ABSTRACT
Sonar systems have become progressively more sophisticated. In the civilian field, sonar has been developed for rapid long-range surveying of the shape of the seabed and a range of higher-resolution sonars have been developed for obtaining closer and more detailed views of the bottom. Some of these sonars operate at high surveying speeds from the surface, while others are towed nearer to the bottom or are mounted on autonomous vehicles. Wide swaths of bathymetry can now be obtained from a single ship using multiple narrow-beam echo sounders and so the uncertainties of the precise shape of the seafloor, at least in limited areas, can be reduced. However, a very high proportion of the ocean floor is still poorly mapped.
The technology now exists for deploying unattended stations at the sea surface, in midwater or on the seafloor, which can make measurements and process data over months and years, before being recovered.
For providing navigational systems and communication channels, satellites are now providing tools for the direct measurement of the sea surface. Various sensors give information on the wave height, wind speed, ocean currents, gravitational field at the sea surface, ocean color in a range of spectral bands, and synthetic aperture radar views of the ocean surface. All of these assist in the utilization of the ocean by improving weather and sea-state prediction, in mapping the variability of sea surface temperature, color, and height, and in locating seabed features.
Ocean mining technology is growing fast with several advancements.
