- المجال: Education
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Founded in 1876, Texas A&M University is a U.S. public and comprehensive university offering a wide variety of academic programs far beyond its original label of agricultural and mechanical trainings. It is one of the few institutions holding triple federal designations as a land-, sea- and ...
A deep–towed multi–sensor sonar sytem that comprises a two–sided 30 kHz sidescan sonar, a 7.5 kHz sub–bottom profiler sonar, a magnetometer, a temperature probe, a transmissometer, and a range of vehicle handling instruments. TOBI is towed on a 200 meter umbilical behind a 600 kg depressor weight attached to the surface ship via the main 0.68 in. armored coaxial cable, which reduces ship–induced heaving that influences the stability of the vehicle. The sidescan sonar has a range of 6 km and a seabed footprint ranging from 4 by 7 meters close to the vehicle to 42 x 2 meters at longer ranges, and the profiler sonar can penetrate up to 60 meters into soft sediments with a vertical resolution of better than 1 meter. This instrument was developed by the IOSDL.
Industry:Earth science
A depth, pressure or density level at which the horizontal current field is either known from direct measurements or indirectly estimated. This may be zero velocity surface or one with non-zero horizontal velocities. This reference level is combined with the relative velocity fields obtained via the geostrophic method to obtain fields of absolute geostrophic velocitiesa The techniques of satellite altimetry have provided another possibility for a reference level, i.e. the ocean surface. If the vertical departure of the ocean surface from the local geoid can be measured with sufficiently accuracy then it can be used as a reference level. This is also known variously as the level of no motion, the level of known motion, the zero velocity surface, etc.
Industry:Earth science
A determining parameter of a system that does not depend on the size and mass of the system, e.g. temperature, pressure, and concentration, as opposed to an extensive parameter.
Industry:Earth science
A determining parameter of a system that is proportional to the size and mass of the system, e.g. volume, internal energy, enthalpy and entropy, as opposed to an intensive parameter.
Industry:Earth science
A device that allows boreholes to be isolated from the ocean water above the seabed and conditions in the hole to be monitored for long periods of time. CORK’s purpose is to provide a long–term seafloor observatory intended to allow a monitored and accessible borehole to return to its pre–drilling state. The CORK data logger can record temperature and pressure data for five years, and store it in memory for an additional five years until it can be retrieved via either a manned submersible or a ROV. The data is obtained by a string of sensors hanging from CORK at the bottom of the borehole. It also has fittings for recovering samples from inside the hole and allows fluid to be injected into the hole for certain kinds of tests.
Industry:Earth science
A device that allows the profiling of the water column by alternately rising to the surface and sinking to a predetermined depth. It does so by adjusting its buoyancy. This device can be used as a platform for a variety of instruments.
Industry:Earth science
A device that uses a photocell to measure the power of a specific light field.
Industry:Earth science
A device used by biological oceanographers to provide continuous qualitative and quantitative records of plankton distribution and patchiness when studying swarms over large areas. The meter is a square or round torpedo-shaped tube about 1 m long that is towed behind a ship underway at full speed. There is a small entrace hole in the front end which leads to a wider tunnel across which a band of silk gauze is stretched. This gauze is slowly wound from one spool to another via a propeller mechanism attached to the outside of the meter, thus being linked to the speed of the meter and therefore the distance it has traveled. Data gathered with the meter is considered supplementary to other types of net tow data gathered separately at individual stations.
Industry:Earth science
A device used in biological oceanography to trawl for pelagic organisms. As opposed to the beam trawl, the opening to this is kept open not by a rigid rectangular frame but rather by otter boards attached to either side of the net opening. These boards are forced apart by the force of the water when the trawl is towed and close when it is not being towed, an eventuality convenient for retaining the organisms caught. The open may be 20 to 26 m wide and the net up to 40 m in length.
Industry:Earth science
A device used in paleoclimate data analysis to obtain proxy data. An equation, or transfer function, is developed using mathematical techniques of regression that relates the actual data (.e.g. planktonic fossil assemblages) to some desired physical variable (.e.g. water temperature).
Industry:Earth science
