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Introduction

This page describes how to access and use the offline version of ECMWF's radiation scheme "ecRad", which is operational in the ECMWF Integrated Forecasting System from Cycle 43R3. It is around 40% faster than the "McRad" scheme used in earlier cycles, and its modular design allows the spectral resolution, the description of cloud and aerosol optical properties, and the solver, to be changed independently of one another. Its offline version is well suited for use as a research tool.

ecRad is written in Fortran 2003 and has been tested using the GNU, PGI and Cray compilers on Linux systems. A prerequisite is the NetCDF library.

From version 1.4.0, ecRad is released under the conditions of the open source Apache License, version 2.0.

Documentation

• The ecRad scheme is described in a paper in JAMES (Hogan and Bozzo 2018)
• An older version is documented in ECMWF Technical Memorandum 787 (Hogan and Bozzo 2016)
• User Guide for the offline version of ecRad
• The best way to get started with ecRad is to try the practical exercises in the package
• Five solvers are available: McICA (Pincus et al. 2003), Tripleclouds (Hogan and Shonk 2008) and SPARTACUS (Hogan et al. 2016), plus the plane-parallel "homogeneous" and "cloudless" solvers
• Gas optical properties are provided by the RRTM-G model from Atmospheric and Environmental Research (AER) or the ECMWF Correlated K-Distribution (ecCKD) tool
• Radiation is documented in Part IV, Chapter 2 of the IFS Documentation (although it unfortunately hasn't yet been updated to cover ecRad)
• Scientific and technical queries should be addressed to Robin Hogan at ecrad-support@ecmwf.int.

Obtaining ecRad

• Latest version: ecrad-1.5.0.tar.gz (15 June 2022, CHANGELOG.txt)
• Older versions: ecrad-1.4.2.tar.gz (15 October 2021, CHANGELOG.txt), ecrad-1.4.1.tar.gz
• Access the latest development version of ecRad through GitHub

Earlier versions of ecRad were distributed under the terms and conditions of the OpenIFS licence, which is the same license as used for the full OpenIFS model.  These more restrictive licenses are still valid for those who have them. Please note that the open source Apache License only applies to ecRad version 1.4.0 and later, which has had an appropriate copyright and license statement added to each source file.

Other resources

• Sample input data file - an ERA5 pole-to-pole slice from 12 UTC, 11 July 2019, at a longitude of 5 degrees East: era5slice.nc; this is now the basis for the practical exercises available in the ecRad package since verson 1.3.0
• Greenhouse gas climatology and timeseries used operationally in IFS Cycle 47R1: greenhouse_gas_climatology_46r1.nc, greenhouse_gas_timeseries_CMIP6_SSP370_CFC11equiv_47r1.nc
• Greenhouse gas timeseries for various CMIP3, CMIP5 and CMIP6 scenarios: greenhouse_gas_timeseries_CMIP.zip
• Total solar irradiance timeseries used operational in IFS Cycle 47R1: total_solar_irradiance_CMIP6_47r1.nc
• 3D monthly aerosol climatology derived from CAMS reanalysis system as described by Bozzo et al. (2020): FTP site containing netCDF file (274 MB)
• Operational version of 3D monthly aerosol climatology (as above but with a manual reduction of absorbing aerosol over central Africa which degraded forecasts): FTP site containing netCDF file (274 MB)