Description of the upgrade

This version includes the following mainly minor, technical modifications :
Data assimilation changes:
  • new snow analysis using NESDIS snow cover product;
  • Improved use of Goes BUFR winds;
  • Improved clouds in 4D-Var minimisation;
  • Re-introduction of ERS-2 scatterometer winds (with adjusted
  • pre-screening and limited coverage) .
  • Variational QC corrected for 3D-Var (with impact of the BC
  • project and ERA-40 reruns only);
Numerics changes:
  • Semi Lagrangian fix for polar vortex instabilities;
  • Several code modifications to prepare the L91 version.
Physics changes:
  • Convection clean-up;
  • Optimisation of linearised physics and more optimisations
  • of physics code;
Oceanic Waves:
  • Introduction of subgrid scale (unresolved) bathymetry effects;
  • A fix to the EPS wave-model interface (Charnock variable)
The overall impact is very small in terms of forecast performance.
The parametrisation of the unresolved bathymetry has resulted in an improved performance of the ocean wave system, while in the free atmosphere a slight negative impact can be detected over the southern hemisphere towards the later stages of the medium-range.
The change to the new cycle is transparent for users apart from a change in the atmospheric model identification number in GRIB headers, which will be set to 122.

The wave model identification numbers will also change and will be:

  • 114 for the Global Wave Model and
  • 214 for the European Waters Wave Model.

Implemented: 09 March 2004