This solver gives a 5X speed-up for the ICON-ART climate model, as compared to the default Rosenbrock solvers. It can also be used in any climate model that uses the KineticPreProcessor KPP software package (https://github.com/KineticPreProcessor/KPP).
This solver is inspired by the IMEX solver. However, an explicit solver is not possible in the case of stiff atmospheric chemistry problems. This solver consists of:
- Backward Euler: L-stable, 1 stage, order 1 with the Fixed step size
- Adaptive Sdirk 2a: L-stable, 2 stages, order 2 with automatic step size selection
This repository only contains two files. Please copy both files, "implicit12.f90" and "implicit12.def," into the directory "kpp/int/", whichever version of KPP you are using.
This can also be used with the CAABA/MECCA box model (https://gitlab.com/RolfSander/caaba-mecca).
With the MECCA chemistry module, make sure to update the ".bat" file.