Comparison of discrete and underway CO2 measurements: Inferences on the temperature dependence of the fugacity of CO2 in seawater

Details

• Journal Title:
  Marine Chemistry
• Personal Author:
  Wanninkhof, Rik ; Pierrot, Denis ; Sullivan, Kevin ; Mears, Patrick ; Barbero, Leticia
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; AOML (Atlantic Oceanographic and Meteorological Laboratory) ; CIMAS (Cooperative Institute for Marine and Atmospheric Studies)
• Description:
  The fugacity or partial pressure of CO2 in surface water (fCO2w) is a key parameter to determine air-sea CO2 fluxes and the evolution of ocean acidification. Despite its importance some key physical chemical characteristics are not fully resolved, notably its dependence on temperature. The fCO2w is mostly measured by autonomous underway systems near in situ sea surface temperature (SST). Subsurface measurements are commonly carried out on individual (discrete) samples at a fixed temperature, normally 20 °C. Here, the underway system observations are compared with co-located discrete observations to determine the consistency of these types of measurements. The co-located discrete fCO2w at 20 °C and underway fCO2w measurements at SST are used to infer the temperature dependence of CO2. In addition, calculated fCO2w from total alkalinity (TA) and total dissolved inorganic carbon (DIC) are compared with the underway and discrete fCO2w measurements. For 21 cruises spanning the major ocean basins from 1992 to 2020 a temperature dependence of 4.13 ± 0.01% °C−1 is determined in close agreement with a widely used previous empirical estimate of 4.23 ± 0.02% °C−1 for North Atlantic surface water. The temperature dependency of calculated fCO2w from TA and DIC using recommended constants is 4.10% °C−1 for 17 cruises where there are co-located measurements of fCO2w, TA and DIC.
• Keywords:
  Environmental Chemistry General Chemistry Oceanography Water Science And Technology Water Science And Technology Water Science And Technology
• Source:
  Marine Chemistry, 247, 104178
• DOI:
  https://doi.org/10.1016/j.marchem.2022.104178
• ISSN:
  0304-4203
• Format:
  PDF
• Publisher:
  Elsevier BV
• Document Type:
  Journal Article
• Funding:
  Grant no. NA20OAR4320472
• Rights Information:
  Accepted Manuscript
• Rights Statement:
  The NOAA IR provides access to this content under the authority of the government's retained license to distribute publications and data resulting from federal funding. While users may legally access this content, the copyright owners retain rights that govern the reproduction, redistribution, and re-use of this work. The user is solely responsible for complying with applicable copyright law.
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:9d8a7b8100e130977302defa66cb40912f43ee72a41a5d27ab91d6f055dd2a3f4897c20808336a393abe7a2bee2db85d23a81a8bc48deb7615d0167d6915850a
• Download URL:
  https://repository.library.noaa.gov/view/noaa/50078/noaa_50078_DS1.pdf
• File Type:
  [PDF - 663.84 KB ]