Implementing BeTR in ACME-v1: progress and results.

Abstract

We integrated the Biogeochemical Transport and Reaction module into ACME-LAND for a mechanistic coupling between biotic and abiotic factors in the plant-soil biogeochemistry feedback. BeTR solves the reactive transport system for an arbitrary number of tracers using the operator splitting approach. It solves the aqueous advection explicitly using the semi-lagrangian approach, and solves the multiphase diffusion implicitly with a second order accurate spatial discretization. BeTR also includes explicit treatment of ebullition and arenchyma transport for different volatile tracers. The biogeochemical reaction is represented using the reaction-based formulation, such that mass balance is naturally guaranteed through the stoichiometry matrix. At every step, all tracer masses are guaranteed to be nonnegative with appropriate numerical treatments. Because BeTR adopted the OOP polymorphism design, it enables the implementation of multiple soil biogeochemical formulations with the same plant-soil BGC interface in ACME-LAND. We have reimplemented the CENTURY-BGC within BeTR, and found there are significant structural uncertainties resulting from code-implementation even for the same mathematical formulations. We expect BeTR to help improve future biogeochemical modeling in ACME-LAND significantly.