CO2SYSv3 for MATLAB

Description:

This is a relatively major update from CO2SYS v3.1.1 to CO2SYS v3.2.0. It is designed to be maximally compatible with PyCO2SYS v1.7.0, a program for CO2 system calculations in Python that introduced a number of additional capabilities, improvements to performance, and fixes to minor errors/simplifications (Humphreys et al., submitted). Rigorous validation was performed against PyCO2SYS v1.7.0 as part of this update.

Major changes since CO2SYS v3.1.1:

1) Initial pH estimates for iterative pH solvers are obtained via the approach of Munhoven (2013), detailed further in Humphreys et al. (submitted), rather than simply using an initial estimate of 8.0 each time.

2) Free scale pH is obtained properly within iterative pH solvers no matter the input scale, rather than making the simplification that input pH is always on the total scale.

3) Uncertainties in parameters calculated at output conditions that are associated with equilibrium constants are calculated calculated with respect to equilibrium constants at output conditions, rather than input conditions as previously. This essentially assume pK uncertainty is constant regardless of temperature and pressure.

4) [CO2(aq)] is calculated from fCO2 and K0 every time, rather than from different combinations of parameters.

5) Substrate-inhibitor ratio (Bach, 2015) is included as an output argument from CO2SYS, rather than calculated in a separate function.

6) Input uncertainty in [CO2], [HCO3], and [CO3] should now be input as an absolute value in mol/kg, rather than a relative value.

7) Modifications were made to allow vector inputs with different input parameters in each row to errors.m.

8) Derivatives and errors for Revelle factor are now calculated.

Be advised:

The addition of substrate-inhibitor ratio to the CO2SYS output arguments (positions 20 and 38) have changed the column references for all output arguments after position 20. Similarly, the addition of Revelle factor uncertainty to the errors.m output arguments (positions 9 and 19), along with the retention of uncertainty from input arguments, has changed the column references for output arguments from errors.m.