page_title: CTD (instrument)
section_title: Deployment
hierarchical_section_title: CTD (instrument) / Deployment
caption_attribution_description: English: Deployment of CTD from a ship
context_page_description: A CTD or Sonde is an oceanography instrument used to measure the conductivity, temperature, and pressure of seawater. The reason to measure conductivity is that it can be used to determine the salinity.
  The CTD may be incorporated into an array of Niskin bottles referred to as a carousel or rosette. The sampling bottles close at predefined depths, triggered either manually or by a computer, and the water samples may subsequently be analyzed further for biological and chemical parameters.
  The CTD may also be used for the calibration of sensors.
context_section_description: Deployment of the rosette is from the deck of a research vessel. The instrument is lowered into the water in what is called the downcast to a determined depth or to a few meters above the ocean floor, generally at a rate of about 0.5 m/s. Most of the time a conducting wire cable is attached to the CTD frame connecting the CTD to an onboard computer, and allows instantaneous uploading and real time visualization of the collected data on the computer screen. The water column profile of the downcast is often used to determine the depths at which the rosette will be stopped on its way back to the surface (the upcast) to collect the water samples using the attached bottles.
caption: Sea-Bird 911 CTD deployment from R/V Endeavor
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