PyCO2SYS: marine carbonate system calculations in Python

PyCO2SYS is a Python toolbox for solving the marine carbonate system and calculating related seawater properties. Its core is a Python implementation of CO2SYS for MATLAB. Documentation is available at PyCO2SYS.rtfd.io.

Changes in v1.4.0

New features

• Added uncertainty module with functions to evaluate derivatives of PyCO2SYS outputs with respect to inputs, along with corresponding documentation.
• Specific input values can optionally be provided for all total concentrations and equilibrium constants that are estimated internally from salinity, temperature and pressure.

General improvements

• Added basic sanity checking to prevent some invalid marine carbonate system parameter input values.
• Nutrient concentrations have always been set to zero internally for K1K2CONSTANTS options 6 and 8, and salinity too for 8, regardless of the input values. This is now reflected in the output values of these variables in the CO2dict.

New outputs

• Substrate:inhibitor ratio (SIR) of B15, calculated with SIratio in new module bio.
• Inputs PAR1 and PAR2.
• The "Peng correction" factor.
• The fugacity factor for converting between CO₂ partial pressure and fugacity.
• The activity coefficient of the H⁺ ion for NBS pH scale conversions.

Validation

• Calculations compare very favourably against the forthcoming CO2SYS for MATLAB v3 - see the validation documentation for a discussion of the results.