Teledyne RDI Citadel CTDs

Teledyne RDI Citadel CTDs

After years as a Doppler manufacturer, we’ve stepped outside of our core technology via the introduction of our Citadel CTD (Conductivity, Temperature, and Depth) product line.

This product line delivers exciting and proven technology that is complementary to Teledyne RDI’s ADCP products, and represents a tremendous opportunity to expand our product offerings and deliver turn-key solutions to our worldwide customer base.

CTDs are used extensively around the globe for the measurement of temperature and salinity, but also for the important derived parameters of density and speed of sound. They are used for academic, commercial and defense applications; and are often used in concert with ADCPs to gain a clearer understanding of the ocean’s complex physical environment.


The Citadel family of CTDs includes the following products:

Citadel CTD-NH:

Internal Field CTD for moored subsurface remote data collection

Citadel CTD-NH

Bio-fouling resistant, high-accuracy conductivity, temperature, and depth with external input, direct digital output, and datalogging capability

Citadel TS-NH:

Thermosalinograph CTD for vessel-mounted data collection

Citadel TS-NH

Thermosalinograph for surface salinity with in-line sensors

Citadel CTD-ES:

External field CTD for moving real-time and remote data collection

Citadel CTD-ES

Compact Conductivity, Temperature and Depth meter with direct digital output

Citadel CTD-EK Digital:

External field CTD OEM kit with and without housing for real time data collection

Citadel CTD-EK Digital

Conductivity and Temperature sensors with digital output for integration into user systems

Citadel CTD-EK Analog:

External field CTD OEM kit with and without housing for real time data collection

Citadel CTD-EK Analog

Conductivity and Temperature Sensors with Analog Output for Integration into User Systems

Citadel CTD-NV:

Internal Field CTD for profiling real-time data collection

Citadel CTD-NV

Scientific-quality conductivity, temperature, and depth measurement capability utilizing patented Non-external Inductive Cell (NXIC) technology

Citadel CT-ETH:

Incorporates proven inductively coupled conductivity sensor technology with a thermistor

Citadel CT-ETH

Compact Conductivity and Temperature Meter with Direct Digital Output

Not sure which CTD is right for your application?

Click on our CTD Product Selection Guide.

CTD Product Selection Guide

Or, contact a member of our sales team to discuss your current application.

Tel: +1-858-454-4044


Integrated Solution!


Integrated Solution
Integrated Solution
Our Citadel CTD has been interfaced with our Workhorse ADCP, providing our customers with the ability to measure both physical and chemical properties via a single deployment
Get the details


How and where are Citadel CTDs used?

CT/CTD Methods of Deployment

CT/CTD Methods of Deployment:

A Moored
Conductivity, Temperature and (optionally) Depth (CTD) sensors mounted on surface/subsurface buoys or mooring lines at multiple depths in the water column for time series measurements at a single location.
B Vessel Underway
CTD sensors mounted on moving surface vessels (research, ferry, container ship, etc) using a ducted flow-through system for measurement of surface temperature and salinity.
C Underwater Vehicles
CTD sensors mounted on sub-surface vessels (AUV, ROV, glider, etc) for measurement of temperature and salinity.


CT/CTD Applications:

1 Environmental Monitoring
Routine Conductivity, Temperature and (optionally) Depth (CTD) measurements for model inputs, outfall monitoring and environmental impact assessments from fixed stations.
2 Fisheries
CTD measurements to support biological studies including: habitat mapping, marine protected area programs, and fisheries stock assessment.
3 Hydrographic Surveys
Speed of Sound measurements to support bathymetry measurements.
4 Ocean Observing Networks
CTD measurements to support long-term monitoring in coastal observation networks.
5 Climate Change Research
CTD measurements to support calculations of the density and temperature in the ocean for global heat conveyor and climate change studies.
6 Remote Surveys
CTD measurements to support ocean models and world ocean circulation studies.


How is my data displayed?

How is my data displayed?Each Citadel CTD product is shipped with a software package that allows you to easily test, configure, calculate power consumption, and deploy your Citadel CTD. After recovering your instrument, this same software package allows you to download your data, and provides a “quick view” to confirm your data integrity. Detailed data processing is just a few clicks away. This same package can export the data in a variety of formats, including one suitable for our post-processing package, which can filter the data, adjust the lags, and create publication-quality graphics.