eCLM

eCLM is based from Community Land Model 5.0 (CLM5.0). It has the same modelling capabilities as CLM5 but with a more simplified infrastructure for build and namelist generation. The build system is handled entirely by CMake and namelists are generated through a small set of Python scripts. Only Fortran source codes necessary for a functional land model simulation were imported from CLM5.

Unlike CLM5, there are no built-in batch scripts in eCLM. It is up to system maintainers or users to craft their own workflows by combining the basic tools in this repo plus the native tools in their respective platforms.

Installation

This section shows you how to install eCLM on your local machine. If you are a user in IBG-3 and wish to run eCLM on JSC supercomputers, please check out the eCLM-JSC repo.

Minimum system requirements

• MPI 3.1
• netCDF-C 4.7.4
• netCDF-Fortran 4.5.2
• PnetCDF 1.12.1
• LAPACK
• CMake 3.16
• Supported compilers
  • GCC 9.3.0
  • Intel 19.1.2

Building eCLM

1. Configure CMake build options.

# User-specific variables
BUILD_DIR="bld"
INSTALL_DIR="eclm"

# Run cmake
cmake -S src -B "$BUILD_DIR" \
      -DCMAKE_INSTALL_PREFIX="$INSTALL_DIR" \
      -DCMAKE_C_COMPILER=mpicc \
      -DCMAKE_Fortran_COMPILER=mpifort

Additionally, you may specify these optional build variables.

• CMAKE_BUILD_TYPE=DEBUG|RELEASE. Defaults to RELEASE.
• CMAKE_PREFIX_PATH. Semicolon-separated list of paths (i.e. install prefixes) where external libraries might be found. You may need to specify this if CMake cannot find some of the required libraries (e.g. NetCDF, PnetCDF, LAPACK).

2. Build and install eCLM.

cmake --build "$BUILD_DIR"
cmake --install "$BUILD_DIR"

Install namelist generator Python package

The namelist generator scripts require Python 3.X.

# Upgrade to latest version of pip
python3 -m pip install --upgrade pip

# Install package
pip3 install --user ./namelist_generator

Run sample test case

# Download and extract data files
wget https://datapub.fz-juelich.de/slts/eclm/1x1_wuestebach.tar.gz
mkdir 1x1_wuestebach
tar xf 1x1_wuestebach.tar.gz -C 1x1_wuestebach

# Generate namelists
cd 1x1_wuestebach
export DATA_DIR="$(pwd)"
clm5nl-gen wtb_1x1.toml

# Validate namelists
clm5nl-check .

# Run eCLM
/path/to/eclm.exe

Status

eCLM has only been lightly tested; so far it could run a single-point and a regional case in Germany. Still, more work has to be done to ensure the correctness of the build process and the generated namelists. A user-friendly and lightweight approach to model configuration also has to be developed. eCLM is still in alpha version and would not be ready for production runs anytime soon.