SolveSAPHE-r2 (Solver Suite for Alkalinity-PH Equations - Release 2)

SolveSAPHE-r2 (Solver Suite for Alkalinity-PH Equations  Release 2) provides a collection of Fortran 90 routines to solve the total alkalinity–pH equation, which relates total alkalinity and pH for a given set of total concentrations of the acid–base systems that contribute to total alkalinity in a given water sample. Carbonate alkalinity can now be expressed by using the total concentration of dissolved inorganic carbon (C_T, as in SolveSAPHE v.1) or by specifying either concentration of CO₂, HCO₃⁻ or CO₃²⁻. The package provides two different iterative solvers for the alkalinity-pH equation, designed to assure convergence with any physically meaningful chemical composition, and in a completely autonomous way. The Alk_T & CO₃²⁻ pair is completely diagnosed and if there are two roots, both are calculated.

Although the Alk_T & C_T pair can also be processed with SolveSAPHE-r2, this is considerably slower than with SolveSAPHE v.1, due to the extra safeguarding that had to be introduced for the other three pairs

This package was first published as a supplement to the discussion paper:

Guy Munhoven (2021) SolveSAPHE-r2: revisiting and extending the Solver Suite for Alkalinity-PH Equations for usage with CO₂, HCO₃⁻ and CO₃²⁻ input data, Geosci. Model Dev. Discuss., 2021 (doi:10.5194/gmd-2020-447).