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The Doppler shift of the first order Bragg lines of the radar echo is used to derive sea current estimates in very much the same way as for the dual frequency microwave radar. Two radar installations are normally required, looking at the same patch of the sea surface from different angles. [ 1 ]
Marine radar has performance adjustment controls for brightness and contrast, also manual or automatic adjustment of gain, tuning, sea clutter and rain clutter suppression, and interference reduction. Other common controls consist of range scale, bearing cursor, fix/variable range marker (VRM) or bearing/distance cursor (EBL).
When stitched together along the direction of motion, these slices form an image of the sea bottom within the swath (coverage width) of the beam. [ 2 ] The sound frequencies used in side-scan sonar usually range from 100 to 500 kHz ; higher frequencies yield better resolution but less range.
In fluid dynamics, wind wave modeling describes the effort to depict the sea state and predict the evolution of the energy of wind waves using numerical techniques.These simulations consider atmospheric wind forcing, nonlinear wave interactions, and frictional dissipation, and they output statistics describing wave heights, periods, and propagation directions for regional seas or global oceans.
A 1976 United States NOAA chart of part of Puerto Rico A nautical chart of the Warnemünde harbor shown on OpenSeaMap. A nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or banks.
The strength and shape of the returning signal also provides information on wind speed and the height of ocean waves. These data are used in ocean models to calculate the speed and direction of ocean currents and the amount and location of heat stored in the ocean, which, in turn, reveals global climate variations ".
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SARs produce a two-dimensional (2-D) image. One dimension in the image is called range and is a measure of the "line-of-sight" distance from the radar to the object. Range is determined by measuring the time from transmission of a pulse to receiving the echo from a target. Also, range resolution is determined by the transmitted pulse width.