Code and configuration

The OpenIFS project at ECMWF provides versions of the OpenIFS model ( based on IFS).OpenIFS is based on ECMWF's operational forecast model IFS (Integrated Forecast System) code.

The first version of OpenIFS released in 2011 was based on IFS Cycle 38R1, the operational model introduced June 2012  (since superseded for operations from June 2013). Further versions of OpenIFS skip IFS cycles as new OpenIFS models are only released on a 2-3 yr basis, rather than yearly like the IFS. However, updates to OpenIFS versions are issued inbetween major upgrades in IFS cycle to account for bug fixes, new compilers and added functionality.

The OpenIFS model is the same as IFS but does not include the data assimilation. All of the forecast capability of IFS is available in OpenIFS .up to and including the operational forecast resolution. The OpenIFS models are designed to be easy to install on external computer systems, though the higher resolution forecasts (near operational resolution) will require use of a high performance parallel computer.

Although the IFS can be run in a number of configurations, OpenIFS only supports forecast mode (NCONF=1) and interpolation mode (NCONF=927).

Scientific capability

OpenIFS includes all the same forecasting capability of IFS but without any data assimilation and observation handling/processing. OpenIFS & IFS are the same with respect to:

• Hydrostatic dynamical core.
• ECMWF physics parametrization scheme.
• ECMWF land surface model.
• ECMWF wave model (40r1 versions and beyond)

Unlike IFS, OpenIFS does not include:

• 4D-Var and any observation handling.
• Non-hydrostatic dynamics.
• Adjoint / tangent-linear versions.
• Ocean model.
• Wave model (38r1 version only)
• Ability to output Arpege file formats, only GRIB output is supported.

Support

Only operational configurations of IFS at ECMWF will be supported and for which documentation is available. Although we may endeavour to provide help on non-standard or untested configurations we cannot provide direct support for them.

Acknowledgements

The dynamical core IPR is shared with Meteo-France and collaborators. The IPR of the 'fullpos' and 'ddh' packages in OpenIFS are acknowledged as held by Meteo-France and we thank our colleagues for permission to include it in OpenIFS. OpenIFS uses the FCM software for compilation and we gratefully acknowledge colleagues at the UK Met Office for their assistance.