NECCTON Best practices for implementing new BGC process modules in CMEMS/FABM

A central objective of NECCTON is the construction of a new interlinked model framework for the Copernicus Marine Service (CMEMS). Existing CMEMS models, new models ported in WP3, and new process descriptions delivered by WP5-8 will build on this framework to ensure their interoperability and usability across CMEMS Monitoring and Forecasting Centres (MFCs). The framework chosen for this purpose is the Framework for Aquatic Biogeochemical Models (FABM), which underpins a wide range of marine biogeochemical models. This currently includes implementations of most biogeochemical models in use within CMEMS (ERSEM, BFM, PISCES, ECOSMO, ERGOM?) and more CMEMS biogeochemical models will be included in NECCTON (BAMHBI). A core strength of FABM is its ability to interface with numerous hydrodynamic models, including those used within CMEMS (NEMO, HYCOM).

This document outlines “best practices” for biogeochemical/ecological model development within NECCTON and documents the FABM functionality introduced to support this. Specifically, (1) it describes the concepts of modular model development and its practical implementation in FABM, (2) it gives recommendations for the implementations of common types of process models, and (3) it provides guidance for model testing and distribution of code. These best practices will guide the implementation of new process models in NECCTON, e.g., FABM implementations of the remaining CMEMS models (BAMHBI, SEAPODYM-LMTL, the latest ERGOM release) in WP3. This will optimize the interoperability of NECCTON model components and the potential for exchanging/sharing them across the CMEMS MFCs.