SBE 37 MicroCAT C-T (P) (DO) Recorder

Moored Conductivity, Temperature, (optional) Pressure, and (optional) Dissolved Oxygen measurements, at user-programmable intervals. Now also available with pH (37-SMP-ODO with SeaFET or Deep SeaFET). Available with RS-232, RS-485, SDI-12, and Inductive Modem interfaces.

SUMMARY

Sea-Bird manufactures a number of instruments within our MicroCAT CTD family, which make measurements at user-programmable intervals. All MicroCATs:

  • Measure Conductivity and Temperature.
  • Can include an optional strain-gauge Pressure sensor.
  • Can include an integrated pump (P in the model number designation) for improved bio-fouling protection and improved conductivity and oxygen sensor response.
  • Have 8 Megabyte memory.
  • Are available for depths to 350 meters (plastic housing) or 7000 meters (titanium housing).

Some MicroCATs also include Dissolved Oxygen:

  • IDO MicroCATs include a membrane-type Dissolved Oxygen sensor.
  • ODO MicroCATs include an Optical Dissolved Oxygen sensor.

The SBE 37-SMP-ODO MicroCAT can be integrated with a pH sensor to provide CTD + DO + pH:

  • SeapHOxTM (37-SMP-ODO with Satlantic SeaFETTM pH Sensor) is rated to 50 m depth.
  • Deep SeapHOxTM (37-SMP-ODO with Satlantic Deep SeaFETTM pH Sensor) is rated to 2000 m depth.

 

FEATURES OF EACH MODEL (click link to go to product page)

Sea-Bird
Model Number
Additional
Included Sensors
Pump* Power Communication Real-Time
Data
Minimum
Sampling Interval
Internal External
37-SMP-ODO Optical Dissolved Oxygen
(plus pH when integrated with
SeaFETTM or Deep SeaFETTM)
RS-232, RS-485, or SDI-12 10 sec
37-SMP-IDO

(replaced by
37-SMP-ODO)
Dissolved Oxygen
(membrane type)
RS-232 or RS-485 10 sec
37-SMP   RS-232, RS-485, or SDI-12 6 sec
37-SM     RS-232 or RS-485 6 sec
37-SIP-IDO Dissolved Oxygen
(membrane type)
  RS-232 1.0 sec
37-SIP     RS-232 or RS-485 1.0 - 1.5 sec ***
37-SI       RS-232 or RS-485 1.0 - 1.5 sec ***
37-IMP-ODO Optical Dissolved Oxygen   Inductive Modem **** ** 10 sec
37-IMP-IDO

(replaced by
37-IMP-ODO)
Dissolved Oxygen
(membrane type)
  Inductive Modem **** ** 10 sec
37-IMP     Inductive Modem **** ** 6 sec
37-IM       Inductive Modem **** ** 6 sec

* Integral pump provides improved conductivity and dissolved oxygen (if applicable) response, and conductivity fouling protection.
** Inductive Modem MicroCATs do not automatically transmit real-time data; controller must query for data.
*** Minimum sampling interval 1.0 sec without optional pressure sensor, 1.5 sec with optional pressure sensor.
**** See Application Note 92 for a description of Inductive Modem telemetry.

The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

How accurate is salinity measured by my CTD? What factors impact accuracy?

One of the reasons that this is not a simple question is that there are several factors to take into consideration regarding the error margin for practical salinity measurements. Salinity itself is a derived measurement from temperature, conductivity, and pressure, so any errors in these sensors can propagate to salinity. For example, Oour initial accuracy specification for the SBE 3plus temperature sensor and SBE 4 conductivity sensor on an SBE 9plus CTD is approximately equivalent to an initial salinity accuracy of 0.003 PSU (note that conductivity units of mS/cm are roughly equivalent in terms of magnitude to PSU).

However, another issue to consider is that this accuracy is defined for a clean, well-mixed calibration bath. In the ocean, some of the biggest factors that impact salinity accuracy are 1) sensor drift from biofouling or surface oils for conductivity in particular and 2) dynamic errors that can occur on moving platforms, particularly when conditions are rapidly changing, which will be true for all sensors that measure salinity. Sea-Bird provides recommendations, design features such as a pumped flow path, and data processing routines to align and improve data for the salinity calculation to account for thermal transients and hysteresis, and to match sensor response times.  Depending on the environment and the steepness of the gradient, and after careful data processing, this may continue to have an impact on salinity on the order of 0.002 PSU or more, for example. For more details, see Application Note 82.

Lastly, note that salinity in PSU is calculated according to the Practical Salinity Scale (PSS-78), which is defined as valid for salinity ranges from 2 – 42 PSU.

Compare  Moored / Time Series Recording Instruments

SBE Measures
(C, T, P)
Auxiliary Sensors Memory Power Communication Real-Time
Data
Comments
Internal External
SBE 16plus V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb RS-232 Optional pump
SBE 16plus SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb RS-232 or -485 Replaced by SBE 16plus V2 in 2008
SBE 16 SeaCAT C-T (P) Recorder
C, T, P* 4 A/D 1 Mb RS-232 Replaced by SBE 16plus in 2001
SBE 16plus-IM V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb   Inductive Modem Optional pump
SBE 16plus-IM SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb   Inductive Modem Replaced by SBE 16plus-IM V2 in 2008
SBE 19plus V2 SeaCAT Profiler CTD C, T, P 6 A/D; 
1 RS-232
64 Mb RS-232 Programmable mode — profiling or moored
SBE 19plus SeaCAT Profiler CTD
C, T, P 4 A/D; optional PAR 8 Mb RS-232 Replaced by SBE 19plus V2 in 2008
SBE 19 SeaCAT Profiler CTD
C, T, P 4 A/D 1 - 8 Mb RS-232 Replaced by SBE 19plus in 2001
SBE 37-SM MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232 or -485  
SBE 37-SMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232, RS-485, or SDI-12 Integral pump
SBE 37-SMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb RS-232 or -485 Integral pump; Replaced by SBE 37-SMP-ODO in 2014
SBE 37-SMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb RS-232, RS-485, or SDI-12 Integral pump
SBE 37-IM MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem  
SBE 37-IMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem Integral pump
SBE 37-IMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb   Inductive modem Integral pump; Replaced by SBE 37-IMP-ODO in 2014
SBE 37-IMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb   Inductive modem Integral pump
SBE 37-SI MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485  
SBE 37-SIP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485 Integral pump

SBE 37-SIP-IDO MicroCAT C-T-DO (P) Sensor

C, T, P* Integrated DO 8 Mb   RS-232 or -485 Integral pump
SBE 39plus Temperature (P) Recorder T, P*   64 Mb Optional USB & RS-232 Optional  
SBE 39 Temperature (P) Recorder
T, P*   32 Mb Optional RS-232 Optional Replaced by SBE 39plus in 2014
SBE 39plus-IM Temperature (P) Recorder T, P*   64 Mb   Inductive Modem & USB  
SBE 39-IM Temperature (P) Recorder T, P*   32 Mb   Inductive modem Replaced by SBE 39plus-IM in 2016
SBE 56 Temperature Logger T   64 Mb   USB    
SBE 26plus Seagauge Wave & Tide Recorder T, P C optional 32 Mb RS-232
(tides, waves, & wave statistics)
Wave & tide recorder
SBE 26 Seagauge Wave & Tide Recorder
T, P C optional 8 Mb RS-232   Replaced by SBE 26plus in 2004
SBE 53 BPR Bottom Pressure Recorder T, P C optional 32 Mb RS-232 Bottom pressure recorder
SBE 54 Tsunameter Tsunami Pressure Sensor T, P   128 Mb Optional RS-232 Tsunami pressure sensor

C = conductivity, T = temperature, P = pressure, DO = dissolved oxygen
* = optional
products are no longer in production. Follow the links above to the product page to retrieve manuals and application notes for these older products.

Compare Inductive Modem Instruments

SBE Measures
(C, T, P)
Auxiliary Sensors Memory Power Comments
Internal External
SBE 16plus-IM V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb   Optional pump
SBE 16plus-IM SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb   Replaced by SBE 16plus-IM V2 in 2008
SBE 37-IM MicroCAT C-T (P) Recorder C, T, P*   8 Mb    
SBE 37-IMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Integral pump
SBE 37-IMP-IDO MicroCAT C-T-ODO (P) Recorder C, T, P* Integrated DO 8 Mb   Integral pump; Replaced by SBE 37-IMP-ODO in 2014
SBE 37-IMP-ODO MicroCAT C-T-ODO (P) Recorder C, T, P* Integrated Optical DO 8 Mb   Integral pump
SBE 39plus-IM Temperature (P) Recorder T, P*   64 Mb   Includes internal USB connector for fast data upload
SBE 39-IM Temperature (P) Recorder T, P*   32 Mb   Replaced by SBE 39plus-IM in 2016
SBE 44 Underwater Inductive Modem (UIM)   1 RS-232 30 Kb buffer Integrates sensor with standard serial interface (current meter, Doppler profiler, etc.) to inductive modem telemetry system
Underwater Inductive Modem Module (UIMM)   1 RS-232 16 Kb Sample Data Memory   Integrates sensor with standard serial interface (current meter, Doppler profiler, etc.) to inductive modem telemetry system; more flexible and economical than SBE 44

C = conductivity, T = temperature, P = pressure, DO = dissolved oxygen
* = optional

Notes:
1. See Inductive Modem Module (IMM) or Surface Inductive Modem (SIM), and Inductive Cable Coupler (ICC) to complete your inductive modem system.
2. See Application Note 92: Real-Time Oceanography with Inductive Moorings and the Inductive Modem Module (IMM) for background information.
3. products are no longer in production. Follow the links above to the product page to retrieve manuals and application notes for these older products.