Sonic Depth Finder & Bathymetry
After the First World War, the sonic depth finder, which determines water depths by measuring the time it takes for a pulse of sound to reach the bottom and return, was invented, and acoustic measuring techniques soon revolutionized bathymetry, the science of deep ocean depth measurements.The bottom of the ocean turned out to be as diversified as the surface of the continents. Huge mountainous areas, volcanic cones, canyons that dwarf the Grand Canyon, and abyssal plains - all were found with the new technology. Now, any ship equipped with a depth finder could crisscross the ocean taking soundings, and contour profiles of the undersea terrain could be produced.
The first bathymetric charts based on sonic soundings appeared in 1923, and they were produced regularly thereafter as new information was collected and processed.
Submarines & Sonar
In the 1920s and 1930s, the 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 significantly widened the range of oceanic phenomena of interest to oceanographers. In addition to 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 military applications.
Oceanography & The Office of Naval Research
After World War II, the Office of Naval Research was established. Through them, private and academic oceanographic institutions began receiving funding support to continue their research, and ships and other specialized platforms for conducting ocean science programs were provided.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. Eventually, the Naval Weather Service, established during the First World War to support naval aviation, was consolidated within the Naval Oceanography community.
