The modern oceanographic definition of salinity is the Practical Salinity Scale of 1978 (PSS-78). By definition, PSS-78 is valid only in the range of 2 to 42 psu. Sea-Bird uses the PSS-78 algorithm in our software, without regard to those limitations on the valid...
FAQs
What is the difference in temperature expressions between IPTS-68 and ITS-90?
ITS-90 was adopted in 1990 as the temperature scale; IPTS-68 was the previous standard. The differences are related to redefining certain triple points and other melt or freeze cells that are used as the fundamental standards for temperature. Over the oceanographic...
What is the difference between initial accuracy and resolution?
Upon receipt of an instrument, the initial accuracy is the accuracy when comparing to a known standard. Resolution is the smallest amount of change that a sensor can see.
Why is sound velocity (SV) computed from a CTD better than sound velocity from direct measuring instruments?
Direct SV probes measure the time (flight time) required for a sound pulse to travel over a fixed length, using a high-speed clock to measure time. The clock starts when the pulse is emitted, and stops when the pulse is received. Theoretically, you only need to know...
Which algorithm for calculating sound velocity (SV) from CTD data should I use?
Sea-Bird real-time data acquisition (Seasave V7) and data processing (SBE Data Processing) software supports calculation of Chen-Millero, Del Grosso, and Wilson sound velocities. The algorithms, as implemented in our software, are provided in the software...
How can I find the density of seawater at different temperatures and/or salinities?
SBE Data Processing includes a module called Seacalc III. Seacalc III can calculate density, sound velocity, and a number of other parameters for a given user input of pressure, temperature, and conductivity (or salinity).
What is the cause of conductivity drift?
Conductivity cells drift primarily as a function of cell fouling. There are several sources of the fouling:Biological growth is the primary source of cell fouling. Rinsing the conductivity cell with clean de-ionized water after each cast helps prevent most growth...
What is “adaptive sampling” and how does it work?
The SUNA V2 contains a 256 channel spectrometer that is programmed to integrate for a specific length of time (usually 300 - 500 ms) while sampling to maximize signal. That is, when the SUNA V2 takes a sample, the spectrograph collects UV light for the length of the...
When I compute sigma-density values, why are they sometimes negative?
For convenience while examining differences in density between two water parcels, Sigma-density values are typically used by oceanographers. Sigma-density values allow the oceanographer to focus on the last 6 to 7 digits in the density value (when assuming 5 decimal...
Why is Teflon tape used?
Adhesive Teflon tape (actually, UHMW tape — Ultra High Molecular Weight polyethylene) provides insulation to prevent damage due to contact of dissimilar metals. It is typically used by Sea-Bird on the inside of hose clamps used for mounting instruments, where U-bolts...
Featured Posts
Scripps Technical Forum 2023 | Recap
Technical Forum in Partnership with Scripps Sea-Bird Scientific is eternally grateful for having had the opportunity to present at a Technical Forum to the Scripps Institute of Oceanography community on April 6, 2023. In this session, our optical experts, Cris...
March 2023 Newsletter
NEW in Optics: The LED AC-SWe are more than ecstatic to announce the release of the NEW LED AC-S Spectral Absorption and Attenuation Sensor. It is the first of its kind, and a standalone transmissometer in the market.The AC-S provides in-situ optical...
Scripps Technical Forum | AC-S: The Telescope Into the Rainbow of Ocean Life
Scripps Technical Forum Time: Thursday, April 06, 2023 | 12:00 PM to 1:00 PM Location: Hydraulics Lab Mezzanine Sea-Bird Scientific is grateful for the opportunity to present at a Technical Forum to the Scripps Institute of Oceanography community. In this session,...