Underway pH of seawater sampled during CCGS John P. Tully cruises in the northeast Pacific Ocean from Vancouver Island to Station P from 2019 to 2020 (NCEI Accession 0278418)

This dataset contains chemical and physical data collected on CCGS John P. Tully during cruise Line-P_cruises in the Coastal Waters of Southeast Alaska and British Columbia and North Pacific Ocean from 2019-06-03 to 2020-02-23. These data include pH, sea surface salinity, and water temperature. The instruments used to collect these data include Sea-Bird SBE 45 MicroTSG Thermosalinograph and pH Sensor. These data were collected by Yuichiro Takeshita of Monterey Bay Aquarium Research Institute, Andrea J. Fassbender of National Oceanic and Atmospheric Administration, and Phoebe J. Lam of University of California-Santa Cruz as part of the "Constraining Upper-Ocean Carbon Export with Biogeochemical Profiling Floats (EXPORTS BGC Floats)" project. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2021-12-22.

The following is the text of the dataset description provided by BCO-DMO:

Acquisition Description:
Underway measurements were made aboard the CCGS John P. Tully during three Canadian Line P cruises (2019-2020) in the northeast Pacific from Vancouver Island to Station P (50°N, 145°W).
Fisheries and Oceans Canada (DFO) Cruise numbers: 2019-006, 2019-008, 2020-001

pH
A prototype instrument (BGC-SUMO) developed by Dr. Yui Takeshita at MBARI was plumbed into the CCGS John P. Tully seawater intake (~5 m below the surface) line in the wet lab. Underway in situ pH on the total hydrogen ion concentration scale was measured with an ion-sensitive field-effect transistor (ISFET) pH sensor (Deep-Sea DuraFET; Johnson et al., 2016). The instrument was powered through an isolation transformer to prevent ground loop issues. The system was polled using a LabView interface and pH measurements were made every 10 milliseconds. pH sensor data were calibrated using discrete pH samples collected from the underway line (near BGC-SUMO) during the three cruises: 2019-006, 2019-008, and 2020-001 (n= 19, n= 5, n= 5, respectively)

Temperature and Salinity
Underway temperature and salinity were measured by a Sea-Bird Scientific SBE45 MicroTSG thermosalinograph located directly downstream (< 10 cm) of the BGC-SUMO pH sensor that was plumbed into the CCGS John P. Tully seawater intake (~5 m below the surface) line in the wet lab. Underway temperature and salinity were also measured with a CCGS John P. Tully thermosalinograph at the seawater intake location. These data were used to correct for warming between the seawater intake and the location where the instruments were plumbed into the underway line. The CCGS John P. Tully thermosalinograph data can be accessed through the Canadian Line P Program data archive (). The instrument was powered through an isolation transformer to prevent ground loop issues. The system was polled using a LabView interface and pH measurements were made every 10 milliseconds.