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Summary of scientific changes compared to OpenIFS 43r3v2

Changes Details about changes to the operational IFS from cycle to cycle can be found on the website (search for “ECMWF IFS changes”)

1.  ECMWF IFS model changes and/or 
2.  Changes to the forecasting system, which is linked from (1)

Below is a summary of the scientific changes from IFS 43r3 to 48r1, which are relevant to OpenIFS.https://www.ecmwf.int/en/forecasts/documentation-and-support/changes-ecmwf-model

45r1 – Cloud microphysics, soil physics

• Improved numerics for warm-rain cloud microphysics and vertical extrapolation for semi-lagrangian trajectory;

• Increased methane oxidation rate to improve (increase) water vapour in the stratosphere;

• Improved representation of super-cooled liquid water in convection, and minor convection updates;

• Correction of soil thermal conductivity formulation and addition of soil ice dependency;

• Modified parameter for non-orographic gravity-wave drag scheme for 91 levels.

46r1 – Radiation and aerosol, convection convection 

• Improvements in convection scheme (entrainment, CAPE closure, shallow convection);

• Activate LW scattering in radiation scheme;

• 3D aerosol climatology replaces 2D climatology;

• Correct scaling of dry mass flux in diffusion scheme. 

47r1 – Albedo, ocean waves drag, quintic interpolation 

• Surface albedo changes including: 1) the use of six climatological fields from MODIS, 2) a better handling of the spectrum from the MODIS datasets;

• Total Solar Irradiance (TSI) and Green House Gases (GHG) timeseries are updated with more recent ones from CMIP6;

• Quintic interpolation in the vertical for semi-Lagrangian advection;

• The drag coefficient over the oceans is reduced for strong winds to account for observational evidences whereby the drag coefficient reduces sharply for high winds;

• Stability corrections to the mid-level and deep convective closures (neutral) and reduced bounds for parcel perturbations.

47r3 – Moist physics upgrade

• A more consistent formulation of boundary layer turbulence, shallow convection and sub-grid cloud including:

  • Simplified and more consistent treatment of sub-grid cloud saturation adjustment

  • Consistent treatment of subgrid cloud from boundary layer turbulent mixing without separate statistical cloud scheme

  • Consistent computation of mixing height for unstable turbulent boundary layer and convection scheme

  • Change from double to single iteration of turbulent mixing scheme

• New method for computing inversion strength based on moist entropy for distinguishing stratocumulus and cumulus cloud

• Limit to convective overshoot based on tropopause stability

• New parametrized deep convection closure with an additional dependence on total advective moisture convergence

• Change from exponential-exponential cloud vertical overlap to random-exponential overlap in closer agreement with observations

• Include vapour deposition process for growth of falling snow particles

• Change from linear to cubic interpolation for cloud liquid, ice, rain and snow semi-Lagrangian departure point calculations, including 3D quasi-monotone limiter

• Interpolation of cloud and precipitation to radiation grid changed from in-cloud to grid-mean

• Inclusion of full supersaturation adjustment in the ensemble SPPT stochastic perturbations

• Mass-weighting and relaxation timescale introduced for ensemble SPPT stochastic perturbations

• Bug fix for vertical interpolation of 3D aerosol climatology

• Improved calculation of extinction coefficients for near-surface visibility in fog, rain and snow

• Revised gustiness parametrization

• Improved calculation of the peak wave period for multi-peaked ocean wave spectra

48r1 – Multi-layer snow, climate fields, water and energy conservation, interactive ozone, freezing drizzle

• Multi-layer snow scheme;

• Revised climate fields – improved orographic fields for atmospheric drag;

• Improved water and energy conservation (dynamics and physics);

• Radiatively interactive prognostic ozone using new Hybrid-Linear Ozone (HLO) scheme;

• New precipitation category - freezing drizzle and revised microphysical processes;

• Revised computation of Semi-Lagrangian advection departure points;

• New model top sponge layer formulation and semi-Lagrangian vertical filter;

• Revised SPPT, removed cloud saturation adjustment from tendency perturbations.