There are many obstacles to scientists who study what is happening in the ocean, including the fact that humans are not designed to spend extended periods of time in or under the water. One of the ways COOLroom scientists gather information about the water below the surface of the ocean is by towing sensors using research vessels, or ships.



One of the instruments that scientists use to study the water beneath the waves is a CTD. CTD stands for "Conductivity-Temperature-Depth." The CTD can be lowered over the side of a research vessel at a particular spot to determine the saltiness (conductivity) and temperature of the water at different depths from the surface to the bottom. This is what a CTD looks like:



Use the tool below to see how a research vessel can use a CTD to sample the water from the surface to the bottom as the ship moves from the shore out to sea. Click on the arrow to the right to see where the ship stopped and lowered the CTD to the bottom. The colors indicate the water temperature detected by the CTD, and the graph at each stop shows the actual data collected by the CTD. What happens to the water temperature as the CTD goes from the surface to the bottom?

If scientists want to tow a CTD behind a boat while it is moving, they put the CTD on its side in a protective case. This is called a minibat. A minibat "flies" underwater, traveling up and down between the surface and the seafloor as the boat moves. It gathers the same information as a regular CTD, but can also use other sensors to test the clarity of the water, and for the presence of certain plants and animals that glow (biological fluorescence).