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Bathymetry (/ b ə ˈ θ ɪ m ə t r i /; from Ancient Greek βαθύς (bathús) 'deep' and μέτρον (métron) 'measure') [1] [2] is the study of underwater depth of ocean floors (seabed topography), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography.
A "sea-gage" for measuring ocean depth was described in Philosophia Britannica in 1747. [3] But it wasn't until 1775 and the development of a depth gauge by the inventor, scientific instrument, and clock maker Isaac Doolittle of New Haven, Connecticut , for David Bushnell 's submarine the Turtle , that one was deployed in an underwater craft.
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water.Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography.
Bathymetric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
The process was labor-intensive and time-consuming and, although each individual depth measurement could be accurate, even a thorough survey as a practical matter could include only a limited number of sounding measurements relative to the area being surveyed, inevitably leaving gaps in coverage between soundings.
The depth was determined (rather inaccurately) by the time it took to surface. [3] Jacob Perkins (1766–1849) proposed a bathometer based on the compressibility of water. [ 4 ] In this instrument the movement of a piston compressing a body of water enclosed in its cylinder is dependent on the pressure of the water outside the cylinder, and ...
The instrument is lowered into the water in what is called the downcast to a determined depth or to a few meters above the ocean floor, generally at a rate of about 0.5 m/s. Most of the time a conducting wire cable is attached to the CTD frame connecting the CTD to an onboard computer, and allows instantaneous uploading and real time ...
Maximum Depth Rated Ship Speed Vertical Resolution T-4: Standard probe used by the U.S. Navy for ASW operations: 460 m 1500 ft: 30 knots: 65 cm T-5: Deep ocean scientific and military applications: 1830 m 6000 ft: 6 knots: 65 cm Fast Deep: Provides maximum depth capabilities at the highest possible ship speed of any XBT: 1000 m 3280 ft: 20 ...