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Sampling was conducted on R/V Pelican cruise PE22-03 in the Northern Gulf of Mexico in August 2021. All CTD casts were conducted according to standard ship operator procedure.
The data were collected using a SeaBird 911 plus system with twelve 12-liter Niskin bottles. The instruments included in the 911 plus suite are dual Temperature (SBE 3), dual Conductivity (SBE 4), and dual Oxygen (SBE 43) sensors. Additionally, the suite included an SBE 27 pH/Oxidation, Chelsea Aquatracka 3 Chl-a, and a Wetlabs CDOM sensor. Serial numbers and calibration information is stored in the Header Information included in the .cnv files (see Supplemental Files).
Data Processing: The data were processed using Seabird's SBEDataProccessing_Win32 software. The data were converted from hexadecimal to engineering units first. Using the software's Bin Averaging tool, it was also averaged in bins of 0.25 meters. The attached Supplemental File, "PE22-03_Seabird_CTD_File_Header.txt", contains the complete Seabird header from one cast (C6C_2).
For the unbinned data, see the related dataset https://www.bco-dmo.org/dataset/879930.
BCO-DMO Processing: - captured starting latitude, starting longitude, and starting date/time from the Seabird headers as columns; - replaced "-9.990e-29" with "nd" (no data); - concatenated separate files (one per cast) into one dataset; - converted starting latitude and longitude to decimal degrees (rounded to 5 decimal places); - converted starting date/time to ISO8601 format; - created Cast column based on the original file name; - removed three rows of data where CTD recording started too early resulting in unusually low data values; - renamed fields to comply with BCO-DMO parameter naming conventions.
SeaBird 911 plus system with twelve 12-liter Niskin bottles
The Sea-Bird SBE 911 plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911 plus includes the SBE 9plus Underwater Unit and the SBE 11plus Deck Unit (for real-time readout using conductive wire) for deployment from a vessel. The combination of the SBE 9 plus and SBE 11 plus is called a SBE 911 plus. The SBE 9 plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3 plus and SBE 4). The SBE 9 plus CTD can be configured with up to eight auxiliary sensors to measure other parameters including dissolved oxygen, pH, turbidity, fluorescence, light (PAR), light transmission, etc.). more information from Sea-Bird Electronics
A fluorometer or fluorimeter is a device used to measure parameters of fluorescence: its intensity and wavelength distribution of emission spectrum after excitation by a certain spectrum of light. The instrument is designed to measure the amount of stimulated electromagnetic radiation produced by pulses of electromagnetic radiation emitted into a water sample or in situ.
A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.
The SBE 27 pH and O.R.P. (Redox) sensor combines a pressure-balanced, glass-electrode, Ag/AgCl reference probe and platinum O.R.P. electrode to provide in-situ measurements at depths to 1200 m. The replaceable pH probe is permanently sealed and is supplied with a soaker bottle attachment that prevents the reference electrode from drying out during storage. The SBE 27 is intended for use as an add-on auxiliary sensor for profiling CTDs (SBE 9plus; SBE 19, 19plus, and 19plus V2 SeaCAT; and SBE 25 and 25plus Sealogger).
The Sea-Bird SBE 43 dissolved oxygen sensor is a redesign of the Clark polarographic membrane type of dissolved oxygen sensors. more information from Sea-Bird Electronics
The SBE-3 is a slow response, frequency output temperature sensor manufactured by Sea-Bird Electronics, Inc. (Bellevue, Washington, USA). It has an initial accuracy of +/- 0.001 degrees Celsius with a stability of +/- 0.002 degrees Celsius per year and measures seawater temperature in the range of -5.0 to +35 degrees Celsius. more information from Sea-Bird Electronics
The Sea-Bird SBE-4 conductivity sensor is a modular, self-contained instrument that measures conductivity from 0 to 7 Siemens/meter. The sensors (Version 2; S/N 2000 and higher) have electrically isolated power circuits and optically coupled outputs to eliminate any possibility of noise and corrosion caused by ground loops. The sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Because the outer electrodes are connected together, electric fields are confined inside the cell, making the measured resistance (and instrument calibration) independent of calibration bath size or proximity to protective cages or other objects.
Cast identifier
Latitude at start of cast
Longitude at start of cast
Date and time (UTC) at start of cast in ISO8601 format: YYYY-MM-DDThh:mm:ssZ
Latitude
Longitude
Depth
Temperature [ITS-90]
Temperature, 2 [ITS-90]
Conductivity
Conductivity, 2
Practical salinity
Practical salinity, 2
Oxygen, SBE 43
Oxygen, SBE 43, 2
Fluorescence, Chelsea Aqua 3 Chl Con
pH
Oxidation Reduction Potential
Fluorescence, WET Labs CDOM
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