More of This Oceanography Feature • Part I Early Oceanography • Part 2 Oceanography and America • Part 3 Oceanography and the World Wars • Part 4 Modern Oceanography

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Between the World Wars, in the 1920s and 1930s, scientific understanding of the behavior of sound in the sea and its application to sonar systems for anti-submarine warfare advanced slowly, and it was only with the emergence of a vastly increased submarine threat at the onset of the Second World War in 1939 that a major national effort was undertaken for the study of underwater acoustics. What emerged was a series of results that showed that the transmission of sound in the sea - and in particular how effectively it could be used to detect submarines - depended crucially on how the temperature and salinity of the seawater varied with depth. It was found that sound rays bend underwater in ways that are intimately linked to the variation of the speed of sound from place to place, and that this could create "shadow zones" in which a target could hide. These discoveries, and the wartime need to apply them to improving our defenses against enemy submarines, significantly widened the range of oceanic phenomena of interest to Naval Oceanographers. In addition to our traditional concerns with water depth, winds, and currents, the need to measure and interpret underwater physical parameters such as water temperature, salinity, and sound speed at increasing depths, assumed major importance. This required the development of new kinds of instruments, new analysis techniques, new ways of looking at data, and in general, a substantial broadening of the scientific disciplines needed in the practice of oceanography for naval applications.

OCEANOGRAPHY AFTER WORLD WAR II

Simultaneously, because the importance of accurate short-term weather forecasts had become apparent during the war, a new emphasis was placed on expanding the meteorological sciences and their applications to naval warfare. Eventually, the Naval Weather Service, established during the First World War to support naval aviation, was consolidated within the Naval Oceanography community. Therefore, we now also hold responsibility within the Navy and Marine Corps for predicting atmospheric influences on ships, aircraft, and weapon systems and providing on-scene weather forecasting to warfighting commanders at sea and on land.

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©Mary Bellis