Profilers/Sounders
CTD
A Conductivity, Temperature, Depth (CTD) is an electronic instrument package that accurately reports conductivity, temperature and depth and transmits data up the conducting wire to a computer on board. The computer calculates salinity from conductivity and temperature. Together, salinity and temperature determine the density of seawater, which in turn affects its movements; and temperature affects biological rates and behavior. Additional information available at "http://octopus.gma.org/onlocation/ctd.html" [Summary provided by Gulf of Maine Aquarium]