A CTD measures Conductivity, Temperature, and Depth. Despite the name, all CTDs actually measure pressure, which is not quite the same thing as depth. The relationship between pressure and depth is a complex one involving water density and compressibility as well as the strength of the local gravity field. The CTD data can be used to calculate salinity, density, sound velocity, and other parameters of interest. The term CTD is often used today to describe a package that includes the actual CTD as well as auxiliary sensors to measure other parameters (such as dissolved oxygen, pH, turbidity, fluorometer, altimeter, etc.) and a water sampler to collect water samples for later analysis in the lab.
A Profiling CTD measures water parameters as it travels through the water, whether lowered over the side of a ship with a winch to take measurements of a vertical column of water or integrated with an autonomous vehicle or glider.
Sea-Bird Profiling CTDs:
See Application Note 82: Guide to Specifying a CTD.
Brochure/specifications - html or pdf 9plus Manual -- Current or All 11plus V2 Manual - Current or All Configuration options & accessories -- 9plus and 11plus V2
The 911plus, consisting of the 9plus underwater CTD and 11plus V2 Deck Unit, is a premium real-time CTD accurate to the highest international standards. It features high resolution sampling (24 Hz), pump-controlled T-C ducted flow, up to 10500 meter (15,000 psia) depth capability, maximum auxiliary sensor flexibility, and modem channel for Water Sampler control. The 911plus has eight 12-bit A/D channels, and supports redundant C&T sensors or custom auxiliary digital inputs.
| Sampling Rate | A/D Channels for Auxiliary Sensors | Memory | Power | Real-Time Data | Water Sampler Control | |
| Internal | External | |||||
| 24 Hz |
8 |
16 Mb with optional SBE 17plus V2 |
√
(with optional SBE 17plus V2) |
√ | √ |
√
(controls SBE 32 Carousel Water Sampler, G.O. 1016, or [with optional interface in Deck Unit] G.O. 1015) |
SBE 11 V1 Deck Unit
Not in production since 1997; replaced by SBE 11plus V2.
Brochure/specifications - html or pdf Manual - Current or All Reference Sheet Configuration options & accessories
The SEALOGGER offers excellent dynamic performance, and is easily configured in the field for a wide range of auxiliary sensors. The SEALOGGER is self-powered, requires no conductive cable, and is designed for use up to 6800 meters (10,000 psia). It uses the same C&T sensors as the 911plus and an external strain gauge pressure sensor. It provides pump-controlled T-C ducted flow, samples at 8 Hz, records internally, provides simultaneous real-time data via its built-in RS-232 interface, and is less expensive than the 911plus.
| Sampling Rate | A/D Channels for Auxiliary Sensors | Memory | Power | Real-Time Data | Water Sampler Control | |
| Internal | External | |||||
| 8 Hz |
7 |
8 Mb | √ | √ |
√
(may require SBE 36 Deck Unit & PDIM) |
SBE
33 Deck Unit controls SBE 32 Carousel Water Sampler (with optional serial interface) or SBE 55 ECO Water Sampler |
Brochure/specifications - html or pdf Manual - Current or All Reference Sheet Configuration options & accessories
The SBE 19plus V2 SEACAT is the next generation Personal CTD: an economical, self-powered mini-CTD that measures conductivity, temperature, and pressure up to 7000 meters (10,000 psia). It provides pump-controlled T-C ducted flow and records data (4 Hz) in FLASH RAM memory. The SEACAT profiler has real-time data capability, and dual mode programmability for profiling or moored time series recording. Auxiliary sensors can be added.
| Sampling Rate | Channels for Auxiliary Sensors | Memory | Power | Real-Time Data | Water Sampler Control | |
| Internal | External | |||||
| 4 Hz |
6 A/D plus 1 RS-232 |
64 Mb | √ | √ |
√
(may require SBE 36 Deck Unit & PDIM) |
SBE
33 Deck Unit controls SBE 32 Carousel Water Sampler (with optional serial interface) or SBE 55 ECO Water Sampler |
SBE 19plus SEACAT Profiler
Not in production since February 2008; replaced by SBE 19plus V2.
SBE 19 SEACAT Profiler
Not in production since 2001; replaced by SBE 19plus.
Brochure/specifications - html or pdf Manual - Current or All Reference Sheet Configuration options & accessories
The SBE 49 FastCAT is an integrated CTD sensor intended for use as a modular component in towed vehicles, ROVs, AUVs, or other autonomous platforms that can supply DC power and acquire serial data. FastCAT's pump-controlled, TC-ducted flow minimizes salinity spiking, and its 16 Hz sampling provides very high spatial resolution of oceanographic structures and gradients.
| Sampling Rate | A/D Channels for Auxiliary Sensors | Memory | Power | Real-Time Data | Water Sampler Control | |
| Internal | External | |||||
| 16 Hz |
|
√ |
√
(may require SBE 36 Deck Unit & PDIM) |
SBE
33 Deck Unit controls SBE 32 Carousel Water Sampler (with optional serial interface) or SBE 55 ECO Water Sampler |
||
Brochure/specifications - html or pdf Manual - Current or All Configuration options & accessories
The SBE 52-MP is a conductivity, temperature, pressure sensor, designed for moored profiling applications in which the instrument makes vertical profile measurements from a device that travels vertically beneath a buoy, or from a buoyant sub-surface sensor package that is winched up and down from a bottom-mounted platform. The 52-MP can optionally be configured with an SBE 43F dissolved oxygen sensor, a frequency output version of our SBE 43. The 52-MP's pump-controlled, TC-ducted flow minimizes salinity spiking.
| Sampling Rate | Channels for Auxiliary Sensors | Memory | Power | Real-Time Data | Water Sampler Control | |
| Internal | External | |||||
| 1 Hz | Frequency channel for optional DO sensor | √ | √ | √ | ||
Brochure/specifications - html Contact Sea-Bird for configuration details
Argo floats are neutrally buoyant at depth, where they are carried by currents until periodically increasing their displacement and slowing rising to the surface. The SBE 41/41CP CTD Module obtains the latest CTD profile each time the Argo float surfaces. At the surface, the float transmits in-situ measurements and drift track data to the ARGOS satellite system.
GPCTD brochure/specifications -
html or
pdf
Current GPCTD manual
Configuration
options & accessories
Slocum brochure/specifications -
html or
pdf Contact Sea-Bird for
configuration details
The generic Glider Payload CTD measures conductivity, temperature, and pressure, and optionally, dissolved oxygen (with the modular SBE 43F DO sensor). It is a modular, low-power profiling instrument for autonomous gliders with the high accuracy necessary for research, inter-comparison with moored observatory sensors, updating circulation models, and leveraging data collection opportunities from operational vehicle missions. The pressure-proof module allows glider users to exchange CTDs (and DO sensors) in the field without opening the glider pressure hull.
A defining mechanical design criteria of the Slocum Glider Payload CTD was to provide a retrofit/replacement for CTDs on the global fleet of existing Slocum gliders. Both designs share many features, but there are also differences in packaging, sampling abilities and power consumption, and in their installation as described in their individual data sheets.
Specifications are subject to change without notice.
Last modified: 25-Apr-2011