From the TN303 cruise report:
Two types of rosette/SBE9plus CTD casts (ODF/30L-Niskin and GT-C/12L-GoFlo) were made at 36 station locations during U.S. GEOTRACES EPZT. Deep ODF/30L-Niskin casts included a device suspended 20 meters below the rosette, designed either to take a core sample or pick up particulates from the sea floor.
ODF/30L-Niskin Rosette/CTD casts were performed with a package consisting of a 12-bottle rosette frame (SIO/STS), a 12- or 24-place carousel (SBE32) and 12 ea. 30L General Oceanics Niskin-style bottles with an absolute volume of 30L each.
A 12-place carousel was used on station 1, but had repeated trip-confirmation failures during stations 2 and 3. It was replaced with an older 24-place carousel mid-station 3, which resolved the trip-confirmation issues. Prior to station 4, the carousel head was replaced by one with titanium instead of stainless steel latches in order to resolve mechanical tripping
issues. This "hybrid" carousel was used successfully for the remainder of the cruise.
Underwater electronic components consisted of a Sea-Bird Electronics CTD (SBE9plus) with dual pumps (SBE5), dual temperature (SBE3plus), reference temperature (SBE35RT), dual conductivity (SBE4C), dissolved oxygen (SBE43), transmissometer (WET Labs C-Star), fluorometer (Seapoint SCF), Oxidation Reduction Potention (ORP) sensor (NOAA), turbidity meter (Seapoint STM11) and altimeter (Simrad 807). A second dissolved oxygen + oxygen temperature sensor (JFE Advantech RINKO-III) was incorporated into the data stream for future sensor evaluation; it was not processed for this cruise. Additionally, an SBE19plus CTD was mounted on the rosette during deep ODF casts for full and super stations beginning with station 25, since it could no longer be deployed on deep McLane pump casts after their wire was damaged.
Shipboard CTD data processing was performed automatically at the end of each deployment using SIO/STS CTD processing software v.5.1.6-1. Raw GT-C CTD data and bottle trip files, acquired by SBE Seasave V 7.17a on a Windows XP workstation, were also imported into the Linux processing system, providing a backup of the raw data.
Pre-cruise laboratory calibrations were applied, then CTD data were processed into a 0.5-second time series, bottle trips were extracted, and a 1-decibar down-cast pressure series of the data was created. The pressure-series data were used by the web service for interactive plots, sections and CTD data distribution. Time-series data, and eventually basic up-cast pressure-series data, were also available for distribution through the website.
SIO/ODF CTD data were examined at the completion of each deployment for clean, corrected sensor response and any calibration shifts. As bottle salinity and oxygen results became available, they were used to refine shipboard conductivity and oxygen sensor calibrations.
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