Description of the upgrade

A new model cycle including a major resolution upgrade was introduced on 1 February 2006.

Datasets affected

• HRES
• ENS
• Wave

Resolution

Changed

Meteorological content

• Increase wave spectral resolution to 24 directions and 30 frequencies (from 12 and 25 respectively) for the EPS ocean wave model.
• Use of grid-point humidity and ozone in 4D-Var.
• Revised coefficients (version 2.3) for the linearised ozone chemistry scheme, supplied by Daniel Cariolle, CERFACS.
• Use of Jason altimeter wave height data and ENVISAT ASAR spectra in the wave model data assimilation. ERS-2 SAR spectra are no longer assimilated.

Meteorological impact

• small but statistically significant improvements to deterministic 500 hPa height forecasts over Europe and for both extra-tropical hemispheres out to day 6.
• overall impact on weather parameters is modest
• precipitation scores over Europe are consistently improved, in particular for large daily rainfall amounts
• tropical temperature and wind forecasts are generally better when verified against radiosondes
• tropical cyclone position and intensity forecasts are improved in the high resolution system with some spectacular results for intense hurricanes
• increased number of observations used in the assimilation with better analysis and background departure statistics
• beneficial impact on the ocean wave analyses.
• improvements in the ocean wave forecasts

• overall benefit of the higher resolution for the ENS is reflected in the results for the probability scores which are consistently improved for 500hPa height anomalies
•  improvement of the evaluation of precipitation events over Europe with respect to the Brier and ROC area scores

Technical content

Model ID and experiment number

• Atmospheric: 127
• Ocean wave: 116
• Limited-area ocean wave: 216

E-suite experiment number = 0029

Resources

ECMWF Newsletter: See Newsletter 106