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 previous release, 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:

• 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