Woods Hole Oceanographic Institution, Department of Physical Oceanography.

The WHOI CTD/Calibration Operations is provides CTD and hydrographic support for the seagoing scientists within and outside of WHOI.  A critical element in this support is the ability to calibrate and maintain the instrumentation in the inventory.  The annual WHOI NSF Instrumentation Proposal and other observational grants which have used the CTD and hydrography services have funded the purchase, operation and maintenance of a well-equipped facility, the CTD Calibration Lab, specifically oriented toward calibration of CTDs and related oceanographic sensors for WHOI and other educational, non-profit and governmental clients.  Occasional assistance is provided by the Lab to commercial entities on a cost-plus-fee, non-interference basis where no other facility has the resources.  The CTD Calibration Lab receives minimal ongoing support from WHOI departmental overhead funds, and is nearly entirely supported by charges to grants on an as-needed basis.

The CTD Calibration Lab maintains both primary physical standards and secondary transfer standards and support equipment, enabling high-accuracy calibration of temperature, conductivity and pressure sensors across the oceanographic range.  The availability of primary standards enables access for other WHOI groups, such as the Meteorological Calibration Lab, to NIST-defined temperature references in the course of their work.  Occasional standards intercomparison efforts are undertaken with other labs to maintain confidence in equipment and techniques.

The CTD Calibration Lab is located in the Clark Annex room 71 on the Quisset Campus, and is operated and maintained by Marshall Swartz of the Physical Oceanography Department.

Requests for calibration services must be made at least ten days in advance.  Please check the current CTD Calibration Lab Schedule here.

For all laboratory use requests, contact Marshall at 508-289-2246, or email to mswartz@whoi.edu.  In Marshall's absence, contact Jason Smith at 508-289-3618, or email to jsmith@whoi.edu.

Major capabilities of the CTD Calibration Lab are described under SETUPS and STANDARDS:


Temperature calibration setups over the range of –2C to +30C and above:

 Salinity calibration setups over the range of 20mS/cm to 60mS/cm:  Pressure calibration setups, with hydraulic fluid medium, in constant temperature baths or in air over the range of 15 psig to 15,000 psig.


Temperature reference points over the ITS-90 subrange 5 (-38.8344C to +29.7646C) include:

Reported temperature results are not claimed to be NIST-traceable.

Temperature transfer standards between these reference points to the temperature bath setups include:

Conductivity is reported as the result of inverted salinity measurements taken from temperature baths, measured on Guildline Autosal 8400-B and 8400-A systems, which the CTD Cal Lab maintains for both in-lab and at-sea use.

Pressure measurements are made by applying standard pressures from a Ruska 2480 deadweight table hydraulic system with calibrated masses, supplying hydraulic oil source pressures to units under test from 15 psig to 15,000 psig.  Accuracy and stability of the pressure output is monitored by a Paroscientific 760-10K laboratory pressure standard reference.

By Marshall Swartz, WHOI CTD/Calibration Operations, contact by phone 508-289-2246, mswartz@whoi.edu.

Updated April 16, 2007. File: ctdcal1.html