Data (including the TAII cruise) and routines used in the estimation of changes in the carbonate system properties of the South Atlantic Ocean

A repository containing the routines and data to reproduce the results of the study: "Ocean acidification and long-term changes in the carbonate system properties of the South Atlantic Ocean" by Andrés Piñango et al. (2022), published in Global Biogeochemical Cycles (DOI: 10.1029/2021GB007196).

A copy of the hydrographic data of each cruise used in this study can be found in the “Data” directory. Except for the /A10.5/A10-2011 cruise, all the data included in this repository was extracted from the GLODAPv2.2021 product (https://glodap.info), without other modifications that the merge of the 318MSAVE5 and 318MHYDROS4 cruises into a unique file (/A16/A16-1989) and minor formatting changes. For more information about this dataset please see the publications of Olsen et al. (2019) and Olsen et al. (2020). The data of the /A10.5/A10-2011 cruise correspond to the first leg of the Trans-Atlantic II (TAII) cruise, conducted from 24/10/11 to 25/11/2011 (austral spring) along 35°S (from Rio Grande, Brazil to Cape Town, South Africa) as part of the Brazilian project: “Measurements and modeling of CO₂ fluxes in the South Atlantic and Southern Oceans” onboard the Brazilian R.V. Cruzeiro do Sul. The methodology used for the processing of this data is described below:

• The CTD-derived data (temperature, salinity, and oxygen) corrected by instrumental drift was gridded to standard depths (those of the Levitus atlas) using the "boxcar" (local average) method of the sectionGrid function from the oce package for R (https://CRAN.R-project.org/package=oce).

• A comparison of the properties in the deep part of the water column (> 1500 m) between the/A10.5/A10-2011 cruise stations and other cruises stations in the same area was done using the MATLAB toolbox developed by Lauvset & Tanhua (2015) (available at https://github.com/sivlauvset/2nd_QC_tool), using data from the GLODAPv2.2020 as the reference data. Salinity and oxygen offsets (−0.007 and 0.955 respectively) were corrected following the GLODAP methodology (see Olsen et al, 2019).

• Dissolved inorganic carbon (DIC), total alkalinity (TA), nitrate (Ni), phosphate (Phos), and silicate (Si) concentrations were estimated from the available variables using the CANYON-B method developed by Bittig et al (2018) (available at https://github.com/HCBScienceProducts/CANYON-B).

• Ancillary variables such as potential temperature (ptemp), apparent oxygen utilization (AOU), neutral density (ndens), and potential density anomalies from 0 to 4000 dbar (S0 to S4) were estimated in Ocean Data View (https://odv.awi.de).

Instructions for the code execution can be found at the start of the SAOchanges_script.R file. Code is also available as a Jupyter notebook (SAOchanges_notebook.ipynb) and can be executed in a binder environment at: https://mybinder.org/v2/gh/andresawa/south-atlantic-change/main?filepath=SAOchanges_notebook.ipynb.

When used, please cite as:

Piñango, A., Kerr, R., Orselli, I. B. M., Carvalho, A. C. O., Azar, E., Karstensen, J., & Garcia, C. A. E. (2022). Ocean acidification and long-term changes in the carbonate system properties of the South Atlantic Ocean. Global Biogeochemical Cycles, 36, e2021GB007196. https://doi.org/10.1029/2021GB007196