climlab-rrtmg

Brian Rose, University at Albany

About

This is a stand-alone Python wrapper for the RRTMG radiation modules.

The primary use-case is to drive the RRTMG radiation processes in climlab, but it can be used as a stand-alone radiation model if you are familiar with the RRTMG Fortran interface. This is a lightweight wrapper that emulates the Fortran interface as closely as possible.

Currently we are wrapping RRTMG_LW v4.85 and RRTMG_SW v4.0. The Fortran source code is included in this repository. The latest versions 5.0 of the RRTMG source code are available on GitHub here

This wrapper includes a modification to RRTMG_LW to allow reporting of OLR components in spectral bands, as illustrated using climlab here. This modification is strictly diagnostic does not change any other behavior of RRTMG_LW.

Installation

Pre-built binaries for many platforms are available from conda-forge.

To install in the current environment:

conda install climlab-rrtmg --channel conda-forge

or create a self-contained environment:

conda create --name my_env python=3.10 climlab-rrtmg --channel conda-forge
conda activate my_env

See below for instructions on how to build from source.

Example usage

You can import the modules into a Python session with

from climlab_rrtmg import rrtmg_lw, rrtmg_sw

The main RRTMG drivers are exposed through

rrtmg_lw.climlab_rrtmg_lw()

and

rrtmg_sw.climlab_rrtmg_sw()

Please see the directory climlab_rrtmg/tests/ directory in this repository for working examples that set up all the necessary input arrays and call the drivers.

Building from source

Here are instructions to create a build environment (including Fortran compiler) with conda/mamba and build using f2py. It should be possible to build using other Fortran compilers, but I haven't tested this.

To build (example for Apple M1 machine, see ./ci/ for other environment files):

mamba create --name rrtmg_build_env python=3.10 --channel conda-forge
mamba env update --file ./ci/requirements-macos-arm64.yml
conda activate rrtmg_build_env
python -m pip install . --no-deps -vv

To run tests, do this from any directory other than the climlab-rrtmg repo:

pytest -v --pyargs climlab_rrtmg

Version history

Version 0.2 is the first public release (April 2022). The Python wrapper code has been extracted from climlab v0.7.13.