose response is essen- 

 tially independent of angle of arrival of the in- 

 cident sound wave. (1) 



ONE-PING PROBABILITY . The probability of detection 

 by using a single ping. (8) 



ONI . Office of Naval Intelligence. 



ONR. Office of Naval Research. 



0/0 . Office of Oceanography (UNESCO) . 



OOP. Oceanographic Observations of the Pacific. 



OOZE . An unconsolidated deposit composed largely 

 of the shells and undissolved remains of FORAMINI- 

 FERA, DIATOMS and other marine life; for example, 

 diatom ooze, foraminiferal ooze, etc. (27) 



OPEN CIRCUIT SCUBA . Open circuit equipment is in 

 general the simplest type of SCUBA. Air or a pre- 

 set mixture of oxygen and nitrogen is stored under 

 high pressure (about 2000 psi) in cylinders. This 

 high pressure gas is reduced to an intermediate 

 pressure (about 55 to 85 psi) by a first stage 

 reduction valve. The gas is obtained by the swimmer 

 on inspiration through a second demand-type reduc- 

 tion valve which is actuated by respiratory action. 

 The pressure of gas delivered to the swimmer is 

 about equal to the ambient hydrostatic pressure. 

 In some equipments (Aqualung and Northill) the two 

 stages of pressure reduction are accomplished with- 

 in the same valve casing. Other units (Scott, 

 Emerson, Swedish) have the two valves in different 

 locations. All exhaled gas is discharged as an 

 intermittent stream of bubbles into the water and 

 the utilization of gas is therefore equal to the 

 mass exhaled. (37) 



OPEN COAST . A coast that is not sheltered from the 

 sea. (17) 



OPEN SEA . 1. That part of the ocean not enclosed 

 by headlands, within narrow straits, etc. 



2. That part of the ocean outside the 

 territorial jurisdiction of any country. The op- 

 posite is closed sea. (17) 



OPERATING RANGE . As applied to reversible trans- 

 ducer, the operating range is the frequency range 

 over which the transducer is operable; that is. 



85 



