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For more details of changes in the IFS cycle 40r1, please see Cycle 40r1 release notes. 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.

It is important to set NRADINT=0 in the namelist &NAERAD. If not the model will abort as the default configuration is for 3D runs where the IFS uses a reduced grid to compute the radiation.

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.