This image shows the SBE 19plus CTD instrument made by Sea-Bird Electronics in Washington State. The HIGH TIDE project uses this model of CTD to measure the water in lower Chesapeake Bay in order to note how salinity, temperature and density change with different wind conditions and various freshwater discharges into the Chesapeake Bay area. Clicking on this image will show you a collage of pictures showing the SBE 19 CTD instrument in use by the HIGH TIDE project.
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Sea-Bird Electronics, Inc.

CTD Instrument

Scientists have been interested in the characteristics of water for a long time. Benjamin Franklin even measured the temperature and salinity of the Atlantic Ocean in the 18th century. Nowadays, scientists use CTD instruments to measure water characteristics like salinity, temperature, pressure, depth and density. CTD stands for Conductivity-Temperature-Depth. You can see a picture of a CTD instrument to the left.

A CTD instrument is placed in the water it is measuring. It can store the measurements it takes or it can send the measurements through a cord to a personal computer on ship or on dock. CTD profilers are pretty fancy equipment, but they can be used in all sorts of situations. The HIGH TIDE project has high school students using a CTD to measure water characteristics in Chesapeake Bay. And they lower their CTD from a bridge into the water below!

Last modified December 13, 2001 by Jennifer Bergman.

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