Conductivity, Temperature, Depth (CTD) Sensors / Profilers

A Conductivity, Temperature, Depth (CTD) Sensor, or CTD Profiler, collects data on water temperature, salinity, and pressure at different depths in the ocean. Typically deployed as part of a profiling system that is incrementally lowered into the water column, data collected by the CTD sensor provides valuable insights into oceanographic processes such as water mass formation, mixing, and currents, as well as the distribution of nutrients and gases, which is vital for understanding marine ecosystems and climate dynamics.

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Sea-Bird Scientific

High-Precision Sensors, Multiparameter CTDs & Integrated Systems for Marine Environmental Research & Monitoring

D-2 Inc

Conductivity, Temperature & Depth (CTD) Sensors for Oceanographic & Marine Survey Applications

NBOSI Ocean Sensors

Compact and Rugged CTD Sensors for AUVs

Teledyne Valeport

High-Precision Oceanographic Sensors & Hydrographic Measurement Solutions for Marine & Subsea Platforms

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Products

AUV CTD

Ultra low power conductivity, temperature & depth sensor for autonomous marine platforms

Ultra low power conductivity, temperature & depth sensor for autonomous marine platforms
The AUV CTD from D-2 Incorporated delivers precise conductivity, temperature, and depth data for... ...ation, the AUV CTD offers multiple mounting options and user configurable settings for sampling and...
CTD Profiler

Precision CTD Profiler for Oceanographic Platforms

Precision CTD Profiler for Oceanographic Platforms
The CTD Profiler from D‑2 Inc. is a high‑accuracy marine profiling instrument engineered to...
Hybrid CTD Sensor

High-performance conductivity, temperature & depth measurement down to 11000m

High-performance conductivity, temperature & depth measurement down to 11000m
The D-2 Hybrid CTD is a unique oceanographic instrument based on patented conductivity sensing...
UL-CTD Sensor

Ultra-low-power conductivity, temperature & depth measurement

Ultra-low-power conductivity, temperature & depth measurement
...f D-2's Hybrid CTD sensor provides the same accuracy and precision and full depth performance, with...
HydroCAT-EP V2

Compact multiparameter CTD for precise water quality analysis

Compact multiparameter CTD for precise water quality analysis
...multiparameter CTD sensor package that combines conductivity, temperature, depth, and optional...
Model 501 CTD

Rugged miniature CTD sensor

Rugged miniature CTD sensor
...’s Model 501 sensor provides research-quality CTD (conductivity, temperature and depth) data in...
Model 503 CTD

Low-profile CTD sensor for installation in flooded hull segments

Low-profile CTD sensor for installation in flooded hull segments
...’s Model 503 CTD provides research-quality CTD (conductivity, temperature and depth) data in real...
100 Series CT

Conductivity & temperature sensors in a variety of form factors

Conductivity & temperature sensors in a variety of form factors
... Series of CT (conductivity and temperature) sensors provides mobile marine platforms such as AUVs,...
MIDAS CTD

High-accuracy CTD profiler for longterm deployment

High-accuracy CTD profiler for longterm deployment
The MIDAS CTD is Valeport's premier CTD profiler, designed for use as a self-recording system and...
SwiFT Deep CTD

Deep-sea CTD measurement down to 6000 metres

Deep-sea CTD measurement down to 6000 metres
The SWiFT Deep CTD profiler provides direct survey-grade measurement of conductivity, temperature...

Conductivity, Temperature, Depth (CTD) Sensors / Profilers

Sarah Simpson

Updated:

Conductivity, Temperature, Depth (CTD) sensors are specialized devices used to measure the electrical conductivity, temperature, and depth of seawater. 

By gauging these three parameters, users of CTD profilers can infer various other properties of seawater (such as salinity and density) which are vital for understanding oceanographic processes. Through CTD surveys and profiling instruments, researchers can gain insights into marine environments. 

Rugged CTD sensor for research-quality conductivity, temperature and depth data

Rugged CTD sensor for research-quality conductivity, temperature and depth data

How CTD Sensors Work

  • Conductivity: The sensor measures the water’s ability to conduct electricity, which correlates directly with the salinity of the water.
  • Temperature: Precise thermometers within the CTD instrument measure the water temperature, providing critical data for understanding thermal stratification.
  • Depth: Pressure sensors determine the depth by measuring the weight of the water column above the device, which increases with depth.

Conductivity, Temperature, Depth Surveys

During a survey, the system is typically lowered into the water using a winch system from a research vessel. As the profiler descends, it continuously records data, which is transmitted to the surface for real-time analysis. This method allows scientists to observe the vertical structure of the ocean, detecting layers such as thermoclines and haloclines.

Applications:

  1. Climate Studies: Surveys are integral in monitoring changes in ocean temperature and salinity, which are critical indicators of climate change.
    CTD profiler with high-accuracy for deep-sea and challenging conditions

    CTD profiler with high-accuracy for deep-sea and challenging conditions

  2. Marine Research: CTD equipment is used to study the distribution of marine organisms, as many species are sensitive to specific temperature and salinity ranges.
  3. Submarine Geology: CTD monitoring helps in understanding the interactions between seawater and geological features on the ocean floor.
  4. Operational Oceanography: Conductivity, temperature, depth systems provide real-time data for naval operations, search and rescue missions, and other maritime activities.
  5. Data Collection: CTD instruments provide data that supports predictive models of ocean behavior, essential for long-term environmental monitoring and assessing human impact on marine ecosystems.

Oceanographic CTD Profiler

An oceanographic CTD profiler is deployed from research vessels and lowered through the water column to collect data at various depths. This data is essential for creating vertical profiles of the ocean’s physical properties. These profiles help scientists understand ocean circulation, thermohaline dynamics, and biological processes.

Profiling CTD Instruments

A profiling CTD instrument is often used in conjunction with other oceanographic instruments to provide a comprehensive view of the marine environment. These instruments are typically mounted on a rosette sampler, which can collect water samples at different depths simultaneously, enhancing a survey’s effectiveness.

Advanced Conductivity, Temperature, Depth Systems
Modern conductivity, temperature, depth systems are equipped with additional sensors to measure parameters like dissolved oxygen, chlorophyll, and turbidity, offering a more comprehensive understanding of marine environments. These advanced sensors are crucial for interdisciplinary studies combining physical oceanography, marine biology, and biogeochemistry.

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