Supporting hierarchical soil biogeochemical modeling: version 2 of the Biogeochemical Transport and Reaction model (BeTR-v2)

Abstract. Reliable soil biogeochemical modeling is a prerequisite for credible projections of climate change and associated ecosystem feedbacks. This recognition has called frameworks that can support flexible efficient development application new or alternative modules in Earth system models (ESMs). The the Biogeochemical Transport Reaction model version 1 (BeTR-v1) code (i.e., CLM4-BeTR) one such framework designed to accelerate integration biogeochemistry formulations into ESMs analyze structural uncertainty ESM simulations. With generic reactive transport capability, BeTR-v1 represent multiphase (e.g., gaseous, aqueous, solid), multi-tracer nitrate organic carbon), multi-organism plants, bacteria, fungi) dynamics. Here, we describe version, 2 (BeTR-v2), which adopts more robust numerical solvers diffusion advection coupling between reactions improves modularization over BeTR-v1. BeTR-v2 better supports different mathematical hierarchical manner by allowing resultant be run single topsoil layer vertically resolved column, it allows fully coupled with land component Energy Exascale System Model (E3SM). We demonstrate capability benchmark cases example (BGC) implementations. By taking advantage BeTR-v2's structure integrated E3SM, then found calibration could not resolve biases introduced strategies plant–soil biogeochemistry. These results highlight importance numerically implementation hydrology, thermal dynamics, plants – capabilities open-source provides. contend should strive minimize this applying solvers.