Description of the upgrade

The complete operational suite was implemented on the Fujitsu VPP700
  • Main T213 ten-day forecast suite
  • Optional project wave forecast suite
  • 00 UTC optional project forecast suite
  • Ensemble prediction suite.
Together with the move to the VPP700 a new model cycle (cy15r5) and changes to the 3D-Var code were introduced:
model cycle cy15r5, introduced on 18 September, had the following changes:
  • revision of boundary layer diffusion and introduction of soil moisture freezing. The effect is a reduction of the near-surface temperature errors in stable situations. It implies a reduction of the night time temperature errors over land in summer and a significant reduction of the winter cold bias of day and night time forecasts;
  • a revised semi-Lagrangian treatment of the thermodynamic equation leading to smoother meteorological fields over steep orography.
This cycle also contained changes necessary for the migration to the Fujitsu, none of which have any detectable meteorological impact, at the same time.
The 3D-Var code has been generalised to allow it to be run on parallel, distributed-memory computers using message passing. A new parallel code is used for observation pre-processing and screening. Quality control and the calculation of background error variances are now based on the variational analysis rather than the earlier OI approach. Objective verification indicates little overall sensitivity of forecast performance to these changes.

Implemented: 18 September 1996  


ECMWF Newsletter: An article "Improvements to the 2m temperature forecasts" from the ECMWF Newsletter No.73