Description of the upgrade

The new cycle includes important changes to the data assimilation system and a new short-wave radiation scheme.

Datasets affected

• HRES
• ENS

Resolution

Unchanged

Meteorological content

• Three-minimization version of 4D- Var assimilation scheme (T95/T159/T255) with improved moist linear physics (cloud and convection)
• Improved parametrization of the heterogeneous ozone chemistry
• New short-wave radiation scheme ( RRTM-SW), plus McICA cloud-radiation interaction   and   MODIS albedo
• Retuned ice particle
• Revised subgrid-orography scheme
• Explicit numerical treatment of convection in the moist tangent linear model used in the calculation of tropical singular vectors

Meteorological impact

• tropical troposphere shows significant improvements at all forecast ranges
• moderate but statistically significant improvements in the extra-tropical troposphere, particularly in the first four days
• at 500 hPa the ensemble-mean error is reduced
• in the tropics the spread at 850 hPa is increased, moving closer to the ensemble-mean error.

Resources

ECMWF Newsletter: See Newsletter 112