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Introduction

This page describes how to access the offline version of the new ECMWF radiation scheme "ECRAD". ECRAD is used in ECMWF Integrated Forecasting System from Cycle 43R3. It is 30-35% 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 90 and has been tested on the GNU, PGI and Cray compilers. A prerequisite is the NetCDF library.

Documentation

• The new scheme is described in the ECMWF Technical Memorandum by Hogan and Bozzo (2016).
• Three solvers are available: McICA (Pincus et al. 2003), Tripleclouds (Hogan and Shonk 2008) and SPARTACUS (Hogan et al. 2016).
• Gas optical properties are provided by the RRTM-G model from Atmospheric and Environmental Research (AER).
• Radiation is documented in Part IV, Chapter 2 of the IFS Documentation.

Getting started

Use of ECRAD requires an OpenIFS license. The license is free and straightforward to complete. Once a license is granted, download access is provided to the source code. ECRAD is written in Fortran 90 and has been tested on the GNU, PGI and Cray compilers. A prerequisite is the NetCDF library.

License

The offline version of ECRAD is provided under the terms and conditions of the OpenIFS licence, which is the same license as used for the full OpenIFS model.  The key points of this license are as follows

• The license is free, but it is not an open-source license (despite the name).
• Licenses are provided per institute and require an authoritative signature from the host institution. Personal licenses are not available.
• If your institute already has an OpenIFS license then you are already permitted to use the offline version of ECRAD.
• The license permits free use for educational and research purposes to research and academic institutions.
• Commercial use of the code is not permitted, nor is dissemination of real-time data products generated using the code.
• The license is perpetual: it does not need to be renewed once signed. The license can be terminated at any time by the licensee.
• Redistribution of supplied software (modified or unmodified) to any non-licensed institute outside the licensed institute is forbidden.

The licence is not intended to be a barrier to the use of ECRAD so please get in touch with any licensing queries.

Getting started

• Please email ecrad-support@ecmwf to request a license, stating your name, institute, position, and a brief summary of what you would like to do with the ECRAD software.
• If approved, complete and sign the license agreement.
• Once a license is granted, download access will be provided to the source codeLicensing : OpenIFS licensing, distribution & contribution agreement.

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