This dataset contains pH time series simultaneously recorded by 4 pH sensors. Two of them were SAMI-pH, and the other two were SeapHOx. Data interval was 15 min. These data were part of an inter-comparison of autonomous in situ instruments for ocean CO2 measurements under laboratory-controlled conditions at Scripps Institution of Oceanography in August of 2016. These data were published in Shangguan et al. (2022).

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

This study used sensors (see Instrument description below) with quality control bottle samples. For bottle sample data and bottle analysis description, see Dataset "Inter-comparison 2016: Bottle Sample TA pH DIC" https://www.bco-dmo.org/dataset/870368

Instrument description:
This dataset has data from two SAMI-pHs (Sunburst Sensors, LLC; p66 and p87) (Seidel et al., 2008), two SeapHOx sensors (SP020 and SP032) (Bresnahan et al., 2014).
pH data have an interval of 15  mins.

 

Each sensor data was processed by its own Matlab script.  MATLAB scripts convert raw data, which are optical intensities or voltages along with temperature and salinity, into their respective carbonate parameters.

BCO-DMO Data Manager Processing Notes:
* Data from source file "2016 pH sensor.xlsx" Sheet1 were imported into the BCO-DMO data system. 
* Parameters (column names) renamed to comply with BCO-DMO naming conventions. See https://www.bco-dmo.org/page/bco-dmo-data-processing-conventions

Coverage: Bermuda

NSF abstract:
The ocean inorganic carbon system is of great interest to marine scientists, and indeed all people, because it contains important information about ocean productivity, the sources and sinks of anthropogenic carbon dioxide, and ocean acidification. Total alkalinity is one of the critical inorganic carbon parameters and has been widely measured through ship and laboratory-based methodologies. At this time, there are no commercially-available in situ sensors for total alkalinity. In this project, researchers at the University of Montana will further develop and test a new autonomous system, known as the SAMI-alk, for measuring total alkalinity. This new system will expand understanding of total alkalinity and the inorganic carbon cycle by making near continuous measurements in locations not frequented by ships. The development of this instrument will have important broader implications for the oceanographic community and ocean acidification research by providing a novel instrument for ocean research. This project will also provide training opportunities to graduate and undergraduate students, and will continue to support public outreach on ocean acidification through a university-affiliated museum.

Studies focused on the marine carbon cycle and ocean acidification pose a number of measurement challenges. While pH is the ocean acidification "smoking gun" and partial pressure of CO2 is critical for gas exchange calculations, the full inorganic carbon system must be quantified for most inorganic carbon studies. Using autonomous sensors to accurately and precisely quantify all of the inorganic carbon species has been a long-standing objective for marine biogeochemists, but full characterization of the inorganic carbon system has, until recently, been limited to ship and laboratory-based measurements. Total alkalinity is one such parameter as its research has been limited by the lack of instrument capable of making in situ measurements. This research will address this problem and advance inorganic carbon studies through the further development of an autonomous, in situ system to measure seawater total alkalinity, known as the submersible autonomous moored instrument for total alkalinity (SAMI-alk). Preliminary testing of the instrument showed great promise, and through this project, researchers will conduct lab experiments to improve its performance. Two new prototype instruments will be tested in laboratory and field evaluations.