Licensed users can obtain the code from the ftp site.

Interested users without a licence should see the Releases page for more information.

Release notes: single column model (SCM)

For more details of changes in the IFS cycle 40r1, please see below. Note the following additional changes to the SCM:

• semi-Lagrangian advection is now available and set as the default (previously only Eulerian advection was possible).
• the simplified physics is now available as an alternative to the full physics. The simplified physics is used in the tangent-linear code at ECMWF.
• new diagnostics quantities available (type of PBL, convection type, lowermost and uppermost levels of convection, ...)

Namelists

There are two namelist files in the scm-40r1.ref-oifs/test-run directory:
           namelist.trref_winds_rel  and  namelist.trref_winds_rel.simpl

The former one defines non-linear physics, the latter one the simplified physics (you may be surprised how close the results from the two packages are). We expect most users to use the full non-linear physics option.

Semi-Lagrangian

By default the semi-Lagrangian scheme is activated (LSLAG=.T.) with the physics being averaged along a trajectory (LSLPHY=.T.). This follows the defaults in the IFS.

If you like to use Eulerian advection set LSLAG=.F., reduce the model timestep (don't forget to change number of time steps accordingly) and disable the semi-Lagrangian physics by setting LSLPHY=.T.

Cycle 40r1

IFS cycle 40r1 was the operational model at ECMWF from 19th November 2013 to 12th May 2015.Several significant changes have been made since the release of the cycle 38r2 version of the single column model, particularly with regard to convection where the diurnal cycle is much improved (see ECMWF Newsletter 136 - pages 15-22).

For more information on the 40r1 release, see the description of the 40r1 cycle, more detailed summary of changes in cycle 40r1 is also available.

Please note these changes are relative to the previous operational model. As OpenIFS models are not released as frequently as the operational model, interested users should also see the changes (if any) for previous operational models.

Model documentation

The IFS cycle 40r1 model documentation (PDF manuals) is available from the main ECMWF website.

Brief summary of changes (relevant to SCM):

• 91 -> 137 levels
• Reduced vertical resolution dependence in the subgrid orography scheme
• Bugfix for the spectral-band split of the albedo in the radiation
• Modified treatment of turbulent diffusion in stable conditions (implying a reduction of the diffusion),
• Adjustment of the drag over orography and the low level blocking
• Adjustment of the land-atmosphere coupling for high vegetation
• Modification of the PBL height diagnostic according to the findings of Seidel et al. 2012
• Diurnal cycle extension of CAPE for land and water that significantly improves diurnal variation of convection.
• formulate CAPE in J/V instead of J/kg from which mass flux follows naturally.
• new interface to the physics

Note also that some features from Fortran 2003 are now used, that may require more recent versions of compilers (allowing support of the ASSOCIATE construct).

Grib-api

Please note that the minimum version of grib-api for use with Cycle 40r1 is 1.11.0

Acknowledgements

The OpenIFS team would like to acknowledge the research and support of ECMWF scientists involved in this release.