Abstract
Abstract. Recent reports by the Global Carbon Project highlight large uncertainties around land surface processes such as land use change, strength of CO2 fertilization, nutrient limitation and supply, and response to variability in climate. Process-based land surface models are well suited to address these complex and emerging global change problems but will require extensive development and evaluation. The coupled Canadian Land Surface Scheme and Canadian Terrestrial Ecosystem Model (CLASS-CTEM) framework has been under continuous development by Environment and Climate Change Canada since 1987. As the open-source model of code development has revolutionized the software industry, scientific software is experiencing a similar evolution. Given the scale of the challenge facing land surface modellers, and the benefits of open-source, or community model, development, we have transitioned CLASS-CTEM from an internally developed model to an open-source community model, which we call the Canadian Land Surface Scheme including Biogeochemical Cycles (CLASSIC) v.1.0. CLASSIC contains many technical features specifically designed to encourage community use including software containerization for serial and parallel simulations, extensive benchmarking software and data (Automated Model Benchmarking; AMBER), self-documenting code, community standard formats for model inputs and outputs, amongst others. Here, we evaluate and benchmark CLASSIC against 31 FLUXNET sites where the model has been tailored to the site-level conditions and driven with observed meteorology. Future versions of CLASSIC will be developed using AMBER and these initial benchmark results to evaluate model performance over time. CLASSIC remains under active development and the code, site-level benchmarking data, software container, and AMBER are freely available for community use.
Highlights
Open collaboration has revolutionized software development leading to a proliferation of open-source software (OSS) projects
CLASSCTEM was written following the Fortran 77 standard, documentation was provided in stand-alone documents that often significantly lagged model development or scientific papers, code management did not use modern version control systems, model parameters such as the number of soil layers and plant functional types (PFTs) were hard-coded into subroutines, and the offline framework used fixed-format ASCII text files for model inputs and outputs
The evaluation of Canadian Land Surface Scheme including Biogeochemical Cycles (CLASSIC) presented in this study is based on International Land Model Benchmarking (ILAMB)’s statistical framework, which we implemented in a new R package, referred to as the Automated Model Benchmarking (AMBER) package (Seiler, 2019)
Summary
Open collaboration has revolutionized software development leading to a proliferation of open-source software (OSS) projects. The CLASSIC model framework includes several key features designed to encourage collaboration and community use including (1) self-documenting code, (2) version control allowing source code management, distributed non-linear workflows, issue tracking, and wiki functionality, (3) native support for Network Common Data Format (NetCDF) input and output along with conversion tools for ASCII legacy inputs, (4) ability for code to run both serially on personal computers and using Message Passing Interface (MPI) on computing clusters, (5) output file description and metadata handled via a web interface, (6) model parameters read in from an external file, (7) containerization, and (8) extensive benchmarking of model state (via checksums) and performance Each of these features will be expanded upon .
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