PHYEX - Physics Parameterization Package

PHYEX is a Fortran library for atmospheric physics parameterizations with Python bindings.

Features

• Mixed-phase cloud microphysics (ICE_ADJUST, RAIN_ICE)
• Shallow convection schemes
• Python bindings via Cython for easy integration

Building

Fortran Library Only

mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
cmake --build .
cmake --install .

Python Package with scikit-build-core

The project uses scikit-build-core for building Python wheels.

Requirements

• Python >= 3.11
• gfortran (GNU Fortran compiler)
• CMake >= 3.15
• NumPy < 2.0
• Cython

Installation from source

# Install in editable mode for development
pip install -e .

# Or build a wheel
pip install build
python -m build

Installation from wheel

pip install dist/phyex-0.1.0-*.whl

Installation from spack

The package is installable from a spack repo

• To install the python extensions :

    spack install phyex +python +double

• To install fortran package :

    spack install phyex ~python +double

Usage

Python

import numpy as np
from phyex import ice_adjust, rain_ice, init_rain_ice

# Initialize microphysics
init_rain_ice(timestep=60.0, dzmin=20.0, krr=6, hcloud="AROME")

# Prepare input arrays (Fortran-contiguous, float32)
nlon, nlev = 10, 50
pabs = np.ones((nlon, nlev), dtype=np.float32, order='F') * 85000.0
# ... initialize other arrays ...

# Call ice_adjust
ice_adjust(
    timestep=60.0, krr=6,
    sigqsat=sigqsat, pabs=pabs, sigs=sigs, th=th,
    exn=exn, exn_ref=exn_ref, rho_dry_ref=rho_dry_ref,
    rv=rv, rc=rc, ri=ri, rr=rr, rs=rs, rg=rg,
    cf_mf=cf_mf, rc_mf=rc_mf, ri_mf=ri_mf,
    rvs=rvs, rcs=rcs, ris=ris, ths=ths,
    cldfr=cldfr, icldfr=icldfr, wcldfr=wcldfr
)

Project Structure

PHYEX/
├── aux/              # Auxiliary routines
├── turb/             # Turbulence parameterizations
├── micro/            # Microphysics schemes
├── conv/             # Convection schemes
├── bridge/           # Python-Fortran bridge
│   ├── phyex_bridge.F90       # Fortran C-interop layer
│   ├── _phyex_wrapper.pyx     # Cython wrapper (CPU)
│   └── _phyex_wrapper_acc.pyx # Cython wrapper (GPU/OpenACC)
├── CMakeLists.txt    # Build configuration
└── pyproject.toml    # Python package configuration

Development

Testing

pip install -e ".[dev]"
pytest tests/

Code Formatting

black phyex/
ruff check phyex/

References

Based on the PHYEX physics package from Météo-France.

License

Apache-2.0